package icecast

import (
	"bytes"
	"context"
	"errors"
	"io"
	"testing"

	"github.com/jan/fm-rds-tx/internal/ingest"
	"github.com/jan/fm-rds-tx/internal/ingest/decoder"
)

type testDecoder struct {
	name   string
	err    error
	called int
}

func (d *testDecoder) Name() string { return d.name }

func (d *testDecoder) DecodeStream(_ context.Context, _ io.Reader, _ decoder.StreamMeta, _ func(ingest.PCMChunk) error) error {
	d.called++
	return d.err
}

type consumingUnsupportedDecoder struct {
	n      int
	called int
}

func (d *consumingUnsupportedDecoder) Name() string { return "native-consuming-unsupported" }

func (d *consumingUnsupportedDecoder) DecodeStream(_ context.Context, r io.Reader, _ decoder.StreamMeta, _ func(ingest.PCMChunk) error) error {
	d.called++
	buf := make([]byte, d.n)
	_, _ = io.ReadFull(r, buf)
	return decoder.ErrUnsupported
}

type captureStreamDecoder struct {
	name    string
	called  int
	payload []byte
}

func (d *captureStreamDecoder) Name() string { return d.name }

func (d *captureStreamDecoder) DecodeStream(_ context.Context, r io.Reader, _ decoder.StreamMeta, _ func(ingest.PCMChunk) error) error {
	d.called++
	data, err := io.ReadAll(r)
	if err != nil {
		return err
	}
	d.payload = data
	return nil
}

func TestDecodeWithPreferenceAutoFallsBackFromNativeUnsupported(t *testing.T) {
	native := &testDecoder{name: "native", err: decoder.ErrUnsupported}
	fallback := &testDecoder{name: "ffmpeg"}

	reg := decoder.NewRegistry()
	reg.Register("mp3", func() decoder.Decoder { return native })
	reg.Register("ffmpeg", func() decoder.Decoder { return fallback })

	src := New("ice-test", "http://example", nil, ReconnectConfig{},
		WithDecoderRegistry(reg),
		WithDecoderPreference("auto"),
	)

	err := src.decodeWithPreference(context.Background(), bytes.NewReader(nil), decoder.StreamMeta{
		ContentType: "audio/mpeg",
		SourceID:    "ice-test",
	})
	if err != nil {
		t.Fatalf("decode: %v", err)
	}
	if native.called != 1 {
		t.Fatalf("native called %d times", native.called)
	}
	if fallback.called != 1 {
		t.Fatalf("fallback called %d times", fallback.called)
	}
}

func TestDecodeWithPreferenceNativeDoesNotFallback(t *testing.T) {
	nativeErr := errors.New("decode failed")
	native := &testDecoder{name: "native", err: nativeErr}
	fallback := &testDecoder{name: "ffmpeg"}

	reg := decoder.NewRegistry()
	reg.Register("mp3", func() decoder.Decoder { return native })
	reg.Register("ffmpeg", func() decoder.Decoder { return fallback })

	src := New("ice-test", "http://example", nil, ReconnectConfig{},
		WithDecoderRegistry(reg),
		WithDecoderPreference("native"),
	)

	err := src.decodeWithPreference(context.Background(), bytes.NewReader(nil), decoder.StreamMeta{
		ContentType: "audio/mpeg",
		SourceID:    "ice-test",
	})
	if !errors.Is(err, nativeErr) {
		t.Fatalf("expected native error, got %v", err)
	}
	if fallback.called != 0 {
		t.Fatalf("fallback should not be called, got %d", fallback.called)
	}
}

func TestDecodeWithPreferenceFFmpegOnly(t *testing.T) {
	native := &testDecoder{name: "native"}
	fallback := &testDecoder{name: "ffmpeg"}

	reg := decoder.NewRegistry()
	reg.Register("mp3", func() decoder.Decoder { return native })
	reg.Register("ffmpeg", func() decoder.Decoder { return fallback })

	src := New("ice-test", "http://example", nil, ReconnectConfig{},
		WithDecoderRegistry(reg),
		WithDecoderPreference("ffmpeg"),
	)

	err := src.decodeWithPreference(context.Background(), bytes.NewReader(nil), decoder.StreamMeta{
		ContentType: "audio/mpeg",
		SourceID:    "ice-test",
	})
	if err != nil {
		t.Fatalf("decode: %v", err)
	}
	if native.called != 0 {
		t.Fatalf("native should not be called in ffmpeg mode, got %d", native.called)
	}
	if fallback.called != 1 {
		t.Fatalf("fallback called %d times", fallback.called)
	}
}

func TestDecodeWithPreferenceAutoUnsupportedContentTypeFallsBack(t *testing.T) {
	fallback := &testDecoder{name: "ffmpeg"}
	reg := decoder.NewRegistry()
	reg.Register("ffmpeg", func() decoder.Decoder { return fallback })

	src := New("ice-test", "http://example", nil, ReconnectConfig{},
		WithDecoderRegistry(reg),
		WithDecoderPreference("auto"),
	)

	err := src.decodeWithPreference(context.Background(), bytes.NewReader(nil), decoder.StreamMeta{
		ContentType: "application/octet-stream",
		SourceID:    "ice-test",
	})
	if err != nil {
		t.Fatalf("decode: %v", err)
	}
	if fallback.called != 1 {
		t.Fatalf("fallback called %d times", fallback.called)
	}
}

func TestDecodeWithPreferenceAutoUsesOggNativeForOggContentType(t *testing.T) {
	ogg := &testDecoder{name: "oggvorbis"}
	fallback := &testDecoder{name: "ffmpeg"}

	reg := decoder.NewRegistry()
	reg.Register("oggvorbis", func() decoder.Decoder { return ogg })
	reg.Register("ffmpeg", func() decoder.Decoder { return fallback })

	src := New("ice-test", "http://example", nil, ReconnectConfig{},
		WithDecoderRegistry(reg),
		WithDecoderPreference("auto"),
	)

	err := src.decodeWithPreference(context.Background(), bytes.NewReader(nil), decoder.StreamMeta{
		ContentType: "audio/ogg",
		SourceID:    "ice-test",
	})
	if err != nil {
		t.Fatalf("decode: %v", err)
	}
	if ogg.called != 1 {
		t.Fatalf("ogg decoder called %d times", ogg.called)
	}
	if fallback.called != 0 {
		t.Fatalf("fallback should not be called, got %d", fallback.called)
	}
}

func TestDecodeWithPreferenceAutoUsesMP3NativeForMPEGContentType(t *testing.T) {
	mp3Native := &testDecoder{name: "mp3"}
	fallback := &testDecoder{name: "ffmpeg"}

	reg := decoder.NewRegistry()
	reg.Register("mp3", func() decoder.Decoder { return mp3Native })
	reg.Register("ffmpeg", func() decoder.Decoder { return fallback })

	src := New("ice-test", "http://example", nil, ReconnectConfig{},
		WithDecoderRegistry(reg),
		WithDecoderPreference("auto"),
	)

	err := src.decodeWithPreference(context.Background(), bytes.NewReader(nil), decoder.StreamMeta{
		ContentType: "audio/mpeg; charset=utf-8",
		SourceID:    "ice-test",
	})
	if err != nil {
		t.Fatalf("decode: %v", err)
	}
	if mp3Native.called != 1 {
		t.Fatalf("mp3 native decoder called %d times", mp3Native.called)
	}
	if fallback.called != 0 {
		t.Fatalf("fallback should not be called, got %d", fallback.called)
	}
}

func TestDecodeWithPreferenceAutoNativeErrorDoesNotFallback(t *testing.T) {
	nativeErr := errors.New("native hard failure")
	mp3Native := &testDecoder{name: "mp3", err: nativeErr}
	fallback := &testDecoder{name: "ffmpeg"}

	reg := decoder.NewRegistry()
	reg.Register("mp3", func() decoder.Decoder { return mp3Native })
	reg.Register("ffmpeg", func() decoder.Decoder { return fallback })

	src := New("ice-test", "http://example", nil, ReconnectConfig{},
		WithDecoderRegistry(reg),
		WithDecoderPreference("auto"),
	)

	err := src.decodeWithPreference(context.Background(), bytes.NewReader(nil), decoder.StreamMeta{
		ContentType: "audio/mpeg",
		SourceID:    "ice-test",
	})
	if !errors.Is(err, nativeErr) {
		t.Fatalf("expected native error, got %v", err)
	}
	if fallback.called != 0 {
		t.Fatalf("fallback should not be called on native hard error, got %d", fallback.called)
	}
}

func TestDecodeWithPreferenceAutoFallbackSeesFullStreamAfterNativeConsumesPrefix(t *testing.T) {
	const consumed = 4
	input := []byte("0123456789abcdef")

	native := &consumingUnsupportedDecoder{n: consumed}
	fallback := &captureStreamDecoder{name: "ffmpeg"}

	reg := decoder.NewRegistry()
	reg.Register("mp3", func() decoder.Decoder { return native })
	reg.Register("ffmpeg", func() decoder.Decoder { return fallback })

	src := New("ice-test", "http://example", nil, ReconnectConfig{},
		WithDecoderRegistry(reg),
		WithDecoderPreference("auto"),
	)

	err := src.decodeWithPreference(context.Background(), bytes.NewReader(input), decoder.StreamMeta{
		ContentType: "audio/mpeg",
		SourceID:    "ice-test",
	})
	if err != nil {
		t.Fatalf("decode: %v", err)
	}
	if native.called != 1 {
		t.Fatalf("native called %d times", native.called)
	}
	if fallback.called != 1 {
		t.Fatalf("fallback called %d times", fallback.called)
	}
	if !bytes.Equal(fallback.payload, input) {
		t.Fatalf("fallback payload mismatch: got %q want %q", string(fallback.payload), string(input))
	}
}

func TestDecodeWithPreferenceNativeUnsupportedContentTypeFailsWithoutFallback(t *testing.T) {
	fallback := &testDecoder{name: "ffmpeg"}
	reg := decoder.NewRegistry()
	reg.Register("ffmpeg", func() decoder.Decoder { return fallback })

	src := New("ice-test", "http://example", nil, ReconnectConfig{},
		WithDecoderRegistry(reg),
		WithDecoderPreference("native"),
	)

	err := src.decodeWithPreference(context.Background(), bytes.NewReader(nil), decoder.StreamMeta{
		ContentType: "application/octet-stream",
		SourceID:    "ice-test",
	})
	if err == nil {
		t.Fatal("expected native-mode select error for unsupported content-type")
	}
	if fallback.called != 0 {
		t.Fatalf("fallback should not be called in native mode, got %d", fallback.called)
	}
}

func TestWithDecoderPreferenceFallbackAliasNormalizesToFFmpeg(t *testing.T) {
	src := New("ice-test", "http://example", nil, ReconnectConfig{}, WithDecoderPreference("fallback"))
	if got := src.Descriptor().Codec; got != "ffmpeg" {
		t.Fatalf("codec=%s want ffmpeg", got)
	}
}