refactor: split playback proxy logic into separate handler files

internal/playback/handler/hls_playlist.go

@@ -0,0 +1,98 @@
+package handler
+
+import (
+	"net/http"
+	"net/url"
+	"strings"
+)
+
+func isHLSPlaylistResponse(targetURL string, headers http.Header) bool {
+	contentType := strings.ToLower(headers.Get("Content-Type"))
+	if strings.Contains(contentType, "mpegurl") || strings.Contains(contentType, "x-mpegurl") {
+		return true
+	}
+
+	parsed, err := url.Parse(targetURL)
+	if err != nil {
+		return strings.Contains(strings.ToLower(targetURL), ".m3u8")
+	}
+	return strings.Contains(strings.ToLower(parsed.Path), ".m3u8")
+}
+
+func (h *PlaybackHandler) rewriteHLSPlaylist(body string, playlistURL string, referer string) (string, error) {
+	baseURL, err := url.Parse(playlistURL)
+	if err != nil {
+		return "", err
+	}
+
+	lines := strings.SplitAfter(body, "\n")
+	var out strings.Builder
+	for _, line := range lines {
+		lineBody := strings.TrimSuffix(line, "\n")
+		newline := ""
+		if strings.HasSuffix(line, "\n") {
+			newline = "\n"
+			lineBody = strings.TrimSuffix(lineBody, "\r")
+			if strings.HasSuffix(line, "\r\n") {
+				newline = "\r\n"
+			}
+		}
+
+		trimmed := strings.TrimSpace(lineBody)
+		rewritten := lineBody
+		if trimmed != "" {
+			if strings.HasPrefix(trimmed, "#") {
+				rewritten, err = h.rewriteHLSQuotedURIs(lineBody, baseURL, referer)
+			} else {
+				rewritten, err = h.proxyPlaylistURI(trimmed, baseURL, referer)
+			}
+			if err != nil {
+				return "", err
+			}
+		}
+		out.WriteString(rewritten)
+		out.WriteString(newline)
+	}
+
+	return out.String(), nil
+}
+
+func (h *PlaybackHandler) rewriteHLSQuotedURIs(line string, baseURL *url.URL, referer string) (string, error) {
+	const marker = `URI="`
+	var out strings.Builder
+	remaining := line
+	for {
+		idx := strings.Index(remaining, marker)
+		if idx < 0 {
+			out.WriteString(remaining)
+			return out.String(), nil
+		}
+		out.WriteString(remaining[:idx+len(marker)])
+		remaining = remaining[idx+len(marker):]
+		end := strings.Index(remaining, `"`)
+		if end < 0 {
+			out.WriteString(remaining)
+			return out.String(), nil
+		}
+		proxied, err := h.proxyPlaylistURI(remaining[:end], baseURL, referer)
+		if err != nil {
+			return "", err
+		}
+		out.WriteString(proxied)
+		remaining = remaining[end:]
+	}
+}
+
+func (h *PlaybackHandler) proxyPlaylistURI(rawURI string, baseURL *url.URL, referer string) (string, error) {
+	target, err := baseURL.Parse(rawURI)
+	if err != nil {
+		return "", err
+	}
+	token, err := h.svc.SignProxyToken(target.String(), referer, "stream")
+	if err != nil {
+		return "", err
+	}
+	params := url.Values{}
+	params.Set("token", token)
+	return "/watch/proxy/stream?" + params.Encode(), nil
+}