| 1 | package sessioninbox |
| 2 | |
| 3 | import ( |
| 4 | "crypto/rand" |
| 5 | "crypto/sha256" |
| 6 | "encoding/hex" |
| 7 | "fmt" |
| 8 | "strings" |
| 9 | "sync" |
| 10 | "unicode/utf8" |
| 11 | ) |
| 12 | |
| 13 | var processRunID = sync.OnceValue(func() string { |
| 14 | return newRandomID() |
| 15 | }) |
| 16 | |
| 17 | // ProcessRunID returns a process-stable run identifier used to detect |
| 18 | // cross-process crash recovery without mistaking tab switches for crashes. |
| 19 | func ProcessRunID() string { |
| 20 | return processRunID() |
| 21 | } |
| 22 | |
| 23 | func newRandomID() string { |
| 24 | var b [16]byte |
| 25 | if _, err := rand.Read(b[:]); err != nil { |
| 26 | // crypto/rand failure is exceptional; fall back to a hashed time-ish value. |
| 27 | sum := sha256.Sum256(fmt.Appendf(nil, "fallback-%p", &b)) |
| 28 | return hex.EncodeToString(sum[:16]) |
| 29 | } |
| 30 | // UUID-like layout without external deps: xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx |
| 31 | b[6] = (b[6] & 0x0f) | 0x40 |
| 32 | b[8] = (b[8] & 0x3f) | 0x80 |
| 33 | h := hex.EncodeToString(b[:]) |
| 34 | return h[0:8] + "-" + h[8:12] + "-" + h[12:16] + "-" + h[16:20] + "-" + h[20:32] |
| 35 | } |
| 36 | |
| 37 | func sha256Hex(data []byte) string { |
| 38 | sum := sha256.Sum256(data) |
| 39 | return hex.EncodeToString(sum[:]) |
| 40 | } |
| 41 | |
| 42 | // PreviewText returns a bounded single-line preview without materializing the |
| 43 | // whole body as []rune when unnecessary. |
| 44 | func PreviewText(text string, maxRunes int) string { |
| 45 | if maxRunes <= 0 { |
| 46 | maxRunes = DefaultPreviewRunes |
| 47 | } |
| 48 | text = strings.TrimSpace(text) |
| 49 | if text == "" { |
| 50 | return "" |
| 51 | } |
| 52 | // Collapse internal whitespace for the shelf preview. |
| 53 | var b strings.Builder |
| 54 | b.Grow(min(len(text), maxRunes*4)) |
| 55 | prevSpace := false |
| 56 | count := 0 |
| 57 | for i := 0; i < len(text); { |
| 58 | r, size := utf8.DecodeRuneInString(text[i:]) |
| 59 | i += size |
| 60 | if r == utf8.RuneError && size == 1 { |
| 61 | continue |
| 62 | } |
| 63 | if r == '\n' || r == '\r' || r == '\t' || r == ' ' { |
| 64 | if prevSpace || count == 0 { |
| 65 | continue |
| 66 | } |
| 67 | b.WriteByte(' ') |
| 68 | prevSpace = true |
| 69 | count++ |
| 70 | if count >= maxRunes { |
| 71 | break |
| 72 | } |
| 73 | continue |
| 74 | } |
| 75 | prevSpace = false |
| 76 | b.WriteRune(r) |
| 77 | count++ |
| 78 | if count >= maxRunes { |
| 79 | // Peek if more content remains. |
| 80 | if i < len(text) { |
| 81 | b.WriteString("…") |
| 82 | } |
| 83 | break |
| 84 | } |
| 85 | } |
| 86 | return strings.TrimSpace(b.String()) |
| 87 | } |
| 88 |