add display_limit to print queue function

- add function to open the channel page for the currently playing video in a new tab
- add error checking for url passed to add_to_queue function
   - ensure url is a YouTube url
   - ensure the url is able to be processed by yt-dlp

mpv-youtube-queue.conf

@@ -6,6 +6,8 @@ move_selection_up=ctrl+UP
 move_selection_down=ctrl+DOWN
 play_selected_video=ctrl+ENTER
 open_video_in_browser=ctrl+o
+open_channel_in_browser=ctrl+O
 print_current_video=ctrl+P
 browser=firefox
 clipboard_command=xclip -o
+display_limit=6

mpv-youtube-queue.lua

@@ -22,7 +22,7 @@ local video_queue = {}
 local current_video = nil
 local index = 0
 local selected_index = 1
-local SLEEP_TIME = 1.5
+local MSG_DURATION = 1.5
 
 local options = {
     add_to_queue = "ctrl+a",
@@ -33,14 +33,22 @@ local options = {
     move_selection_down = "ctrl+DOWN",
     play_selected_video = "ctrl+ENTER",
     open_video_in_browser = "ctrl+o",
+    open_channel_in_browser = "ctrl+O",
     print_current_video = "ctrl+P",
     browser = "firefox",
-    clipboard_command = "xclip -o"
+    clipboard_command = "xclip -o",
+    display_limit = 6
 }
 mp.options.read_options(options, "mpv-youtube-queue")
 
+local display_limit = options.display_limit
+local display_offset = 0
+
 -- HELPERS {{{
 
+-- run sleep shell command for n seconds
+local function sleep(n) os.execute("sleep " .. tonumber(n)) end
+
 -- print the name of the current video to the OSD
 local function print_video_name(video, duration)
     if not video then return end
@@ -58,6 +66,26 @@ local function get_video_name(url)
     return result:gsub("%s+$", "")
 end
 
+-- get the channel url from a video url
+local function get_channel_url(url)
+    local command = 'yt-dlp --print channel_url --playlist-items 1 ' .. url
+    local handle = io.popen(command)
+    if not handle then return nil end
+    local result = handle:read("*a")
+    handle:close()
+    return result:gsub("%s+$", "")
+end
+
+local function is_valid_ytdlp_url(url)
+    local command = 'yt-dlp --simulate \'' .. url .. '\' >/dev/null 2>&1'
+    local handle = io.popen(command .. "; echo $?")
+    if not handle then return false end
+    local result = handle:read("*a")
+    if not result then return false end
+    handle:close()
+    return result:gsub("%s+$", "") == "0"
+end
+
 -- }}}
 
 -- QUEUE GETTERS AND SETTERS {{{
@@ -91,6 +119,7 @@ function YouTubeQueue.add_to_queue(video) table.insert(video_queue, video) end
 function YouTubeQueue.next_in_queue()
     if index < #video_queue then
         index = index + 1
+        selected_index = index
         current_video = video_queue[index]
         return current_video
     end
@@ -99,6 +128,7 @@ end
 function YouTubeQueue.prev_in_queue()
     if index > 1 then
         index = index - 1
+        selected_index = index
         current_video = video_queue[index]
     else
         current_video = video_queue[1]
@@ -112,8 +142,8 @@ function YouTubeQueue.play_video_at(idx)
         return nil
     end
     index = idx
+    selected_index = index
     current_video = video_queue[index]
-    mp.msg.log("info", "Playing video at index " .. index)
     mp.set_property_number("playlist-pos", index - 1) -- zero-based index
     return current_video
 end
@@ -134,6 +164,7 @@ function YouTubeQueue.update_current_index()
     end
     -- if not found, reset the index
     index = 0
+    selected_index = index
     current_video = YouTubeQueue.get_video_at(index)
 end
 
@@ -151,17 +182,21 @@ function YouTubeQueue.on_track_changed() YouTubeQueue.update_current_index() end
 function YouTubeQueue.on_playback_restart() YouTubeQueue.update_current_index() end
 
 function YouTubeQueue.print_queue(duration)
-    local queue = YouTubeQueue.get_video_queue()
-    local current_index = YouTubeQueue.get_current_index()
-    if not duration then duration = 5 end
-    if #queue > 0 then
+    local current_index = index
+    if not duration then duration = 3 end
+    if #video_queue > 0 then
         local message = ""
-        for i, v in ipairs(queue) do
+        local start_index = math.max(1, selected_index - display_limit / 2)
+        local end_index =
+            math.min(#video_queue, start_index + display_limit - 1)
+        display_offset = start_index - 1
+
+        for i = start_index, end_index do
             local prefix = (i == current_index and i == selected_index) and
                 "=>> " or (i == current_index) and "=> " or
                 (i == selected_index) and "> " or "   "
-            -- prefix = (i == selected_index) and prefix .. "> " or prefix
-            message = message .. prefix .. i .. ". " .. v.name .. "\n"
+            message = message .. prefix .. i .. ". " .. video_queue[i].name ..
+                "\n"
         end
         mp.osd_message(message, duration)
     else
@@ -176,7 +211,10 @@ end
 -- returns the content of the clipboard
 local function get_clipboard_content()
     local handle = io.popen(options.clipboard_command)
-    if not handle then return nil end
+    if not handle then
+        mp.osd_message("Error getting clipboard content")
+        return nil
+    end
     local result = handle:read("*a")
     handle:close()
     return result
@@ -186,7 +224,10 @@ local function move_selection_up()
     -- selected_index = YouTubeQueue.get_current_index()
     if selected_index > 1 then
         selected_index = selected_index - 1
-        YouTubeQueue.print_queue()
+        if selected_index < display_offset + 1 then
+            display_offset = display_offset - 1
+        end
+        YouTubeQueue.print_queue(MSG_DURATION)
     end
 end
 
@@ -195,18 +236,19 @@ local function move_selection_down()
     if selected_index < YouTubeQueue.size() then
         selected_index = selected_index + 1
         -- YouTubeQueue.set_current_index(current_index)
-        YouTubeQueue.print_queue()
+        if selected_index > display_offset + display_limit then
+            display_offset = display_offset + 1
+        end
+        YouTubeQueue.print_queue(MSG_DURATION)
     end
 end
 
-local function sleep(n) os.execute("sleep " .. tonumber(n)) end
-
 local function play_selected_video()
     -- local current_index = YouTubeQueue.get_current_index()
     local video = YouTubeQueue.play_video_at(selected_index)
-    YouTubeQueue.print_queue(SLEEP_TIME - 0.5)
-    sleep(SLEEP_TIME)
-    print_video_name(video, SLEEP_TIME)
+    YouTubeQueue.print_queue(MSG_DURATION - 0.5)
+    sleep(MSG_DURATION)
+    print_video_name(video, MSG_DURATION)
 end
 
 -- play the next video in the queue
@@ -220,22 +262,35 @@ local function play_next_in_queue()
     else
         mp.commandv("loadfile", next_video_url, "replace")
     end
-    print_video_name(next_video, SLEEP_TIME)
-    sleep(SLEEP_TIME)
+    print_video_name(next_video, MSG_DURATION)
+    sleep(MSG_DURATION)
 end
 
 -- add the video to the queue from the clipboard
 local function add_to_queue()
     local url = get_clipboard_content()
-    -- get video name in background
-    local name = get_video_name(url)
-
-    -- check to make sure the video is not already in the queue
+    if not url then
+        mp.osd_message("Nothing found in the clipboard.")
+        return
+    end
+    if not string.match(url, "^https://www.youtube.com") then
+        mp.osd_message("Not a YouTube URL.")
+        return
+    end
     if YouTubeQueue.is_in_queue(url) then
         mp.osd_message("Video already in queue.")
         return
+    elseif not is_valid_ytdlp_url(url) then
+        mp.osd_message("Invalid URL.")
+        return
     end
-    YouTubeQueue.add_to_queue({ url = url, name = name })
+    local name = get_video_name(url)
+    local channel_url = get_channel_url(url)
+    YouTubeQueue.add_to_queue({
+        url = url,
+        name = name,
+        channel_url = channel_url
+    })
     if not YouTubeQueue.get_current_video() then
         play_next_in_queue()
     else
@@ -252,8 +307,8 @@ local function play_previous_video()
         return
     end
     mp.set_property_number("playlist-pos", YouTubeQueue.get_current_index() - 1)
-    print_video_name(previous_video, SLEEP_TIME)
-    sleep(SLEEP_TIME)
+    print_video_name(previous_video, MSG_DURATION)
+    sleep(MSG_DURATION)
 end
 
 local function open_url_in_browser(url)
@@ -261,9 +316,10 @@ local function open_url_in_browser(url)
     os.execute(command)
 end
 
-local function open_video_in_browser()
-    local current_url = mp.get_property("path")
-    open_url_in_browser(current_url)
+local function open_video_in_browser() open_url_in_browser(current_video.url) end
+
+local function open_channel_in_browser()
+    open_url_in_browser(current_video.channel_url)
 end
 
 local function print_current_video()
@@ -288,6 +344,8 @@ mp.add_key_binding(options.open_video_in_browser, "open_video_in_browser",
     open_video_in_browser)
 mp.add_key_binding(options.print_current_video, "print_current_video",
     print_current_video)
+mp.add_key_binding(options.open_channel_in_browser, "open_channel_in_browser",
+    open_channel_in_browser)
 
 -- Listen for the file-loaded event
 mp.register_event("end-file", YouTubeQueue.on_end_file)