package ingest

import (
	"context"
	"errors"
	"sync"
	"testing"
	"time"

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

type fakeSource struct {
	desc   SourceDescriptor
	chunks chan PCMChunk
	errs   chan error
	stats  SourceStats
	once   sync.Once
}

func newFakeSource() *fakeSource {
	return &fakeSource{
		desc:   SourceDescriptor{ID: "fake", Kind: "stdin-pcm"},
		chunks: make(chan PCMChunk, 4),
		errs:   make(chan error, 1),
		stats:  SourceStats{State: "running", Connected: true},
	}
}

func (s *fakeSource) Descriptor() SourceDescriptor { return s.desc }
func (s *fakeSource) Start(context.Context) error  { return nil }
func (s *fakeSource) Stop() error                  { s.once.Do(func() { close(s.chunks) }); return nil }
func (s *fakeSource) Chunks() <-chan PCMChunk      { return s.chunks }
func (s *fakeSource) Errors() <-chan error         { return s.errs }
func (s *fakeSource) Stats() SourceStats           { return s.stats }

func TestRuntimeWritesFramesToStreamSink(t *testing.T) {
	sink := audio.NewStreamSource(128, 44100)
	src := newFakeSource()
	rt := NewRuntime(sink, src)
	if err := rt.Start(context.Background()); err != nil {
		t.Fatalf("start: %v", err)
	}
	defer rt.Stop()

	src.chunks <- PCMChunk{
		Channels:     2,
		SampleRateHz: 44100,
		Samples:      []int32{1000 << 16, -1000 << 16},
	}

	deadline := time.Now().Add(1 * time.Second)
	for sink.Available() < 1 && time.Now().Before(deadline) {
		time.Sleep(10 * time.Millisecond)
	}
	if sink.Available() < 1 {
		t.Fatal("expected at least one frame in sink")
	}
}

func TestRuntimeRecoversToRunningAfterSourceError(t *testing.T) {
	sink := audio.NewStreamSource(128, 44100)
	src := newFakeSource()
	rt := NewRuntime(sink, src)
	if err := rt.Start(context.Background()); err != nil {
		t.Fatalf("start: %v", err)
	}
	defer rt.Stop()

	src.errs <- errors.New("decode transient failure")
	waitForRuntimeState(t, rt, "degraded")

	src.chunks <- PCMChunk{
		Channels:     2,
		SampleRateHz: 44100,
		Samples:      []int32{500 << 16, -500 << 16},
	}
	waitForRuntimeState(t, rt, "running")
}

func TestRuntimeRecoversToRunningAfterConvertError(t *testing.T) {
	sink := audio.NewStreamSource(128, 44100)
	src := newFakeSource()
	rt := NewRuntime(sink, src)
	if err := rt.Start(context.Background()); err != nil {
		t.Fatalf("start: %v", err)
	}
	defer rt.Stop()

	// Invalid stereo chunk: odd sample count causes conversion error.
	src.chunks <- PCMChunk{
		Channels:     2,
		SampleRateHz: 44100,
		Samples:      []int32{100 << 16},
	}
	waitForRuntimeState(t, rt, "degraded")

	if got := rt.Stats().Runtime.ConvertErrors; got != 1 {
		t.Fatalf("convertErrors=%d want 1", got)
	}

	src.chunks <- PCMChunk{
		Channels:     2,
		SampleRateHz: 44100,
		Samples:      []int32{300 << 16, -300 << 16},
	}
	waitForRuntimeState(t, rt, "running")
}

func waitForRuntimeState(t *testing.T, rt *Runtime, want string) {
	t.Helper()
	deadline := time.Now().Add(1 * time.Second)
	for time.Now().Before(deadline) {
		if got := rt.Stats().Runtime.State; got == want {
			return
		}
		time.Sleep(10 * time.Millisecond)
	}
	t.Fatalf("timeout waiting for runtime state %q; last=%q", want, rt.Stats().Runtime.State)
}