94 lines
1.9 KiB
Go
94 lines
1.9 KiB
Go
package transcript
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import (
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"bufio"
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"bytes"
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"encoding/json"
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"errors"
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"io"
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"os"
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"strings"
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"unicode/utf8"
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)
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const tailWindow = 256 * 1024
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// LastMessages reads a JSONL transcript and returns the last user and assistant
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// messages, each truncated to maxLen runes.
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func LastMessages(path string, maxLen int) (lastUser, lastAgent string, err error) {
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f, err := os.Open(path)
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if err != nil {
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if os.IsNotExist(err) {
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return "", "", err
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}
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return "", "", err
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}
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defer f.Close()
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info, err := f.Stat()
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if err != nil {
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return "", "", err
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}
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size := info.Size()
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var r io.Reader = f
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if size > tailWindow {
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start := size - tailWindow
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if _, err := f.Seek(start, io.SeekStart); err != nil {
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return "", "", err
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}
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tail := make([]byte, tailWindow)
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n, err := io.ReadFull(f, tail)
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if err != nil && !errors.Is(err, io.ErrUnexpectedEOF) {
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return "", "", err
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}
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tail = tail[:n]
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if i := bytes.IndexByte(tail, '\n'); i >= 0 {
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tail = tail[i+1:]
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}
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r = bytes.NewReader(tail)
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}
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sc := bufio.NewScanner(r)
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sc.Buffer(make([]byte, 0, 64*1024), 1024*1024)
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for sc.Scan() {
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line := strings.TrimSpace(sc.Text())
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if line == "" {
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continue
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}
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var row struct {
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Role string `json:"role"`
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Type string `json:"type"`
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Content string `json:"content"`
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}
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if err := json.Unmarshal([]byte(line), &row); err != nil {
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continue
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}
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role := row.Role
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if role == "" {
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role = row.Type
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}
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switch role {
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case "user":
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lastUser = row.Content
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case "assistant":
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lastAgent = row.Content
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}
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}
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if err := sc.Err(); err != nil {
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return "", "", err
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}
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lastUser = truncateRunes(lastUser, maxLen)
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lastAgent = truncateRunes(lastAgent, maxLen)
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return lastUser, lastAgent, nil
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}
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func truncateRunes(s string, maxLen int) string {
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if maxLen <= 0 || utf8.RuneCountInString(s) <= maxLen {
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return s
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}
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runes := []rune(s)
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return string(runes[:maxLen])
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}
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