batch script for removing old subtitles and adding ass format subtitles in the same directory as an MKV file

rm_old_subtitles_and_add_chi_subtitle.sh

#!/bin/bash

# Set default values
current_dir="$(pwd)"
work_dir=$(gum input --placeholder "work_dir (default: $current_dir)")
test -z "$work_dir" && work_dir=$current_dir
with_subdir="true"
output_dir="$work_dir/output"

if [ ! -d "$output_dir" ]; then
    # If not, create the directory
    mkdir -p "$output_dir"
    echo "Directory created: $output_dir"
else
    echo "Directory already exists: $output_dir"
fi

# Function to process mkv files
process_mkv() {
    local mkv_file="$1"

    mkv_filename=$(basename "$mkv_file")
    mkv_filename_no_suffix="${mkv_filename%.*}"
    directory=$(dirname "$mkv_file")

    ass_path="$directory/$mkv_filename_no_suffix.ass"
    output_path="$output_dir/$mkv_filename_no_suffix.mkv"

    if [ -e "$ass_path" ]; then
      gum spin --spinner dot --title "Processing file: $mkv_file..." -- ffmpeg -hide_banner -loglevel warning -y \
      -i "$mkv_file" -i "$ass_path" -c copy -map 0 -map -0:s -map 1 -metadata:s:s:0 language=chi "$output_path"
      echo "$mkv_file -- Processed Done!"
    fi
}

# Process mkv files in the given directory
process_files() {
    local dir="$1"

    for mkv_file in "$dir"/*.mkv; do
        if [ -f "$mkv_file" ]; then
            process_mkv "$mkv_file"
        fi
    done
}

# Process mkv files in subdirectories recursively
process_subdirs() {
    local dir="$1"
    # Process files in the current directory
    process_files "$dir"
    subdirs="$dir/*"

    # Process subdirectories
    if [ "$with_subdir" = "true" ]; then
        for subdir in "${subdirs[@]}"; do
          if [ -d "$subdir" ];then
            process_subdirs "$subdir"
          fi
        done
    fi
}

# Start processing
process_subdirs "$work_dir"