Open more YouTube link types and playlists from links

Route YouTube search results links to search and nocookie embeds to the
video, match YouTube hosts exactly, and report YouTube pages without a
video as unsupported instead of sending them to yt-dlp. A watch link
inside a playlist shows both the video and the playlist when loaded, and
plays the video with the playlist queued around it. URL scheme play,
queue and bookmark actions accept playlist links.

Yattee/Services/Navigation/URLRouter.swift

@@ -56,6 +56,18 @@ struct URLRouter: Sendable {
             return .video(.id(.global(videoID)))
         }
 
+        // youtube.com/results?search_query=…
+        if let query = parseYouTubeSearchURL(url) {
+            return .search(query)
+        }
+
+        // YouTube pages that hold no video (home, feeds, hashtags, Music
+        // browse pages) go nowhere rather than to a yt-dlp extraction that
+        // can only fail
+        if isYouTubeNonVideoPage(url) {
+            return nil
+        }
+
         // Try PeerTube URLs
         if let (instance, videoID) = parsePeerTubeURL(url) {
             return .video(.id(.federated(videoID, instance: instance, uuid: nil)))
@@ -343,12 +355,61 @@ struct URLRouter: Sendable {
 
     // MARK: - YouTube URL Parsing
 
+    /// Whether the host is YouTube's: youtube.com and its subdomains (www, m,
+    /// music), youtube-nocookie.com, youtu.be. Exact, so look-alike hosts such
+    /// as `notyoutube.com` don't match.
+    func isYouTubeHost(_ host: String?) -> Bool {
+        guard let host = host?.lowercased() else { return false }
+        return host == "youtu.be"
+            || host == "youtube.com" || host.hasSuffix(".youtube.com")
+            || host == "youtube-nocookie.com" || host.hasSuffix(".youtube-nocookie.com")
+    }
+
+    /// The playlist a YouTube watch link plays the video within
+    /// (`watch?v=X&list=Y`), when it is a real playlist. Mixes (`RD…`) and
+    /// private lists (Liked, Watch Later) can't be opened as playlists.
+    func youTubePlaylistContext(_ url: URL) -> String? {
+        guard isYouTubeHost(url.host), parseYouTubeURL(url) != nil,
+              let listID = URLComponents(url: url, resolvingAgainstBaseURL: false)?
+                .queryItems?.first(where: { $0.name == "list" })?.value,
+              !listID.isEmpty,
+              !listID.hasPrefix("RD"),
+              !["LL", "WL", "LM"].contains(listID) else {
+            return nil
+        }
+        return listID
+    }
+
+    /// Parse `youtube.com/results?search_query=…` into the search query.
+    private func parseYouTubeSearchURL(_ url: URL) -> String? {
+        guard isYouTubeHost(url.host), url.path == "/results" || url.path == "/search" else { return nil }
+        // Raw items: form encoding writes spaces as `+`, which must become
+        // spaces before percent-decoding (an encoded `%2B` stays a plus)
+        let items = URLComponents(url: url, resolvingAgainstBaseURL: false)?.percentEncodedQueryItems
+        let query = (items?.first(where: { $0.name == "search_query" }) ?? items?.first(where: { $0.name == "q" }))?
+            .value?
+            .replacingOccurrences(of: "+", with: " ")
+            .removingPercentEncoding?
+            .trimmingCharacters(in: .whitespacesAndNewlines)
+        guard let query, !query.isEmpty else { return nil }
+        return query
+    }
+
+    /// YouTube pages that are not a video, playlist, channel or search.
+    private func isYouTubeNonVideoPage(_ url: URL) -> Bool {
+        guard isYouTubeHost(url.host), url.host?.lowercased() != "youtu.be" else { return false }
+        let path = url.pathComponents.dropFirst()
+        guard let first = path.first?.lowercased() else { return true } // home page
+        return ["feed", "hashtag", "results", "search", "browse", "account", "premium", "explore", "gaming", "watch"]
+            .contains(first)
+    }
+
     /// Parse YouTube URLs and extract video ID.
     private func parseYouTubeURL(_ url: URL) -> String? {
         let host = url.host?.lowercased() ?? ""
 
-        // youtube.com/watch?v=VIDEO_ID
-        if host.contains("youtube.com") {
+        // youtube.com/watch?v=VIDEO_ID (also youtube-nocookie.com/embed/VIDEO_ID)
+        if isYouTubeHost(host), host != "youtu.be" {
             let components = URLComponents(url: url, resolvingAgainstBaseURL: false)
             if let videoID = components?.queryItems?.first(where: { $0.name == "v" })?.value {
                 return videoID
@@ -464,7 +525,7 @@ struct URLRouter: Sendable {
     func parseYouTubeChannelURL(_ url: URL) -> String? {
         let host = url.host?.lowercased() ?? ""
 
-        guard host.contains("youtube.com") else { return nil }
+        guard isYouTubeHost(host), host != "youtu.be" else { return nil }
 
         let pathComponents = url.pathComponents
 
@@ -500,7 +561,7 @@ struct URLRouter: Sendable {
     private func parseYouTubePlaylistURL(_ url: URL) -> String? {
         let host = url.host?.lowercased() ?? ""
 
-        guard host.contains("youtube.com") else { return nil }
+        guard isYouTubeHost(host), host != "youtu.be" else { return nil }
 
         // youtube.com/playlist?list=PLAYLIST_ID
         let components = URLComponents(url: url, resolvingAgainstBaseURL: false)