Script to generate data shown in post 'At what time of day does famous programmers work? Part 2. Workweek vs Weekend.' — https://ivan.bessarabov.com/blog/famous-programmers-work-time-part-2-workweek-vs-weekend

script.go

/*
# Overview

git log --author="$GIT_USER_NAME" --format="%H %ai" の結果を集計するプログラムです。

# Usage

	$ gcw --help
	Usage of ./gcw:
	-dir string
			Path of git repository (default ".")
	-tz string
			Local Timezone (default "Asia/Tokyo")
	-user string
			Git username

	$ gcw -user Gitユーザ名 -dir リポジトリのパス -tz ローカルタイムゾーン(デフォルトはAsia/Tokyo)

# Memo

このプログラムは、以下のブログ記事で利用されていたPerlスクリプトをGoに移植したものです。
元のスクリプトは

	$ git log --author="$GIT_USER_NAME" --format="%H %ai" | perl script.pl

とパイプ経由で入力を受け取り、処理するようになっていましたが、Windows環境でも実行しやすいように
処理内で git コマンドも実行するように変更しています。

# REFERENCES

At what time of day do famous programmers work?
  - https://ivan.bessarabov.com/blog/famous-programmers-work-time

At what time of day do famous programmers work? Part 2. Workweek vs Weekend.
  - https://ivan.bessarabov.com/blog/famous-programmers-work-time-part-2-workweek-vs-weekend

Script to generate data shown in post 'At what time of day does famous programmers work? Part 2. Workweek vs Weekend.
  - https://gist.github.com/bessarabov/30aee15c5a7c438fe5f9f3f623222b39
*/
package main

import (
	"bufio"
	"bytes"
	"flag"
	"fmt"
	"log"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"time"
)

type (
	Args struct {
		dir      string
		userName string
		timeZone string
	}
)

var (
	args Args
)

func init() {
	flag.StringVar(&args.dir, "dir", ".", "Path of git repository")
	flag.StringVar(&args.userName, "user", "", "Git username")
	flag.StringVar(&args.timeZone, "tz", "Asia/Tokyo", "Local Timezone")
}

func main() {
	flag.Parse()

	if args.userName == "" {
		flag.PrintDefaults()
		os.Exit(1)
	}

	if args.dir == "" {
		args.dir = "."
	}

	if args.timeZone == "" {
		args.timeZone = "Asia/Tokyo"
	}

	var (
		absPath string
		err     error
	)
	absPath, err = filepath.Abs(args.dir)
	if err != nil {
		log.Fatalf("無効なディレクトリ: %s (%v)", args.dir, err)
	}

	args.dir = absPath

	if err := run(); err != nil {
		log.Fatal(err)
	}
}

func run() error {
	var (
		output []byte
		err    error
	)
	output, err = exec.Command("git", "-C", args.dir, "log", fmt.Sprintf("--author=%s", args.userName), "--format=%H %ai").Output()
	if err != nil {
		return fmt.Errorf("gitコマンド実行エラー: %w", err)
	}

	var (
		workweek = make(map[int]int)
		weekend  = make(map[int]int)
		localTz  *time.Location
	)
	localTz, err = time.LoadLocation("Asia/Tokyo")
	if err != nil {
		return fmt.Errorf("ローカルタイムゾーン取得エラー: %w", err)
	}

	var (
		reader  = bytes.NewReader(output)
		scanner = bufio.NewScanner(reader)
	)
	for scanner.Scan() {
		var (
			line      = scanner.Text()
			fields    = strings.Fields(line)
			timestamp time.Time
			localTime time.Time
		)
		if len(fields) < 2 {
			continue
		}

		timestamp, err = time.Parse("2006-01-02 15:04:05 -0700", fields[1]+" "+fields[2]+" "+fields[3])
		if err != nil {
			fmt.Printf("日付解析エラー: %v\n", err)
			continue
		}

		localTime = timestamp.In(localTz)
		switch localTime.Weekday() {
		case time.Saturday:
			fallthrough
		case time.Sunday:
			weekend[localTime.Hour()]++
		default:
			workweek[localTime.Hour()]++
		}
	}

	if err = scanner.Err(); err != nil {
		return fmt.Errorf("読み取りエラー: %w", err)
	}

	printGraph(workweek, weekend)

	return nil
}

func printGraph(workweek, weekend map[int]int) {
	fmt.Printf("%6s %6s %-30s %6s %-30s\n", "hour", "", "Monday to Friday", "", "Saturday and Sunday")

	var (
		max  = 0
		hour = 0
	)
	for hour = 0; hour < 24; hour++ {
		if max < workweek[hour] {
			max = workweek[hour]
		}

		if max < weekend[hour] {
			max = weekend[hour]
		}
	}

	for hour = 0; hour < 24; hour++ {
		var (
			workweekCount = workweek[hour]
			weekendCount  = weekend[hour]
			workweekStars = strings.Repeat("*", int(float64(workweekCount)/float64(max)*25))
			weekendStars  = strings.Repeat("*", int(float64(weekendCount)/float64(max)*25))
		)
		fmt.Printf("%02d %6d %-30s %6d %-30s\n", hour, workweekCount, workweekStars, weekendCount, weekendStars)
	}

	var (
		totalWorkweek = sum(workweek)
		totalWeekend  = sum(weekend)
		total         = totalWorkweek + totalWeekend
	)
	fmt.Printf("\nTotal: %6d (%.1f%%) %6d (%.1f%%)\n",
		totalWorkweek, float64(totalWorkweek)*100/float64(total),
		totalWeekend, float64(totalWeekend)*100/float64(total))
}

func sum(m map[int]int) int {
	var (
		total = 0
	)
	for _, v := range m {
		total += v
	}

	return total
}

script.pl

#!/usr/bin/perl

# This script is made to show graphs with git commit time made on workweek vs weekend
#
# The desription of this script and results of its usage is avaliable at:
# https://ivan.bessarabov.com/blog/famous-programmers-work-time-part-2-workweek-vs-weekend
#
# usage:
#
#   git log --author="Sebastian Riedel" --format="%H %ai" | perl script.pl
#


use strict;
use warnings FATAL => 'all';
use utf8;
use open qw(:std :utf8);
use feature qw(say);

use List::Util qw(max sum);
use Time::Local;

my %workweek;
my %weekend;

sub is_saturday_or_is_sunday {
    my ($yyyy_mm_dd) = @_;

        my ($year, $month, $day) = split /-/, $yyyy_mm_dd;

        my $timestamp = timegm(
                0,
                0,
                0,
                $day,
                $month - 1,
                $year,
        );

        my $wday = [gmtime($timestamp)]->[6];

        return $wday == 0 || $wday == 6;
}

while (my $line = <>) {

    # 181971ff7774853fceb0459966177d51eeab032c 2019-04-26 19:53:58 +0200

    my ($commit_hash, $date, $time, $timezone) = split / /, $line;
    my ($hour, $minute, $second) = split /:/, $time;

    $hour += 0;

    if (is_saturday_or_is_sunday($date)) {
        $weekend{$hour}++;
    } else {
        $workweek{$hour}++;
    }
}

my $max = max(values(%workweek), values(%weekend));

my $format = "%6s   %6s %-30s  %6s %-30s",

say '';
say sprintf $format, 'hour', '', 'Monday to Friday', '', 'Saturday and Sunday';

foreach my $hour (0..23) {
    $workweek{$hour} //= 0;
    $weekend{$hour} //= 0;
    say sprintf $format,
        sprintf('%02d', $hour),
        $workweek{$hour},
        '*' x ($workweek{$hour} / $max * 25),

        $weekend{$hour},
        '*' x ($weekend{$hour} / $max * 25),
        ;
}

my $total_commits_workweek = sum(values %workweek);
my $total_commits_weekend = sum(values %weekend);
my $total_commits = $total_commits_workweek + $total_commits_weekend;

say '';
say sprintf $format,
    'Total:',
    $total_commits_workweek,
    sprintf('(%.1f%%)', $total_commits_workweek * 100 / $total_commits),
    $total_commits_weekend,
    sprintf('(%.1f%%)', $total_commits_weekend* 100 / $total_commits),
    ;

say '';

https://github.com/devlights/try-golang/tree/main/examples/singleapp/git_calc_worktime

https://github.com/devlights/git-calc-worktime