1. 1
2. 2
3. 3
4. 4
5. 5
6. 6
7. 7
8. 8
9. 9
10. 10
11. 11
12. 12
13. 13
14. 14
15. 15
16. 16
17. 17
18. 18
19. 19
20. 20
21. 21
22. 22
23. 23
24. 24
25. 25
26. 26
27. 27
28. 28
29. 29
30. 30
31. 31
32. 32
33. 33
34. 34
35. 35
36. 36
37. 37
38. 38
39. 39
40. 40
41. 41
42. 42
43. 43
44. 44
45. 45
46. 46
47. 47
48. 48
49. 49
50. 50
51. 51
52. 52
53. 53
54. 54
55. 55
56. 56
57. 57
58. 58
59. 59
60. 60
61. 61
62. 62
63. 63
64. 64
65. 65
66. 66
67. 67
68. 68
69. 69
70. 70
71. 71
72. 72
73. 73
74. 74
75. 75
76. 76
77. 77
78. 78
79. 79
80. 80
81. 81
82. 82
83. 83
84. 84
85. 85
86. 86
87. 87
88. 88
89. 89
90. 90
91. 91
92. 92
93. 93
94. 94
95. 95
96. 96
97. 97
98. 98
99. 99
100. 100
101. 101
102. 102
103. 103
104. 104
105. 105
106. 106
107. 107
108. 108
109. 109
110. 110
111. 111
112. 112
113. 113
114. 114
115. 115
116. 116
117. 117
118. 118
119. 119
120. 120
121. 121
122. 122
123. 123
124. 124
125. 125
126. 126
127. 127
128. 128
129. 129
130. 130
131. 131
132. 132
133. 133
134. 134
135. 135
136. 136
137. 137
138. 138
139. 139
140. 140
141. 141
142. 142

// Copyright 2026 Shota FUJI <pockawoooh@gmail.com>
// SPDX-License-Identifier: MIT

// save-commit-pages is a helper program for detecting markup changes
// for commit pages. This program saves all commit pages of a repository
// into a single directory. The intended usecase is to run this program
// against a repository A on legit at revision X and the same repository
// A on legit at revision Y, then compare the two output directories using
// diff command line tool.
package main

import (
	"context"
	"flag"
	"fmt"
	"io"
	"log"
	"net/http"
	"net/url"
	"os"
	"os/signal"
	"path/filepath"
	"sync"

	"github.com/go-git/go-git/v5"
	"github.com/go-git/go-git/v5/plumbing"
)

func main() {
	baseUrl := flag.String("base-url", "http://localhost:5555/", "legit server URL, excluding project directory")
	outdir := flag.String("outdir", "", "Output directory to store downloaded HTML files")
	workers := flag.Uint("workers", 1, "Number of workers")
	flag.Parse()

	if *outdir == "" {
		log.Fatal("--outdir is required")
	}

	if *workers == 0 {
		log.Fatal("--workers must be greater than 0")
	}

	repoPath := flag.Arg(0)
	if repoPath == "" {
		log.Fatal("Argument is required for repository path")
	}

	repoName := filepath.Base(repoPath)
	commitUrlPrefix, err := url.JoinPath(*baseUrl, repoName, "commit")
	if err != nil {
		log.Fatal(err)
	}

	repo, err := git.PlainOpen(repoPath)
	if err != nil {
		log.Fatal(err)
	}

	if err := os.Mkdir(*outdir, 0o755); err != nil {
		log.Fatal(err)
	}

	iter, err := repo.Log(&git.LogOptions{})
	if err != nil {
		log.Fatal(err)
	}

	ctx, _ := signal.NotifyContext(context.Background(), os.Interrupt)

	commits := make(chan plumbing.Hash)

	var wg sync.WaitGroup
	for range *workers {
		wg.Go(func() {
			startWorker(ctx, commitUrlPrefix, *outdir, commits)
		})
	}

	for {
		if next, err := iter.Next(); err != nil {
			if err == io.EOF {
				break
			}

			log.Fatal(err)
		} else {
			commits <- next.Hash
		}
	}

	close(commits)
	wg.Wait()
}

func startWorker(ctx context.Context, baseUrl string, outdir string, commits <-chan plumbing.Hash) {
	for {
		select {
		case hash, ok := <-commits:
			if ok {
				if err := fetchAndSave(ctx, hash, baseUrl, outdir); err != nil {
					log.Printf("Download failed (%s): %s", hash, err)
				}
			} else {
				return
			}
		case <-ctx.Done():
			return
		}
	}
}

func fetchAndSave(_ context.Context, hash plumbing.Hash, baseUrl string, outdir string) error {
	target, err := url.JoinPath(baseUrl, hash.String())
	if err != nil {
		return err
	}

	client := http.Client{}
	resp, err := client.Get(target)
	if err != nil {
		return err
	}

	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		return fmt.Errorf("expected HTTP %d, got HTTP %d", http.StatusOK, resp.StatusCode)
	}

	file, err := os.Create(filepath.Join(outdir, fmt.Sprintf("%s.html", hash)))
	if err != nil {
		return err
	}

	defer file.Close()

	if _, err := io.Copy(file, resp.Body); err != nil {
		return err
	}

	return nil
}