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1	package changelog
2
3	import (
4	"bytes"
5	"fmt"
6	"os/exec"
7	"regexp"
8	"strconv"
9	"strings"
10	"time"
11	)
12
13	// ExecGit reads a local checkout with git. Tags, Amadan's tombstones
14	// (refs/amadan/closed/*) and origin's branches must already be fetched.
15	type ExecGit struct {
16	Dir string
17	tombstones map[string]Tag
18	live map[string]bool
19	}
20
21	func NewExecGit(dir string) (*ExecGit, error) {
22	g := &ExecGit{Dir: dir, tombstones: map[string]Tag{}, live: map[string]bool{}}
23	out, err := g.run("for-each-ref", "--format=%(refname)%00%(objectname)%00%(committerdate:iso-strict)", "refs/amadan/closed", "refs/remotes/origin")
24	if err != nil {
25	return nil, err
26	}
27	for _, line := range strings.Split(strings.TrimSpace(out), "\n") {
28	f := strings.Split(line, "\x00")
29	if len(f) != 3 {
30	continue
31	}
32	if b, ok := strings.CutPrefix(f[0], "refs/amadan/closed/"); ok {
33	when, _ := time.Parse(time.RFC3339, f[2])
34	g.tombstones[b] = Tag{Name: b, SHA: f[1], Date: when}
35	} else if b, ok := strings.CutPrefix(f[0], "refs/remotes/origin/"); ok && b != "HEAD" {
36	g.live[b] = true
37	}
38	}
39	return g, nil
40	}
41
42	func (g *ExecGit) run(args ...string) (string, error) {
43	cmd := exec.Command("git", append([]string{"-C", g.Dir}, args...)...)
44	var stderr bytes.Buffer
45	cmd.Stderr = &stderr
46	out, err := cmd.Output()
47	if err != nil {
48	return "", fmt.Errorf("git %s: %v: %s", strings.Join(args, " "), err, strings.TrimSpace(stderr.String()))
49	}
50	return string(out), nil
51	}
52
53	var releaseTagRe = regexp.MustCompile(`^v\d+\.\d+\.\d+$`)
54
55	func (g *ExecGit) Tags() ([]Tag, error) {
56	out, err := g.run("for-each-ref", "--format=%(refname:short)%00%(*objectname)%00%(objectname)%00%(creatordate:iso-strict)", "refs/tags")
57	if err != nil {
58	return nil, err
59	}
60	var tags []Tag
61	for _, line := range strings.Split(strings.TrimSpace(out), "\n") {
62	f := strings.Split(line, "\x00")
63	if len(f) != 4 || !releaseTagRe.MatchString(f[0]) {
64	continue
65	}
66	sha := f[1]
67	if sha == "" {
68	sha = f[2] // a lightweight tag points at the commit itself
69	}
70	when, err := time.Parse(time.RFC3339, f[3])
71	if err != nil {
72	return nil, fmt.Errorf("tag %s: date %q: %w", f[0], f[3], err)
73	}
74	tags = append(tags, Tag{Name: f[0], SHA: sha, Date: when})
75	}
76	return tags, nil
77	}
78
79	const logFormat = "--format=%H%x00%P%x00%an%x00%ae%x00%cI%x00%B%x1e"
80
81	func (g *ExecGit) log(args ...string) ([]Commit, error) {
82	out, err := g.run(append([]string{"log", logFormat}, args...)...)
83	if err != nil {
84	return nil, err
85	}
86	var commits []Commit
87	for _, rec := range strings.Split(out, "\x1e") {
88	rec = strings.TrimLeft(rec, "\n")
89	if rec == "" {
90	continue
91	}
92	f := strings.SplitN(rec, "\x00", 6)
93	if len(f) != 6 {
94	return nil, fmt.Errorf("git log: malformed record %q", rec)
95	}
96	when, err := time.Parse(time.RFC3339, f[4])
97	if err != nil {
98	return nil, err
99	}
100	commits = append(commits, Commit{
101	SHA: f[0], Parents: strings.Fields(f[1]),
102	AuthorName: f[2], AuthorEmail: f[3], Date: when,
103	Message: strings.TrimRight(f[5], "\n"),
104	})
105	}
106	return commits, nil
107	}
108
109	func (g *ExecGit) FirstParent(to string, exclude []string) ([]Commit, error) {
110	args := []string{"--first-parent", to}
111	for _, e := range exclude {
112	args = append(args, "^"+e)
113	}
114	return g.log(append(args, "--")...)
115	}
116
117	func (g *ExecGit) Range(from, to string) ([]Commit, error) {
118	return g.log("--no-merges", from+".."+to, "--")
119	}
120
121	func (g *ExecGit) Tombstone(branch string) (string, time.Time, bool) {
122	t, ok := g.tombstones[branch]
123	return t.SHA, t.Date, ok
124	}
125
126	func (g *ExecGit) LiveBranch(branch string) bool { return g.live[branch] }
127
128	var hunkRe = regexp.MustCompile(`^@@ -\d+(?:,\d+)? \+(\d+)(?:,(\d+))? @@`)
129
130	// DocsChanges diffs a commit against its first parent (a root commit
131	// against nothing) under docs/site and reports the lines each markdown
132	// page gained.
133	func (g *ExecGit) DocsChanges(c Commit) ([]DocsChange, error) {
134	var out string
135	var err error
136	if len(c.Parents) == 0 {
137	out, err = g.run("show", "--format=", "--unified=0", c.SHA, "--", "docs/site")
138	} else {
139	out, err = g.run("diff", "--unified=0", c.Parents[0], c.SHA, "--", "docs/site")
140	}
141	if err != nil {
142	return nil, err
143	}
144	var changes []DocsChange
145	var cur *DocsChange
146	for _, line := range strings.Split(out, "\n") {
147	if p, ok := strings.CutPrefix(line, "+++ "); ok {
148	cur = nil
149	p = strings.TrimPrefix(p, "b/")
150	slug, ok := strings.CutPrefix(p, "docs/site/")
151	if !ok || !strings.HasSuffix(slug, ".md") {
152	continue
153	}
154	changes = append(changes, DocsChange{Page: strings.TrimSuffix(slug, ".md")})
155	cur = &changes[len(changes)-1]
156	continue
157	}
158	if cur == nil {
159	continue
160	}
161	if m := hunkRe.FindStringSubmatch(line); m != nil {
162	start, _ := strconv.Atoi(m[1])
163	n := 1
164	if m[2] != "" {
165	n, _ = strconv.Atoi(m[2])
166	}
167	for i := 0; i < n; i++ {
168	cur.Added = append(cur.Added, start+i)
169	}
170	}
171	}
172	for i := range changes {
173	body, err := g.run("show", c.SHA+":docs/site/"+changes[i].Page+".md")
174	if err != nil {
175	return nil, err
176	}
177	changes[i].Body = body
178	}
179	return changes, nil
180	}
181