add: log parser json

x-tba/xxx-log-parser-json/log.txt

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

x-tba/xxx-log-parser-json/log_err_missing.txt

@@ -0,0 +1,6 @@
+learngoprogramming.com 10
+learngoprogramming.com 10
+golang.org
+golang.org 6
+blog.golang.org 20
+blog.golang.org 10

x-tba/xxx-log-parser-json/log_err_negative.txt

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

x-tba/xxx-log-parser-json/log_err_str.txt

@@ -0,0 +1,6 @@
+learngoprogramming.com 10
+learngoprogramming.com 10
+golang.org FOUR
+golang.org 6
+blog.golang.org 20
+blog.golang.org 10

x-tba/xxx-log-parser-json/main.go

@@ -0,0 +1,93 @@
+// 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"
+	"encoding/json"
+	"fmt"
+	"os"
+	"sort"
+	"strconv"
+	"strings"
+)
+
+// Visit stores metrics for a domain
+type Visit struct {
+	Domain string `json:"domain"`
+	Total  int    `json:"total_visits"`
+	// add more metrics if needed
+}
+
+// Parser keep tracks of the parsing
+type Parser struct {
+	Sum     map[string]Visit `json:"visits_per_domain"` // metrics per domain
+	Domains []string         `json:"unique_domains"`    // unique domain names
+	Total   int              `json:"total_visits"`      // total visits for all domains
+	Lines   int              `json:"-"`                 // number of parsed lines (for the error messages)
+}
+
+func main() {
+	p := Parser{Sum: make(map[string]Visit)}
+
+	// Scan the standard-in line by line
+	in := bufio.NewScanner(os.Stdin)
+	for in.Scan() {
+		p.Lines++
+
+		// Parse the fields
+		fields := strings.Fields(in.Text())
+		if len(fields) != 2 {
+			fmt.Printf("wrong input: %v (line #%d)\n", fields, p.Lines)
+			return
+		}
+
+		// Sum the total visits per domain
+		visits, err := strconv.Atoi(fields[1])
+		if visits < 0 || err != nil {
+			fmt.Printf("wrong input: %q (line #%d)\n", fields[1], p.Lines)
+			return
+		}
+
+		name := fields[0]
+
+		// Collect the unique domains
+		if _, ok := p.Sum[name]; !ok {
+			p.Domains = append(p.Domains, name)
+		}
+
+		// Keep track of total and per domain visits
+		p.Total += visits
+
+		// You cannot assign to composite values
+		// p.Sum[name].Total += visits
+
+		// create and assign a new copy of `visit`
+		p.Sum[name] = Visit{
+			Domain: name,
+			Total:  visits + p.Sum[name].Total,
+		}
+	}
+
+	// Print the visits per domain
+	sort.Strings(p.Domains)
+
+	// fmt.Printf("%-30s %10s\n", "DOMAIN", "VISITS")
+	// fmt.Println(strings.Repeat("-", 45))
+
+	// for _, name := range p.Domains {
+	// 	visits := p.Sum[name]
+	// 	fmt.Printf("%-30s %10d\n", name, visits.Total)
+	// }
+
+	// // Print the total visits for all domains
+	// fmt.Printf("\n%-30s %10d\n", "TOTAL", p.Total)
+
+	s, _ := json.MarshalIndent(p, "", "\t")
+	fmt.Println(string(s))
+}