// Fenrir console screen reader.
// Copyright (c) 2026 Storm Dragon
// SPDX-License-Identifier: GPL-3.0-or-later

package sound

import (
	"context"
	"errors"
	"slices"
	"syscall"
	"testing"
	"time"

	"git.stormux.org/storm/fenrir/internal/presentation"
)

type fakePCM struct {
	writeSamples                 func([]float32) (int, error)
	drainResult                  func() error
	received                     []float32
	preparations, drains, closes int
}

func (p *fakePCM) write(samples []float32) (int, error) {
	if p.writeSamples != nil {
		return p.writeSamples(samples)
	}
	p.received = append(p.received, samples...)
	return len(samples), nil
}
func (p *fakePCM) prepare() error { p.preparations++; return nil }
func (p *fakePCM) drain() error {
	p.drains++
	if p.drainResult != nil {
		return p.drainResult()
	}
	return nil
}
func (p *fakePCM) close() { p.closes++ }

func TestPCMShortWritesAndUnderrunRecoveryPreserveSampleOrder(t *testing.T) {
	s := &Service{done: make(chan struct{})}
	pcm := &fakePCM{}
	calls := 0
	pcm.writeSamples = func(samples []float32) (int, error) {
		calls++
		switch calls {
		case 1:
			return 0, syscall.EPIPE
		case 2:
			return 0, syscall.EAGAIN
		case 3:
			return 0, syscall.ESTRPIPE
		case 4:
			return 0, syscall.EINTR
		}
		pcm.received = append(pcm.received, samples[:2]...)
		return 2, nil
	}
	samples := []float32{1, -1, .5, -.5, .25, -.25}
	if err := s.write_pcm(pcm, samples); err != nil {
		t.Fatal(err)
	}
	if !slices.Equal(pcm.received, samples) || pcm.preparations != 2 {
		t.Fatal(pcm.received, pcm.preparations)
	}
}

func TestPCMStallsAndDrainRespectCancellation(t *testing.T) {
	s := &Service{done: make(chan struct{})}
	pcm := &fakePCM{writeSamples: func([]float32) (int, error) { return 0, syscall.EAGAIN }, drainResult: func() error { return syscall.EAGAIN }}
	if err := s.write_pcm(pcm, []float32{1, 1}); !errors.Is(err, context.DeadlineExceeded) {
		t.Fatal("write did not expire", err)
	}
	ctx, cancel := context.WithCancel(context.Background())
	cancel()
	if err := s.drain_pcm(ctx, pcm); !errors.Is(err, context.Canceled) {
		t.Fatal("drain did not cancel", err)
	}
	close(s.done)
	if err := s.drain_pcm(context.Background(), pcm); !errors.Is(err, context.Canceled) {
		t.Fatal("close did not cancel drain", err)
	}
}

func TestPCMShutdownUsesSharedCueVolumeAndDrainsBeforeClose(t *testing.T) {
	s := &Service{clips: map[presentation.Cue]*clip{presentation.Stopped: {samples: []float32{.8, -.8, .4, -.4}}}, done: make(chan struct{}), errors: make(chan error, 1)}
	s.Set_volume(.5)
	pcm := &fakePCM{}
	s.start_pcm(pcm)
	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
	defer cancel()
	if err := s.Finish(ctx); err != nil {
		t.Fatal(err)
	}
	// Finish waits for the worker's completed drain, making its samples readable.
	if pcm.drains != 1 || pcm.closes != 0 || !slices.Equal(pcm.received[:4], []float32{.4, -.4, .2, -.2}) {
		t.Fatal(pcm)
	}
	s.Close()
	s.Close()
	if pcm.closes != 1 {
		t.Fatal("PCM closed incorrectly", pcm.closes)
	}
}

func TestPCMFailureDisablesOutputWithoutBlockingAdmission(t *testing.T) {
	s := &Service{done: make(chan struct{}), errors: make(chan error, 1)}
	pcm := &fakePCM{writeSamples: func([]float32) (int, error) { return 0, syscall.ENODEV }}
	s.start_pcm(pcm)
	select {
	case err := <-s.Errors():
		if !errors.Is(err, syscall.ENODEV) {
			t.Fatal(err)
		}
	case <-time.After(time.Second):
		t.Fatal("PCM failure was not reported")
	}
	s.Close()
	if pcm.closes != 1 {
		t.Fatal(pcm.closes)
	}
}

func TestALSANullSinkLifecycleWithoutHardwareOrDesktopAudio(t *testing.T) {
	s, err := Open([]string{"../../config/sound/default"}, Options{Driver: "alsa", Device: "null", Volume: .7})
	if err != nil {
		t.Fatal(err)
	}
	defer s.Close()
	if !s.Play(presentation.Ready) || !s.Play_progress(50) {
		t.Fatal("shared audio admission failed")
	}
	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
	defer cancel()
	if err := s.Finish(ctx); err != nil {
		t.Fatal(err)
	}
}

func TestMissingPackKeepsGeneratedTonesOnALSANull(t *testing.T) {
	s, err := Open([]string{t.TempDir()}, Options{Driver: "alsa", Device: "null", Volume: .7})
	if s == nil || err == nil {
		t.Fatal(s, err)
	}
	defer s.Close()
	if s.Play(presentation.Ready) || !s.Play_progress(50) {
		t.Fatal("missing cue or generated tone admission")
	}
}