0.2.56 - Reliable trailer playback

2026-08-12 11:05:07 +12:00
parent 9777eb0952
commit f2d052dbf6
22 changed files with 1438 additions and 55 deletions
@@ -0,0 +1,428 @@
+// Package trailer resolves remote trailer pages to native media streams.
+package trailer
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"html"
+	"io"
+	"net/http"
+	"net/url"
+	"regexp"
+	"sort"
+	"strings"
+	"sync"
+	"time"
+)
+
+const (
+	maxPageBytes = 2 << 20
+	cacheTTL     = 30 * time.Minute
+)
+
+var ErrUnavailable = errors.New("trailer unavailable")
+
+type Source struct {
+	Provider string
+	URL      string
+}
+
+type Result struct {
+	URL      string
+	MimeType string
+}
+
+type Provider interface {
+	Name() string
+	Supports(string) bool
+	Resolve(context.Context, string) (Result, error)
+}
+
+type cacheEntry struct {
+	result    Result
+	expiresAt time.Time
+}
+
+// Resolver is an ordered provider chain with a short-lived successful mapping cache.
+// The cached value avoids repeating YouTube page resolution on Back → Trailer while its
+// signed media URL is still useful; failures are never cached.
+type Resolver struct {
+	providers []Provider
+	mu        sync.Mutex
+	cache     map[string]cacheEntry
+}
+
+func New(client *http.Client) *Resolver {
+	if client == nil {
+		client = &http.Client{Timeout: 8 * time.Second}
+	}
+	return &Resolver{
+		providers: []Provider{newAppleProvider(client), newYouTubeProvider(client)},
+		cache:     map[string]cacheEntry{},
+	}
+}
+
+func (r *Resolver) Resolve(ctx context.Context, source Source) (Result, error) {
+	key := strings.ToLower(strings.TrimSpace(source.Provider)) + "\x00" + strings.TrimSpace(source.URL)
+	now := time.Now()
+	r.mu.Lock()
+	if cached, ok := r.cache[key]; ok && cached.expiresAt.After(now) {
+		r.mu.Unlock()
+		return cached.result, nil
+	}
+	delete(r.cache, key)
+	r.mu.Unlock()
+
+	for _, provider := range r.providers {
+		if source.Provider != "" && !strings.EqualFold(source.Provider, provider.Name()) {
+			continue
+		}
+		if !provider.Supports(source.URL) {
+			continue
+		}
+		result, err := provider.Resolve(ctx, source.URL)
+		if err != nil {
+			return Result{}, err
+		}
+		r.mu.Lock()
+		r.cache[key] = cacheEntry{result: result, expiresAt: now.Add(cacheTTL)}
+		if len(r.cache) > 128 {
+			for candidate, entry := range r.cache {
+				if entry.expiresAt.Before(now) {
+					delete(r.cache, candidate)
+				}
+			}
+		}
+		r.mu.Unlock()
+		return result, nil
+	}
+	return Result{}, ErrUnavailable
+}
+
+func (r *Resolver) Invalidate(source Source) {
+	key := strings.ToLower(strings.TrimSpace(source.Provider)) + "\x00" + strings.TrimSpace(source.URL)
+	r.mu.Lock()
+	delete(r.cache, key)
+	r.mu.Unlock()
+}
+
+type appleProvider struct{ client *http.Client }
+
+func newAppleProvider(client *http.Client) Provider { return &appleProvider{client: client} }
+func (*appleProvider) Name() string                 { return "apple" }
+func (*appleProvider) Supports(raw string) bool {
+	parsed, err := url.Parse(raw)
+	return err == nil && (isHostOrSubdomain(parsed.Hostname(), "apple.com") ||
+		isHostOrSubdomain(parsed.Hostname(), "apple.co"))
+}
+
+func (p *appleProvider) Resolve(ctx context.Context, raw string) (Result, error) {
+	if looksLikeMediaURL(raw) {
+		return p.validate(ctx, raw)
+	}
+	body, err := fetchLimited(ctx, p.client, raw, maxPageBytes, "text/html")
+	if err != nil {
+		return Result{}, err
+	}
+	links := mediaLinks(string(body))
+	if len(links) == 0 {
+		return Result{}, ErrUnavailable
+	}
+	sort.SliceStable(links, func(i, j int) bool { return mediaQuality(links[i]) > mediaQuality(links[j]) })
+	for _, candidate := range links {
+		if result, err := p.validate(ctx, candidate); err == nil {
+			return result, nil
+		}
+	}
+	return Result{}, ErrUnavailable
+}
+
+func (p *appleProvider) validate(ctx context.Context, raw string) (Result, error) {
+	contentType, err := validateMediaURL(ctx, p.client, raw)
+	if err != nil {
+		return Result{}, err
+	}
+	return Result{URL: raw, MimeType: contentType}, nil
+}
+
+var appleMediaURL = regexp.MustCompile(`https?:\\?/\\?/[^"'<> ]+\.(?:mov|mp4|m3u8)(?:\?[^"'<> ]*)?`)
+
+func mediaLinks(body string) []string {
+	matches := appleMediaURL.FindAllString(body, -1)
+	seen := map[string]bool{}
+	out := make([]string, 0, len(matches))
+	for _, match := range matches {
+		candidate := html.UnescapeString(strings.ReplaceAll(match, `\/`, `/`))
+		if !seen[candidate] {
+			seen[candidate] = true
+			out = append(out, candidate)
+		}
+	}
+	return out
+}
+
+func mediaQuality(raw string) int {
+	lower := strings.ToLower(raw)
+	for _, quality := range []int{2160, 1440, 1080, 720, 480, 360} {
+		if strings.Contains(lower, fmt.Sprintf("%d", quality)) {
+			return quality
+		}
+	}
+	return 0
+}
+
+type youTubeProvider struct{ client *http.Client }
+
+func newYouTubeProvider(client *http.Client) Provider { return &youTubeProvider{client: client} }
+func (*youTubeProvider) Name() string                 { return "youtube" }
+func (*youTubeProvider) Supports(raw string) bool     { return youtubeVideoID(raw) != "" }
+
+func (p *youTubeProvider) Resolve(ctx context.Context, raw string) (Result, error) {
+	videoID := youtubeVideoID(raw)
+	if videoID == "" {
+		return Result{}, ErrUnavailable
+	}
+	responses := []func(context.Context, string) (youtubePlayer, error){
+		p.innerTubePlayer,
+		p.watchPagePlayer,
+	}
+	for _, load := range responses {
+		player, err := load(ctx, videoID)
+		if err != nil || !strings.EqualFold(player.PlayabilityStatus.Status, "OK") {
+			continue
+		}
+		// YouTube's formats list contains progressive audio+video streams. AdaptiveFormats
+		// are separate tracks and would begin silently if handed straight to Media3.
+		formats := player.StreamingData.Formats
+		sort.SliceStable(formats, func(i, j int) bool {
+			return formats[i].Height > formats[j].Height ||
+				(formats[i].Height == formats[j].Height && formats[i].Bitrate > formats[j].Bitrate)
+		})
+		for _, format := range formats {
+			// Native playback needs one progressive stream carrying both tracks. Adaptive
+			// video-only formats are deliberately skipped rather than starting silent.
+			if format.URL == "" || !strings.Contains(format.MimeType, "video/") {
+				continue
+			}
+			contentType, validationErr := validateMediaURL(ctx, p.client, format.URL)
+			if validationErr == nil {
+				return Result{URL: format.URL, MimeType: contentType}, nil
+			}
+		}
+	}
+	return Result{}, ErrUnavailable
+}
+
+type youtubePlayer struct {
+	PlayabilityStatus struct {
+		Status string `json:"status"`
+	} `json:"playabilityStatus"`
+	StreamingData struct {
+		Formats         []youtubeFormat `json:"formats"`
+		AdaptiveFormats []youtubeFormat `json:"adaptiveFormats"`
+	} `json:"streamingData"`
+}
+
+type youtubeFormat struct {
+	URL      string `json:"url"`
+	MimeType string `json:"mimeType"`
+	Height   int    `json:"height"`
+	Bitrate  int    `json:"bitrate"`
+}
+
+func (p *youTubeProvider) innerTubePlayer(ctx context.Context, videoID string) (youtubePlayer, error) {
+	payload := map[string]any{
+		"videoId": videoID, "contentCheckOk": true, "racyCheckOk": true,
+		"context": map[string]any{"client": map[string]any{
+			"clientName": "ANDROID", "clientVersion": "20.10.38", "hl": "en", "gl": "NZ",
+		}},
+	}
+	body, _ := json.Marshal(payload)
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, "https://www.youtube.com/youtubei/v1/player", bytes.NewReader(body))
+	if err != nil {
+		return youtubePlayer{}, err
+	}
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("User-Agent", "com.google.android.youtube/20.10.38 (Linux; U; Android 12) gzip")
+	return p.doPlayer(req)
+}
+
+func (p *youTubeProvider) watchPagePlayer(ctx context.Context, videoID string) (youtubePlayer, error) {
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet,
+		"https://www.youtube.com/watch?v="+url.QueryEscape(videoID)+"&bpctr=9999999999&has_verified=1", nil)
+	if err != nil {
+		return youtubePlayer{}, err
+	}
+	req.Header.Set("User-Agent", "Mozilla/5.0 (Linux; Android 12; Android TV) AppleWebKit/537.36 Chrome/122 Safari/537.36")
+	body, err := p.do(req)
+	if err != nil {
+		return youtubePlayer{}, err
+	}
+	for _, marker := range []string{"ytInitialPlayerResponse = ", `"playerResponse":`} {
+		if raw := balancedJSONObject(body, marker); raw != "" {
+			var player youtubePlayer
+			if json.Unmarshal([]byte(raw), &player) == nil {
+				return player, nil
+			}
+		}
+	}
+	return youtubePlayer{}, ErrUnavailable
+}
+
+func (p *youTubeProvider) doPlayer(req *http.Request) (youtubePlayer, error) {
+	body, err := p.do(req)
+	if err != nil {
+		return youtubePlayer{}, err
+	}
+	var player youtubePlayer
+	if err := json.Unmarshal([]byte(body), &player); err != nil {
+		return youtubePlayer{}, err
+	}
+	return player, nil
+}
+
+func (p *youTubeProvider) do(req *http.Request) (string, error) {
+	resp, err := p.client.Do(req)
+	if err != nil {
+		return "", err
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
+		return "", ErrUnavailable
+	}
+	body, err := io.ReadAll(io.LimitReader(resp.Body, maxPageBytes+1))
+	if err != nil || len(body) > maxPageBytes {
+		return "", ErrUnavailable
+	}
+	return string(body), nil
+}
+
+func youtubeVideoID(raw string) string {
+	parsed, err := url.Parse(strings.TrimSpace(raw))
+	if err != nil {
+		return ""
+	}
+	host := strings.TrimPrefix(strings.ToLower(parsed.Hostname()), "www.")
+	var id string
+	switch {
+	case host == "youtu.be":
+		id = strings.Trim(parsed.Path, "/")
+	case isHostOrSubdomain(host, "youtube.com"), isHostOrSubdomain(host, "youtube-nocookie.com"):
+		id = parsed.Query().Get("v")
+		if id == "" {
+			parts := strings.Split(strings.Trim(parsed.Path, "/"), "/")
+			if len(parts) == 2 && (parts[0] == "embed" || parts[0] == "shorts") {
+				id = parts[1]
+			}
+		}
+	}
+	if len(id) != 11 {
+		return ""
+	}
+	for _, char := range id {
+		if !(char == '-' || char == '_' || char >= 'a' && char <= 'z' ||
+			char >= 'A' && char <= 'Z' || char >= '0' && char <= '9') {
+			return ""
+		}
+	}
+	return id
+}
+
+func isHostOrSubdomain(host, root string) bool {
+	host = strings.ToLower(strings.TrimSuffix(strings.TrimSpace(host), "."))
+	root = strings.ToLower(strings.TrimSuffix(strings.TrimSpace(root), "."))
+	return host == root || strings.HasSuffix(host, "."+root)
+}
+
+func balancedJSONObject(body, marker string) string {
+	start := strings.Index(body, marker)
+	if start < 0 {
+		return ""
+	}
+	start += len(marker)
+	for start < len(body) && body[start] != '{' {
+		start++
+	}
+	if start == len(body) {
+		return ""
+	}
+	depth, quoted, escaped := 0, false, false
+	for index := start; index < len(body); index++ {
+		char := body[index]
+		if quoted {
+			if escaped {
+				escaped = false
+			} else if char == '\\' {
+				escaped = true
+			} else if char == '"' {
+				quoted = false
+			}
+			continue
+		}
+		switch char {
+		case '"':
+			quoted = true
+		case '{':
+			depth++
+		case '}':
+			depth--
+			if depth == 0 {
+				return body[start : index+1]
+			}
+		}
+	}
+	return ""
+}
+
+func looksLikeMediaURL(raw string) bool {
+	path := strings.ToLower(strings.Split(raw, "?")[0])
+	return strings.HasSuffix(path, ".mov") || strings.HasSuffix(path, ".mp4") || strings.HasSuffix(path, ".m3u8")
+}
+
+func validateMediaURL(ctx context.Context, client *http.Client, raw string) (string, error) {
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, raw, nil)
+	if err != nil {
+		return "", err
+	}
+	req.Header.Set("Range", "bytes=0-0")
+	req.Header.Set("User-Agent", "Memby trailer resolver")
+	resp, err := client.Do(req)
+	if err != nil {
+		return "", err
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != http.StatusOK && resp.StatusCode != http.StatusPartialContent {
+		return "", ErrUnavailable
+	}
+	contentType := strings.ToLower(strings.TrimSpace(strings.Split(resp.Header.Get("Content-Type"), ";")[0]))
+	if !strings.HasPrefix(contentType, "video/") && contentType != "application/vnd.apple.mpegurl" &&
+		contentType != "application/x-mpegurl" && contentType != "application/octet-stream" {
+		return "", ErrUnavailable
+	}
+	return contentType, nil
+}
+
+func fetchLimited(ctx context.Context, client *http.Client, raw string, limit int64, accept string) ([]byte, error) {
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, raw, nil)
+	if err != nil {
+		return nil, err
+	}
+	req.Header.Set("Accept", accept)
+	req.Header.Set("User-Agent", "Mozilla/5.0 (Linux; Android TV) AppleWebKit/537.36 Safari/537.36")
+	resp, err := client.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
+		return nil, ErrUnavailable
+	}
+	body, err := io.ReadAll(io.LimitReader(resp.Body, limit+1))
+	if err != nil || int64(len(body)) > limit {
+		return nil, ErrUnavailable
+	}
+	return body, nil
+}
@@ -0,0 +1,116 @@
+package trailer
+
+import (
+	"context"
+	"io"
+	"net/http"
+	"strings"
+	"testing"
+)
+
+type roundTripFunc func(*http.Request) (*http.Response, error)
+
+func (fn roundTripFunc) RoundTrip(request *http.Request) (*http.Response, error) {
+	return fn(request)
+}
+
+func TestYouTubeVideoID(t *testing.T) {
+	for _, raw := range []string{
+		"https://www.youtube.com/watch?v=dQw4w9WgXcQ",
+		"https://youtu.be/dQw4w9WgXcQ",
+		"https://www.youtube.com/embed/dQw4w9WgXcQ",
+		"https://youtube.com/shorts/dQw4w9WgXcQ",
+	} {
+		if got := youtubeVideoID(raw); got != "dQw4w9WgXcQ" {
+			t.Fatalf("youtubeVideoID(%q) = %q", raw, got)
+		}
+	}
+	if got := youtubeVideoID("https://example.com/watch?v=dQw4w9WgXcQ"); got != "" {
+		t.Fatalf("accepted a non-YouTube host: %q", got)
+	}
+}
+
+func TestProviderHostMatchingRejectsLookalikeDomains(t *testing.T) {
+	if newAppleProvider(http.DefaultClient).Supports("https://notapple.com/trailer.mov") {
+		t.Fatal("lookalike Apple host was accepted")
+	}
+	if youtubeVideoID("https://notyoutube.com/watch?v=dQw4w9WgXcQ") != "" {
+		t.Fatal("lookalike YouTube host was accepted")
+	}
+}
+
+func TestYouTubeResolverReturnsValidatedProgressiveStream(t *testing.T) {
+	client := &http.Client{Transport: roundTripFunc(func(request *http.Request) (*http.Response, error) {
+		body := ""
+		status := http.StatusOK
+		headers := http.Header{}
+		switch request.URL.Host {
+		case "www.youtube.com":
+			body = `{"playabilityStatus":{"status":"OK"},"streamingData":{"formats":[` +
+				`{"url":"https://media.example/trailer.mp4","mimeType":"video/mp4; codecs=avc1,mp4a","height":720,"bitrate":1000}]}}`
+			headers.Set("Content-Type", "application/json")
+		case "media.example":
+			status = http.StatusPartialContent
+			headers.Set("Content-Type", "video/mp4")
+		default:
+			t.Fatalf("unexpected request to %s", request.URL)
+		}
+		return &http.Response{
+			StatusCode: status,
+			Header:     headers,
+			Body:       io.NopCloser(strings.NewReader(body)),
+			Request:    request,
+		}, nil
+	})}
+
+	resolver := New(client)
+	result, err := resolver.Resolve(context.Background(), Source{
+		Provider: "youtube",
+		URL:      "https://youtu.be/dQw4w9WgXcQ",
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if result.URL != "https://media.example/trailer.mp4" || result.MimeType != "video/mp4" {
+		t.Fatalf("unexpected result: %+v", result)
+	}
+}
+
+func TestApplePageChoosesBestValidatedStream(t *testing.T) {
+	client := &http.Client{Transport: roundTripFunc(func(request *http.Request) (*http.Response, error) {
+		body := ""
+		headers := http.Header{}
+		status := http.StatusOK
+		if request.URL.Path == "/page" {
+			body = `<a href="https://trailers.apple.com/film_h720p.mov">720</a>` +
+				`<a href="https://trailers.apple.com/film_h1080p.mov">1080</a>`
+			headers.Set("Content-Type", "text/html")
+		} else {
+			status = http.StatusPartialContent
+			headers.Set("Content-Type", "video/quicktime")
+		}
+		return &http.Response{
+			StatusCode: status,
+			Header:     headers,
+			Body:       io.NopCloser(strings.NewReader(body)),
+			Request:    request,
+		}, nil
+	})}
+	resolver := New(client)
+	result, err := resolver.Resolve(context.Background(), Source{
+		Provider: "apple", URL: "https://trailers.apple.com/page",
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !strings.Contains(result.URL, "1080") {
+		t.Fatalf("did not choose the best stream: %+v", result)
+	}
+}
+
+func TestBalancedJSONObjectIgnoresBracesInsideStrings(t *testing.T) {
+	body := `before marker = {"value":"}" ,"nested":{"ok":true}} after`
+	if got := balancedJSONObject(body, "marker = "); got != `{"value":"}" ,"nested":{"ok":true}}` {
+		t.Fatalf("balanced object = %q", got)
+	}
+}