#!/bin/bash

# ==============================================================================================
# ================================= Music Artwork Fetcher ======================================
# ==============================================================================================
#
# SAFE DESIGN
#   - READS from Lidarr only
#   - NEVER modifies tags
#   - NEVER renames media
#   - NEVER writes to Lidarr
#   - ONLY writes missing artwork files
#
# ARTWORK
#
#   Album Folder:
#       cover.jpg
#       cdart.png
#       back.jpg
#
#   Artist Folder:
#       folder.jpg
#       fanart.jpg
#       logo.png
#       banner.jpg
#
# SOURCES
#
#   Album Covers:
#       fanart.tv
#       iTunes fallback
#
#   Artist Art:
#       fanart.tv
#       Deezer fallback
#       Last.fm fallback

# ================================= CONFIG =====================================================


LIDARR_URL="http://localhost:8686"
LIDARR_API_KEY="b2977e71ef074bc0a0529d9fcce3b2dc"

FANART_API_KEY="Yd7147a43b692df0b364b94dc47efb81"
LASTFM_API_KEY="be6dc169c33ae263e690c30d18b7491d"

LOG="/tmp/artfetch.log"

MIN_SIZE=10000
MAX_PARALLEL=4
RETRIES=2
SLEEP_BETWEEN=0.2

# ================================= FLAGS ======================================================

DRY_RUN=0

if [[ "$1" == "--dry-run" ]]; then
    DRY_RUN=1
    echo "Running in DRY-RUN mode"
fi

# ================================= LOGGING ====================================================

log() {
    echo "$(date '+%F %T') | $1" >> "$LOG"
}

# ================================= HELPERS ====================================================

curl_json() {
    curl -s \
        --connect-timeout 5 \
        --max-time 20 \
        "$1"
}

job_count() {
    jobs -rp | wc -l
}

wait_for_slot() {
    while (( $(job_count) >= MAX_PARALLEL )); do
        sleep 0.2
    done
}

# ================================= DOWNLOAD ===================================================

download_if_valid() {

    local url="$1"
    local dest="$2"

    [[ -z "$url" || "$url" == "null" ]] && return 1

    # never overwrite existing
    [[ -f "$dest" ]] && return 0

    if [[ "$DRY_RUN" -eq 1 ]]; then
        log "[DRY] $dest"
        return 0
    fi

    for ((i=0; i<=RETRIES; i++)); do

        tmp="${dest}.tmp"

        curl -s \
            --connect-timeout 5 \
            --max-time 20 \
            -L \
            -o "$tmp" \
            "$url"

        size=$(stat -c%s "$tmp" 2>/dev/null)

        if [[ "$size" -gt "$MIN_SIZE" ]]; then
            mv "$tmp" "$dest"
            log "[OK] $dest"
            return 0
        fi

        rm -f "$tmp"
        sleep 1
    done

    log "[FAIL] $dest"
    return 1
}

# ================================= DEEZER =====================================================

deezer_artist_image() {

    local artist="$1"

    query=$(printf "%s" "$artist" | sed 's/ /+/g')

    curl_json \
        "https://api.deezer.com/search/artist?q=$query" |
        jq -r '.data[0].picture_xl // empty'
}

# ================================= LASTFM =====================================================

lastfm_artist_image() {

    local artist="$1"

    encoded=$(printf "%s" "$artist" | sed 's/ /%20/g')

    curl_json \
        "https://ws.audioscrobbler.com/2.0/?method=artist.getinfo&artist=$encoded&api_key=$LASTFM_API_KEY&format=json" |
        jq -r '.artist.image[-1]["#text"] // empty'
}

# ==============================================================================================
# ====================================== ALBUMS =================================================
# ==============================================================================================

echo "===== PROCESSING ALBUMS ====="

albums=$(curl_json \
    "$LIDARR_URL/api/v1/album?apikey=$LIDARR_API_KEY")

[[ -z "$albums" || "$albums" == "null" ]] && {
    echo "ERROR: Lidarr album API failed"
    exit 1
}

total_albums=$(echo "$albums" | jq '. | length')
album_count=0

echo "$albums" | jq -c '.[]?' | while read -r album; do

    ((album_count++))

    path=$(echo "$album" | jq -r '.path')
    mbid=$(echo "$album" | jq -r '.foreignAlbumId')
    artist=$(echo "$album" | jq -r '.artist.artistName')
    name=$(echo "$album" | jq -r '.title')

    [[ ! -d "$path" ]] && continue

    printf '[ALBUM %s/%s] %s - %s\n' \
        "$album_count" "$total_albums" "$artist" "$name"

    # skip complete albums
    if [[ -f "$path/cover.jpg" &&
          -f "$path/cdart.png" &&
          -f "$path/back.jpg" ]]; then
        echo "  -> complete"
        continue
    fi

    wait_for_slot

    (

        JSON=""

        if [[ -n "$mbid" && "$mbid" != "null" ]]; then

            JSON=$(curl_json \
                "http://webservice.fanart.tv/v3/music/albums/$mbid?api_key=$FANART_API_KEY")

            sleep "$SLEEP_BETWEEN"
        fi

        # ================= COVER =================

        if [[ ! -f "$path/cover.jpg" ]]; then

            IMG=$(echo "$JSON" | jq -r '.[].albumcover[0].url // empty')

            if ! download_if_valid "$IMG" "$path/cover.jpg"; then

                query=$(printf "%s %s" "$artist" "$name" | sed 's/ /+/g')

                itunes=$(curl_json \
                    "https://itunes.apple.com/search?term=$query&entity=album&limit=1" |
                    jq -r '.results[0].artworkUrl100 // empty' |
                    sed 's/100x100/600x600/')

                download_if_valid "$itunes" "$path/cover.jpg"
            fi
        fi

        # ================= CDART =================

        if [[ ! -f "$path/cdart.png" ]]; then

            IMG=$(echo "$JSON" | jq -r '.[].cdart[0].url // empty')

            download_if_valid "$IMG" "$path/cdart.png"
        fi

        # ================= BACK =================

        if [[ ! -f "$path/back.jpg" ]]; then

            IMG=$(echo "$JSON" | jq -r '.[].albumback[0].url // empty')

            download_if_valid "$IMG" "$path/back.jpg"
        fi

    ) &

done

wait

# ==============================================================================================
# ====================================== ARTISTS ================================================
# ==============================================================================================

echo
echo "===== PROCESSING ARTISTS ====="

artists=$(curl_json \
    "$LIDARR_URL/api/v1/artist?apikey=$LIDARR_API_KEY")

[[ -z "$artists" || "$artists" == "null" ]] && {
    echo "ERROR: Lidarr artist API failed"
    exit 1
}

total_artists=$(echo "$artists" | jq '. | length')
artist_count=0

echo "$artists" | jq -c '.[]?' | while read -r artist; do

    ((artist_count++))

    path=$(echo "$artist" | jq -r '.path')
    mbid=$(echo "$artist" | jq -r '.foreignArtistId')
    name=$(echo "$artist" | jq -r '.artistName')

    [[ ! -d "$path" ]] && continue
    [[ -z "$mbid" || "$mbid" == "null" ]] && continue

    printf '[ARTIST %s/%s] %s\n' \
        "$artist_count" "$total_artists" "$name"

    # skip complete artists
    if [[ -f "$path/folder.jpg" &&
          -f "$path/fanart.jpg" &&
          -f "$path/logo.png" &&
          -f "$path/banner.jpg" ]]; then
        echo "  -> complete"
        continue
    fi

    wait_for_slot

    (

        JSON=$(curl_json \
            "http://webservice.fanart.tv/v3/music/$mbid?api_key=$FANART_API_KEY")

        sleep "$SLEEP_BETWEEN"

        # ================= folder.jpg =================

        if [[ ! -f "$path/folder.jpg" ]]; then

            IMG=$(echo "$JSON" | jq -r '.artistthumb[0].url // empty')

            if ! download_if_valid "$IMG" "$path/folder.jpg"; then

                IMG=$(deezer_artist_image "$name")

                if ! download_if_valid "$IMG" "$path/folder.jpg"; then

                    IMG=$(lastfm_artist_image "$name")

                    download_if_valid "$IMG" "$path/folder.jpg"
                fi
            fi
        fi

        # ================= fanart.jpg =================

        if [[ ! -f "$path/fanart.jpg" ]]; then

            IMG=$(echo "$JSON" | jq -r '.artistbackground[0].url // empty')

            if ! download_if_valid "$IMG" "$path/fanart.jpg"; then

                IMG=$(deezer_artist_image "$name")

                download_if_valid "$IMG" "$path/fanart.jpg"
            fi
        fi

        # ================= logo.png =================

        if [[ ! -f "$path/logo.png" ]]; then

            IMG=$(echo "$JSON" | jq -r '.hdmusiclogo[0].url // empty')

            download_if_valid "$IMG" "$path/logo.png"
        fi

        # ================= banner.jpg =================

        if [[ ! -f "$path/banner.jpg" ]]; then

            IMG=$(echo "$JSON" | jq -r '.musicbanner[0].url // empty')

            download_if_valid "$IMG" "$path/banner.jpg"
        fi

    ) &

done

wait

echo
echo "===== COMPLETE ====="

log "===== COMPLETE ====="