massive: move a lot of things

25-functions-and-pointers/03-refactor-to-funcs/main.go

@@ -0,0 +1,62 @@
+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"sort"
+	"strings"
+)
+
+func main() {
+	p := newParser()
+
+	// Scan the standard-in line by line
+	in := bufio.NewScanner(os.Stdin)
+	for in.Scan() {
+		p.lines++
+
+		parsed, err := parse(p, in.Text())
+		if err != nil {
+			fmt.Println(err)
+			return
+		}
+
+		domain, visits := parsed.domain, parsed.visits
+
+		// Collect the unique domains
+		if _, ok := p.sum[domain]; !ok {
+			p.domains = append(p.domains, domain)
+		}
+
+		// Keep track of total and per domain visits
+		p.total += visits
+
+		// create and assign a new copy of `visit`
+		p.sum[domain] = result{
+			domain: domain,
+			visits: visits + p.sum[domain].visits,
+		}
+	}
+
+	// Print the visits per domain
+	sort.Strings(p.domains)
+
+	fmt.Printf("%-30s %10s\n", "DOMAIN", "VISITS")
+	fmt.Println(strings.Repeat("-", 45))
+
+	for _, domain := range p.domains {
+		parsed := p.sum[domain]
+		fmt.Printf("%-30s %10d\n", domain, parsed.visits)
+	}
+
+	// Print the total visits for all domains
+	fmt.Printf("\n%-30s %10d\n", "TOTAL", p.total)
+}

25-functions-and-pointers/03-refactor-to-funcs/parser.go

@@ -0,0 +1,53 @@
+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+)
+
+// result stores the parsed result for a domain
+type result struct {
+	domain string
+	visits int
+	// add more metrics if needed
+}
+
+// parser keep tracks of the parsing
+type parser struct {
+	sum     map[string]result // metrics per domain
+	domains []string          // unique domain names
+	total   int               // total visits for all domains
+	lines   int               // number of parsed lines (for the error messages)
+}
+
+// newParser constructs, initializes and returns a new parser
+func newParser() parser {
+	return parser{sum: make(map[string]result)}
+}
+
+// parse parses a log line and returns the parsed result with an error
+func parse(p parser, line string) (parsed result, err error) {
+	fields := strings.Fields(line)
+	if len(fields) != 2 {
+		err = fmt.Errorf("wrong input: %v (line #%d)", fields, p.lines)
+		return
+	}
+
+	parsed.domain = fields[0]
+
+	parsed.visits, err = strconv.Atoi(fields[1])
+	if parsed.visits < 0 || err != nil {
+		err = fmt.Errorf("wrong input: %q (line #%d)", fields[1], p.lines)
+		return
+	}
+
+	return
+}

25-functions-and-pointers/04-pass-by-value-semantics/main.go

@@ -0,0 +1,48 @@
+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"sort"
+	"strings"
+)
+
+func main() {
+	p := newParser()
+
+	// Scan the standard-in line by line
+	in := bufio.NewScanner(os.Stdin)
+	for in.Scan() {
+		p.lines++
+
+		parsed, err := parse(p, in.Text())
+		if err != nil {
+			fmt.Println(err)
+			break
+		}
+
+		p = update(p, parsed)
+	}
+
+	// Print the visits per domain
+	sort.Strings(p.domains)
+
+	fmt.Printf("%-30s %10s\n", "DOMAIN", "VISITS")
+	fmt.Println(strings.Repeat("-", 45))
+
+	for _, domain := range p.domains {
+		parsed := p.sum[domain]
+		fmt.Printf("%-30s %10d\n", domain, parsed.visits)
+	}
+
+	// Print the total visits for all domains
+	fmt.Printf("\n%-30s %10d\n", "TOTAL", p.total)
+}

25-functions-and-pointers/04-pass-by-value-semantics/parse.go

@@ -0,0 +1,71 @@
+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+)
+
+// result stores metrics for a domain
+type result struct {
+	domain string
+	visits int
+	// add more metrics if needed
+}
+
+// parser keep tracks of the parsing
+type parser struct {
+	sum     map[string]result // metrics per domain
+	domains []string          // unique domain names
+	total   int               // total visits for all domains
+	lines   int               // number of parsed lines (for the error messages)
+}
+
+func newParser() parser {
+	return parser{sum: make(map[string]result)}
+}
+
+func parse(p parser, line string) (parsed result, err error) {
+	fields := strings.Fields(line)
+	if len(fields) != 2 {
+		err = fmt.Errorf("wrong input: %v (line #%d)", fields, p.lines)
+		return
+	}
+
+	parsed.domain = fields[0]
+
+	parsed.visits, err = strconv.Atoi(fields[1])
+	if parsed.visits < 0 || err != nil {
+		err = fmt.Errorf("wrong input: %q (line #%d)", fields[1], p.lines)
+		return
+	}
+
+	return
+}
+
+func update(p parser, parsed result) parser {
+	domain, visits := parsed.domain, parsed.visits
+
+	// Collect the unique domains
+	if _, ok := p.sum[domain]; !ok {
+		p.domains = append(p.domains, domain)
+	}
+
+	// Keep track of total and per domain visits
+	p.total += visits
+
+	// create and assign a new copy of `visit`
+	p.sum[domain] = result{
+		domain: domain,
+		visits: visits + p.sum[domain].visits,
+	}
+
+	return p
+}

25-functions-and-pointers/08-log-parser-pointers/main.go

@@ -19,21 +19,18 @@ func main() {
 	p := newParser()
 
 	for in.Scan() {
-		p.lines++
-
-		d, err := parse(p, in.Text())
-		if err != nil {
-			fmt.Println(err)
-			return
-		}
-
-		p = push(p, d)
+		add(p, in.Text())
 	}
 
-	for _, d := range p.domains {
-		vis := p.sum[d.name]
+	for _, name := range p.domains {
+		// vis := p.sum[d.name]
+		d := p.sum[name]
 
-		fmt.Printf("%-25s -> %d\n", d.name, vis)
+		fmt.Printf("%-25s -> %d\n", d.name, d.visits)
 	}
 	fmt.Printf("\n%-25s -> %d\n", "TOTAL", p.total)
+
+	if p.lerr != nil {
+		fmt.Printf("> Err: %s\n", p.lerr)
+	}
 }

25-functions-and-pointers/08-log-parser-pointers/parser.go

@@ -0,0 +1,99 @@
+package main
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+)
+
+// TODO: add add() func
+// TODO: add error handling (variadics)
+// TODO: add iterator func values
+// TODO: add summarizer to main()
+
+// domain represents a single domain log record
+type domain struct {
+	name   string
+	visits int
+}
+
+// parser parses a log file and provides an iterator to iterate upon the domains
+//
+// the parser struct is carefully crafted to be usable using its zero values except the map field
+type parser struct {
+	// sum     map[string]int // visits per unique domain
+	// domains []domain       // unique domain names
+	sum     map[string]domain // visits per unique domain
+	domains []string          // unique domain names
+
+	total int   // total visits to all domains
+	lines int   // number of parsed lines (for the error messages)
+	lerr  error // saves the last error occurred
+}
+
+// newParser creates and returns a new parser.
+func newParser() *parser {
+	// return &parser{sum: make(map[string]int)}
+	return &parser{sum: make(map[string]domain)}
+}
+
+// add parses the given line and saves the result to the internal list of
+// domains. it doesn't add the record when the parsing fails.
+func add(p *parser, line string) {
+	// if there was a previous error do not add
+	if p.lerr != nil {
+		return
+	}
+
+	dom, err := parse(p, line)
+
+	// store only the last error
+	if err != nil {
+		p.lerr = err
+		return
+	}
+
+	push(p, dom)
+}
+
+// parse parses the given text and returns a domain struct
+func parse(p *parser, line string) (dom domain, err error) {
+	p.lines++
+
+	fields := strings.Fields(line)
+	if len(fields) != 2 {
+		err = fmt.Errorf("wrong input: %v (line #%d)", fields, p.lines)
+		return
+	}
+
+	dom.name = fields[0]
+
+	dom.visits, err = strconv.Atoi(fields[1])
+	if dom.visits < 0 || err != nil {
+		err = fmt.Errorf("wrong input: %q (line #%d)", fields[1], p.lines)
+	}
+
+	return
+}
+
+// push pushes the given domain to the internal list of domains.
+// it also increases the total visits for all the domains.
+func push(p *parser, d domain) {
+	// TODO:
+	// if _, ok := p.sum[d.name]; !ok {
+	// 	p.domains = append(p.domains, d)
+	// }
+
+	// p.sum[d.name] += d.visits
+	// p.total += d.visits
+	name := d.name
+
+	// collect the unique domains
+	if _, ok := p.sum[name]; !ok {
+		p.domains = append(p.domains, name)
+	}
+
+	p.total += d.visits
+	d.visits += p.sum[name].visits
+	p.sum[name] = d
+}

25-functions-and-pointers/08x-log-parser-pointers/main.go

@@ -0,0 +1,57 @@
+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+)
+
+func main() {
+	in := bufio.NewScanner(os.Stdin)
+
+	p := newParser()
+	for in.Scan() {
+		// dom, err := parse(p, in.Text())
+		// if err != nil {
+		// 	fmt.Println(err)
+		// 	return
+		// }
+
+		// p = push(p, dom)
+
+		add(p, in.Text())
+	}
+
+	summarize(p)
+	dumpErrs(in.Err(), err(p))
+}
+
+// funcs not always need to be reused.
+// here, it tells about what it does: it summarizes the parsing result.
+func summarize(p *parser) {
+	// multiple iterators can be created. each one remembers the last
+	// read domain record.
+
+	next, cur := iterator(p)
+	for next() {
+		dom := cur()
+		fmt.Printf("%-25s -> %d\n", dom.name, dom.visits)
+	}
+	fmt.Printf("\n%-25s -> %d\n", "TOTAL", p.total)
+}
+
+// this variadic func simplifies the multiple error handling
+func dumpErrs(errs ...error) {
+	for _, err := range errs {
+		if err != nil {
+			fmt.Printf("> Err: %s\n", err)
+		}
+	}
+}

25-functions-and-pointers/08x-log-parser-pointers/parser.go

@@ -0,0 +1,110 @@
+package main
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+)
+
+// domain represents a domain log record
+type domain struct {
+	name   string
+	visits int
+}
+
+// parser parses a log file and provides an iterator to iterate upon the domains
+//
+// the parser struct is carefully crafted to be usable using its zero values except the map field
+type parser struct {
+	sum     map[string]domain // visits per unique domain
+	domains []string          // unique domain names
+	total   int               // total visits to all domains
+	lines   int               // number of parsed lines (for the error messages)
+	lerr    error             // saves the last error occurred
+}
+
+// newParser creates and returns a new parser.
+func newParser() *parser {
+	return &parser{sum: make(map[string]domain)}
+}
+
+// add parses the given line and saves the result to the internal list of
+// domains. it doesn't add the record when the parsing fails.
+func add(p *parser, line string) {
+	// if there was a previous error do not add
+	if p.lerr != nil {
+		return
+	}
+
+	dom, err := parse(p, line)
+
+	// store only the last error
+	if err != nil {
+		p.lerr = err
+		return
+	}
+
+	push(p, dom)
+}
+
+// iterator returns two functions for iterating over domains.
+// next = returns true when there are more domains to iterate on.
+// cur  = returns the current domain
+func iterator(p *parser) (next func() bool, cur func() domain) {
+	// remember the last received line
+	var last int
+
+	next = func() bool {
+		defer func() { last++ }()
+		return len(p.domains) > last
+	}
+
+	cur = func() domain {
+		// return a copy so the caller cannot change it
+		name := p.domains[last-1]
+		return p.sum[name]
+	}
+
+	return
+}
+
+// error returns the last error occurred
+func err(p *parser) error {
+	return p.lerr
+}
+
+// parse parses the given text and returns a domain struct
+func parse(p *parser, line string) (dom domain, err error) {
+	p.lines++ // increase the parsed line counter (only write is here)
+
+	fields := strings.Fields(line)
+	if len(fields) != 2 {
+		err = fmt.Errorf("wrong input: %v (line #%d)", fields, p.lines)
+		return
+	}
+
+	name, visits := fields[0], fields[1]
+
+	n, err := strconv.Atoi(visits)
+	if n < 0 || err != nil {
+		err = fmt.Errorf("wrong input: %q (line #%d)", visits, p.lines)
+		return
+	}
+
+	return domain{name: name, visits: n}, nil
+}
+
+// push pushes the given domain to the internal list of domains.
+// it also increases the total visits for all the domains.
+func push(p *parser, d domain) {
+	name := d.name
+
+	// collect the unique domains
+	if _, ok := p.sum[name]; !ok {
+		p.domains = append(p.domains, name)
+	}
+
+	p.total += d.visits
+	d.visits += p.sum[name].visits
+	p.sum[name] = d
+}

26-functions-and-pointers/03-refactor-to-funcs/main.go

@@ -1,44 +0,0 @@
-// For more tutorials: https://blog.learngoprogramming.com
-//
-// Copyright © 2018 Inanc Gumus
-// Learn Go Programming Course
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-//
-
-package main
-
-import (
-	"bufio"
-	"fmt"
-	"os"
-)
-
-func main() {
-	in := bufio.NewScanner(os.Stdin)
-
-	p := newParser()
-
-	for in.Scan() {
-		p.lines++
-
-		d, err := parse(p, in.Text())
-		if err != nil {
-			fmt.Println(err)
-			return
-		}
-
-		if _, ok := p.sum[d.name]; !ok {
-			p.domains = append(p.domains, d)
-		}
-
-		p.sum[d.name] += d.visits
-		p.total += d.visits
-	}
-
-	for _, d := range p.domains {
-		vis := p.sum[d.name]
-
-		fmt.Printf("%-25s -> %d\n", d.name, vis)
-	}
-	fmt.Printf("\n%-25s -> %d\n", "TOTAL", p.total)
-}

26-functions-and-pointers/03-refactor-to-funcs/parser.go

@@ -1,49 +0,0 @@
-package main
-
-import (
-	"fmt"
-	"strconv"
-	"strings"
-)
-
-// domain represents a domain log record
-type domain struct {
-	name   string
-	visits int
-}
-
-// parser parses a log file and provides an iterator to iterate upon the domains
-//
-// the parser struct is carefully crafted to be usable using its zero values except the map field
-type parser struct {
-	sum     map[string]int // visits per unique domain
-	domains []domain       // unique domain names
-	total   int            // total visits to all domains
-	lines   int            // number of parsed lines (for the error messages)
-}
-
-// newParser creates and returns a new parser.
-func newParser() parser {
-	return parser{sum: make(map[string]int)}
-}
-
-// parse parses the given text and returns a domain struct
-func parse(p parser, line string) (dom domain, err error) {
-	// var dom domain
-	// var err error
-
-	fields := strings.Fields(line)
-	if len(fields) != 2 {
-		err = fmt.Errorf("wrong input: %v (line #%d)", fields, p.lines)
-		return
-	}
-	name, visits := fields[0], fields[1]
-
-	n, err := strconv.Atoi(visits)
-	if n < 0 || err != nil {
-		err = fmt.Errorf("wrong input: %q (line #%d)", visits, p.lines)
-		return
-	}
-
-	return domain{name: name, visits: n}, nil
-}

26-functions-and-pointers/04-pass-by-value-semantics/parser.go

@@ -1,59 +0,0 @@
-package main
-
-import (
-	"fmt"
-	"strconv"
-	"strings"
-)
-
-// domain represents a domain log record
-type domain struct {
-	name   string
-	visits int
-}
-
-// parser parses a log file and provides an iterator to iterate upon the domains
-//
-// the parser struct is carefully crafted to be usable using its zero values except the map field
-type parser struct {
-	sum     map[string]int // visits per unique domain
-	domains []domain       // unique domain names
-	total   int            // total visits to all domains
-	lines   int            // number of parsed lines (for the error messages)
-}
-
-// newParser creates and returns a new parser.
-func newParser() parser {
-	return parser{sum: make(map[string]int)}
-}
-
-// parse parses the given text and returns a domain struct
-func parse(p parser, line string) (dom domain, err error) {
-	fields := strings.Fields(line)
-	if len(fields) != 2 {
-		err = fmt.Errorf("wrong input: %v (line #%d)", fields, p.lines)
-		return
-	}
-	name, visits := fields[0], fields[1]
-
-	n, err := strconv.Atoi(visits)
-	if n < 0 || err != nil {
-		err = fmt.Errorf("wrong input: %q (line #%d)", visits, p.lines)
-		return
-	}
-
-	return domain{name: name, visits: n}, nil
-}
-
-// push pushes the given domain to the internal list of domains.
-// it also increases the total visits for all the domains.
-func push(p parser, d domain) parser {
-	if _, ok := p.sum[d.name]; !ok {
-		p.domains = append(p.domains, d)
-	}
-
-	p.sum[d.name] += d.visits
-	p.total += d.visits
-
-	return p
-}

26-methods/xxx-log-parser-methods/packaged/log.txt

@@ -0,0 +1,6 @@
+learngoprogramming.com 10 200
+learngoprogramming.com 10 300
+golang.org 4 50
+golang.org 6 100
+blog.golang.org 20 25
+blog.golang.org 10 1

26-methods/xxx-log-parser-methods/packaged/log_err_missing.txt

@@ -0,0 +1,6 @@
+learngoprogramming.com 10 200
+learngoprogramming.com 10
+golang.org 4 50
+golang.org 6 100
+blog.golang.org 20 25
+blog.golang.org 10 1

26-methods/xxx-log-parser-methods/packaged/log_err_negative.txt

@@ -0,0 +1,6 @@
+learngoprogramming.com 10 200
+learngoprogramming.com 10 -500
+golang.org -100 50
+golang.org 6 100
+blog.golang.org 20 25
+blog.golang.org 10 1

26-methods/xxx-log-parser-methods/packaged/log_err_str.txt

@@ -0,0 +1,6 @@
+learngoprogramming.com 10 200
+learngoprogramming.com 10 THREE-HUNDRED
+golang.org FOUR 50
+golang.org 6 100
+blog.golang.org 20 25
+blog.golang.org 10 1

26-methods/xxx-log-parser-methods/packaged/metrics/parser.go

@@ -17,7 +17,7 @@ type Parser struct {
 	lerr  error // the last error occurred
 }
 
-// Parsed wraps a result for generating parser error
+// Parsed wraps a result for generating a parser error
 type Parsed struct {
 	result       // use struct embedding
 	err    error // inject an error

26-methods/xxx-log-parser-methods/packaged/metrics/report.go

@@ -20,18 +20,19 @@ type Report struct {
 }
 
 // NewReport constructs and initializes a new report
+// You can't use its methods without pointer mechanics
 func NewReport() *Report {
 	return &Report{sum: make(map[string]result)}
 }
 
 // Update updates the report for the given parsing result
-func (r *Report) Update(parsed Parsed) {
+func (r *Report) Update(p Parsed) {
 	// do not update the report if the result has an error
-	if parsed.err != nil {
+	if p.err != nil {
 		return
 	}
 
-	domain := parsed.Domain
+	domain := p.Domain
 	if _, ok := r.sum[domain]; !ok {
 		r.domains = append(r.domains, domain)
 	}
@@ -39,8 +40,8 @@ func (r *Report) Update(parsed Parsed) {
 	// let the result handle the addition
 	// this allows us to manage the result in once place
 	// and this way it becomes easily extendable
-	r.total = r.total.add(parsed.result)
-	r.sum[domain] = parsed.add(r.sum[domain])
+	r.total = r.total.add(p.result)
+	r.sum[domain] = p.add(r.sum[domain])
 }
 
 // Iterator returns `next()` to detect when the iteration ends,

26-methods/xxx-log-parser-methods/packaged/metrics/result.go

@@ -19,33 +19,40 @@ import (
 // it uses the value mechanics,
 // because it doesn't have to update anything
 type result struct {
-	Domain string
-	Visits int
+	Domain    string
+	Visits    int
+	TimeSpent int
 	// add more metrics if needed
 }
 
 // add adds the metrics of another Result to itself and returns a new Result
 func (r result) add(other result) result {
 	return result{
-		Domain: r.Domain,
-		Visits: r.Visits + other.Visits,
+		Domain:    r.Domain,
+		Visits:    r.Visits + other.Visits,
+		TimeSpent: r.TimeSpent + other.TimeSpent,
 	}
 }
 
 // parse parses a single log line
-func parse(line string) (parsed result, err error) {
+func parse(line string) (r result, err error) {
 	fields := strings.Fields(line)
-	if len(fields) != 2 {
+	if len(fields) != 3 {
 		err = fmt.Errorf("wrong input: %v", fields)
 		return
 	}
 
-	parsed.Domain = fields[0]
+	r.Domain = fields[0]
 
-	parsed.Visits, err = strconv.Atoi(fields[1])
-	if parsed.Visits < 0 || err != nil {
+	r.Visits, err = strconv.Atoi(fields[1])
+	if r.Visits < 0 || err != nil {
 		err = fmt.Errorf("wrong input: %q", fields[1])
 	}
 
+	r.TimeSpent, err = strconv.Atoi(fields[2])
+	if r.TimeSpent < 0 || err != nil {
+		err = fmt.Errorf("wrong input: %q", fields[2])
+	}
+
 	return
 }

26-methods/xxx-log-parser-methods/packaged/summarize.go

@@ -16,15 +16,23 @@ import (
 
 // summarize prints the report and errors if any
 func summarize(rep *metrics.Report, errs ...error) {
-	fmt.Printf("%-30s %10s\n", "DOMAIN", "VISITS")
-	fmt.Println(strings.Repeat("-", 45))
+	// TODO: make it strings.Builder
+
+	const format = "%-30s %10s %20s\n"
+	const formatValue = "%-30s %10d %20d\n"
+
+	fmt.Printf(format, "DOMAIN", "VISITS", "TIME SPENT")
+	fmt.Println(strings.Repeat("-", 65))
 
 	next, cur := rep.Iterator()
 	for next() {
 		rec := cur()
-		fmt.Printf("%-30s %10d\n", rec.Domain, rec.Visits)
+		fmt.Printf(formatValue, rec.Domain, rec.Visits, rec.TimeSpent)
 	}
-	fmt.Printf("\n%-30s %10d\n", "TOTAL", rep.Total().Visits)
+
+	fmt.Printf("\n"+formatValue, "TOTAL",
+		rep.Total().Visits, rep.Total().TimeSpent,
+	)
 
 	// only handle the errors once
 	dumpErrs(errs...)

26-methods/xxx-log-parser-methods/report.go

@@ -22,13 +22,13 @@ func newReport() *report {
 }
 
 // update updates the errors for the given parsing result
-func (r *report) update(parsed parsed) {
+func (r *report) update(p parsed) {
 	// do not update the report if the result has an error
-	if parsed.err != nil {
+	if p.err != nil {
 		return
 	}
 
-	domain := parsed.domain
+	domain := p.domain
 	if _, ok := r.sum[domain]; !ok {
 		r.domains = append(r.domains, domain)
 	}
@@ -36,8 +36,8 @@ func (r *report) update(parsed parsed) {
 	// let the result handle the addition
 	// this allows us to manage the result in once place
 	// and this way it becomes easily extendable
-	r.total = r.total.add(parsed.result)
-	r.sum[domain] = parsed.add(r.sum[domain])
+	r.total = r.total.add(p.result)
+	r.sum[domain] = p.add(r.sum[domain])
 }
 
 // iterator returns `next()` to detect when the iteration ends,

26-methods/xxx-log-parser-methods/result.go

@@ -33,17 +33,17 @@ func (r result) add(other result) result {
 }
 
 // parseLine parses a single result line
-func parseLine(line string) (parsed result, err error) {
+func parseLine(line string) (p result, err error) {
 	fields := strings.Fields(line)
 	if len(fields) != 2 {
 		err = fmt.Errorf("wrong input: %v", fields)
 		return
 	}
 
-	parsed.domain = fields[0]
+	p.domain = fields[0]
 
-	parsed.visits, err = strconv.Atoi(fields[1])
-	if parsed.visits < 0 || err != nil {
+	p.visits, err = strconv.Atoi(fields[1])
+	if p.visits < 0 || err != nil {
 		err = fmt.Errorf("wrong input: %q", fields[1])
 	}
 

28-concurrency/xxx-concurrent-downloader/fetch/danger/main.go

@@ -0,0 +1,46 @@
+package main
+
+import (
+	"fmt"
+	"time"
+)
+
+/*
+when the default case exists, messages are not guaranteed
+*/
+func main() {
+	ch := make(chan int)
+
+	// if this GR is fast enough
+	// the main GR can miss the signals
+	go func() {
+		var i int
+
+		for {
+			i++
+
+			select {
+			case ch <- i:
+			default:
+				// message is lost
+				// it doesn't matter whether the chan is buffered or not
+			}
+
+			if i == 10000 {
+				fmt.Println("gopher dies")
+				close(ch)
+				return
+			}
+		}
+	}()
+
+	var total int
+	for i := range ch {
+		// works slower — misses some of the signals
+		time.Sleep(time.Nanosecond)
+		total += i
+	}
+
+	// should be: 50005000
+	fmt.Println(total)
+}

28-concurrency/xxx-concurrent-downloader/fetch/danger2/main.go

@@ -0,0 +1,40 @@
+package main
+
+import (
+	"fmt"
+	"time"
+)
+
+func main() {
+	a, b := make(chan bool), make(chan bool)
+
+	go func() {
+		for a != nil || b != nil {
+			fmt.Println("loop starts")
+
+			select {
+			case <-a:
+				fmt.Println("recv: a")
+				a = nil
+			case <-b:
+				b = nil
+				fmt.Println("recv: b")
+			}
+
+			fmt.Println("loop ends")
+		}
+		fmt.Println("gopher dies")
+	}()
+
+	time.Sleep(time.Second)
+	// 	a <- true
+	close(a)
+	time.Sleep(time.Second)
+	//b <- true
+	close(b)
+	time.Sleep(time.Second * 2)
+
+	// closed chan never blocks
+	// nil chan always blocks
+	//   if in the loop chans not set to nil, the loop will loop forever
+}

28-concurrency/xxx-concurrent-downloader/fetch/drain.go

@@ -0,0 +1,12 @@
+package fetch
+
+// Drain drains the progress updates and returns the latest progresses
+func Drain(updates <-chan Progress) map[string]Progress {
+	latest := make(map[string]Progress)
+
+	// save the latest progress
+	for p := range updates {
+		latest[p.URL] = p
+	}
+	return latest
+}

28-concurrency/xxx-concurrent-downloader/fetch/httpget.go

@@ -0,0 +1,31 @@
+package fetch
+
+import (
+	"fmt"
+	"net/http"
+	"time"
+)
+
+// HTTPGet requests to a url with the specified timeout.
+// And it returns the response with an error.
+// The caller should drain and close the body or it will leak.
+func HTTPGet(url string, timeout time.Duration) (*http.Response, error) {
+	req, err := http.NewRequest("GET", url, nil)
+	req.Close = true
+	if err != nil {
+		return nil, err
+	}
+
+	c := &http.Client{Timeout: timeout}
+	resp, err := c.Do(req)
+	if err != nil {
+		return nil, err
+	}
+
+	// checkout for the bad urls
+	if s := resp.StatusCode; s < 200 || s > 299 {
+		return resp, fmt.Errorf("bad status: %d", s)
+	}
+
+	return resp, nil
+}

28-concurrency/xxx-concurrent-downloader/fetch/httptransfer.go

@@ -0,0 +1,126 @@
+package fetch
+
+import (
+	"fmt"
+	"io"
+	"net/http"
+	"os"
+	"path"
+	"time"
+)
+
+// HTTPTransfer uses a fetcher and a storager to fetch and store an url
+type HTTPTransfer struct {
+	Progress
+	r io.ReadCloser
+	w io.WriteCloser
+
+	timeout time.Duration
+
+	done    <-chan bool
+	updates chan<- Progress
+}
+
+// NewHTTPTransfer creates and returns a new transfer
+func NewHTTPTransfer(url string, timeout time.Duration) *HTTPTransfer {
+	return &HTTPTransfer{
+		Progress: Progress{URL: url},
+		timeout:  timeout,
+	}
+}
+
+// Start starts the transfer progress
+// The transfer will send its updates to the update chan
+// and it will stop when receives a signal from the done chan
+//
+// All the t.signal calls are here. I believe this increases the visibility
+// of the Start function (what it does). If the signal calls were in the
+// other funcs of HTTPTransfer, it could easily lead to bugs.
+func (t *HTTPTransfer) Start(updates chan<- Progress, done <-chan bool) {
+	defer t.cleanup()
+
+	t.done, t.updates = done, updates
+
+	t.w, t.Error = os.Create(path.Base(t.URL))
+	if t.Error != nil {
+		t.signal()
+		return
+	}
+
+	t.request()
+	if !t.signal() {
+		return
+	}
+
+	// sniff the on-going transfer until the signal returns false
+	sniff := sniffer(func(p []byte) bool {
+		l := len(p)
+		t.Current = l
+		t.Downloaded += l
+
+		return t.signal()
+	})
+
+	t.transfer(sniff)
+	t.signal()
+}
+
+func (t *HTTPTransfer) cleanup() {
+	if t.r != nil {
+		t.r.Close()
+	}
+	if t.w != nil {
+		t.w.Close()
+	}
+}
+
+func (t *HTTPTransfer) request() {
+	var resp *http.Response
+
+	resp, t.Error = HTTPGet(t.URL, t.timeout)
+	if t.Error != nil {
+		return
+	}
+
+	t.Total = int(resp.ContentLength) // TODO: int(int64)
+	if t.Total <= 0 {
+		t.Error = fmt.Errorf("unknown content length: %d", t.Total)
+	}
+
+	t.r = resp.Body
+}
+
+func (t *HTTPTransfer) transfer(sniff sniffer) {
+	// initiate the transfer and monitor it
+	_, t.Error = io.Copy(io.MultiWriter(t.w, sniff), t.r)
+
+	// if the err is from sniffer ignore it
+	if _, ok := t.Error.(sniffer); ok {
+		t.Error = nil
+	}
+
+	// the next signal will say: "no new bytes received" and its done
+	t.Current = 0
+	t.Done = true
+}
+
+// signal signals the listeners about the last transfer progress.
+// it returns false when the done signal is received or there was an error
+// in the transfer.
+func (t *HTTPTransfer) signal() bool {
+	select {
+	case t.updates <- t.Progress:
+	case <-t.done:
+		// shutting down signal received
+		return false
+	}
+
+	// check the error only after sending the last progress
+	// if this check was above, the last update won't be sent
+	if t.Error != nil {
+		return false
+	}
+
+	// go on your duties
+	return true
+}

28-concurrency/xxx-concurrent-downloader/fetch/httptransfer_fake.go

@@ -0,0 +1,71 @@
+package fetch
+
+import (
+	"errors"
+	"fmt"
+	"math/rand"
+	"time"
+)
+
+func (t *HTTPTransfer) fakeStart() {
+	jitter()
+	t.fakeRequest()
+	t.signal()
+
+	for t.Downloaded < 100 {
+		jitter()
+		t.fakeFetch()
+
+		if !t.signal() {
+			// done signal received or there was an error
+			break
+		}
+	}
+
+	t.fakeFinish()
+	t.signal()
+}
+
+// request requests to the url and adjusts the total length.
+func (t *HTTPTransfer) fakeRequest() {
+	t.Total = 100
+
+	if debug {
+		fmt.Printf("[TRANSFER] started: %s\n", t.URL)
+	}
+}
+
+// fetch fetches a bit from the resource
+func (t *HTTPTransfer) fakeFetch() {
+	// TODO: right now hanged goroutine may hang the download completion
+	// needs timeout
+	// if t.URL == "url1" {
+	// 	select {}
+	// }
+
+	// NOTE: burada sayacli io.Writer kullan
+	if t.URL == "url1" && t.Downloaded > rand.Intn(50) {
+		t.Error = errors.New("cekemedim netten")
+	}
+
+	n := rand.Intn(20) + 1
+	if nn := t.Downloaded + n; nn > 100 {
+		n = 100 - t.Downloaded
+	}
+	t.Current = n
+	t.Downloaded += n
+}
+
+// finish signals the finish signal to the listeners
+func (t *HTTPTransfer) fakeFinish() {
+	t.Current = 0
+	t.Done = true
+
+	if debug {
+		fmt.Printf("[TRANSFER] DONE: %s\n", t.URL)
+	}
+}
+
+func jitter() {
+	time.Sleep(time.Millisecond * time.Duration(rand.Intn(500)+1))
+}

28-concurrency/xxx-concurrent-downloader/fetch/progress.go

@@ -0,0 +1,10 @@
+package fetch
+
+// Progress contains data about the downloading progress
+type Progress struct {
+	URL string
+
+	Total, Downloaded, Current int
+	Done                       bool
+	Error                      error
+}

28-concurrency/xxx-concurrent-downloader/fetch/session.go

@@ -0,0 +1,57 @@
+package fetch
+
+import (
+	"fmt"
+	"sync"
+)
+
+const debug = true
+
+// Session manages the downloading process
+type Session struct {
+	done chan bool
+}
+
+// Transfer sends `updates` and terminates when `done` closes
+type Transfer interface {
+	Start(updates chan<- Progress, done <-chan bool)
+}
+
+// NewSession creates a new downloading session
+func NewSession() *Session {
+	return &Session{done: make(chan bool)}
+}
+
+// Start starts the downloading process
+func (s *Session) Start(transfers ...Transfer) <-chan Progress {
+	// a buffered chan may unblock transfers in case of a slow ui
+	updates := make(chan Progress)
+
+	var wg sync.WaitGroup
+	wg.Add(len(transfers))
+
+	for _, t := range transfers {
+		go func(t Transfer) {
+			t.Start(updates, s.done)
+			wg.Done()
+		}(t)
+	}
+
+	go func() {
+		wg.Wait()      // wait until all downloads complete
+		close(updates) // let the watchers (ui) know that we're shutting down
+	}()
+
+	return updates
+}
+
+// Shutdown stops the downloading process and sends a signal to all parties
+func (s *Session) Shutdown() {
+	// let the transfers know we're shutting down
+	// when this is done s.updates will be closed in the Start() routine above
+	close(s.done)
+
+	if debug {
+		fmt.Printf("[SESSION ] DONE\n")
+	}
+}

28-concurrency/xxx-concurrent-downloader/fetch/sniffer.go

@@ -0,0 +1,27 @@
+package fetch
+
+// sniffer converts a function to a sniffer that can sniff from the
+// on-going io.Writer call such as request -> file.
+//
+// This is here just for simplifying the logic of HTTPTransfer.
+type sniffer func(p []byte) bool
+
+// Write satistifes io.Writer interface to sniff from it.
+// It can be used through a io.MultiWriter.
+func (f sniffer) Write(p []byte) (n int, err error) {
+	n = len(p)
+
+	// if the sniffer returns false, terminate with a non-nil error.
+	// it used to abrupt the sniffing process, such as abrupting the
+	// io.MultiWriter.
+	if !f(p) {
+		err = f
+	}
+	return
+}
+
+// Error satisfies the Error interface. So the returned error from the
+// sniffer.Write func can return itself as an error. This is only used when
+// the sniff.Write wants to terminate. So that we can distinguish it from a
+// real error.
+func (f sniffer) Error() string { return "" }

28-concurrency/xxx-concurrent-downloader/fetch/storage.go

@@ -0,0 +1,44 @@
+package fetch
+
+import (
+	"fmt"
+	"io"
+)
+
+// TODO: let main func hand the "TransferFactory" to "Session"
+// instead of "StorageFactory"
+//
+// Because: "Session" duplicates almost everything for "Transfer"
+
+// StorageFactory func allows to switch storage implementations
+// When called it may return a FileStore
+// The transfer will call its Write method
+//
+// Why a func rather than an interface?
+// Because: We don't have to store any state
+// Storage will return its own io.Writer and the state will be in it
+//   However, before invoking the storage, we don't need any state
+//   We let us the storage manage its own state, we don't care about it
+type StorageFactory func(url string) io.Writer
+
+// FileStorage is the default storage mechanism for the downloader
+// It writes to files
+type FileStorage struct {
+	url   string
+	saved int
+}
+
+// FileStorageFactory creates and returns a new FileStorage
+func FileStorageFactory(url string) io.Writer {
+	return &FileStorage{url: url}
+}
+
+func (f *FileStorage) Write(p []byte) (int, error) {
+	if debug {
+		fmt.Println("[FILESTORAGE]", string(p), "for", f.url)
+	}
+	// TODO:
+	// if not exists create it
+	// if exists update it
+	return 0, nil
+}

28-concurrency/xxx-concurrent-downloader/fetch/ui.go

@@ -0,0 +1,96 @@
+package fetch
+
+import (
+	"fmt"
+	"time"
+
+	"github.com/inancgumus/screen"
+)
+
+const refreshPeriod = time.Second / 10
+
+// uiProgress is the default UI for the downloader
+type uiProgress struct {
+	urls      []string
+	transfers map[string]Progress
+}
+
+// UI listens for the progress updates from the updates chan
+// and it refreshes the ui
+func UI(updates <-chan Progress) {
+	ui := &uiProgress{transfers: make(map[string]Progress)}
+
+	// NOTE: we didn't use time.After here directly
+	// because doing so can create a lot of Timer chans unnecessarily
+	// instead we're just waiting on the same timer value
+	tick := time.After(refreshPeriod)
+	for {
+		select {
+		case p, ok := <-updates:
+			// if no more updates close the ui
+			if !ok {
+				ui.shutdown()
+				return
+			}
+			ui.update(p)
+
+		case <-tick:
+			// `case <-tick:` allows updating the ui independently
+			// from the progress update signals. or the ui would hang
+			// the updaters (transfers).
+			ui.refresh()
+			tick = time.After(refreshPeriod)
+		}
+	}
+
+}
+
+// shutdown refreshes the ui for the last time and closes it
+func (ui *uiProgress) shutdown() {
+	ui.refresh()
+
+	if debug {
+		fmt.Printf("[ UI ] DONE\n")
+	}
+}
+
+// update updates the progress data from the received message
+func (ui *uiProgress) update(p Progress) {
+	if _, ok := ui.transfers[p.URL]; !ok {
+		ui.urls = append(ui.urls, p.URL)
+	}
+
+	// update the latest progress for the url
+	ui.transfers[p.URL] = p
+}
+
+// refresh refreshes the UI with the latest progress
+func (ui *uiProgress) refresh() {
+	if !debug {
+		screen.Clear()
+		screen.MoveTopLeft()
+	}
+
+	var total, downloaded int
+
+	for _, u := range ui.urls {
+		p := ui.transfers[u]
+
+		msg := "Downloading"
+		if p.Done && p.Error == nil {
+			msg = "👍 Completed"
+		}
+		if p.Error != nil {
+			msg = fmt.Sprintf("❌ %s", p.Error)
+		}
+
+		fmt.Println(p.URL)
+		fmt.Printf("\t%d/%d\n", p.Downloaded, p.Total)
+		fmt.Printf("\t%s\n", msg)
+
+		total += p.Total
+		downloaded += p.Downloaded
+	}
+
+	fmt.Printf("\n%s %d/%d\n", "TOTAL DOWNLOADED BYTES:", downloaded, total)
+}

28-concurrency/xxx-concurrent-downloader/main.go

@@ -0,0 +1,103 @@
+package main
+
+import (
+	"time"
+
+	dl "github.com/inancgumus/course-experimentations/xxx-concurrent-downloader/0419-experimental/fetch"
+)
+
+//
+//       +--- transfer #1 (on done/error signals and quits)
+//       |
+// UI <--+--- transfer #2
+//       |
+//       +--- transfer #N
+//               ^
+//               |
+// SESSION ------+ launches goroutines
+//
+
+//
+//       +--- transfer #1
+//       |
+// UI <--+--- transfer #2
+//       |
+//       +--- transfer #N
+//               ^
+//               |
+// SESSION ------+ launches goroutines
+//
+
+//
+//       +--- transfer #1
+//       |
+// UI <--+--- transfer #2
+// ^     |
+// |     +--- transfer #N
+// |             ^
+// |             |
+// +--------- SESSION
+//
+// Session can close the transfers with session.Shutdown()
+// (through session.done chan)
+//
+// Session closes the watcher chan when the transfers end
+// Possible problem: If any of the transfers never quit, session will hang.
+// I think, I'm going to manage that using context.Context in the transfers.
+//
+
+func main() {
+	// ========================================================================
+
+	// to := time.Second * 5
+	// res, err := dl.HTTPGet("https://jsonplaceholder.typicode.com/todos/1", to)
+	// if err != nil {
+	// 	fmt.Println(err)
+	// 	return
+	// }
+	// defer res.Body.Close()
+
+	// io.Copy(os.Stdout, res.Body)
+
+	// return
+
+	// ========================================================================
+
+	sess := dl.NewSession()
+
+	// simulate a manual shutdown
+	// time.AfterFunc(time.Second, func() {
+	// 	sess.Shutdown()
+	// })
+
+	to := time.Second * 5
+	transfers := []dl.Transfer{
+		dl.NewHTTPTransfer("https://inancgumus.github.io/samples/jpg-beach-1020x670-160kb.jpg", to),
+		dl.NewHTTPTransfer("https://inancgumus.github.io/samples/jpg-beach-1020x670-610kb.jpg", to),
+		dl.NewHTTPTransfer("https://inancgumus.github.io/samples/jpg-beach-1020x670-80kb.jpg", to),
+		dl.NewHTTPTransfer("https://inancgumus.github.io/samples/jpg-beach-1900x1250-1700kb.jpg", to),
+	}
+
+	// transfers := []dl.Transfer{
+	// 	dl.NewHTTPTransfer(ctx, "http://inanc.io/1"),
+	// 	dl.NewHTTPTransfer(ctx, "http://inanc.io/2"),
+	// 	dl.NewHTTPTransfer(ctx, "http://inanc.io/3"),
+	// }
+
+	dl.UI(sess.Start(transfers...))
+
+	// results := dl.Drain(sess.Start(urls))
+	// for _, r := range results {
+	// 	fmt.Printf("%s [err: %v — %d/%d]\n",
+	// 		r.URL, r.Error, r.Downloaded, r.Total)
+	// }
+
+	// how to handle ctrl+c signals?
+	//   register a signal
+	//   let the downloader now that the operation halts
+	//   with Downloader.onCancel or "context.Context"
+
+	// run with: GOTRACEBACK=all go run -race main.go
+	// time.Sleep(time.Second * 2)
+	// panic("give me the stack trace")
+}

x-tba/swapi-api-client/film.go

@@ -0,0 +1,38 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"strings"
+)
+
+// Film represents a single Star Wars film
+type Film struct {
+	// All fields should be exported to be decoded
+	Title     string   `json:"title"`
+	Opening   string   `json:"opening_crawl"`
+	Starships []string `json:"starships"`
+}
+
+func (f Film) String() string {
+	var buf strings.Builder
+
+	fmt.Fprintln(&buf, f.Title)
+	fmt.Fprintln(&buf, strings.Repeat("-", len(f.Title)))
+	buf.WriteByte('\n')
+	fmt.Fprintln(&buf, f.Opening)
+
+	return buf.String()
+}
+
+// fetchFilm returns a Film resource by its id
+func fetchFilm(ctx context.Context, id int) (film Film, err error) {
+	fmt.Println("requesting", fmt.Sprintf(swapi+"films/%d/", id))
+	c, err := request(ctx, fmt.Sprintf(swapi+"films/%d/", id))
+	if err != nil {
+		return film, err
+	}
+
+	return film, json.Unmarshal(c, &film)
+}

x-tba/swapi-api-client/main.go

@@ -0,0 +1,84 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"strconv"
+	"time"
+)
+
+// const
+// nil, string, int, float64, bool, comparison
+// variables
+//   multiple short variables
+//   assignment?
+// if
+// error handling
+// functions
+//   returns
+//   defer
+// struct
+//   encoding/json
+// pointers
+// concurrency
+//   select
+//   chan receive
+// fmt
+//   Printf
+//   Sprintf
+//   Errorf
+// net/http
+//   Get
+// context/Context
+
+// TODO: convert fmt calls to log
+// TODO: you can make the fetcher a library and main package the user
+// TODO: you can generate an html for the ship details? template pkg.
+
+const timeout = 10 * time.Second
+
+func main() {
+	args := os.Args[1:]
+	quit("give me a film id", len(args) != 1)
+
+	id, err := strconv.Atoi(args[0])
+	quit("film id is incorrrect", err)
+
+	ctx, cancel := context.WithTimeout(context.Background(), timeout)
+	defer cancel()
+
+	// TODO: print the ship details to a text file (or any io.Writer)
+
+	film, err := fetchFilm(ctx, id)
+	quit("Error occurred while fetching the film data", err)
+	fmt.Println(film)
+
+	// a channel also can be used to print as they come
+	ships := make([]Starship, len(film.Starships))
+	err = fetchStarships(ctx, film.Starships, ships)
+	quit("Error occurred while fetching starships", err)
+
+	fmt.Println("Ships used in the movie:")
+	fmt.Println("------------------------")
+	for _, ship := range ships {
+		fmt.Println(ship)
+	}
+}
+
+func quit(message string, cond interface{}) {
+	var quit bool
+
+	switch v := cond.(type) {
+	case error:
+		quit = true
+		message += ": " + v.Error()
+	case bool:
+		quit = v
+	}
+
+	if quit {
+		fmt.Fprintln(os.Stderr, message)
+		os.Exit(1)
+	}
+}

x-tba/swapi-api-client/request.go

@@ -0,0 +1,44 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"net/http"
+)
+
+// MaxResponseSize limits the response bytes from the API
+const MaxResponseSize = 2 << 16
+
+// creating a robust http getter (lecture? :))
+func request(ctx context.Context, url string) ([]byte, error) {
+	req, err := http.NewRequest("GET", url, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	req = req.WithContext(ctx)
+
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		// Get the error from the context.
+		// It may contain more useful data.
+		select {
+		case <-ctx.Done():
+			err = ctx.Err()
+		default:
+		}
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("Bad Status: %d", resp.StatusCode)
+	}
+
+	// Prevents the api to shoot us unlimited amount of data
+	r := io.LimitReader(resp.Body, MaxResponseSize)
+
+	return ioutil.ReadAll(r)
+}

x-tba/swapi-api-client/starship.go

@@ -0,0 +1,69 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"regexp"
+	"strconv"
+	"strings"
+)
+
+// Starship represents a Star Wars space ship
+type Starship struct {
+	// All fields should be exported to be decoded
+	Name    string      `json:"name"`
+	Credits json.Number `json:"cost_in_credits"`
+	Rating  float64     `json:"hyperdrive_rating,string"`
+}
+
+func (ship Starship) String() string {
+	var buf strings.Builder
+
+	fmt.Fprintf(&buf, "Ship Name: %s\n", ship.Name)
+	fmt.Fprintf(&buf, "Price    : %s\n", ship.Credits)
+
+	return buf.String()
+}
+
+// TODO: return error instead of quit()
+func fetchStarships(ctx context.Context, shipUrls []string, ships []Starship) error {
+	ships = ships[:0]
+
+	re := regexp.MustCompile(`/([0-9]+)/$`)
+	for _, url := range shipUrls {
+		ids := re.FindAllStringSubmatch(url, -1)
+		if ids == nil {
+			continue
+		}
+
+		sid := ids[0][1]
+		id, _ := strconv.Atoi(sid)
+
+		// TODO: goroutine
+		ship, err := fetchStarship(ctx, id)
+		if err != nil {
+			return err
+		}
+
+		ships = append(ships, ship)
+	}
+	return nil
+}
+
+// fetchStarship returns Starship info by its id
+func fetchStarship(ctx context.Context, id int) (ship Starship, err error) {
+	c, err := request(ctx, fmt.Sprintf(swapi+"starships/%d/", id))
+	if err != nil {
+		return ship, err
+	}
+
+	// -> If your response body is small enough,
+	//    just read it all into memory using ioutil.ReadAll
+	//    and use json.Unmarshal.
+	//
+	// -> Do not use json.Decoder if you are not dealing
+	//    with JSON streaming.
+
+	return ship, json.Unmarshal(c, &ship)
+}

x-tba/swapi-api-client/swapi.go

@@ -0,0 +1,3 @@
+package main
+
+const swapi = "https://swapi.co/api/"

x-tba/tictactoe/01-without-funcs/main.go

@@ -0,0 +1,141 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+)
+
+const (
+	// skin options :-)
+	emptyMark = "☆"
+	mark1     = "💀"
+	mark2     = "🎈"
+	banner    = `
+~~~~~~~~~~~~~~~
+  TIC~TAC~TOE 
+~~~~~~~~~~~~~~~`
+
+	maxTurn = 9
+
+	prompt = "\n%s [1-9]: "
+)
+
+func main() {
+	// -------------------------------------------------
+	// INITIALIZE THE GAME
+	// -------------------------------------------------
+
+	fmt.Println(banner)
+
+	in := bufio.NewScanner(os.Stdin)
+
+	var (
+		turn   int
+		player = mark1
+		board  = [3][3]string{
+			{emptyMark, emptyMark, emptyMark},
+			{emptyMark, emptyMark, emptyMark},
+			{emptyMark, emptyMark, emptyMark},
+		}
+	)
+
+game:
+	for {
+		// -------------------------------------------------
+		// PRINT THE BOARD AND THE PROMPT
+		// -------------------------------------------------
+		fmt.Println()
+		fmt.Println("---+----+---")
+		for _, line := range board {
+			fmt.Printf("%s\n", strings.Join(line[:], "  | "))
+			fmt.Println("---+----+---")
+		}
+		fmt.Printf(prompt, player)
+
+		// get the input
+		if !in.Scan() {
+			break
+		}
+
+		// -------------------------------------------------
+		// CHECK THE MOVE AND PLAY
+		// -------------------------------------------------
+		var (
+			pos      int
+			row, col int
+		)
+
+		// Atoi already return 0 on error; no need to check
+		// it for the following switch to work
+		pos, _ = strconv.Atoi(in.Text())
+
+		switch {
+		case pos >= 7 && pos <= 9:
+			row = 2
+		case pos >= 4 && pos <= 6:
+			row = 1
+		case pos >= 1 && pos <= 3:
+			row = 0
+		default:
+			fmt.Println("\n>>>", "wrong position!")
+			continue
+		}
+
+		col = pos - row*3 - 1
+
+		if board[row][col] != emptyMark {
+			fmt.Println("\n>>>", "already played!")
+			continue
+		}
+
+		// put a mark on the board
+		board[row][col] = player
+
+		// -------------------------------------------------
+		// IS THERE A WINNER? OR IS IT A TIE?
+		// -------------------------------------------------
+		var won bool
+
+		for _, m := range [2]string{mark1, mark2} {
+			b, mmm := board, strings.Repeat(m, 3)
+
+			won = /* horizontals */
+				strings.Join(b[0][:], "") == mmm ||
+					strings.Join(b[1][:], "") == mmm ||
+					strings.Join(b[2][:], "") == mmm ||
+
+					/* verticals */
+					b[0][0]+b[1][0]+b[2][0] == mmm ||
+					b[0][1]+b[1][1]+b[2][1] == mmm ||
+					b[0][2]+b[1][2]+b[2][2] == mmm ||
+
+					/* diagonals */
+					b[0][0]+b[1][1]+b[2][2] == mmm ||
+					b[0][2]+b[1][1]+b[2][0] == mmm
+
+			if won {
+				break
+			}
+		}
+
+		if won {
+			fmt.Printf("\nWINNER: %s\n", player)
+			break game
+		} else if turn++; turn == maxTurn {
+			fmt.Printf("\nTIE!\n")
+			break game
+		}
+
+		// -------------------------------------------------
+		// CHANGE THE MARKER TO THE NEXT PLAYER
+		// -------------------------------------------------
+		if player == mark1 {
+			player = mark2
+		} else {
+			player = mark1
+		}
+	}
+}

x-tba/tictactoe/02-with-funcs/main.go

@@ -0,0 +1,156 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+)
+
+const (
+	// skin options :-)
+	emptyMark = "☆"
+	mark1     = "💀"
+	mark2     = "🎈"
+	banner    = `
+~~~~~~~~~~~~~~~
+  TIC~TAC~TOE 
+~~~~~~~~~~~~~~~`
+
+	maxTurn = 9
+)
+
+func main() {
+	fmt.Println(banner)
+
+	loop(bufio.NewScanner(os.Stdin))
+}
+
+func loop(in *bufio.Scanner) {
+	var (
+		turn   int
+		player = mark1
+		board  = createBoard()
+	)
+
+	for {
+		prompt(board, player)
+
+		if !in.Scan() {
+			break
+		}
+
+		msg := play(board, player, getMove(in.Text()))
+		if msg != "" {
+			fmt.Println("\n>>>", msg)
+			continue
+		}
+
+		turn++
+		if msg := finito(board, turn, player); msg != "" {
+			printBoard(board, player)
+			fmt.Printf("\n%s\n", msg)
+			break
+		}
+
+		player = switchTo(player)
+	}
+}
+
+func createBoard() [][]string {
+	return [][]string{
+		{emptyMark, emptyMark, emptyMark},
+		{emptyMark, emptyMark, emptyMark},
+		{emptyMark, emptyMark, emptyMark},
+	}
+}
+
+func prompt(board [][]string, player string) {
+	printBoard(board, player)
+	fmt.Printf("\n%s [1-9]: ", player)
+}
+
+func printBoard(board [][]string, player string) {
+	fmt.Println()
+	fmt.Println("---+----+---")
+	for _, line := range board {
+		fmt.Printf("%s\n", strings.Join(line, "  | "))
+		fmt.Println("---+----+---")
+	}
+}
+
+func getMove(move string) int {
+	// Atoi already return 0 on error; no need to check
+	// it for the following switch to work
+	pos, _ := strconv.Atoi(move)
+	return pos
+}
+
+func play(board [][]string, player string, pos int) string {
+	var row int
+
+	switch {
+	case pos >= 7 && pos <= 9:
+		row = 2
+	case pos >= 4 && pos <= 6:
+		row = 1
+	case pos >= 1 && pos <= 3:
+		row = 0
+	default:
+		return "wrong position"
+	}
+
+	col := pos - row*3 - 1
+
+	if board[row][col] != emptyMark {
+		return "already played!"
+	}
+
+	// put the player
+	board[row][col] = player
+
+	return ""
+}
+
+func finito(board [][]string, turn int, player string) string {
+	switch {
+	case won(board):
+		return fmt.Sprintf("WINNER: %s", player)
+	case turn == maxTurn:
+		return "TIE!"
+	}
+	return ""
+}
+
+func won(board [][]string) (won bool) {
+	for _, m := range [2]string{mark1, mark2} {
+		b, mmm := board, strings.Repeat(m, 3)
+
+		won = /* horizontals */
+			strings.Join(b[0], "") == mmm ||
+				strings.Join(b[1], "") == mmm ||
+				strings.Join(b[2], "") == mmm ||
+
+				/* verticals */
+				b[0][0]+b[1][0]+b[2][0] == mmm ||
+				b[0][1]+b[1][1]+b[2][1] == mmm ||
+				b[0][2]+b[1][2]+b[2][2] == mmm ||
+
+				/* diagonals */
+				b[0][0]+b[1][1]+b[2][2] == mmm ||
+				b[0][2]+b[1][1]+b[2][0] == mmm
+
+		if won {
+			return true
+		}
+	}
+	return false
+}
+
+func switchTo(player string) string {
+	if player == mark1 {
+		return mark2
+	}
+	return mark1
+}

x-tba/tictactoe/03-with-structs/main.go

@@ -0,0 +1,162 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+)
+
+const (
+	// skin options :-)
+	emptyMark = "☆"
+	mark1     = "💀"
+	mark2     = "🎈"
+	banner    = `
+~~~~~~~~~~~~~~~
+  TIC~TAC~TOE 
+~~~~~~~~~~~~~~~`
+
+	maxTurn = 9
+)
+
+type game struct {
+	board  [][]string
+	turn   int
+	player string
+}
+
+func main() {
+	fmt.Println(banner)
+
+	loop(bufio.NewScanner(os.Stdin))
+}
+
+func loop(in *bufio.Scanner) {
+	g := game{
+		player: mark1,
+		board:  createBoard(),
+	}
+
+	for {
+		prompt(g)
+
+		if !in.Scan() {
+			break
+		}
+
+		msg := play(g, getMove(in.Text()))
+		if msg != "" {
+			fmt.Println("\n>>>", msg)
+			continue
+		}
+
+		g.turn++
+		if msg := finito(g); msg != "" {
+			printBoard(g.board)
+			fmt.Printf("\n%s\n", msg)
+			break
+		}
+
+		g.player = switchTo(g.player)
+	}
+}
+
+func createBoard() [][]string {
+	return [][]string{
+		{emptyMark, emptyMark, emptyMark},
+		{emptyMark, emptyMark, emptyMark},
+		{emptyMark, emptyMark, emptyMark},
+	}
+}
+
+func prompt(g game) {
+	printBoard(g.board)
+	fmt.Printf("\n%s [1-9]: ", g.player)
+}
+
+func printBoard(board [][]string) {
+	fmt.Println()
+	fmt.Println("---+----+---")
+	for _, line := range board {
+		fmt.Printf("%s\n", strings.Join(line, "  | "))
+		fmt.Println("---+----+---")
+	}
+}
+
+func getMove(move string) int {
+	// Atoi already return 0 on error; no need to check
+	// it for the following switch to work
+	pos, _ := strconv.Atoi(move)
+	return pos
+}
+
+// NOTE: manipulates the game object
+func play(g game, pos int) string {
+	var row int
+
+	switch {
+	case pos >= 7 && pos <= 9:
+		row = 2
+	case pos >= 4 && pos <= 6:
+		row = 1
+	case pos >= 1 && pos <= 3:
+		row = 0
+	default:
+		return "wrong position"
+	}
+
+	col := pos - row*3 - 1
+
+	if g.board[row][col] != emptyMark {
+		return "already played!"
+	}
+
+	// put the player
+	g.board[row][col] = g.player
+
+	return ""
+}
+
+func finito(g game) string {
+	switch {
+	case won(g.board):
+		return fmt.Sprintf("WINNER: %s", g.player)
+	case g.turn == maxTurn:
+		return "TIE!"
+	}
+	return ""
+}
+
+func won(board [][]string) (won bool) {
+	for _, m := range [2]string{mark1, mark2} {
+		b, mmm := board, strings.Repeat(m, 3)
+
+		won = /* horizontals */
+			strings.Join(b[0], "") == mmm ||
+				strings.Join(b[1], "") == mmm ||
+				strings.Join(b[2], "") == mmm ||
+
+				/* verticals */
+				b[0][0]+b[1][0]+b[2][0] == mmm ||
+				b[0][1]+b[1][1]+b[2][1] == mmm ||
+				b[0][2]+b[1][2]+b[2][2] == mmm ||
+
+				/* diagonals */
+				b[0][0]+b[1][1]+b[2][2] == mmm ||
+				b[0][2]+b[1][1]+b[2][0] == mmm
+
+		if won {
+			return true
+		}
+	}
+	return false
+}
+
+func switchTo(player string) string {
+	if player == mark1 {
+		return mark2
+	}
+	return mark1
+}

x-tba/tictactoe/04-with-methods/main.go

@@ -0,0 +1,158 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+)
+
+const (
+	// skin options :-)
+	emptyMark = "☆"
+	mark1     = "💀"
+	mark2     = "🎈"
+	banner    = `
+~~~~~~~~~~~~~~~
+  TIC~TAC~TOE 
+~~~~~~~~~~~~~~~`
+
+	maxTurn = 9
+)
+
+func main() {
+	fmt.Println(banner)
+
+	loop(bufio.NewScanner(os.Stdin))
+}
+
+type game struct {
+	board  [][]string
+	turn   int
+	player string
+}
+
+func loop(in *bufio.Scanner) {
+	g := newGame()
+
+	for {
+		g.prompt()
+
+		if !in.Scan() {
+			break
+		}
+
+		// Atoi already return 0 on error; no need to check
+		// it for the following switch to work
+		pos, _ := strconv.Atoi(in.Text())
+
+		msg := g.play(pos)
+		if msg != "" {
+			fmt.Println("\n>>>", msg)
+			continue
+		}
+
+		g.turn++
+		if msg := g.finito(); msg != "" {
+			g.print()
+			fmt.Printf("\n%s\n", msg)
+			break
+		}
+
+		g.player = switchTo(g.player)
+	}
+}
+
+func newGame() game {
+	return game{
+		player: mark1,
+		board: [][]string{
+			{emptyMark, emptyMark, emptyMark},
+			{emptyMark, emptyMark, emptyMark},
+			{emptyMark, emptyMark, emptyMark},
+		},
+	}
+}
+
+func (g game) prompt() {
+	g.print()
+	fmt.Printf("\n%s [1-9]: ", g.player)
+}
+
+func (g game) print() {
+	fmt.Println()
+	fmt.Println("---+----+---")
+	for _, line := range g.board {
+		fmt.Printf("%s\n", strings.Join(line, "  | "))
+		fmt.Println("---+----+---")
+	}
+}
+
+func (g game) play(pos int) string {
+	var row int
+
+	switch {
+	case pos >= 7 && pos <= 9:
+		row = 2
+	case pos >= 4 && pos <= 6:
+		row = 1
+	case pos >= 1 && pos <= 3:
+		row = 0
+	default:
+		return "wrong position"
+	}
+
+	col := pos - row*3 - 1
+
+	if g.board[row][col] != emptyMark {
+		return "already played!"
+	}
+
+	// put the player
+	g.board[row][col] = g.player
+
+	return ""
+}
+
+func (g game) finito() string {
+	switch {
+	case g.won():
+		return fmt.Sprintf("WINNER: %s", g.player)
+	case g.turn == maxTurn:
+		return "TIE!"
+	}
+	return ""
+}
+
+func (g game) won() (won bool) {
+	for _, m := range [2]string{mark1, mark2} {
+		b, mmm := g.board, strings.Repeat(m, 3)
+
+		won = /* horizontals */
+			strings.Join(b[0], "") == mmm ||
+				strings.Join(b[1], "") == mmm ||
+				strings.Join(b[2], "") == mmm ||
+
+				/* verticals */
+				b[0][0]+b[1][0]+b[2][0] == mmm ||
+				b[0][1]+b[1][1]+b[2][1] == mmm ||
+				b[0][2]+b[1][2]+b[2][2] == mmm ||
+
+				/* diagonals */
+				b[0][0]+b[1][1]+b[2][2] == mmm ||
+				b[0][2]+b[1][1]+b[2][0] == mmm
+
+		if won {
+			return true
+		}
+	}
+	return false
+}
+
+func switchTo(player string) string {
+	if player == mark1 {
+		return mark2
+	}
+	return mark1
+}

x-tba/tictactoe/05-with-pointers/main.go

@@ -0,0 +1,166 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+)
+
+func main() {
+	fmt.Println(`
+~~~~~~~~~~~~~~~
+  TIC~TAC~TOE 
+~~~~~~~~~~~~~~~`)
+
+	loop(bufio.NewScanner(os.Stdin))
+}
+
+const (
+	// skin options :-)
+	emptyMark = "☆"
+	mark1     = "💀"
+	mark2     = "🎈"
+
+	maxTurn = 9
+)
+
+type game struct {
+	board  [][]string
+	turn   int
+	player string
+
+	buf strings.Builder
+}
+
+func loop(in *bufio.Scanner) {
+	g := newGame()
+
+	for {
+		g.prompt()
+
+		if !in.Scan() {
+			break
+		}
+
+		// Atoi already return 0 on error; no need to check
+		// it for the following switch to work
+		pos, _ := strconv.Atoi(in.Text())
+
+		msg := g.play(pos)
+		if msg != "" {
+			fmt.Println("\n>>>", msg)
+			continue
+		}
+
+		if msg := g.finito(); msg != "" {
+			fmt.Printf("\n%s%s\n", g, msg)
+			break
+		}
+
+		g.next()
+	}
+}
+
+func newGame() *game {
+	return &game{
+		player: mark1,
+		board: [][]string{
+			{emptyMark, emptyMark, emptyMark},
+			{emptyMark, emptyMark, emptyMark},
+			{emptyMark, emptyMark, emptyMark},
+		},
+	}
+}
+
+func (g *game) prompt() {
+	fmt.Printf("\n%s%s [1-9]: ", g, g.player)
+}
+
+func (g *game) String() string {
+	g.buf.Reset()
+
+	g.buf.WriteRune('\n')
+	g.buf.WriteString("---+----+---\n")
+
+	for _, line := range g.board {
+		g.buf.WriteString(strings.Join(line, "  | "))
+		g.buf.WriteRune('\n')
+
+		g.buf.WriteString("---+----+---\n")
+	}
+
+	return g.buf.String()
+}
+
+func (g *game) play(pos int) string {
+	var row int
+
+	switch {
+	case pos >= 7 && pos <= 9:
+		row = 2
+	case pos >= 4 && pos <= 6:
+		row = 1
+	case pos >= 1 && pos <= 3:
+		row = 0
+	default:
+		return "wrong position"
+	}
+
+	col := pos - row*3 - 1
+
+	if g.board[row][col] != emptyMark {
+		return "already played!"
+	}
+
+	// put the player
+	g.board[row][col] = g.player
+
+	return ""
+}
+
+func (g *game) finito() string {
+	g.turn++
+
+	switch {
+	case g.won():
+		return fmt.Sprintf("WINNER: %s", g.player)
+	case g.turn == maxTurn:
+		return "TIE!"
+	}
+	return ""
+}
+
+func (g *game) won() (won bool) {
+	for _, m := range [2]string{mark1, mark2} {
+		b, mmm := g.board, strings.Repeat(m, 3)
+
+		won = /* horizontals */
+			strings.Join(b[0], "") == mmm ||
+				strings.Join(b[1], "") == mmm ||
+				strings.Join(b[2], "") == mmm ||
+
+				/* verticals */
+				b[0][0]+b[1][0]+b[2][0] == mmm ||
+				b[0][1]+b[1][1]+b[2][1] == mmm ||
+				b[0][2]+b[1][2]+b[2][2] == mmm ||
+
+				/* diagonals */
+				b[0][0]+b[1][1]+b[2][2] == mmm ||
+				b[0][2]+b[1][1]+b[2][0] == mmm
+
+		if won {
+			return true
+		}
+	}
+	return false
+}
+
+func (g *game) next() {
+	if g.player == mark1 {
+		g.player = mark2
+	} else {
+		g.player = mark1
+	}
+}

x-tba/tictactoe/06-refactor/game.go

@@ -0,0 +1,152 @@
+package main
+
+import (
+	"strings"
+)
+
+type state int
+
+const (
+	maxTurn = 9
+
+	wrongPosition = -2
+
+	statePlaying state = iota
+	stateWon
+	stateTie
+
+	stateAlreadyPlayed
+	stateWrongPosition
+)
+
+type game struct {
+	board [][]string
+
+	turn   int
+	player string
+
+	skin   // embed the skin
+	logger // embed the logger
+}
+
+func newGame(s skin, l logger) *game {
+	return &game{
+		player: s.mark1,
+		board: [][]string{
+			{s.empty, s.empty, s.empty},
+			{s.empty, s.empty, s.empty},
+			{s.empty, s.empty, s.empty},
+		},
+		skin:   s,
+		logger: l,
+	}
+}
+
+func (g *game) play(pos int) state {
+	if st := g.move(pos); st != statePlaying {
+		return st
+	}
+
+	g.turn++ // increment the turn
+
+	// first check the winner then check the tie
+	// or the last mover won't win
+	switch {
+	case g.won():
+		return stateWon
+	case g.turn == maxTurn:
+		return stateTie
+	}
+
+	g.changePlayer()
+	return statePlaying
+}
+
+func (g *game) move(pos int) state {
+	row, col := position(pos)
+	if row+col == wrongPosition {
+		return stateWrongPosition
+	}
+
+	if g.board[row][col] != g.empty {
+		return stateAlreadyPlayed
+	}
+
+	// put the player's mark on the board
+	g.board[row][col] = g.player
+
+	return statePlaying
+}
+
+// we can detect the winning state just by comparing the strings
+// because, the game board is a bunch of strings
+func (g *game) won() (won bool) {
+	for _, m := range [2]string{g.mark1, g.mark2} {
+		b, mmm := g.board, strings.Repeat(m, 3)
+
+		won = /* horizontals */
+			strings.Join(b[0], "") == mmm ||
+				strings.Join(b[1], "") == mmm ||
+				strings.Join(b[2], "") == mmm ||
+
+				/* verticals */
+				b[0][0]+b[1][0]+b[2][0] == mmm ||
+				b[0][1]+b[1][1]+b[2][1] == mmm ||
+				b[0][2]+b[1][2]+b[2][2] == mmm ||
+
+				/* diagonals */
+				b[0][0]+b[1][1]+b[2][2] == mmm ||
+				b[0][2]+b[1][1]+b[2][0] == mmm
+
+		if won {
+			return true
+		}
+	}
+	return false
+}
+
+// this method should have a pointer receiver
+// because, it changes the game value
+func (g *game) changePlayer() {
+	if g.player == g.mark1 {
+		g.player = g.mark2
+	} else {
+		g.player = g.mark1
+	}
+}
+
+func (g *game) print() {
+	g.Println()
+	g.Println(g.header)
+
+	for i, line := range g.board {
+		g.Print(g.separator)
+
+		for _, m := range line {
+			g.Printf("%2s%s", m, g.separator)
+		}
+
+		if i+1 != len(g.board) {
+			g.Printf("\n%s\n", g.middle)
+		}
+	}
+
+	g.Printf("\n%s\n", g.footer)
+}
+
+// this function doesn't depend on the game state
+// so, make it a function instead of a method
+func position(pos int) (row, col int) {
+	switch {
+	case pos >= 1 && pos <= 3:
+		row = 0
+	case pos >= 4 && pos <= 6:
+		row = 1
+	case pos >= 7 && pos <= 9:
+		row = 2
+	default:
+		return -1, -1
+	}
+
+	return row, pos - row*3 - 1
+}

x-tba/tictactoe/06-refactor/logger.go

@@ -0,0 +1,19 @@
+package main
+
+type logger struct {
+	print   func(...interface{}) (int, error)
+	printf  func(fmt string, args ...interface{}) (int, error)
+	println func(...interface{}) (int, error)
+}
+
+func (l logger) Print(args ...interface{}) {
+	l.print(args...)
+}
+
+func (l logger) Printf(fmt string, args ...interface{}) {
+	l.printf(fmt, args...)
+}
+
+func (l logger) Println(args ...interface{}) {
+	l.println(args...)
+}

x-tba/tictactoe/06-refactor/main.go

@@ -0,0 +1,93 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"strconv"
+
+	c "github.com/fatih/color"
+	rainbow "github.com/guineveresaenger/golang-rainbow"
+)
+
+// TODO: move the main logic into a helper
+
+func main() {
+	const banner = `
+~~~~~~~~~~~~~~~~
+  TIC~TAC~TOE
+~~~~~~~~~~~~~~~~`
+
+	in := bufio.NewScanner(os.Stdin)
+	sk := selectSkin(in)
+	lg := logger{
+		print:   fmt.Print,
+		printf:  fmt.Printf,
+		println: fmt.Println,
+	}
+
+	for {
+		g := newGame(sk, lg)
+
+	game:
+		for {
+			rainbow.Rainbow(banner, 3)
+			g.print()
+			fmt.Printf(c.CyanString("\n%s [1-9]: ", g.player))
+
+			if !in.Scan() {
+				break
+			}
+
+			pos, _ := strconv.Atoi(in.Text())
+
+			switch st := g.play(pos); st {
+			case stateAlreadyPlayed, stateWrongPosition:
+				announce(g, st)
+				continue
+			case stateWon, stateTie:
+				announce(g, st)
+				break game
+			}
+			g.Print("\033[2J")
+
+		}
+
+		fmt.Print(c.MagentaString("One more game? [y/n]: "))
+		if in.Scan(); in.Text() != "y" {
+			fmt.Println("OK, bye!")
+			break
+		}
+	}
+}
+
+func announce(g *game, st state) {
+	red := c.New(c.FgRed, c.Bold)
+	green := c.New(c.BgBlack, c.FgGreen, c.Bold)
+
+	switch st {
+	case stateAlreadyPlayed, stateWrongPosition:
+		red.Printf("\n>>> You can't play there!\n")
+	case stateWon:
+		g.print()
+		green.Printf("\nWINNER: %s\n", g.player)
+	case stateTie:
+		g.print()
+		green.Printf("\nTIE!\n")
+	}
+}
+
+func selectSkin(in *bufio.Scanner) skin {
+	fmt.Println(c.MagentaString("Our finest selection of skins:"))
+	for name := range skins {
+		fmt.Printf("- %s\n", name)
+	}
+
+	fmt.Print(c.GreenString("\nEnter the name of the skin: "))
+
+	in.Scan()
+	if sk, ok := skins[in.Text()]; ok {
+		return sk
+	}
+	return defaultSkin
+}

x-tba/tictactoe/06-refactor/resources.md

@@ -0,0 +1,5 @@
+https://github.com/mattn/go-runewidth
+
+https://github.com/olekukonko/tablewriter
+
+https://www.cl.cam.ac.uk/~mgk25/ucs/wcwidth.c

x-tba/tictactoe/06-refactor/skins.go

@@ -0,0 +1,91 @@
+package main
+
+import "github.com/fatih/color"
+
+// skin options :-)
+type skin struct {
+	empty, mark1, mark2               string
+	header, middle, footer, separator string
+
+	unicode bool
+}
+
+var skins = map[string]skin{
+	"colorful": colorfulSkin,
+	"poseidon": poseidonSkin,
+	"statues":  statuesSkin,
+	"aliens":   aliensSkin,
+	"snow":     snowSkin,
+	"monkeys":  monkeysSkin,
+}
+
+var defaultSkin = skin{
+	empty: "   ",
+	mark1: " X ",
+	mark2: " O ",
+
+	header:    "┌───┬───┬───┐",
+	middle:    "├───┼───┼───┤",
+	footer:    "└───┴───┴───┘",
+	separator: "│",
+}
+
+var colorfulSkin = skin{
+	empty:     "   ",
+	mark1:     color.CyanString(" X "),
+	mark2:     color.HiMagentaString(" O "),
+	header:    color.HiBlueString("┌───┬───┬───┐"),
+	middle:    color.HiBlueString("├───┼───┼───┤"),
+	footer:    color.HiBlueString("└───┴───┴───┘"),
+	separator: color.BlueString("│"),
+}
+
+var poseidonSkin = skin{
+	empty:     "❓  ",
+	mark1:     "🔱  ",
+	mark2:     "⚓️  ",
+	header:    "●————●————●————●",
+	middle:    "●————●————●————●",
+	footer:    "●————●————●————●",
+	separator: "⎮ ",
+}
+
+var statuesSkin = skin{
+	empty:     "❓  ",
+	mark1:     "🗿  ",
+	mark2:     "🗽  ",
+	header:    "┌────┬────┬────┐",
+	middle:    "├────┼────┼────┤",
+	footer:    "└────┴────┴────┘",
+	separator: "│ ",
+}
+
+var aliensSkin = skin{
+	empty:     "❓  ",
+	mark1:     "👽  ",
+	mark2:     "👾  ",
+	header:    "┌────┬────┬────┐",
+	middle:    "├────┼────┼────┤",
+	footer:    "└────┴────┴────┘",
+	separator: "│ ",
+}
+
+var snowSkin = skin{
+	empty:     "❓  ",
+	mark1:     "⛄ ️ ",
+	mark2:     "❄️  ",
+	header:    "╔════╦════╦════╗",
+	middle:    "╠════╬════╬════╣",
+	footer:    "╚════╩════╩════╝",
+	separator: "║ ",
+}
+
+var monkeysSkin = skin{
+	empty:     "🍌  ",
+	mark1:     "🙈  ",
+	mark2:     "🙉  ",
+	header:    "┌────┬────┬────┐",
+	middle:    "├────┼────┼────┤",
+	footer:    "└────┴────┴────┘",
+	separator: "│ ",
+}

x-tba/tictactoe/README.md

@@ -0,0 +1,3 @@
+**Check out:**
+Tic-Tac-Toe Gist:
+https://gist.github.com/agalal/bff3cb779c337274d2a3462c630f4d74