streamrip-go/internal/provider/qobuz/client.go

package qobuz

import (
	"bytes"
	"context"
	"crypto/aes"
	"crypto/cipher"
	"crypto/md5"
	"crypto/sha256"
	"encoding/base64"
	"encoding/hex"
	"encoding/json"
	"errors"
	"fmt"
	"hash"
	"io"
	"net/http"
	"net/url"
	"os"
	"path/filepath"
	"regexp"
	"sort"
	"strconv"
	"strings"
	"sync"
	"time"

	"streamrip-go/internal/config"
	"streamrip-go/internal/jsonutil"
	"streamrip-go/internal/netutil"
	"streamrip-go/internal/provider"
	"streamrip-go/internal/ratelimit"
	"streamrip-go/internal/verbose"

	"github.com/vbauerster/mpb/v8"
	"github.com/vbauerster/mpb/v8/decor"
	"golang.org/x/crypto/hkdf"
)

const baseURL = "https://www.qobuz.com/api.json/0.2"

const (
	mobileUserAgent    = "Dalvik/2.1.0 (Linux; U; Android 9; Nexus 6P Build/PQ3A.190801.002) QobuzMobileAndroid/9.7.0.3-b26022717"
	mobileAppVersion   = "9.7.0.3"
	mobileSessionProf  = "qbz-1"
	mobileSegmentTries = 3
)

var qobuzUUIDBytes = []byte{
	0x3b, 0x42, 0x12, 0x92, 0x56, 0xf3, 0x5f, 0x75,
	0x92, 0x36, 0x63, 0xb6, 0x9a, 0x1f, 0x52, 0xb2,
}

var (
	errMissingCredentials = errors.New("missing qobuz credentials")
	errNotLoggedIn        = errors.New("qobuz client not logged in")
)

type Client struct {
	cfg        *config.Config
	http       *http.Client
	streamHTTP *http.Client
	limiter    *ratelimit.Limiter
	baseURL    string
	fetchCfg   func(ctx context.Context) (string, []string, error)
	// authMu guards loggedIn and the login/refresh path, which download
	// workers can reach concurrently.
	authMu   sync.Mutex
	loggedIn bool
	secret   string
	uat      string

	mobileMu          sync.Mutex
	mobileAccessToken string
	mobileSessionID   string
	mobileSessionInfo string
	mobileKEK         []byte
}

type mobileFileURL struct {
	URL         string  `json:"url"`
	URLTemplate string  `json:"url_template"`
	NSegments   int     `json:"n_segments"`
	FormatID    int     `json:"format_id"`
	MimeType    string  `json:"mime_type"`
	Sampling    float64 `json:"sampling_rate"`
	BitDepth    int     `json:"bits_depth"`
	Key         string  `json:"key"`
}

func New(cfg *config.Config) *Client {
	return &Client{
		cfg:  cfg,
		http: netutil.NewHTTPClient(30*time.Second, cfg.Session.Downloads.VerifySSL, cfg.Session.Downloads.MaxConnections),
		// Separate client with no Timeout for streaming a whole track body.
		// http.Client.Timeout bounds the entire request including the body
		// read, so the 30s API client aborted any track that took longer than
		// 30s to stream. internal/download does the same for this reason.
		streamHTTP: netutil.NewHTTPClient(0, cfg.Session.Downloads.VerifySSL, cfg.Session.Downloads.MaxConnections),
		limiter:    ratelimit.New(cfg.Session.Downloads.RequestsPerMinute, cfg.Session.Downloads.MaxConnections),
		baseURL:    baseURL,
		fetchCfg:   nil,
	}
}

func (c *Client) Source() string {
	return "qobuz"
}

func (c *Client) LoggedIn() bool {
	c.authMu.Lock()
	defer c.authMu.Unlock()
	return c.loggedIn
}

func (c *Client) Login(ctx context.Context) error {
	c.authMu.Lock()
	defer c.authMu.Unlock()
	q := &c.cfg.Session.Qobuz
	q.EmailOrUserID = strings.TrimSpace(q.EmailOrUserID)
	q.PasswordOrToken = strings.TrimSpace(q.PasswordOrToken)
	if q.EmailOrUserID == "" || q.PasswordOrToken == "" {
		return errMissingCredentials
	}

	refreshed := false
	if err := c.ensureAppCredentials(ctx, q); err != nil {
		return err
	}

	loginOnce := func() (map[string]any, int, error) {
		headers := map[string]string{"X-App-Id": q.AppID}
		params := url.Values{}
		params.Set("app_id", q.AppID)
		if q.UseAuthToken {
			params.Set("user_id", q.EmailOrUserID)
			params.Set("user_auth_token", q.PasswordOrToken)
		} else {
			params.Set("email", q.EmailOrUserID)
			params.Set("password", q.PasswordOrToken)
		}
		return c.apiRequest(ctx, "user/login", params, headers)
	}

	resp, status, err := loginOnce()
	if err != nil {
		return err
	}
	if status != http.StatusOK && !refreshed {
		if refreshErr := c.refreshAppCredentials(ctx, q); refreshErr == nil {
			refreshed = true
			resp, status, err = loginOnce()
			if err != nil {
				return err
			}
		}
	}
	if status != http.StatusOK {
		return fmt.Errorf("qobuz login failed: status=%d body=%v", status, resp)
	}

	uat, _ := resp["user_auth_token"].(string)
	if uat == "" {
		return fmt.Errorf("qobuz login missing user_auth_token")
	}

	headers := map[string]string{"X-App-Id": q.AppID, "X-User-Auth-Token": uat}
	validSecret, err := c.getValidSecret(ctx, q.Secrets, headers)
	if err != nil && !refreshed {
		if refreshErr := c.refreshAppCredentials(ctx, q); refreshErr == nil {
			refreshed = true
			headers["X-App-Id"] = q.AppID
			validSecret, err = c.getValidSecret(ctx, q.Secrets, headers)
		}
	}
	if err != nil {
		return err
	}

	c.secret = validSecret
	c.uat = uat
	c.loggedIn = true

	return nil
}

func (c *Client) ensureAppCredentials(ctx context.Context, q *config.QobuzConfig) error {
	q.AppID = strings.TrimSpace(q.AppID)
	if q.AppID != "" && len(q.Secrets) > 0 {
		return nil
	}
	return c.refreshAppCredentials(ctx, q)
}

func (c *Client) refreshAppCredentials(ctx context.Context, q *config.QobuzConfig) error {
	fetch := c.fetchCfg
	if fetch == nil {
		fetch = c.fetchAppIDAndSecrets
	}
	appID, secrets, err := fetch(ctx)
	if err != nil {
		return err
	}
	q.AppID = strings.TrimSpace(appID)
	if q.AppID == "" {
		return errors.New("qobuz app credential refresh returned empty app_id")
	}
	clean := make([]string, 0, len(secrets))
	for _, s := range secrets {
		if v := strings.TrimSpace(s); v != "" {
			clean = append(clean, v)
		}
	}
	if len(clean) == 0 {
		return errors.New("qobuz app credential refresh returned no secrets")
	}
	q.Secrets = append([]string(nil), clean...)
	refreshedAppID := q.AppID
	if err := c.cfg.UpdateTokens(func(file, session *config.ConfigData) {
		file.Qobuz.AppID = refreshedAppID
		file.Qobuz.Secrets = append([]string(nil), clean...)
	}); err != nil {
		verbose.Printf(verbose.V, "qobuz: could not persist refreshed credentials: %v\n", err)
	}
	return nil
}

func (c *Client) GetMetadata(ctx context.Context, item, mediaType string) (map[string]any, error) {
	if !c.LoggedIn() {
		return nil, errNotLoggedIn
	}
	if mediaType == "playlist" {
		return c.getPlaylist(ctx, item)
	}
	if mediaType == "label" {
		return c.getLabel(ctx, item)
	}
	if mediaType == "artist" {
		return c.getArtist(ctx, item)
	}

	params := url.Values{}
	params.Set("app_id", c.cfg.Session.Qobuz.AppID)
	params.Set(mediaType+"_id", item)
	params.Set("limit", "500")
	params.Set("offset", "0")

	switch mediaType {
	case "playlist":
		params.Set("extra", "tracks")
	case "label":
		params.Set("extra", "albums")
	}

	resp, status, err := c.apiRequest(ctx, mediaType+"/get", params, c.authHeaders())
	if err != nil {
		return nil, err
	}
	if status != http.StatusOK {
		msg, _ := resp["message"].(string)
		if msg == "" {
			msg = "non-streamable"
		}
		return nil, fmt.Errorf("metadata error: %s", msg)
	}

	return resp, nil
}

func (c *Client) Search(ctx context.Context, mediaType, query string, limit int) ([]map[string]any, error) {
	if !c.LoggedIn() {
		return nil, errNotLoggedIn
	}
	if limit <= 0 {
		limit = 100
	}

	params := url.Values{}
	params.Set("query", query)
	params.Set("limit", strconv.Itoa(limit))

	resp, status, err := c.apiRequest(ctx, mediaType+"/search", params, c.authHeaders())
	if err != nil {
		return nil, err
	}
	if status != http.StatusOK {
		return nil, fmt.Errorf("search failed: status=%d", status)
	}

	return []map[string]any{resp}, nil
}

func (c *Client) GetDownloadable(ctx context.Context, item string, quality int) (*provider.Downloadable, error) {
	if !c.LoggedIn() {
		return nil, errNotLoggedIn
	}
	if quality < 1 || quality > 4 {
		quality = c.cfg.Session.Qobuz.Quality
	}

	formatID := qualityMap(quality)
	requestTS := strconv.FormatInt(time.Now().Unix(), 10)
	sigRaw := "trackgetFileUrlformat_id" + strconv.Itoa(formatID) + "intentstreamtrack_id" + item + requestTS + c.secret
	hash := md5.Sum([]byte(sigRaw))
	requestSig := hex.EncodeToString(hash[:])

	params := url.Values{}
	params.Set("request_ts", requestTS)
	params.Set("request_sig", requestSig)
	params.Set("track_id", item)
	params.Set("format_id", strconv.Itoa(formatID))
	params.Set("intent", "stream")

	resp, status, err := c.apiRequest(ctx, "track/getFileUrl", params, c.authHeaders())
	if err != nil {
		return nil, err
	}
	if status != http.StatusOK {
		return nil, fmt.Errorf("downloadable lookup failed: status=%d body=%v", status, resp)
	}

	streamURL, _ := resp["url"].(string)
	streamURL = strings.TrimSpace(streamURL)
	if streamURL == "" {
		return nil, fmt.Errorf("track is not streamable")
	}

	ext := qobuzDownloadExtension(resp, quality, streamURL)
	profile := qobuzAudioProfile(resp, quality, ext)

	return &provider.Downloadable{
		URL:       streamURL,
		Extension: ext,
		Source:    "qobuz",
		Audio:     profile,
	}, nil
}

func qobuzDownloadExtension(resp map[string]any, quality int, streamURL string) string {
	if parsed, err := url.Parse(strings.TrimSpace(streamURL)); err == nil {
		p := strings.ToLower(parsed.Path)
		if strings.HasSuffix(p, ".flac") {
			return "flac"
		}
		if strings.HasSuffix(p, ".mp3") {
			return "mp3"
		}
	}

	mimeType, _ := resp["mime_type"].(string)
	mimeType = strings.ToLower(strings.TrimSpace(mimeType))
	if strings.Contains(mimeType, "flac") {
		return "flac"
	}
	if strings.Contains(mimeType, "mpeg") || strings.Contains(mimeType, "mp3") {
		return "mp3"
	}

	if formatID, ok := intValue(resp["format_id"]); ok {
		if formatID == 5 {
			return "mp3"
		}
		if formatID > 5 {
			return "flac"
		}
	}

	if quality > 1 {
		return "flac"
	}
	return "mp3"
}

func qobuzAudioProfile(resp map[string]any, requestedQuality int, ext string) provider.AudioProfile {
	exactBitDepth, _ := intValue(firstNonNil(resp["bit_depth"], resp["bits_depth"], resp["maximum_bit_depth"]))
	exactSampling, _ := floatValue(firstNonNil(resp["sampling_rate"], resp["sample_rate"], resp["maximum_sampling_rate"]))
	if formatID, ok := intValue(resp["format_id"]); ok {
		switch formatID {
		case 5:
			if exactBitDepth == 0 {
				exactBitDepth = 16
			}
			if exactSampling == 0 {
				exactSampling = 44.1
			}
			return provider.AudioProfile{
				Container:    "MP3",
				Codec:        "MP3",
				Quality:      "HIGH",
				BitDepth:     exactBitDepth,
				SamplingRate: formatSamplingRate(exactSampling),
				BitrateKbps:  320,
			}
		case 6:
			if exactBitDepth == 0 {
				exactBitDepth = 16
			}
			if exactSampling == 0 {
				exactSampling = 44.1
			}
			return provider.AudioProfile{
				Container:    "FLAC",
				Codec:        "FLAC",
				Quality:      "LOSSLESS",
				BitDepth:     exactBitDepth,
				SamplingRate: formatSamplingRate(exactSampling),
			}
		case 7:
			if exactBitDepth == 0 {
				exactBitDepth = 24
			}
			return provider.AudioProfile{
				Container:    "FLAC",
				Codec:        "FLAC",
				Quality:      "HI_RES",
				BitDepth:     exactBitDepth,
				SamplingRate: formatSamplingRate(exactSampling),
			}
		case 27:
			if exactBitDepth == 0 {
				exactBitDepth = 24
			}
			return provider.AudioProfile{
				Container:    "FLAC",
				Codec:        "FLAC",
				Quality:      "HI_RES",
				BitDepth:     exactBitDepth,
				SamplingRate: formatSamplingRate(exactSampling),
			}
		}
	}

	if strings.EqualFold(ext, "mp3") {
		bitrate := 128
		if requestedQuality >= 1 {
			bitrate = 320
		}
		return provider.AudioProfile{
			Container:    "MP3",
			Codec:        "MP3",
			Quality:      "HIGH",
			BitDepth:     16,
			SamplingRate: "44.1",
			BitrateKbps:  bitrate,
		}
	}

	quality := "LOSSLESS"
	bitDepth := 16
	sampling := "44.1"
	if requestedQuality >= 4 {
		quality = "HI_RES"
		bitDepth = 24
		sampling = "192"
	} else if requestedQuality >= 3 {
		quality = "HI_RES"
		bitDepth = 24
		sampling = "96"
	}
	return provider.AudioProfile{
		Container:    "FLAC",
		Codec:        "FLAC",
		Quality:      quality,
		BitDepth:     bitDepth,
		SamplingRate: sampling,
	}
}

func firstNonNil(vals ...any) any {
	for _, v := range vals {
		if v != nil {
			return v
		}
	}
	return nil
}

func formatSamplingRate(v float64) string {
	if v <= 0 {
		return ""
	}
	return strconv.FormatFloat(v, 'f', -1, 64)
}

func (c *Client) Close() error {
	return nil
}

func (c *Client) DownloadTrackFallback(ctx context.Context, trackID string, quality int, outputPath string) error {
	q := &c.cfg.Session.Qobuz
	if strings.TrimSpace(q.EmailOrUserID) == "" || strings.TrimSpace(q.PasswordOrToken) == "" || q.UseAuthToken {
		return errors.New("qobuz mobile fallback requires email/password credentials")
	}
	if quality < 1 || quality > 4 {
		quality = q.Quality
	}
	formatID := qualityMap(quality)

	if err := c.ensureMobileSession(ctx); err != nil {
		return err
	}
	fileURL, err := c.mobileGetFileURL(ctx, trackID, formatID)
	if err != nil {
		return err
	}

	if err = os.MkdirAll(filepath.Dir(outputPath), 0o755); err != nil {
		return err
	}
	out, err := os.Create(outputPath)
	if err != nil {
		return err
	}
	success := false
	defer func() {
		_ = out.Close()
		if !success {
			_ = os.Remove(outputPath)
		}
	}()

	progress := mpb.New(mpb.WithWidth(40), mpb.WithOutput(os.Stderr))
	defer progress.Wait()
	desc := shortenName(filepath.Base(outputPath), 54)
	bar := progress.AddSpinner(
		0,
		mpb.PrependDecorators(
			decor.Name(desc+" ", decor.WC{W: 56, C: decor.DSyncWidth | decor.DindentRight}),
		),
		mpb.AppendDecorators(
			decor.CurrentKibiByte("% .1f", decor.WCSyncWidthR),
			decor.Name(" | ", decor.WCSyncWidth),
			decor.Elapsed(decor.ET_STYLE_GO, decor.WCSyncWidthR),
		),
		mpb.BarRemoveOnComplete(),
	)
	defer func() {
		if !success {
			bar.Abort(true)
		}
		bar.SetTotal(-1, true)
	}()

	if strings.TrimSpace(fileURL.URL) != "" && fileURL.NSegments == 0 {
		err = c.mobileCopyURLToWriter(ctx, strings.TrimSpace(fileURL.URL), out, bar)
		if err != nil {
			return err
		}
		success = true
		return nil
	}
	if strings.TrimSpace(fileURL.URLTemplate) == "" {
		return errors.New("qobuz mobile fallback: no download URL available")
	}

	var trackKey []byte
	if strings.TrimSpace(fileURL.Key) != "" {
		trackKey, err = c.mobileDeriveTrackKey(fileURL.Key)
		if err != nil {
			return fmt.Errorf("derive mobile track key: %w", err)
		}
	}

	nSegs := fileURL.NSegments
	if nSegs == 0 {
		nSegs = 1
	}
	initURL := strings.Replace(fileURL.URLTemplate, "$SEGMENT$", "0", 1)
	initData, err := c.mobileDownloadSegment(ctx, initURL)
	if err != nil {
		return fmt.Errorf("download init segment: %w", err)
	}

	if hdr := extractFLACHeader(initData); hdr != nil {
		if _, err = out.Write(hdr); err != nil {
			return err
		}
		bar.IncrBy(len(hdr))
	} else {
		if _, err = out.Write(initData); err != nil {
			return err
		}
		bar.IncrBy(len(initData))
	}

	for seg := 1; seg <= nSegs; seg++ {
		segURL := strings.Replace(fileURL.URLTemplate, "$SEGMENT$", strconv.Itoa(seg), 1)
		data, dlErr := c.mobileDownloadSegment(ctx, segURL)
		if dlErr != nil {
			return fmt.Errorf("download segment %d: %w", seg, dlErr)
		}
		frames := extractFrames(data, trackKey)
		if _, err = out.Write(frames); err != nil {
			return err
		}
		bar.IncrBy(len(frames))
	}
	if err = out.Sync(); err != nil {
		return err
	}
	success = true
	return nil
}

func (c *Client) getPlaylist(ctx context.Context, playlistID string) (map[string]any, error) {
	pageLimit := 500
	params := url.Values{}
	params.Set("app_id", c.cfg.Session.Qobuz.AppID)
	params.Set("playlist_id", playlistID)
	params.Set("limit", strconv.Itoa(pageLimit))
	params.Set("offset", "0")
	params.Set("extra", "tracks")

	resp, status, err := c.apiRequest(ctx, "playlist/get", params, c.authHeaders())
	if err != nil {
		return nil, err
	}
	if status != http.StatusOK {
		return nil, fmt.Errorf("playlist/get failed: status=%d", status)
	}

	total, _ := intValue(resp["tracks_count"])
	if total <= pageLimit {
		return resp, nil
	}

	tracksObj, ok := mapValue(resp["tracks"])
	if !ok {
		return resp, nil
	}
	items, ok := tracksObj["items"].([]any)
	if !ok {
		return resp, nil
	}

	for offset := pageLimit; offset < total; offset += pageLimit {
		pageParams := url.Values{}
		pageParams.Set("app_id", c.cfg.Session.Qobuz.AppID)
		pageParams.Set("playlist_id", playlistID)
		pageParams.Set("limit", strconv.Itoa(pageLimit))
		pageParams.Set("offset", strconv.Itoa(offset))
		pageParams.Set("extra", "tracks")

		pageResp, pageStatus, pageErr := c.apiRequest(ctx, "playlist/get", pageParams, c.authHeaders())
		if pageErr != nil {
			return nil, pageErr
		}
		if pageStatus != http.StatusOK {
			return nil, fmt.Errorf("playlist/get pagination failed: status=%d offset=%d", pageStatus, offset)
		}
		pageTracks, ok := mapValue(pageResp["tracks"])
		if !ok {
			continue
		}
		pageItems, ok := pageTracks["items"].([]any)
		if !ok {
			continue
		}
		items = append(items, pageItems...)
	}

	tracksObj["items"] = items
	resp["tracks"] = tracksObj
	return resp, nil
}

func (c *Client) getLabel(ctx context.Context, labelID string) (map[string]any, error) {
	pageLimit := 500
	params := url.Values{}
	params.Set("app_id", c.cfg.Session.Qobuz.AppID)
	params.Set("label_id", labelID)
	params.Set("limit", strconv.Itoa(pageLimit))
	params.Set("offset", "0")
	params.Set("extra", "albums")

	resp, status, err := c.apiRequest(ctx, "label/get", params, c.authHeaders())
	if err != nil {
		return nil, err
	}
	if status != http.StatusOK {
		return nil, fmt.Errorf("label/get failed: status=%d", status)
	}

	total, _ := intValue(resp["albums_count"])
	if total <= pageLimit {
		return resp, nil
	}

	albumsObj, ok := mapValue(resp["albums"])
	if !ok {
		return resp, nil
	}
	items, ok := albumsObj["items"].([]any)
	if !ok {
		return resp, nil
	}

	for offset := pageLimit; offset < total; offset += pageLimit {
		pageParams := url.Values{}
		pageParams.Set("app_id", c.cfg.Session.Qobuz.AppID)
		pageParams.Set("label_id", labelID)
		pageParams.Set("limit", strconv.Itoa(pageLimit))
		pageParams.Set("offset", strconv.Itoa(offset))
		pageParams.Set("extra", "albums")

		pageResp, pageStatus, pageErr := c.apiRequest(ctx, "label/get", pageParams, c.authHeaders())
		if pageErr != nil {
			return nil, pageErr
		}
		if pageStatus != http.StatusOK {
			return nil, fmt.Errorf("label/get pagination failed: status=%d offset=%d", pageStatus, offset)
		}
		pageAlbums, ok := mapValue(pageResp["albums"])
		if !ok {
			continue
		}
		pageItems, ok := pageAlbums["items"].([]any)
		if !ok {
			continue
		}
		items = append(items, pageItems...)
	}

	albumsObj["items"] = items
	resp["albums"] = albumsObj
	return resp, nil
}

func (c *Client) getArtist(ctx context.Context, artistID string) (map[string]any, error) {
	pageLimit := 500
	params := url.Values{}
	params.Set("app_id", c.cfg.Session.Qobuz.AppID)
	params.Set("artist_id", artistID)
	params.Set("limit", strconv.Itoa(pageLimit))
	params.Set("offset", "0")
	params.Set("extra", "albums")

	resp, status, err := c.apiRequest(ctx, "artist/get", params, c.authHeaders())
	if err != nil {
		return nil, err
	}
	if status != http.StatusOK {
		return nil, fmt.Errorf("artist/get failed: status=%d", status)
	}

	albumsObj, ok := mapValue(resp["albums"])
	if !ok {
		return resp, nil
	}
	items, ok := albumsObj["items"].([]any)
	if !ok {
		return resp, nil
	}

	total, _ := intValue(resp["albums_count"])
	if total <= 0 {
		total, _ = intValue(albumsObj["total"])
	}
	if total <= pageLimit && len(items) < pageLimit {
		return resp, nil
	}

	for offset := pageLimit; ; offset += pageLimit {
		if total > 0 && offset >= total {
			break
		}
		pageParams := url.Values{}
		pageParams.Set("app_id", c.cfg.Session.Qobuz.AppID)
		pageParams.Set("artist_id", artistID)
		pageParams.Set("limit", strconv.Itoa(pageLimit))
		pageParams.Set("offset", strconv.Itoa(offset))
		pageParams.Set("extra", "albums")

		pageResp, pageStatus, pageErr := c.apiRequest(ctx, "artist/get", pageParams, c.authHeaders())
		if pageErr != nil {
			return nil, pageErr
		}
		if pageStatus != http.StatusOK {
			return nil, fmt.Errorf("artist/get pagination failed: status=%d offset=%d", pageStatus, offset)
		}
		pageAlbums, ok := mapValue(pageResp["albums"])
		if !ok {
			break
		}
		pageItems, ok := pageAlbums["items"].([]any)
		if !ok || len(pageItems) == 0 {
			break
		}
		items = append(items, pageItems...)
		if len(pageItems) < pageLimit {
			break
		}
	}

	albumsObj["items"] = items
	resp["albums"] = albumsObj
	return resp, nil
}

func (c *Client) authHeaders() map[string]string {
	headers := map[string]string{"X-App-Id": c.cfg.Session.Qobuz.AppID}
	if c.uat != "" {
		headers["X-User-Auth-Token"] = c.uat
	} else if c.cfg.Session.Qobuz.PasswordOrToken != "" && c.cfg.Session.Qobuz.UseAuthToken {
		headers["X-User-Auth-Token"] = c.cfg.Session.Qobuz.PasswordOrToken
	}
	return headers
}

func (c *Client) getValidSecret(ctx context.Context, secrets []string, headers map[string]string) (string, error) {
	type candidate struct {
		secret string
		valid  bool
	}

	results := make([]candidate, 0, len(secrets))
	for _, secret := range secrets {
		ok := c.testSecret(ctx, secret, headers)
		results = append(results, candidate{secret: secret, valid: ok})
	}

	for _, result := range results {
		if result.valid {
			return result.secret, nil
		}
	}

	return "", fmt.Errorf("no valid qobuz app secret")
}

func (c *Client) testSecret(ctx context.Context, secret string, headers map[string]string) bool {
	formatID := qualityMap(4)
	requestTS := strconv.FormatInt(time.Now().Unix(), 10)
	sigRaw := "trackgetFileUrlformat_id" + strconv.Itoa(formatID) + "intentstreamtrack_id19512574" + requestTS + secret
	hash := md5.Sum([]byte(sigRaw))

	params := url.Values{}
	params.Set("request_ts", requestTS)
	params.Set("request_sig", hex.EncodeToString(hash[:]))
	params.Set("track_id", "19512574")
	params.Set("format_id", strconv.Itoa(formatID))
	params.Set("intent", "stream")

	_, status, err := c.apiRequest(ctx, "track/getFileUrl", params, headers)
	if err != nil {
		return false
	}
	return status == http.StatusOK || status == http.StatusUnauthorized
}

func (c *Client) apiRequest(ctx context.Context, endpoint string, params url.Values, headers map[string]string) (map[string]any, int, error) {
	if err := c.limiter.Wait(ctx); err != nil {
		return nil, 0, err
	}

	reqURL := baseURL + "/" + endpoint
	if c.baseURL != "" {
		reqURL = c.baseURL + "/" + endpoint
	}
	if len(params) > 0 {
		reqURL += "?" + params.Encode()
	}

	req, err := http.NewRequestWithContext(ctx, http.MethodGet, reqURL, nil)
	if err != nil {
		return nil, 0, err
	}
	for k, v := range headers {
		req.Header.Set(k, v)
	}
	req.Header.Set("User-Agent", "streamrip-go/0.1")

	resp, err := c.http.Do(req)
	if err != nil {
		return nil, 0, err
	}
	defer func() { _ = resp.Body.Close() }()

	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, resp.StatusCode, err
	}

	parsed := map[string]any{}
	if len(body) > 0 {
		if err = json.Unmarshal(body, &parsed); err != nil {
			return nil, resp.StatusCode, err
		}
	}

	return parsed, resp.StatusCode, nil
}

func qualityMap(quality int) int {
	mapVals := []int{5, 6, 7, 27}
	if quality < 1 || quality > 4 {
		return mapVals[2]
	}
	return mapVals[quality-1]
}

func (c *Client) fetchAppIDAndSecrets(ctx context.Context) (string, []string, error) {
	loginReq, err := http.NewRequestWithContext(ctx, http.MethodGet, "https://play.qobuz.com/login", nil)
	if err != nil {
		return "", nil, err
	}
	loginResp, err := c.http.Do(loginReq)
	if err != nil {
		return "", nil, err
	}
	defer func() { _ = loginResp.Body.Close() }()

	loginBody, err := io.ReadAll(loginResp.Body)
	if err != nil {
		return "", nil, err
	}

	bundleRe := regexp.MustCompile(`<script src="(/resources/\d+\.\d+\.\d+-[a-z]\d{3}/bundle\.js)"></script>`)
	bundleMatch := bundleRe.FindStringSubmatch(string(loginBody))
	if len(bundleMatch) < 2 {
		return "", nil, fmt.Errorf("could not find qobuz bundle js")
	}

	bundleURL := "https://play.qobuz.com" + bundleMatch[1]
	bundleReq, err := http.NewRequestWithContext(ctx, http.MethodGet, bundleURL, nil)
	if err != nil {
		return "", nil, err
	}
	bundleResp, err := c.http.Do(bundleReq)
	if err != nil {
		return "", nil, err
	}
	defer func() { _ = bundleResp.Body.Close() }()
	bundleBody, err := io.ReadAll(bundleResp.Body)
	if err != nil {
		return "", nil, err
	}

	bundle := string(bundleBody)
	appIDRe := regexp.MustCompile(`production:{api:{appId:"(?P<app_id>\d{9})",appSecret:"(\w{32})`)
	appIDMatch := appIDRe.FindStringSubmatch(bundle)
	if len(appIDMatch) < 2 {
		return "", nil, fmt.Errorf("could not parse qobuz app id")
	}
	appID := appIDMatch[1]

	seedTZRe := regexp.MustCompile(`[a-z]\.initialSeed\("(?P<seed>[\w=]+)",window\.utimezone\.(?P<timezone>[a-z]+)\)`)
	infoExtrasTemplate := `name:"\w+/(?P<timezone>%s)",info:"(?P<info>[\w=]+)",extras:"(?P<extras>[\w=]+)"`

	type seedParts struct {
		timezone string
		parts    []string
	}

	matches := seedTZRe.FindAllStringSubmatch(bundle, -1)
	idxSeed := seedTZRe.SubexpIndex("seed")
	idxTZ := seedTZRe.SubexpIndex("timezone")
	if len(matches) < 2 {
		return appID, nil, fmt.Errorf("could not parse qobuz secrets seeds")
	}

	ordered := make([]seedParts, 0, len(matches))
	seen := map[string]bool{}
	for _, m := range matches {
		tz := m[idxTZ]
		seed := m[idxSeed]
		if !seen[tz] {
			ordered = append(ordered, seedParts{timezone: tz, parts: []string{seed}})
			seen[tz] = true
		}
	}
	if len(ordered) >= 2 {
		ordered[0], ordered[1] = ordered[1], ordered[0]
	}

	tzNames := make([]string, 0, len(ordered))
	for _, o := range ordered {
		tzNames = append(tzNames, jsonutil.TitleCase(o.timezone))
	}
	infoRe := regexp.MustCompile(fmt.Sprintf(infoExtrasTemplate, strings.Join(tzNames, "|")))
	idxInfo := infoRe.SubexpIndex("info")
	idxExtras := infoRe.SubexpIndex("extras")
	idxInfoTZ := infoRe.SubexpIndex("timezone")

	byTZ := map[string][]string{}
	for _, o := range ordered {
		byTZ[o.timezone] = append([]string(nil), o.parts...)
	}

	for _, m := range infoRe.FindAllStringSubmatch(bundle, -1) {
		tz := strings.ToLower(m[idxInfoTZ])
		byTZ[tz] = append(byTZ[tz], m[idxInfo], m[idxExtras])
	}

	final := make([]string, 0, len(byTZ))
	for _, tz := range sortedKeys(byTZ) {
		joined := strings.Join(byTZ[tz], "")
		if len(joined) < 44 {
			continue
		}
		dec, err := base64.StdEncoding.DecodeString(joined[:len(joined)-44])
		if err != nil {
			continue
		}
		secret := string(dec)
		if secret != "" {
			final = append(final, secret)
		}
	}

	if len(final) == 0 {
		return appID, nil, fmt.Errorf("could not decode qobuz secrets")
	}

	return appID, final, nil
}

func sortedKeys(m map[string][]string) []string {
	keys := make([]string, 0, len(m))
	for k := range m {
		keys = append(keys, k)
	}
	sort.Strings(keys)
	return keys
}

func (c *Client) ensureMobileSession(ctx context.Context) error {
	c.mobileMu.Lock()
	defer c.mobileMu.Unlock()
	if c.mobileAccessToken != "" && c.mobileSessionID != "" && c.mobileSessionInfo != "" {
		return nil
	}
	q := &c.cfg.Session.Qobuz
	if err := c.mobileLogin(ctx, q.EmailOrUserID, q.PasswordOrToken); err != nil {
		return err
	}
	if err := c.mobileStartSession(ctx); err != nil {
		c.mobileAccessToken = ""
		return err
	}
	return nil
}

func (c *Client) mobileLogin(ctx context.Context, username, password string) error {
	ts := time.Now().Unix()
	params := url.Values{}
	params.Set("app_id", c.mobileAppID())
	params.Set("username", username)
	params.Set("password", password)
	params.Set("request_ts", strconv.FormatInt(ts, 10))
	params.Set("request_sig", mobileSignRequest(c.mobileAppSecret(), "oauth2/login", []kv{{"password", password}, {"username", username}}, ts))

	reqURL := baseURL + "/oauth2/login?" + params.Encode()
	req, err := http.NewRequestWithContext(ctx, http.MethodGet, reqURL, nil)
	if err != nil {
		return err
	}
	c.setMobileHeaders(req)
	resp, err := c.http.Do(req)
	if err != nil {
		return fmt.Errorf("mobile login request failed: %w", err)
	}
	defer func() { _ = resp.Body.Close() }()
	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return err
	}
	if resp.StatusCode != http.StatusOK {
		return fmt.Errorf("mobile login failed: status=%d body=%s", resp.StatusCode, string(body))
	}
	var parsed struct {
		OAuth2 struct {
			AccessToken string `json:"access_token"`
		} `json:"oauth2"`
	}
	if err = json.Unmarshal(body, &parsed); err != nil {
		return fmt.Errorf("mobile login parse failed: %w", err)
	}
	if strings.TrimSpace(parsed.OAuth2.AccessToken) == "" {
		return errors.New("mobile login returned empty token")
	}
	c.mobileAccessToken = strings.TrimSpace(parsed.OAuth2.AccessToken)
	return nil
}

func (c *Client) mobileStartSession(ctx context.Context) error {
	ts := time.Now().Unix()
	params := url.Values{}
	params.Set("app_id", c.mobileAppID())
	params.Set("request_ts", strconv.FormatInt(ts, 10))
	params.Set("request_sig", mobileSignRequest(c.mobileAppSecret(), "session/start", []kv{{"profile", mobileSessionProf}}, ts))

	reqURL := baseURL + "/session/start?" + params.Encode()
	form := url.Values{}
	form.Set("profile", mobileSessionProf)
	req, err := http.NewRequestWithContext(ctx, http.MethodPost, reqURL, strings.NewReader(form.Encode()))
	if err != nil {
		return err
	}
	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	c.setMobileHeaders(req)
	resp, err := c.http.Do(req)
	if err != nil {
		return fmt.Errorf("mobile session request failed: %w", err)
	}
	defer func() { _ = resp.Body.Close() }()
	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return err
	}
	if resp.StatusCode != http.StatusOK {
		return fmt.Errorf("mobile session start failed: status=%d body=%s", resp.StatusCode, string(body))
	}
	var parsed struct {
		SessionID string `json:"session_id"`
		Infos     string `json:"infos"`
	}
	if err = json.Unmarshal(body, &parsed); err != nil {
		return fmt.Errorf("mobile session parse failed: %w", err)
	}
	if strings.TrimSpace(parsed.SessionID) == "" || strings.TrimSpace(parsed.Infos) == "" {
		return errors.New("mobile session start returned incomplete session data")
	}
	c.mobileSessionID = strings.TrimSpace(parsed.SessionID)
	c.mobileSessionInfo = strings.TrimSpace(parsed.Infos)
	c.mobileKEK = nil
	return nil
}

func (c *Client) mobileGetFileURL(ctx context.Context, trackID string, formatID int) (*mobileFileURL, error) {
	ts := time.Now().Unix()
	params := url.Values{}
	params.Set("app_id", c.mobileAppID())
	params.Set("track_id", trackID)
	params.Set("format_id", strconv.Itoa(formatID))
	params.Set("intent", "stream")
	params.Set("request_ts", strconv.FormatInt(ts, 10))
	params.Set("request_sig", mobileSignRequest(c.mobileAppSecret(), "file/url", []kv{{"format_id", strconv.Itoa(formatID)}, {"intent", "stream"}, {"track_id", trackID}}, ts))
	reqURL := baseURL + "/file/url?" + params.Encode()
	req, err := http.NewRequestWithContext(ctx, http.MethodGet, reqURL, nil)
	if err != nil {
		return nil, err
	}
	c.setMobileHeaders(req)
	resp, err := c.http.Do(req)
	if err != nil {
		return nil, err
	}
	defer func() { _ = resp.Body.Close() }()
	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, err
	}
	if resp.StatusCode != http.StatusOK {
		return nil, fmt.Errorf("mobile file url failed: status=%d body=%s", resp.StatusCode, string(body))
	}
	var parsed mobileFileURL
	if err = json.Unmarshal(body, &parsed); err != nil {
		return nil, fmt.Errorf("mobile file url parse failed: %w", err)
	}
	return &parsed, nil
}

func (c *Client) mobileCopyURLToWriter(ctx context.Context, sourceURL string, out io.Writer, bar *mpb.Bar) error {
	req, err := http.NewRequestWithContext(ctx, http.MethodGet, sourceURL, nil)
	if err != nil {
		return err
	}
	c.setMobileHeaders(req)
	client := c.streamHTTP
	if client == nil {
		client = c.http
	}
	resp, err := client.Do(req)
	if err != nil {
		return err
	}
	defer func() { _ = resp.Body.Close() }()
	if resp.StatusCode != http.StatusOK {
		return fmt.Errorf("mobile fallback download failed: status=%d", resp.StatusCode)
	}
	written, err := io.Copy(out, &countingReader{r: resp.Body, onRead: func(n int) {
		if bar != nil && n > 0 {
			bar.IncrBy(n)
		}
	}})
	if err != nil {
		return err
	}
	if resp.ContentLength > 0 && written != resp.ContentLength {
		return io.ErrUnexpectedEOF
	}
	return nil
}

type countingReader struct {
	r      io.Reader
	onRead func(int)
}

func (c *countingReader) Read(p []byte) (int, error) {
	n, err := c.r.Read(p)
	if n > 0 && c.onRead != nil {
		c.onRead(n)
	}
	return n, err
}

func shortenName(name string, max int) string {
	if max <= 0 {
		return name
	}
	r := []rune(name)
	if len(r) <= max {
		return name
	}
	if max <= 3 {
		return string(r[:max])
	}
	return string(r[:max-3]) + "..."
}

func (c *Client) mobileDownloadSegment(ctx context.Context, sourceURL string) ([]byte, error) {
	var lastErr error
	for attempt := 0; attempt < mobileSegmentTries; attempt++ {
		req, err := http.NewRequestWithContext(ctx, http.MethodGet, sourceURL, nil)
		if err != nil {
			return nil, err
		}
		c.setMobileHeaders(req)
		resp, err := c.http.Do(req)
		if err != nil {
			lastErr = err
			time.Sleep(time.Duration(500*(attempt+1)) * time.Millisecond)
			continue
		}
		if resp.StatusCode != http.StatusOK {
			lastErr = fmt.Errorf("status=%d", resp.StatusCode)
			_ = resp.Body.Close()
			time.Sleep(time.Duration(500*(attempt+1)) * time.Millisecond)
			continue
		}
		data, readErr := io.ReadAll(resp.Body)
		_ = resp.Body.Close()
		if readErr != nil {
			lastErr = readErr
			time.Sleep(time.Duration(500*(attempt+1)) * time.Millisecond)
			continue
		}
		return data, nil
	}
	if lastErr == nil {
		lastErr = errors.New("unknown segment error")
	}
	return nil, fmt.Errorf("mobile segment download failed after retries: %w", lastErr)
}

func (c *Client) setMobileHeaders(req *http.Request) {
	req.Header.Set("User-Agent", mobileUserAgent)
	req.Header.Set("X-App-Id", c.mobileAppID())
	req.Header.Set("X-App-Version", mobileAppVersion)
	req.Header.Set("X-Device-Platform", "android")
	req.Header.Set("X-Device-Model", "Nexus 6P")
	req.Header.Set("X-Device-Os-Version", "9")
	if c.mobileAccessToken != "" {
		req.Header.Set("Authorization", "Bearer "+c.mobileAccessToken)
	}
	if c.mobileSessionID != "" {
		req.Header.Set("X-Session-Id", c.mobileSessionID)
	}
}

// mobileSignRequest signs a mobile API request. appSecret comes from config
// (Client.mobileAppSecret) so a rotation can be fixed without a rebuild.
func mobileSignRequest(appSecret, endpoint string, params []kv, ts int64) string {
	method := strings.ReplaceAll(endpoint, "/", "")
	sortKVs(params)
	var sb strings.Builder
	sb.WriteString(method)
	for _, p := range params {
		sb.WriteString(p.Key)
		sb.WriteString(p.Value)
	}
	sb.WriteString(strconv.FormatInt(ts, 10))
	sb.WriteString(appSecret)
	h := md5.Sum([]byte(sb.String()))
	return hex.EncodeToString(h[:])
}

type kv struct {
	Key   string
	Value string
}

func sortKVs(s []kv) {
	for i := 0; i < len(s); i++ {
		for j := i + 1; j < len(s); j++ {
			if s[j].Key < s[i].Key {
				s[i], s[j] = s[j], s[i]
			}
		}
	}
}

func (c *Client) mobileDeriveTrackKey(encryptedKey string) ([]byte, error) {
	if len(c.mobileKEK) == 16 {
		return unwrapQobuzTrackKey(encryptedKey, c.mobileKEK)
	}
	parts := strings.SplitN(c.mobileSessionInfo, ".", 2)
	if len(parts) != 2 {
		return nil, errors.New("invalid mobile session infos format")
	}
	salt, err := base64.RawURLEncoding.DecodeString(parts[0])
	if err != nil {
		return nil, fmt.Errorf("decode mobile salt: %w", err)
	}
	info, err := base64.RawURLEncoding.DecodeString(parts[1])
	if err != nil {
		return nil, fmt.Errorf("decode mobile info: %w", err)
	}
	// A non-hex secret used to be swallowed and HKDF keyed on nil, which
	// derives a wrong KEK and yields silently corrupt audio rather than an
	// error.
	secretKey, err := hex.DecodeString(c.mobileAppSecret())
	if err != nil {
		return nil, fmt.Errorf("decode mobile app secret: %w", err)
	}
	if len(secretKey) == 0 {
		return nil, errors.New("mobile app secret is empty")
	}
	reader := hkdf.New(func() hash.Hash { return sha256.New() }, secretKey, salt, info)
	kek := make([]byte, 16)
	if _, err = io.ReadFull(reader, kek); err != nil {
		return nil, fmt.Errorf("mobile hkdf derive failed: %w", err)
	}
	c.mobileKEK = kek
	return unwrapQobuzTrackKey(encryptedKey, kek)
}

func unwrapQobuzTrackKey(encryptedKey string, kek []byte) ([]byte, error) {
	parts := strings.SplitN(encryptedKey, ".", 3)
	if len(parts) != 3 || parts[0] != mobileSessionProf {
		return nil, errors.New("invalid qobuz track key format")
	}
	encKey, err := base64.RawURLEncoding.DecodeString(parts[1])
	if err != nil {
		return nil, fmt.Errorf("decode encrypted key failed: %w", err)
	}
	iv, err := base64.RawURLEncoding.DecodeString(parts[2])
	if err != nil {
		return nil, fmt.Errorf("decode key iv failed: %w", err)
	}
	block, err := aes.NewCipher(kek)
	if err != nil {
		return nil, err
	}
	decrypted := make([]byte, len(encKey))
	mode := cipher.NewCBCDecrypter(block, iv)
	mode.CryptBlocks(decrypted, encKey)
	if len(decrypted) < 16 {
		return nil, errors.New("decrypted key too short")
	}
	return decrypted[:16], nil
}

func extractFLACHeader(data []byte) []byte {
	blocks := findDFLABlocks(data)
	if blocks == nil {
		return nil
	}
	out := make([]byte, 4+len(blocks))
	copy(out, "fLaC")
	copy(out[4:], blocks)
	return out
}

func findDFLABlocks(data []byte) []byte {
	pos := 0
	for pos+8 <= len(data) {
		size := int(uint32(data[pos])<<24 | uint32(data[pos+1])<<16 | uint32(data[pos+2])<<8 | uint32(data[pos+3]))
		if size < 8 || pos+size > len(data) {
			break
		}
		t := data[pos+4 : pos+8]
		if string(t) == "dfLa" {
			body := data[pos+8 : pos+size]
			if len(body) > 4 {
				return body[4:]
			}
		}
		var inner []byte
		switch string(t) {
		case "moov", "trak", "mdia", "minf", "stbl":
			inner = data[pos+8 : pos+size]
		case "stsd":
			if pos+16 <= pos+size {
				inner = data[pos+16 : pos+size]
			}
		case "fLaC":
			if pos+36 <= pos+size {
				inner = data[pos+36 : pos+size]
			}
		}
		if inner != nil {
			if result := findDFLABlocks(inner); result != nil {
				return result
			}
		}
		pos += size
	}
	return nil
}

func extractFrames(data []byte, key []byte) []byte {
	var frames []byte
	pos := 0
	for pos+8 <= len(data) {
		boxSize := int(uint32(data[pos])<<24 | uint32(data[pos+1])<<16 | uint32(data[pos+2])<<8 | uint32(data[pos+3]))
		if boxSize < 8 || pos+boxSize > len(data) {
			break
		}
		if string(data[pos+4:pos+8]) == "uuid" && boxSize >= 36 {
			if pos+24 > len(data) {
				pos += boxSize
				continue
			}
			if bytes.Equal(data[pos+8:pos+24], qobuzUUIDBytes) {
				f := parseUUIDBox(data, pos, boxSize, key)
				frames = append(frames, f...)
			}
		}
		pos += boxSize
	}
	return frames
}

func parseUUIDBox(data []byte, boxStart, boxSize int, key []byte) []byte {
	bodyOff := boxStart + 24
	if bodyOff+12 > len(data) {
		return nil
	}
	rawOffset := readU32BE(data, bodyOff+4)
	numSamples := int(readU24BE(data, bodyOff+9))
	if numSamples == 0 || numSamples > 10000 {
		return nil
	}
	tableOff := bodyOff + 12
	sampleDataOff := boxStart + int(rawOffset)
	var frames []byte
	offset := sampleDataOff
	for i := 0; i < numSamples; i++ {
		et := tableOff + i*16
		if et+16 > len(data) || offset >= len(data) {
			break
		}
		size := readU32BE(data, et)
		encFlag := data[et+6] != 0 || data[et+7] != 0
		end := offset + int(size)
		if end > len(data) {
			break
		}
		if encFlag && len(key) == 16 {
			iv := make([]byte, 16)
			copy(iv[:8], data[et+8:et+16])
			block, err := aes.NewCipher(key)
			if err != nil {
				return frames
			}
			stream := cipher.NewCTR(block, iv)
			decrypted := make([]byte, end-offset)
			stream.XORKeyStream(decrypted, data[offset:end])
			frames = append(frames, decrypted...)
		} else {
			frames = append(frames, data[offset:end]...)
		}
		offset = end
	}
	return frames
}

func readU32BE(data []byte, off int) uint32 {
	if off+4 > len(data) {
		return 0
	}
	return uint32(data[off])<<24 | uint32(data[off+1])<<16 | uint32(data[off+2])<<8 | uint32(data[off+3])
}

func readU24BE(data []byte, off int) uint32 {
	if off+3 > len(data) {
		return 0
	}
	return uint32(data[off])<<16 | uint32(data[off+1])<<8 | uint32(data[off+2])
}

// mobileAppID and mobileAppSecret read the vendor mobile app credentials from
// config, falling back to the built-in defaults.
func (c *Client) mobileAppID() string {
	if v := strings.TrimSpace(c.cfg.Session.Qobuz.MobileAppID); v != "" {
		return v
	}
	return config.DefaultQobuzMobileAppID
}

func (c *Client) mobileAppSecret() string {
	if v := strings.TrimSpace(c.cfg.Session.Qobuz.MobileAppSecret); v != "" {
		return v
	}
	return config.DefaultQobuzMobileAppSecret
}

// AlbumTracksAreComplete reports that Qobuz's album/get response embeds track
// objects complete enough to tag from, so internal/app can skip the per-track
// track/get call.
//
// Checked against the live API for a 68-track release: the embedded items
// carry title, version, track_number, media_number, parental_warning, isrc,
// copyright, performer, performers, composer, duration, audio_info,
// maximum_bit_depth, maximum_sampling_rate and release_date_original. The only
// field track/get adds that this app reads is the nested album object, and the
// caller attaches the parent album itself. Everything else track/get returns
// (articles, created_at, has_lyrics, indexed_at) is unused.
func (c *Client) AlbumTracksAreComplete() bool { return true }

// Qobuz serves lyrics in two steps, mirroring its Android app: track/lyricsUrl
// returns a short-lived signed CloudFront URL, and that URL serves the lyrics
// document itself.
//
// Verified against the live API:
//
//	GET track/lyricsUrl?track_id=&app_id=&request_ts=&request_sig=
//	  -> {"track_id","album_id","lyrics_url"}
//	GET <lyrics_url>
//	  -> {"original":{"type","lang","lines":[{"line","start","end"}]},
//	      "translation_langs":[...],"writers","publishers":[...]}
//
// "type" is plain, lsync (line-synced) or wsync (word-synced); start and end
// are milliseconds. Passing a language parameter returns a translation
// document instead of the original, and only for languages that exist for the
// track, so this deliberately omits it and always takes the original.
const lyricsURLEndpoint = "track/lyricsUrl"

// lyricsExcluded reports whether the user opted out via
// metadata.exclude = ["lyrics"].
func (c *Client) lyricsExcluded() bool {
	for _, k := range c.cfg.Session.Metadata.Exclude {
		if strings.EqualFold(strings.TrimSpace(k), "lyrics") {
			return true
		}
	}
	return false
}

// TrackLyrics returns the plain and synced (LRC) lyrics for a track, or empty
// strings when Qobuz has none. It is exposed separately from GetMetadata so
// that album rips, which reuse the track objects embedded in the album
// payload, can still fetch lyrics without a full per-track metadata call.
func (c *Client) TrackLyrics(ctx context.Context, trackID string) (string, string, error) {
	trackID = strings.TrimSpace(trackID)
	if trackID == "" || c.lyricsExcluded() {
		return "", "", nil
	}
	if !c.LoggedIn() {
		return "", "", errNotLoggedIn
	}

	requestTS := strconv.FormatInt(time.Now().Unix(), 10)
	sigRaw := "tracklyricsUrltrack_id" + trackID + requestTS + c.secret
	sum := md5.Sum([]byte(sigRaw))

	params := url.Values{}
	params.Set("app_id", c.cfg.Session.Qobuz.AppID)
	params.Set("track_id", trackID)
	params.Set("request_ts", requestTS)
	params.Set("request_sig", hex.EncodeToString(sum[:]))

	resp, status, err := c.apiRequest(ctx, lyricsURLEndpoint, params, c.authHeaders())
	if err != nil {
		return "", "", err
	}
	if status != http.StatusOK {
		// A track without lyrics is not an error worth failing a rip over.
		verbose.Printf(verbose.V, "qobuz: no lyrics for track %s (status=%d)\n", trackID, status)
		return "", "", nil
	}
	docURL := strings.TrimSpace(jsonutil.StringFromAny(resp["lyrics_url"]))
	if docURL == "" {
		return "", "", nil
	}

	return c.fetchLyricsDocument(ctx, trackID, docURL)
}

// fetchLyricsDocument retrieves the signed lyrics document. The URL points at
// a CDN rather than the Qobuz API, so it deliberately bypasses the API rate
// limiter: it is a different host and does not count against the provider's
// request budget.
func (c *Client) fetchLyricsDocument(ctx context.Context, trackID, docURL string) (string, string, error) {
	req, err := http.NewRequestWithContext(ctx, http.MethodGet, docURL, nil)
	if err != nil {
		return "", "", err
	}
	resp, err := c.http.Do(req)
	if err != nil {
		return "", "", err
	}
	defer func() { _ = resp.Body.Close() }()

	if resp.StatusCode != http.StatusOK {
		// The signed URL 403s when the document does not exist, which is how
		// Qobuz represents "no lyrics in this language".
		verbose.Printf(verbose.V, "qobuz: lyrics document for track %s unavailable (status=%d)\n", trackID, resp.StatusCode)
		return "", "", nil
	}

	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return "", "", err
	}
	var doc map[string]any
	if err = json.Unmarshal(body, &doc); err != nil {
		return "", "", fmt.Errorf("qobuz lyrics document: %w", err)
	}

	plain, synced := parseQobuzLyrics(jsonutil.NestedMap(doc, "original"))
	return plain, synced, nil
}

// parseQobuzLyrics turns a lyrics object into plain text and, when the lines
// carry timings, an LRC transcript.
func parseQobuzLyrics(obj map[string]any) (string, string) {
	lines, ok := obj["lines"].([]any)
	if !ok || len(lines) == 0 {
		return "", ""
	}
	// wsync documents are line objects that additionally carry per-word
	// timings; the line text and start are in the same place, so both synced
	// variants are handled identically.
	synced := strings.EqualFold(jsonutil.StringFromAny(obj["type"]), "lsync") ||
		strings.EqualFold(jsonutil.StringFromAny(obj["type"]), "wsync")

	plainParts := make([]string, 0, len(lines))
	lrcParts := make([]string, 0, len(lines))
	timed := false
	for _, raw := range lines {
		m, ok := raw.(map[string]any)
		if !ok {
			continue
		}
		text := strings.TrimSpace(jsonutil.StringFromAny(m["line"]))
		if text == "" {
			continue
		}
		plainParts = append(plainParts, text)
		if synced {
			if start, has := m["start"]; has {
				ms := jsonutil.IntFromAny(start)
				lrcParts = append(lrcParts, fmt.Sprintf("[%02d:%05.2f]%s", ms/60000, float64(ms%60000)/1000.0, text))
				timed = true
			}
		}
	}
	if len(plainParts) == 0 {
		return "", ""
	}
	lrc := ""
	if timed {
		lrc = strings.Join(lrcParts, "\n")
	}
	return strings.Join(plainParts, "\n"), lrc
}