renamesubs

#!/bin/bash

#  ------------------- renamesubs -------------------
#  A script for renaming subtitles file names to match
#  corresponding media files on the same folder,
#  matched by season and episode numbers (SXXEXX format).
#
#  Usage:
#    renamesubs <Directory> <Media Extension> <Subtitles Extension> [Suffix]
#
#  Arguments:
#    1. Directory - The directory to search and replace media files and subtitles.
#    2. Media Extension - Media file extension to look for.
#    3. Subtitles Extension - Subtitles file extension to look for.
#    4. Suffix (optional)- An optional suffix to append to renamed subtitles file (before file extension).
#  --------------------------------------------------

function pring_usage
{
    echo "Usage: $(basename "$0") <Directory> <Media Extension> <Subtitles Extension> [Suffix]"
}


# Assure a valid amount of command-line arguments was passed
if [[ $# -lt 3 ]]; then
    echo "Error: Missing parameters." >&2
    pring_usage
    exit 1
fi

folder_path=${1%/}
media_file_extension="$2"
subtitles_file_extension="$3"
suffix="$4"

# Assure source directory exists and is a directory
if [[ ! -d "$folder_path" ]]; then
	echo -e "\"$folder_path\" is an invalid directory."
fi


while IFS= read -r filename;
do
    # Assure file extension is valid
    if [[ "$filename" != *$media_file_extension ]]; then continue; fi

    # Assure file name contains a season and an episode number
    episode=$(grep -oP "[Ss]\d{2}[Ee]\d{2}" <<< "$filename")
    if [[ -z "$episode" ]]; then continue; fi

    subtitles_file=$(find "$folder_path" -name "*$episode*.$subtitles_file_extension" -maxdepth 1)
    if [[ -z "$subtitles_file" ]]; then continue; fi
    subtitles_extension="${subtitles_file##*.}"

    new_file_name="${filename%."$media_file_extension"}$suffix.$subtitles_extension"

    if [[ "$subtitles_file" != "$new_file_name" ]]; then
        mv "$subtitles_file" "$new_file_name"
    fi
done <<< "$(find "$folder_path" -name "*.$media_file_extension" -maxdepth 1)"