go-whisper-api/punctuation/sherpa.go

//go:build sherpa

package punctuation

import (
    "context"
    "fmt"
    "os"
    "strings"
    "sync"

    "go-whisper-api/config"

    sherpa "github.com/k2-fsa/sherpa-onnx-go/sherpa_onnx"
)

type Sherpa struct {
    offline *sherpa.OfflinePunctuation
    online  *sherpa.OnlinePunctuation
    mu      sync.Mutex
}

func newSherpaRestorer(cfg config.Punctuation) (Restorer, error) {
    return newSherpa(cfg)
}

func newSherpa(cfg config.Punctuation) (*Sherpa, error) {
    cfg = cfg.WithDefaults()
    engine := strings.ToLower(cfg.Engine)
    s := &Sherpa{}
    switch engine {
    case "sherpa-online", "online":
        modelPath := cfg.ModelPath()
        vocabPath := cfg.BpeVocabPath()
        if _, err := os.Stat(modelPath); err != nil {
            return nil, fmt.Errorf("sherpa online punctuation model %q: %w", modelPath, err)
        }
        if _, err := os.Stat(vocabPath); err != nil {
            return nil, fmt.Errorf("sherpa bpe vocab %q: %w", vocabPath, err)
        }
        conf := sherpa.OnlinePunctuationConfig{}
        conf.Model.CnnBilstm = modelPath
        conf.Model.BpeVocab = vocabPath
        conf.Model.NumThreads = cfg.NumThreads
        conf.Model.Provider = "cpu"
        s.online = sherpa.NewOnlinePunctuation(&conf)
        if s.online == nil {
            return nil, fmt.Errorf("failed to create sherpa online punctuation")
        }
    default:
        modelPath := cfg.ModelPath()
        if _, err := os.Stat(modelPath); err != nil {
            return nil, fmt.Errorf("sherpa offline punctuation model %q: %w (run: make download-punctuation-model)", modelPath, err)
        }
        conf := sherpa.OfflinePunctuationConfig{}
        conf.Model.CtTransformer = modelPath
        conf.Model.NumThreads = cfg.NumThreads
        conf.Model.Provider = "cpu"
        s.offline = sherpa.NewOfflinePunctuation(&conf)
        if s.offline == nil {
            return nil, fmt.Errorf("failed to create sherpa offline punctuation")
        }
    }
    return s, nil
}

func (s *Sherpa) Active() bool {
    return true
}

func (s *Sherpa) Restore(ctx context.Context, text, language string) (string, error) {
    _ = ctx
    _ = language
    text = strings.TrimSpace(text)
    if text == "" {
        return text, nil
    }
    s.mu.Lock()
    defer s.mu.Unlock()
    var out string
    switch {
    case s.offline != nil:
        out = s.offline.AddPunct(text)
    case s.online != nil:
        out = s.online.AddPunct(text)
    default:
        return text, fmt.Errorf("sherpa punctuation not initialized")
    }
    out = strings.TrimSpace(out)
    if out == "" {
        return text, nil
    }
    return out, nil
}

func (s *Sherpa) Close() {
    s.mu.Lock()
    defer s.mu.Unlock()
    if s.offline != nil {
        sherpa.DeleteOfflinePunc(s.offline)
        s.offline = nil
    }
    if s.online != nil {
        sherpa.DeleteOnlinePunctuation(s.online)
        s.online = nil
    }
}