#!/usr/bin/env bash
#
# song_downloader.sh — Songs aus segments.json suchen und als Video- oder
# Audio-Segment mit yt-dlp herunterladen.
#
# Abhaengigkeiten: jq, yt-dlp, ffmpeg (fuer --force-keyframes-at-cuts / mp3-Extraktion)
#   Arch:   sudo pacman -S jq yt-dlp ffmpeg
#
# Nutzung:
#   ./song_downloader.sh                  # interaktiver Suchmodus
#   ./song_downloader.sh <suchbegriff>    # direkt mit Suchbegriff starten
#   ./song_downloader.sh -a <suchbegriff> # Audio (mp3) statt Video
#   ./song_downloader.sh -f meine.json    # andere segments.json verwenden
#
set -euo pipefail

SCRIPT_DIR="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" &>/dev/null && pwd)"
JSON_FILE="${SCRIPT_DIR}/segments.json"
OUT_DIR="${SCRIPT_DIR}/downloads"
MODE="video"   # video | audio

# ---------------------------------------------------------------------------
# Argumente parsen
# ---------------------------------------------------------------------------
QUERY=""
while [[ $# -gt 0 ]]; do
    case "$1" in
        -a|--audio)
            MODE="audio"
            shift
            ;;
        -v|--video)
            MODE="video"
            shift
            ;;
        -f|--file)
            JSON_FILE="$2"
            shift 2
            ;;
        -o|--out)
            OUT_DIR="$2"
            shift 2
            ;;
        -h|--help)
            grep '^#' "$0" | sed 's/^#//'
            exit 0
            ;;
        *)
            QUERY="$1"
            shift
            ;;
    esac
done

# ---------------------------------------------------------------------------
# Vorbedingungen pruefen
# ---------------------------------------------------------------------------
for bin in jq yt-dlp; do
    if ! command -v "$bin" &>/dev/null; then
        echo "Fehler: '$bin' ist nicht installiert (siehe Kopf des Scripts)." >&2
        exit 1
    fi
done

if [[ ! -f "$JSON_FILE" ]]; then
    echo "Fehler: Segment-Datei nicht gefunden: $JSON_FILE" >&2
    exit 1
fi

mkdir -p "$OUT_DIR"

# ---------------------------------------------------------------------------
# JSON in eine flache, mit Tabs getrennte Liste umwandeln:
# songname \t videoId \t start \t end \t herkunfts-videotitel
# ---------------------------------------------------------------------------
build_index() {
    jq -r '
        .[] as $stream
        | $stream.songs[]
        | [ .name, $stream.videoId, (.range[0]|tostring), (.range[1]|tostring), $stream.name ]
        | @tsv
    ' "$JSON_FILE"
}

sanitize_filename() {
    # Entfernt Zeichen, die auf den meisten Dateisystemen Probleme machen
    echo "$1" | sed -e 's#[/\\:*?"<>|]#_#g' -e 's/  */ /g' -e 's/^ *//;s/ *$//'
}

format_time() {
    local secs="$1"
    printf '%02d:%02d:%02d' $((secs/3600)) $(((secs%3600)/60)) $((secs%60))
}

# ---------------------------------------------------------------------------
# Song(s) anhand des Suchbegriffs finden (case-insensitive, Substring)
# ---------------------------------------------------------------------------
search_songs() {
    local term="$1"
    build_index | awk -F'\t' -v term="$term" '
        BEGIN { IGNORECASE = 1 }
        index($1, term) > 0 { print }
    '
}

# ---------------------------------------------------------------------------
# Einen Treffer herunterladen
# song_name, video_id, start, end, source_title
# ---------------------------------------------------------------------------
download_segment() {
    local song_name="$1" video_id="$2" start="$3" end="$4" source_title="$5"
    local clean_name url start_ts end_ts outfile

    clean_name="$(sanitize_filename "$song_name")"
    url="https://www.youtube.com/watch?v=${video_id}"
    start_ts="$(format_time "$start")"
    end_ts="$(format_time "$end")"

    echo "-> Lade '${song_name}' (${start_ts}-${end_ts}) aus '${source_title}' [${video_id}] ..."

    if [[ "$MODE" == "audio" ]]; then
        outfile="${OUT_DIR}/${clean_name}.%(ext)s"
        yt-dlp \
            --download-sections "*${start}-${end}" \
            --force-keyframes-at-cuts \
            -x --audio-format mp3 \
            --embed-thumbnail --embed-metadata \
            -o "$outfile" \
            "$url"
    else
        outfile="${OUT_DIR}/${clean_name}.%(ext)s"
        yt-dlp \
            --download-sections "*${start}-${end}" \
            --force-keyframes-at-cuts \
            -f "bv*+ba/b" --merge-output-format mp4 \
            --embed-thumbnail --embed-metadata \
            -o "$outfile" \
            "$url"
    fi
}

# ---------------------------------------------------------------------------
# Auswahl aus Treffern anzeigen und Download anstossen
# ---------------------------------------------------------------------------
select_and_download() {
    local matches="$1"
    local count
    count="$(echo "$matches" | grep -c . || true)"

    if [[ "$count" -eq 0 ]]; then
        echo "Keine Songs gefunden."
        return
    fi

    echo
    echo "Gefundene Songs (Modus: $MODE):"
    local i=1
    while IFS=$'\t' read -r song_name video_id start end source_title; do
        printf '  [%2d] %-45s (%s-%s, aus "%s")\n' \
            "$i" "$song_name" "$(format_time "$start")" "$(format_time "$end")" "$source_title"
        i=$((i+1))
    done <<< "$matches"
    echo "  [ a] alle herunterladen"
    echo "  [ q] abbrechen"
    echo
    read -rp "Auswahl (Nummer, 'a' oder Komma-getrennte Liste): " choice

    if [[ "$choice" == "q" ]]; then
        echo "Abgebrochen."
        return
    fi

    if [[ "$choice" == "a" ]]; then
        while IFS=$'\t' read -r song_name video_id start end source_title; do
            download_segment "$song_name" "$video_id" "$start" "$end" "$source_title"
        done <<< "$matches"
        return
    fi

    IFS=',' read -ra picks <<< "$choice"
    for pick in "${picks[@]}"; do
        pick="$(echo "$pick" | tr -d ' ')"
        line="$(echo "$matches" | sed -n "${pick}p")"
        if [[ -z "$line" ]]; then
            echo "Ungueltige Auswahl: $pick" >&2
            continue
        fi
        IFS=$'\t' read -r song_name video_id start end source_title <<< "$line"
        download_segment "$song_name" "$video_id" "$start" "$end" "$source_title"
    done
}

# ---------------------------------------------------------------------------
# Main
# ---------------------------------------------------------------------------
if [[ -z "$QUERY" ]]; then
    read -rp "Suchbegriff (Songname): " QUERY
fi

matches="$(search_songs "$QUERY")"
select_and_download "$matches"