package download

import (
	"context"
	"crypto/aes"
	"crypto/cipher"
	"errors"
	"encoding/hex"
	"io"
	"net/http"
	"net/http/httptest"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"testing"
	"time"

	"golang.org/x/crypto/blowfish"
)

func TestDownloaderHasNoClientTimeout(t *testing.T) {
	d := NewWithOptions(true, false, 0)
	if d.http.Timeout != 0 {
		t.Fatalf("http timeout = %v, want 0 (no global timeout)", d.http.Timeout)
	}
}

func TestDownloaderFile(t *testing.T) {
	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		_, _ = w.Write([]byte("abc123"))
	}))
	defer ts.Close()

	d := New()
	out := filepath.Join(t.TempDir(), "x", "a.bin")
	if err := d.File(context.Background(), ts.URL, out); err != nil {
		t.Fatalf("File() error = %v", err)
	}

	b, err := os.ReadFile(out)
	if err != nil {
		t.Fatalf("ReadFile() error = %v", err)
	}
	if string(b) != "abc123" {
		t.Fatalf("contents = %q, want %q", string(b), "abc123")
	}
}

func TestManifestDetection(t *testing.T) {
	if !isManifestResponse("application/dash+xml", []byte("x")) {
		t.Fatalf("expected dash content-type to be manifest")
	}
	if !isManifestResponse("application/vnd.apple.mpegurl", []byte("x")) {
		t.Fatalf("expected mpegurl content-type to be manifest")
	}
	if !isManifestResponse("application/octet-stream", []byte("<?xml version='1.0'?><MPD></MPD>")) {
		t.Fatalf("expected MPD XML body to be manifest")
	}
	if !isManifestResponse("application/octet-stream", []byte("<MPD type='static'></MPD>")) {
		t.Fatalf("expected MPD body without xml prolog to be manifest")
	}
	if !isManifestResponse("text/plain", []byte("#EXTM3U\n#EXT-X-VERSION:3")) {
		t.Fatalf("expected HLS body to be manifest")
	}
	if isManifestResponse("audio/flac", []byte("fLaC")) {
		t.Fatalf("did not expect flac to be manifest")
	}
}

func TestDeezerBlowfishKeyDerivation(t *testing.T) {
	trackID := "3135556"
	key := deriveDeezerBlowfishKey(trackID)
	if len(key) != 16 {
		t.Fatalf("blowfish key len = %d, want 16", len(key))
	}
}

func TestFileDeezerEncrypted(t *testing.T) {
	trackID := "3135556"
	plain := make([]byte, deezerBFChunkSize+777)
	for i := range plain {
		plain[i] = byte((i * 7) % 251)
	}
	enc := make([]byte, len(plain))
	copy(enc, plain)

	block, err := blowfish.NewCipher(deriveDeezerBlowfishKey(trackID))
	if err != nil {
		t.Fatalf("cipher error: %v", err)
	}
	cbc := cipher.NewCBCEncrypter(block, deezerBFIV)
	cbc.CryptBlocks(enc[:deezerBFChunkSize], enc[:deezerBFChunkSize])

	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		_, _ = w.Write(enc)
	}))
	defer ts.Close()

	d := NewWithOptions(true, false, 0)
	out := filepath.Join(t.TempDir(), "x", "a.flac")
	if err = d.FileDeezerEncrypted(context.Background(), ts.URL, out, trackID); err != nil {
		t.Fatalf("FileDeezerEncrypted() error = %v", err)
	}

	got, err := os.ReadFile(out)
	if err != nil {
		t.Fatalf("ReadFile() error = %v", err)
	}
	if string(got) != string(plain) {
		t.Fatalf("decrypted file mismatch")
	}
}

func TestFileYandexEncrypted(t *testing.T) {
	plain := make([]byte, 8192+333)
	for i := range plain {
		plain[i] = byte((i * 11) % 251)
	}
	keyHex := "00112233445566778899aabbccddeeff"
	key, err := hex.DecodeString(keyHex)
	if err != nil {
		t.Fatalf("DecodeString() error = %v", err)
	}
	block, err := aes.NewCipher(key)
	if err != nil {
		t.Fatalf("NewCipher() error = %v", err)
	}
	enc := make([]byte, len(plain))
	copy(enc, plain)
	stream := cipher.NewCTR(block, make([]byte, aes.BlockSize))
	stream.XORKeyStream(enc, enc)

	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		_, _ = w.Write(enc)
	}))
	defer ts.Close()

	d := NewWithOptions(true, false, 0)
	out := filepath.Join(t.TempDir(), "x", "a.m4a")
	if err = d.FileYandexEncrypted(context.Background(), ts.URL, out, keyHex); err != nil {
		t.Fatalf("FileYandexEncrypted() error = %v", err)
	}

	got, err := os.ReadFile(out)
	if err != nil {
		t.Fatalf("ReadFile() error = %v", err)
	}
	if string(got) != string(plain) {
		t.Fatalf("decrypted file mismatch")
	}
}

func TestDownloaderFileTruncatedResponseRemovesPartialFile(t *testing.T) {
	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		w.Header().Set("Content-Length", "10")
		_, _ = w.Write([]byte("abc"))
	}))
	defer ts.Close()

	d := NewWithOptions(true, false, 0)
	out := filepath.Join(t.TempDir(), "x", "a.bin")
	err := d.File(context.Background(), ts.URL, out)
	if err == nil || !errors.Is(err, io.ErrUnexpectedEOF) {
		t.Fatalf("expected unexpected EOF, got %v", err)
	}
	if _, statErr := os.Stat(out); !errors.Is(statErr, os.ErrNotExist) {
		t.Fatalf("expected no partial file, stat err=%v", statErr)
	}
}

func TestFileDeezerEncryptedTruncatedResponseRemovesPartialFile(t *testing.T) {
	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		w.Header().Set("Content-Length", "4096")
		_, _ = w.Write([]byte("short"))
	}))
	defer ts.Close()

	d := NewWithOptions(true, false, 0)
	out := filepath.Join(t.TempDir(), "x", "a.flac")
	err := d.FileDeezerEncrypted(context.Background(), ts.URL, out, "3135556")
	if err == nil || !errors.Is(err, io.ErrUnexpectedEOF) {
		t.Fatalf("expected unexpected EOF, got %v", err)
	}
	if _, statErr := os.Stat(out); !errors.Is(statErr, os.ErrNotExist) {
		t.Fatalf("expected no partial file, stat err=%v", statErr)
	}
}

func TestFileDeezerEncryptedBadStatus(t *testing.T) {
	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		w.WriteHeader(http.StatusForbidden)
	}))
	defer ts.Close()

	d := NewWithOptions(true, false, 0)
	out := filepath.Join(t.TempDir(), "x", "a.flac")
	err := d.FileDeezerEncrypted(context.Background(), ts.URL, out, "3135556")
	if err == nil || !strings.Contains(err.Error(), "status=403") {
		t.Fatalf("expected status error, got %v", err)
	}
}

func TestFileYandexEncryptedBadKey(t *testing.T) {
	d := NewWithOptions(true, false, 0)
	out := filepath.Join(t.TempDir(), "x", "a.m4a")
	err := d.FileYandexEncrypted(context.Background(), "https://example.com/file", out, "abcd")
	if err == nil || !strings.Contains(err.Error(), "invalid yandex key length") {
		t.Fatalf("expected key length error, got %v", err)
	}
}

func TestDownloaderFileContextCancellationRemovesPartialFile(t *testing.T) {
	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Type", "application/octet-stream")
		_, _ = w.Write([]byte("partial-data"))
		if f, ok := w.(http.Flusher); ok {
			f.Flush()
		}
		<-r.Context().Done()
	}))
	defer ts.Close()

	d := NewWithOptions(true, false, 0)
	out := filepath.Join(t.TempDir(), "x", "cancel.bin")
	ctx, cancel := context.WithTimeout(context.Background(), 60*time.Millisecond)
	defer cancel()
	err := d.File(ctx, ts.URL, out)
	if err == nil {
		t.Fatalf("expected context cancellation error")
	}
	if _, statErr := os.Stat(out); !errors.Is(statErr, os.ErrNotExist) {
		t.Fatalf("expected no partial file, stat err=%v", statErr)
	}
}

func TestStreamManifestWithFFmpegMissing(t *testing.T) {
	d := NewWithOptions(true, false, 0)
	t.Setenv("PATH", "")
	err := d.streamManifestWithFFmpeg(context.Background(), "https://example.com/live.m3u8", filepath.Join(t.TempDir(), "out.m4a"), false)
	if err == nil || !strings.Contains(strings.ToLower(err.Error()), "ffmpeg not found") {
		t.Fatalf("expected ffmpeg missing error, got %v", err)
	}
}

func TestStreamManifestWithFFmpegFailureRemovesPartialFile(t *testing.T) {
	if _, err := exec.LookPath("ffmpeg"); err != nil {
		t.Skip("ffmpeg not installed")
	}
	d := NewWithOptions(true, false, 0)
	out := filepath.Join(t.TempDir(), "out.m4a")
	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()
	err := d.streamManifestWithFFmpeg(ctx, "https://127.0.0.1:1/unreachable.m3u8", out, false)
	if err == nil || !strings.Contains(err.Error(), "ffmpeg stream copy failed") {
		t.Fatalf("expected ffmpeg failure error, got %v", err)
	}
	if _, statErr := os.Stat(out); !errors.Is(statErr, os.ErrNotExist) {
		t.Fatalf("expected no partial file after ffmpeg failure, stat err=%v", statErr)
	}
}

func TestParseFFmpegDurationLine(t *testing.T) {
	totalMS, ok := parseFFmpegDurationLine("  Duration: 00:04:52.57, start: 0.000000, bitrate: 975 kb/s")
	if !ok {
		t.Fatalf("expected duration parse to succeed")
	}
	if want := int64(292570); totalMS != want {
		t.Fatalf("unexpected duration ms: got=%d want=%d", totalMS, want)
	}
}

func TestParseFFmpegDurationBitrateBPS(t *testing.T) {
	bps, ok := parseFFmpegDurationBitrateBPS("  Duration: 00:04:52.57, start: 0.000000, bitrate: 975 kb/s")
	if !ok {
		t.Fatalf("expected bitrate parse to succeed")
	}
	if want := int64(975000); bps != want {
		t.Fatalf("unexpected bitrate: got=%d want=%d", bps, want)
	}
}

func TestParseFFmpegProgressBitrateBPS(t *testing.T) {
	bps, ok := parseFFmpegProgressBitrateBPS("bitrate=1706.8kbits/s")
	if !ok {
		t.Fatalf("expected progress bitrate parse to succeed")
	}
	if want := int64(1706800); bps != want {
		t.Fatalf("unexpected bitrate: got=%d want=%d", bps, want)
	}
}

func TestParseFFmpegTotalSize(t *testing.T) {
	size, ok := parseFFmpegTotalSize("total_size=1234567")
	if !ok {
		t.Fatalf("expected total_size parse to succeed")
	}
	if want := int64(1234567); size != want {
		t.Fatalf("unexpected total_size: got=%d want=%d", size, want)
	}
}

func TestParseFFmpegOutTime(t *testing.T) {
	currentMS, ok := parseFFmpegOutTime("out_time=00:01:02.340000")
	if !ok {
		t.Fatalf("expected out_time parse to succeed")
	}
	if want := int64(62340); currentMS != want {
		t.Fatalf("unexpected out_time ms: got=%d want=%d", currentMS, want)
	}
}

func TestParseClockDurationMSInvalid(t *testing.T) {
	if _, ok := parseClockDurationMS("bad"); ok {
		t.Fatalf("expected invalid duration to fail")
	}
	if _, ok := parseClockDurationMS("00:12"); ok {
		t.Fatalf("expected short duration to fail")
	}
}

func TestEstimateTotalBytesFromBitrate(t *testing.T) {
	total := estimateTotalBytesFromBitrate(10000, 1600000)
	if want := int64(2000000); total != want {
		t.Fatalf("unexpected estimate from bitrate: got=%d want=%d", total, want)
	}
}

func TestEstimateTotalBytesFromProgress(t *testing.T) {
	total := estimateTotalBytesFromProgress(10000, 2500, 500000)
	if want := int64(2000000); total != want {
		t.Fatalf("unexpected estimate from progress: got=%d want=%d", total, want)
	}
}

func TestBuildFFmpegStreamArgsAudioOnly(t *testing.T) {
	args := buildFFmpegStreamArgs("https://example.com/master.m3u8", "/tmp/out.m4a", false)
	if !containsArgPair(args, "-map", "0:a:0") {
		t.Fatalf("expected audio map in args: %v", args)
	}
	if containsArgPair(args, "-map", "0:v:0?") {
		t.Fatalf("did not expect video map in audio-only args: %v", args)
	}
	if containsArgPair(args, "-map", "0") {
		t.Fatalf("did not expect broad map=0 in args: %v", args)
	}
}

func TestBuildFFmpegStreamArgsIncludeVideo(t *testing.T) {
	args := buildFFmpegStreamArgs("https://example.com/master.m3u8", "/tmp/out.mp4", true)
	if !containsArgPair(args, "-map", "0:v:0?") {
		t.Fatalf("expected video map in args: %v", args)
	}
	if !containsArgPair(args, "-map", "0:a:0?") {
		t.Fatalf("expected audio map in args: %v", args)
	}
	if containsArgPair(args, "-map", "0") {
		t.Fatalf("did not expect broad map=0 in args: %v", args)
	}
}

func containsArgPair(args []string, key, value string) bool {
	for i := 0; i+1 < len(args); i++ {
		if args[i] == key && args[i+1] == value {
			return true
		}
	}
	return false
}