add beet_add_genres script

scripts/beet_add_genres.fish

@@ -0,0 +1,44 @@
+#!/usr/bin/env fish
+
+# Ensure we have the required arguments
+if test (count $argv) -lt 2
+    echo "Usage: script.fish <user_genres> <query>"
+    exit 1
+end
+
+set user_genres $argv[1]
+set query $argv[2..]
+
+echo "User-supplied genre list is '$user_genres'."
+echo "Database query is '$query'"
+
+# Get the current genres from beets
+set beet_output (beet list -af '$genre' $query)
+
+set query_lines (string split0 $beet_output)
+
+if test (count $query_lines) -gt 1
+	echo "Database query has to be a single line"
+	#exit 1
+end
+
+function list_merge_sort
+ 	string split "\n" (echo -e (string join "\n" $argv) | sort)
+end
+
+function list_merge_unique
+ 	string split "\n" (echo -e (string join "\n" $argv) | sort -u)
+end
+
+set -l current_genres (string split ', ' $beet_output)
+set -l current_genres_count (count $current_genres)
+echo "Current genres ($current_genres_count): $(string join ", " $(list_merge_sort $current_genres))"
+set -l additional_genres (string split ', ' $user_genres)
+echo "Additional genres ($(count $additional_genres)): $(string join ", " $(list_merge_sort $additional_genres))"
+
+set -l combined_genres (list_merge_unique $current_genres $additional_genres)
+set -l combined_genres_count (count $combined_genres)
+echo "Combined genres ($combined_genres_count): $(string join ", " $combined_genres)"
+echo "Unique new genres: $(math $combined_genres_count - $current_genres_count)"
+
+beet modify -a genre="$(string join ", " $combined_genres)" $query