package media

import (
	"context"
	"errors"
	"math"
	"os"
	"os/exec"
	"path/filepath"
	"sort"
	"strconv"
	"strings"
	"testing"
	"time"
)

// The real thing, when ffmpeg is here: a generated clip goes through as H.264 and comes out
// as a playlist of segments, the status follows it to the end, and closing removes it all.
func TestStreamWithFFmpeg(t *testing.T) {
	if _, err := exec.LookPath("ffmpeg"); err != nil {
		t.Skip("no ffmpeg")
	}
	c := Probe(context.Background())
	if c.Error != "" {
		t.Skip(c.Error)
	}
	if EngineFor(c, "h264") == "" {
		t.Skip("nothing here encodes h264")
	}
	dir := t.TempDir()
	clip := filepath.Join(dir, "clip.mp4")
	out, err := exec.Command("ffmpeg", "-nostdin", "-v", "error", "-f", "lavfi", "-i", "testsrc=size=640x360:rate=25:duration=9", "-f", "lavfi", "-i", "sine=frequency=440:duration=9",
		"-c:v", "mpeg4", "-q:v", "5", "-c:a", "aac", "-shortest", clip).CombinedOutput()
	if err != nil {
		t.Skipf("could not make a clip: %s", out)
	}
	src, err := Inspect(context.Background(), c, clip, false)
	if err != nil || src.Video == nil || src.Audio == nil || src.Video.Codec != "mpeg4" || src.Duration < 8 {
		t.Fatalf("inspect: %+v %v", src, err)
	}
	m := NewStreamer(dir, "hamlab", 2)
	s, err := m.Open(context.Background(), c, false, clip, "h264", "480p", src)
	if err != nil {
		t.Fatal(err)
	}
	if s.Width != 640 || s.Height != 360 || s.Engine == "" || !s.Seekable {
		t.Fatalf("stream: %+v", s)
	}
	if _, ok := s.File("index.m3u8"); !ok {
		t.Fatal("no playlist")
	}
	if pl := string(s.Playlist()); !strings.Contains(pl, "#EXT-X-PLAYLIST-TYPE:VOD") || !strings.HasSuffix(pl, "#EXT-X-ENDLIST\n") || strings.Count(pl, "#EXTINF") != 3 {
		t.Fatalf("playlist for 9 s:\n%s", pl)
	}
	if !exists(s.segPath(0)) {
		t.Fatal("Open returned before the first segment")
	}
	for _, bad := range []string{"../x", "progress", "seg1.m4s", "index.m3u8/", "init.mp4.tmp"} {
		if _, ok := s.File(bad); ok {
			t.Fatalf("%q must not be served", bad)
		}
	}
	// the same request is the same stream
	if again, err := m.Open(context.Background(), c, false, clip, "h264", "480p", src); err != nil || again.ID != s.ID {
		t.Fatal("not reused")
	}
	var st StreamStatus
	for i := 0; i < 120; i++ {
		st = s.Status()
		if st.Done || st.Error != "" {
			break
		}
		time.Sleep(250 * time.Millisecond)
	}
	if !st.Done || st.Error != "" || st.Segments != 3 || st.Progress < 8 {
		t.Fatalf("status at the end: %+v", st)
	}
	if init, _ := s.File("init.mp4"); !exists(init) {
		t.Fatal("no init segment")
	}
	m.Close(s.ID)
	if _, ok := m.Find(s.ID); ok || exists(s.dir) {
		t.Fatal("close must forget and remove")
	}
	// an unplayable source is a DecodeError, and leaves nothing behind
	bad := filepath.Join(dir, "bad.mkv")
	_ = os.WriteFile(bad, []byte("not a video"), 0o644)
	if _, err := Inspect(context.Background(), c, bad, false); err == nil {
		t.Fatal("inspect of garbage")
	}
	if left, _ := os.ReadDir(m.dir); len(left) != 0 {
		t.Fatalf("left behind: %v", left)
	}
}

// A seek ahead of the encode: the run moves there, the segment comes from a run that started
// at it, the gaps are filled afterwards, and the segments of the different runs, joined, are
// one film with no hole and nothing twice beyond a frame at a join.
func TestSeekRestartsTheEncode(t *testing.T) {
	if _, err := exec.LookPath("ffmpeg"); err != nil {
		t.Skip("no ffmpeg")
	}
	c := Probe(context.Background())
	if c.Error != "" || EngineFor(c, "h264") == "" {
		t.Skip("nothing here encodes h264")
	}
	dir := t.TempDir()
	clip := filepath.Join(dir, "clip.mkv")
	// big and busy enough that the first run is still near the start when the seek comes
	out, err := exec.Command("ffmpeg", "-nostdin", "-v", "error", "-f", "lavfi", "-i", "testsrc2=size=1920x1080:rate=30000/1001:duration=64", "-f", "lavfi", "-i", "sine=frequency=440:duration=64",
		"-c:v", "libx264", "-preset", "ultrafast", "-g", "250", "-c:a", "libopus", "-shortest", clip).CombinedOutput()
	if err != nil {
		t.Skipf("could not make a clip: %s", out)
	}
	src, err := Inspect(context.Background(), c, clip, false)
	if err != nil {
		t.Fatal(err)
	}
	m := NewStreamer(dir, "hamlab", 2)
	s, err := m.Open(context.Background(), c, false, clip, "h264", "1080p", src)
	if err != nil {
		t.Fatal(err)
	}
	defer m.Close(s.ID)
	if s.n != 16 {
		t.Fatalf("%d segments for 64 s", s.n)
	}
	ctx, cancel := context.WithTimeout(context.Background(), 60*time.Second)
	defer cancel()
	p, err := s.Segment(ctx, 12)
	if err != nil {
		t.Fatal(err)
	}
	s.mu.Lock()
	from := s.run.from
	s.mu.Unlock()
	if from != 12 {
		t.Fatalf("the run after the seek starts at segment %d, not 12 (the first run was already there?)", from)
	}
	if got := firstVideoPTS(t, filepath.Join(s.dir, "init.mp4"), p); math.Abs(got-(48+tsBase)) > 0.05 {
		t.Fatalf("segment 12 starts at %.3f, want %d", got, 48+tsBase)
	}
	if _, err := s.Segment(ctx, 16); !errors.Is(err, ErrNotInFilm) {
		t.Fatalf("past the end: %v", err)
	}
	var st StreamStatus
	for i := 0; i < 480; i++ {
		if st = s.Status(); st.Done || st.Error != "" {
			break
		}
		time.Sleep(250 * time.Millisecond)
	}
	if !st.Done || st.Segments != 16 {
		t.Fatalf("not filled in: %+v", st)
	}
	// the joined film: every segment in order behind the one init segment
	joined := filepath.Join(dir, "joined.mp4")
	f, _ := os.Create(joined)
	for _, n := range append([]string{"init.mp4"}, segNames(16)...) {
		b, err := os.ReadFile(filepath.Join(s.dir, n))
		if err != nil {
			t.Fatal(err)
		}
		_, _ = f.Write(b)
	}
	f.Close()
	if out, err := exec.Command("ffmpeg", "-v", "error", "-i", joined, "-f", "null", "-").CombinedOutput(); err != nil || strings.Contains(string(out), "error") {
		t.Fatalf("the joined film doesn't decode cleanly: %v %s", err, out)
	}
	pts := videoPTS(t, joined)
	if len(pts) < 1900 || pts[0] > tsBase+0.1 || pts[len(pts)-1] < tsBase+63.5 {
		t.Fatalf("%d frames, %.3f .. %.3f", len(pts), pts[0], pts[len(pts)-1])
	}
	for i := 1; i < len(pts); i++ {
		if d := pts[i] - pts[i-1]; d > 0.07 { // a frame is 0.033; a join may lose up to one
			t.Fatalf("a hole of %.3f s at %.3f", d, pts[i-1])
		}
	}
}

func segNames(n int) []string {
	var out []string
	for i := 0; i < n; i++ {
		out = append(out, "seg"+strconv.FormatInt(int64(100000+i), 10)[1:]+".m4s")
	}
	return out
}

func videoPTS(t *testing.T, file string) []float64 {
	out, err := exec.Command("ffprobe", "-v", "error", "-select_streams", "v", "-show_entries", "packet=pts_time", "-of", "csv=p=0", file).Output()
	if err != nil {
		t.Fatal(err)
	}
	var pts []float64
	seen := map[string]bool{}
	for _, l := range strings.Fields(string(out)) {
		if seen[l] { // the same frame from both runs at a join
			continue
		}
		seen[l] = true
		if v, err := strconv.ParseFloat(l, 64); err == nil {
			pts = append(pts, v)
		}
	}
	sort.Float64s(pts)
	return pts
}

func firstVideoPTS(t *testing.T, init, seg string) float64 {
	dir := t.TempDir()
	j := filepath.Join(dir, "one.mp4")
	a, _ := os.ReadFile(init)
	b, _ := os.ReadFile(seg)
	_ = os.WriteFile(j, append(a, b...), 0o644)
	pts := videoPTS(t, j)
	if len(pts) == 0 {
		t.Fatal("no frames in the segment")
	}
	return pts[0]
}