init: dec-music 项目初始化

decrypt/dispatch.go

@@ -0,0 +1,59 @@
+package decrypt
+
+import (
+	"io"
+	"path/filepath"
+	"strings"
+
+	"jsuse.com/dev/dec-music/log"
+)
+
+// DecoderParams configures a decoder instance.
+type DecoderParams struct {
+	Reader    io.ReadSeeker
+	Extension string
+	FilePath  string
+	Logger    *log.Logger
+}
+
+// Factory creates decoders for a registered file suffix.
+type Factory struct {
+	Suffix string
+	Noop   bool
+	Create func(*DecoderParams) Decoder
+}
+
+var registry []Factory
+
+// RegisterDecoder registers a file suffix handler (called from format init).
+func RegisterDecoder(ext string, noop bool, fn func(*DecoderParams) Decoder) {
+	registry = append(registry, Factory{
+		Noop: noop, Create: fn, Suffix: "." + strings.TrimPrefix(ext, "."),
+	})
+}
+
+// GetDecoder returns matching factories for a file name.
+func GetDecoder(filename string, skipNoop bool) []Factory {
+	var result []Factory
+	name := strings.ToLower(filepath.Base(filename))
+	for _, dec := range registry {
+		if !strings.HasSuffix(name, dec.Suffix) {
+			continue
+		}
+		if skipNoop && dec.Noop {
+			continue
+		}
+		result = append(result, dec)
+	}
+	return result
+}
+
+// SupportedExtensions returns registered suffixes and handler counts.
+func SupportedExtensions() map[string]int {
+	extSet := make(map[string]int)
+	for _, f := range registry {
+		ext := strings.TrimPrefix(f.Suffix, ".")
+		extSet[ext]++
+	}
+	return extSet
+}