Add ability to specifiy youtube URL source

Added a new flag (-u) to specify a youtube URL source when downloading a
single song.

README.md

@@ -54,6 +54,7 @@ Arguments:
     -s, --song <song>           Specify song name to download
     -A, --album <album>         Specify the album name to download
     -p, --playlist <playlist>   Specify the playlist name to download
+    -u, --url <url>             Specify the youtube url to download from
 
 Examples:
     $ irs --song "Bohemian Rhapsody" --artist "Queen"

src/bottle/cli.cr

@@ -20,6 +20,7 @@ class CLI
     [["-s", "--song"], "song", "string"],
     [["-A", "--album"], "album", "string"],
     [["-p", "--playlist"], "playlist", "string"],
+    [["-u", "--url"], "url", "string"],
   ]
 
   @args : Hash(String, String)
@@ -48,6 +49,7 @@ class CLI
         #{Style.blue "-s, --song <song>"}           Specify song name to download
         #{Style.blue "-A, --album <album>"}         Specify the album name to download
         #{Style.blue "-p, --playlist <playlist>"}   Specify the playlist name to download
+        #{Style.blue "-u, --url <url>"}             Specify the youtube url to download from (for single songs only)
 
     #{Style.bold "Examples:"}
         $ #{Style.green %(irs --song "Bohemian Rhapsody" --artist "Queen")}
@@ -82,7 +84,7 @@ class CLI
     elsif @args["song"]? && @args["artist"]?
       s = Song.new(@args["song"], @args["artist"])
       s.provide_client_keys(Config.client_key, Config.client_secret)
-      s.grab_it
+      s.grab_it(@args["url"]?)
       s.organize_it(Config.music_directory)
       exit
     elsif @args["album"]? && @args["artist"]?

src/glue/song.cr

@@ -24,7 +24,9 @@ class Song
     ],
     "url" => [
       "  Searching for URL ...\r",
-      Style.green("  + ") + Style.dim("URL found                       \n")
+      Style.green("  + ") + Style.dim("URL found                       \n"),
+      "  Validating URL ...\r",
+      Style.green("  + ") + Style.dim("URL validated                   \n")
     ],
     "download" => [
       "  Downloading video:\n",
@@ -47,11 +49,12 @@ class Song
   end
 
   # Find, downloads, and tags the mp3 song that this class represents.
-  #
+  # Optionally takes a youtube URL to download from
+  # 
   # ```
   # Song.new("Bohemian Rhapsody", "Queen").grab_it
   # ```
-  def grab_it
+  def grab_it(url : (String | Nil) = nil)
     outputter("intro", 0)
 
     if !@spotify_searcher.authorized? && !@metadata
@@ -81,14 +84,23 @@ class Song
     data = @metadata.as(JSON::Any)
     @filename = data["track_number"].to_s + " - #{data["name"].to_s}.mp3"
 
-    outputter("url", 0)
-    url = Youtube.find_url(@song_name, @artist_name, search_terms: "lyrics")
     if !url
-      raise("There was no url found on youtube for " +
+      outputter("url", 0)
-            %("#{@song_name}" by "#{@artist_name}. ) +
+      url = Youtube.find_url(@song_name, @artist_name, search_terms: "lyrics")
-            "Check your input and try again.")
+      if !url
+        raise("There was no url found on youtube for " +
+              %("#{@song_name}" by "#{@artist_name}. ) +
+              "Check your input and try again.")
+      end
+      outputter("url", 1)
+    else
+      outputter("url", 2)
+      if !Youtube.is_valid_url(url)
+        raise("The url '#{url}' is an invalid youtube URL " +
+              "Check the URL and try again")
+      end
+      outputter("url", 3)
     end
-    outputter("url", 1)
 
     outputter("download", 0)
     Ripper.download_mp3(url.as(String), @filename)

src/search/youtube.cr

@@ -23,6 +23,17 @@ module Youtube
 
   alias NODES_CLASS = Array(Hash(String, String))
 
+  # Checks if the given URL is a valid youtube URL
+  #
+  # ```
+  # Youtube.is_valid_url("https://www.youtube.com/watch?v=NOTANACTUALVIDEOID")
+  # => false
+  # ```
+  def is_valid_url(url : String) : Bool
+    response = HTTP::Client.get(url)
+    return !(response.status_code == 404)
+  end
+
   # Finds a youtube url based off of the given information.
   # The query to youtube is constructed like this:
   #   "<song_name> <artist_name> <search terms>"