#!/bin/bash

set -e

YTDLP=$(which yt-dlp)
JQ=$(which jq)
FFMPEG=$(which ffmpeg)

download() {
    DOWNLOAD_LINK="${1}"
    SAVE_PATH="${2}"

    ${YTDLP} -o "${SAVE_PATH}/%(id)s.%(ext)s" \
        -f 'bestvideo[ext=mp4]+bestaudio[ext=m4a]/best[ext=mp4]/best' \
        --write-auto-subs --write-subs --sub-lang en,ru --convert-subs srt --sub-format vtt \
        ${DOWNLOAD_LINK}
}

download_playlist() {
    PLAYLIST="${1}"
    JSON="$(${YTDLP} --flat-playlist -j "${PLAYLIST}" 2>/dev/null)"
    TITLE="$(echo ${JSON} | ${JQ} -r '.playlist_title' | head -n 1)"
    VIDEOS="$(echo ${JSON} | ${JQ} -r '.title')"
    IDS="$(echo ${JSON} | ${JQ} -r '.id')"
    LINKS="$(echo ${JSON} | ${JQ} -r '.original_url')"
    ALL_LINES=$(echo "${JSON}" | wc -l)
    
    mkdir -v "${TITLE}"

    for ((NUMBER=1; NUMBER<=ALL_LINES; NUMBER++)); do
        VIDEO="$(echo "${VIDEOS}" | awk "NR==${NUMBER}")"
        LINK="$(echo "${LINKS}" | awk "NR==${NUMBER}")"
        VIDEO="${VIDEO//\//-}"
        DIR_NAME="${NUMBER} - ${VIDEO}"

        mkdir -v "${TITLE}/${DIR_NAME}"

        download "${LINK}" "${TITLE}/${DIR_NAME}"
    done
}

merge() {
    MP3="${1}"
    MP4="${2}"
    SRT_EN="${3}"
    SRT_RU="${4}"
    CURRENT_PATH="${5}"
    OUTPUT="$(basename "${CURRENT_PATH}")"

    cd "${CURRENT_PATH}"

    ${FFMPEG} -i "${MP4}" -i "${MP3}" -i "${SRT_RU}" -i "${SRT_EN}" \
        -map 0 -map 1 -map 2 -map 3 \
        -c:v copy -c:a copy -metadata:s:a:0 language=eng -metadata:s:a:1 language=rus \
        -c:s mov_text -metadata:s:s:0 language=rus -metadata:s:s:1 language=eng -disposition:s:0 default -disposition:s:1 default \
        "${OUTPUT}.mp4"
}

merge_mp3() {
    SRCDIR="$(realpath "${1}")"

    for DIR in "${SRCDIR}"/*
    do
        for FILE in $(ls "${DIR}")
        do
            if [[ "${FILE}" == *".mp3" ]]; then
                MP3="${FILE}"
            elif [[ "${FILE}" == *".en.srt" ]]; then
                SRT_EN="${FILE}"
            elif [[ "${FILE}" == *".ru.srt" ]]; then
                SRT_RU="${FILE}"
            elif [[ "${FILE}" == *".mp4" ]]; then
                MP4="${FILE}"
            fi
        done
        [ ! -z "${MP3}" ] && [ ! -z "${SRT_EN}" ] && [ ! -z "${SRT_RU}" ] && [ ! -z "${MP4}" ] || continue
        merge "${MP3}" "${MP4}" "${SRT_EN}" "${SRT_RU}" "${DIR}"
    done
}

move_mp4() {
    SRCDIR="$(realpath "${1}")"
    DSTDIR="${2}"

    mkdir -p "${DSTDIR}"

    for DIR in "${SRCDIR}"/*
    do
        FILE="$(basename "${DIR}").mp4"
        mv -v "${DIR}/${FILE}" "${DSTDIR}"
    done
}

main() {
    COMMAND="${1}"
    [ ! -z ${COMMAND} ] && shift

    while [[ $# -gt 0 ]]; do
        KEY="${1}"
        VALUE="${2}"
        case "${KEY}" in
            -p|--playlist)
                PLAYLIST="${VALUE}"
                shift
                ;;
            -s|--source)
                SRCDIR="${VALUE}"
                shift
                ;;
            -d|--destination)
                DSTDIR="${VALUE}"
                shift
                ;;
            *)
                ;;
        esac
        shift
    done

    case "${COMMAND}" in
        download)
            [ -z "${PLAYLIST}" ] && echo "Playlist link unknown" && exit 1
            download_playlist "${PLAYLIST}"
            ;;
        merge)
            [ -z "${SRCDIR}" ] && echo "Source directory not set" && exit 1
            merge_mp3 "${SRCDIR}"
            ;;
        move)
            [ -z "${SRCDIR}" ] && echo "Source directory not set" && exit 1
            [ -z "${DSTDIR}" ] && echo "Destination directory not set" && exit 1
            move_mp4 "${SRCDIR}" "${DSTDIR}"
            ;;
        *)
            exit 1
            ;;
    esac
}

main "${@}"