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package gitread
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import (
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"context"
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"strconv"
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"strings"
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"time"
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"github.com/barerepo/server/internal/cache"
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"github.com/barerepo/server/internal/gitx"
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// File carries blame already, because "what is this line" and "why" are one question. 24.
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type File struct {
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Path string
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Blob string
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Size int64
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Binary bool
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// TooBig is chapter 42.4's cap, rather than sending a browser what it will choke on.
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TooBig bool
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Lines []FileLine
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type FileLine struct {
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Number int
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Text string
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SHA string // the commit that last touched this line
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Short string
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Author string
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When time.Time
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// renderCap is the largest file that is rendered whole. Chapter 42.4.
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const renderCap = 1 << 20
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// binarySniff is how many bytes are checked for a null byte. Chapter 42.4.
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const binarySniff = 8000
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// Open reads a file at a revision.
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func Open(ctx context.Context, dir, rev, path string) (*File, error) {
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if !gitx.ValidRev(rev) || !gitx.ValidPath(path) {
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return nil, nil
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// One process for hash, size and content, because three is what chapter 25 cannot afford.
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obj, err := gitx.CatFile(ctx, dir, rev+":"+path)
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if err != nil || obj.Type != "blob" {
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return nil, nil // no such file at that revision
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f := &File{Path: path, Size: obj.Size, Blob: obj.SHA}
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body := obj.Body
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head := body
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if len(head) > binarySniff {
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head = head[:binarySniff]
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if strings.IndexByte(head, 0) >= 0 {
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f.Binary = true
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return f, nil
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if obj.Size > renderCap {
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f.TooBig = true
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return f, nil
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text := strings.Split(strings.TrimSuffix(body, "\n"), "\n")
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blame, err := blameAt(ctx, dir, rev, path)
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if err != nil {
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blame = nil // a file with no history still renders
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f.Lines = make([]FileLine, len(text))
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for i, line := range text {
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f.Lines[i] = FileLine{Number: i + 1, Text: line}
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if i < len(blame) {
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b := blame[i]
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f.Lines[i].SHA = b.SHA
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f.Lines[i].Short = b.Short
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f.Lines[i].Author = b.Author
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f.Lines[i].When = b.When
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return f, nil
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// BlameLine is who last touched one line.
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type BlameLine struct {
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SHA string
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Short string
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Author string
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When time.Time
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// Cache holds answers that cannot change. Nil means compute every time.
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var Cache *cache.Disk
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// Blame reads porcelain output, cached by commit and path, because that is the question it answers.
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func Blame(ctx context.Context, dir, rev, path string) ([]BlameLine, error) {
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if !gitx.ValidRev(rev) || !gitx.ValidPath(path) {
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return nil, nil
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return blameAt(ctx, dir, rev, path)
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// blameAt keys on commit and path, not blob: two paths can share a blob and a revert reuses one, and either serves the wrong author and commit on every line.
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func blameAt(ctx context.Context, dir, rev, path string) ([]BlameLine, error) {
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key := ""
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if sha := revObject(dir, rev); sha != "" {
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key = sha + ":" + path
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}
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if key != "" {
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if body, ok := Cache.Get("blame", key); ok {
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return parseBlame(string(body)), nil
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}
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}
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out, err := gitx.Run(ctx, dir, "blame", "--porcelain", rev, "--", path)
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if err != nil {
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return nil, err
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}
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if key != "" {
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Cache.Put("blame", key, []byte(out))
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}
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return parseBlame(out), nil
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// parseBlame remembers each commit's details as they pass, since the format states them once.
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func parseBlame(out string) []BlameLine {
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type meta struct {
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author string
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when time.Time
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}
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seen := map[string]meta{}
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var lines []BlameLine
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var cur BlameLine
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var curMeta meta
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inEntry := false
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for _, line := range strings.Split(out, "\n") {
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switch {
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case strings.HasPrefix(line, "\t"):
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// The content line ends an entry.
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if inEntry {
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if curMeta.author == "" {
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curMeta = seen[cur.SHA]
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} else {
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seen[cur.SHA] = curMeta
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}
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cur.Author = curMeta.author
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cur.When = curMeta.when
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lines = append(lines, cur)
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inEntry = false
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curMeta = meta{}
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}
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case strings.HasPrefix(line, "author "):
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curMeta.author = strings.TrimPrefix(line, "author ")
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case strings.HasPrefix(line, "author-time "):
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if secs, err := strconv.ParseInt(strings.TrimPrefix(line, "author-time "), 10, 64); err == nil {
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curMeta.when = time.Unix(secs, 0)
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}
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case len(line) >= 40 && isHex(line[:40]):
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cur = BlameLine{SHA: line[:40], Short: line[:7]}
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inEntry = true
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}
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}
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return lines
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func isHex(s string) bool {
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for i := 0; i < len(s); i++ {
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c := s[i]
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if !(c >= '0' && c <= '9' || c >= 'a' && c <= 'f') {
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return false
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}
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}
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return true