detect chat template from KV

templates/template.go

@@ -0,0 +1,69 @@
+package templates
+
+import (
+	"bytes"
+	"embed"
+	"encoding/json"
+	"errors"
+	"io"
+	"math"
+	"sync"
+
+	"github.com/agnivade/levenshtein"
+)
+
+//go:embed index.json
+var indexBytes []byte
+
+//go:embed *.gotmpl
+var templatesFS embed.FS
+
+var templatesOnce = sync.OnceValues(func() ([]*Template, error) {
+	var templates []*Template
+	if err := json.Unmarshal(indexBytes, &templates); err != nil {
+		return nil, err
+	}
+
+	for _, t := range templates {
+		bts, err := templatesFS.ReadFile(t.Name + ".gotmpl")
+		if err != nil {
+			return nil, err
+		}
+
+		t.Bytes = bts
+	}
+
+	return templates, nil
+})
+
+type Template struct {
+	Name     string `json:"name"`
+	Template string `json:"template"`
+	Bytes []byte
+}
+
+func (t Template) Reader() io.Reader {
+	return bytes.NewReader(t.Bytes)
+}
+
+func NamedTemplate(s string) (*Template, error) {
+	templates, err := templatesOnce()
+	if err != nil {
+		return nil, err
+	}
+
+	var template *Template
+	score := math.MaxInt
+	for _, t := range templates {
+		if s := levenshtein.ComputeDistance(s, t.Template); s < score {
+			score = s
+			template = t
+		}
+	}
+
+	if score < 100 {
+		return template, nil
+	}
+
+	return nil, errors.New("no matching template found")
+}