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
}