refactor stream service helpers

internal/service/stream_file.go

@@ -0,0 +1,96 @@
+package service
+
+import (
+	"context"
+	"net/http"
+	"net/url"
+	"os"
+	"strings"
+
+	"github.com/ShukeBta/MediaStationGo/internal/model"
+	"github.com/ShukeBta/MediaStationGo/internal/repository"
+)
+
+// ServeFile streams the file backing the given media ID using
+// http.ServeContent so HEAD / Range / If-Modified-Since are handled for free.
+//
+// When the media row has a STRMURL set we redirect (302) to that URL
+// instead of opening a local file. This lets WebDAV / Alist / S3 / HTTP
+// direct links flow through the rest of the player UI unchanged.
+func (s *StreamService) ServeFile(w http.ResponseWriter, r *http.Request, mediaID string) error {
+	return s.ServeFileWithCloudMode(w, r, mediaID, "")
+}
+
+func (s *StreamService) ServeFileWithCloudMode(w http.ResponseWriter, r *http.Request, mediaID, cloudMode string) error {
+	m, err := s.repo.Media.FindByID(r.Context(), mediaID)
+	if err != nil {
+		return err
+	}
+	if m == nil {
+		return ErrMediaNotFound
+	}
+	if strmURL := strings.TrimSpace(m.STRMURL); strmURL != "" && playableSTRMTarget(r.Context(), s.repo, strmURL, m) {
+		if !cloudPlaybackModeEnabled(r.Context(), s.repo, cloudMode) {
+			return ErrCloudPlaybackDisabled
+		}
+		// 云盘播放 URL 先规范化为相对路径，免疫扫描时固化的旧 host。
+		target := normalizeCloudPlayTarget(strmURL)
+		target = withAuthTokenForInternalRedirect(target, r, PublicServerURL(r.Context(), s.repo, s.cfg))
+		setCloudRedirectNoStore(w)
+		http.Redirect(w, r, absoluteInternalRedirect(target, r), http.StatusFound)
+		return nil
+	}
+	if strings.HasPrefix(strings.ToLower(strings.TrimSpace(m.Path)), "cloud://") {
+		// 云盘媒体没有本地文件可回退；走到这里说明 STRM 播放被关闭或
+		// STRMURL 缺失。返回明确错误而不是笼统的「文件不存在」，
+		// 处理器据此回 502 + 原因，方便用户在播放器/日志里定位。
+		return ErrCloudPlaybackUnavailable
+	}
+	f, err := os.Open(m.Path)
+	if err != nil {
+		return ErrMediaNotFound
+	}
+	defer f.Close()
+	stat, err := f.Stat()
+	if err != nil {
+		return err
+	}
+	w.Header().Set("Accept-Ranges", "bytes")
+	w.Header().Set("Content-Disposition", "inline")
+	w.Header().Set("X-Content-Type-Options", "nosniff")
+	http.ServeContent(w, r, stat.Name(), stat.ModTime(), f)
+	return nil
+}
+
+func setCloudRedirectNoStore(w http.ResponseWriter) {
+	if w == nil {
+		return
+	}
+	w.Header().Set("Cache-Control", "no-store, no-cache, must-revalidate, max-age=0")
+	w.Header().Set("Pragma", "no-cache")
+	w.Header().Set("Expires", "0")
+}
+
+func isCloudPlaybackTarget(raw string) bool {
+	_, _, ok := parseCloudMediaPlaybackURL(raw)
+	return ok
+}
+
+func playableSTRMTarget(ctx context.Context, repo *repository.Container, raw string, m *model.Media) bool {
+	if isCloudPlaybackTarget(raw) || isHTTPPlaybackTarget(raw) {
+		return true
+	}
+	if m != nil && strings.EqualFold(strings.TrimSpace(m.Container), "strm") {
+		return true
+	}
+	return STRMPlaybackEnabled(ctx, repo)
+}
+
+func isHTTPPlaybackTarget(raw string) bool {
+	u, err := url.Parse(strings.TrimSpace(raw))
+	if err != nil || u == nil || !u.IsAbs() {
+		return false
+	}
+	scheme := strings.ToLower(strings.TrimSpace(u.Scheme))
+	return scheme == "http" || scheme == "https"
+}