add: new interfaces

interfaces/logparser-testing/summarize.go

@@ -0,0 +1,73 @@
+// 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 (
+	"encoding/json"
+	"fmt"
+	"os"
+	"strings"
+
+	"github.com/inancgumus/learngo/27-interfaces/logparser-testing/report"
+)
+
+// summarize prints the parsing results.
+//
+// it prints the errors and returns if there are any.
+//
+// --json flag encodes to json and prints.
+func summarize(sum *report.Summary, errors ...error) {
+	if errs(errors...) {
+		return
+	}
+
+	if args := os.Args[1:]; len(args) == 1 && args[0] == "--json" {
+		encode(sum)
+		return
+	}
+	stdout(sum)
+}
+
+// encodes the summary to json
+func encode(sum *report.Summary) {
+	out, err := json.MarshalIndent(sum, "", "\t")
+	if err != nil {
+		panic(err)
+	}
+	os.Stdout.Write(out)
+}
+
+// prints the summary to standard out
+func stdout(sum *report.Summary) {
+	const (
+		head = "%-30s %10s %20s\n"
+		val  = "%-30s %10d %20d\n"
+	)
+
+	fmt.Printf(head, "DOMAIN", "VISITS", "TIME SPENT")
+	fmt.Println(strings.Repeat("-", 65))
+
+	for next, cur := sum.Iterator(); next(); {
+		r := cur()
+		fmt.Printf(val, r.Domain, r.Visits, r.TimeSpent)
+	}
+
+	t := sum.Total()
+	fmt.Printf("\n"+val, "TOTAL", t.Visits, t.TimeSpent)
+}
+
+// this variadic func simplifies the multiple error handling
+func errs(errs ...error) (wasErr bool) {
+	for _, err := range errs {
+		if err != nil {
+			fmt.Printf("> Err: %s\n", err)
+			wasErr = true
+		}
+	}
+	return
+}