align-subs.sh

#!/bin/bash

function find_video {
  local path="$1"
  local name="$2"
  find "$path" -type f \( -iname "*$name*.mp4" -or -iname "*$name*.mkv" -or -iname "*$name*.avi" \) | sort | head -n 1 
}

for srt_file in "$@" ; do
    # Check if the file is an srt file
    if [[ "$srt_file" != *.srt ]] ; then
        echo "$srt_file is not an srt file"
        continue
    fi

    filename="$(basename -- "$srt_file")"
    path="$(dirname -- "$srt_file")"
    lang="$(echo $filename | sed "s/.*\.\([A-z][A-z]\)\.srt$/\1/")"
    filename_without_lang="$(echo "$filename" | sed 's/\(\.[A-z][A-z]\)\{0,1\}\.srt//')"

    # Find the video file that matches the filename
    video_file=$(find_video "$path" "$filename_without_lang")

    # If no video found, let's be wild
    if [ -z "$video_file" ] ; then
        greedymatch=$(echo "$filename_without_lang" | grep -o -i -w -E 'S[0-9]+E[0-9]+')
        video_file=$(find_video "$path" "$greedymatch")
    fi

    # Well, we tried enough
    if [ -z "$video_file" ] ; then
        echo "No video file found for $filename_without_lang"
        continue
    fi

    if [[ $lang ]] ; then
        new_srt="${video_file%.*}.${lang}.srt"
    else
        new_srt="${video_file%.*}.srt"
    fi

    # Execute the command ffs video.mp4 -i subtitle.srt -o new_subtitle.srt
    ffs "$video_file" -i "$srt_file" -o "${srt_file%.*}.new.srt"

    # If the execution returns an error, log that there was an error and continue
    if [ $? -ne 0 ] ; then
        echo "Error executing ffs for $srt_file"
        continue
    fi

    # If the output video doesn't exist after the execution, log that there was an issue, then continue
    if [ ! -f "${srt_file%.*}.new.srt" ] ; then
        echo "Output file not found for $srt_file"
        continue
    fi

    # Swap the new subtitles file with the original subtitles, keep the original subtitles with a suffix .backup
    mv "$srt_file" "${srt_file}.backup"
    mv "${srt_file%.*}.new.srt" "${new_srt}"
done