#!/usr/bin/env bash
#
# kel-music — YouTube-Audio → SQLite-Musikbibliothek

set -euo pipefail

# =========================================================================
# KONFIGURATION (XDG-konform)
# =========================================================================
CONFIG_DIR="$HOME/.config/kel/music"
CONFIG_FILE="$CONFIG_DIR/config"
MUSIC_ROOT_DEFAULT="$HOME/.local/kel/music/audio"
DB_PATH_DEFAULT="$HOME/.local/kel/music/library.db"

_env_MUSIC_ROOT="${MUSIC_ROOT-}"
_env_DB_PATH="${DB_PATH-}"

if [[ ! -f $CONFIG_FILE ]]; then
    mkdir -p "$CONFIG_DIR"
    cat > "$CONFIG_FILE" <<EOF
# ~/.config/kel/music/config
MUSIC_ROOT="$MUSIC_ROOT_DEFAULT"
DB_PATH="$DB_PATH_DEFAULT"
EOF
fi

# shellcheck disable=SC1090
source "$CONFIG_FILE"

[[ -n $_env_MUSIC_ROOT ]] && MUSIC_ROOT="$_env_MUSIC_ROOT"
[[ -n $_env_DB_PATH    ]] && DB_PATH="$_env_DB_PATH"
: "${MUSIC_ROOT:=$MUSIC_ROOT_DEFAULT}"
: "${DB_PATH:=$DB_PATH_DEFAULT}"

mkdir -p "$MUSIC_ROOT" "$(dirname "$DB_PATH")"
export MUSIC_ROOT DB_PATH

# =========================================================================
# URL-EINGABE + NORMALISIERUNG
# =========================================================================
read -r -p "YouTube URL : " youtube_url
[[ -n $youtube_url ]]            || { echo "URL erforderlich" >&2; exit 1; }
[[ $youtube_url =~ ^https?:// ]] || { echo "URL muss http(s) sein" >&2; exit 1; }

normalize_url() {
    local u="$1"
    if [[ $u =~ (v=|youtu\.be/|shorts/|embed/|/v/)([A-Za-z0-9_-]{11}) ]]; then
        printf 'https://youtu.be/%s' "${BASH_REMATCH[2]}"
    else
        printf '%s' "$u"
    fi
}
norm_url=$(normalize_url "$youtube_url")
export youtube_url norm_url

# =========================================================================
# NIX-SHELL
# =========================================================================
nix-shell -p sqlite coreutils findutils yt-dlp eyed3 ffmpeg flac \
    --run "$(cat <<'NIX_SCRIPT'
set -euo pipefail
IFS=$'\n\t'
SEP=$'\x1f'

# =========================================================================
# META + SCHEMA-HASH
# =========================================================================
init_db() {
    sqlite3 -batch "$DB_PATH" <<'SQL'
PRAGMA foreign_keys = ON;
CREATE TABLE IF NOT EXISTS meta (
    key TEXT PRIMARY KEY, value TEXT NOT NULL);
CREATE TABLE IF NOT EXISTS artists (
    id INTEGER PRIMARY KEY,
    name TEXT NOT NULL UNIQUE COLLATE NOCASE);
CREATE TABLE IF NOT EXISTS albums (
    id INTEGER PRIMARY KEY,
    artist_id INTEGER NOT NULL REFERENCES artists(id) ON DELETE CASCADE,
    name TEXT NOT NULL COLLATE NOCASE,
    UNIQUE(artist_id, name));
CREATE TABLE IF NOT EXISTS songs (
    id INTEGER PRIMARY KEY,
    album_id INTEGER NOT NULL REFERENCES albums(id) ON DELETE CASCADE,
    title TEXT NOT NULL,
    youtube_url TEXT NOT NULL UNIQUE,
    file_path TEXT NOT NULL,
    format TEXT NOT NULL,
    downloaded_at TEXT NOT NULL DEFAULT (datetime('now')));
SQL

    local current_hash stored_hash stored_version
    current_hash=$(
        sqlite3 -batch "$DB_PATH" \
            "SELECT sql FROM sqlite_master
             WHERE type='table'
               AND name NOT LIKE 'sqlite_%'
               AND name != 'meta'
             ORDER BY name;" | sha256sum | cut -d' ' -f1
    )
    stored_hash=$(sqlite3 -batch "$DB_PATH" \
        "SELECT value FROM meta WHERE key='schema_hash';" 2>/dev/null || true)
    stored_version=$(sqlite3 -batch "$DB_PATH" \
        "SELECT value FROM meta WHERE key='db_version';" 2>/dev/null || true)

    if [[ -z $stored_hash ]]; then
        sqlite3 -batch "$DB_PATH" "
            BEGIN;
            INSERT INTO meta(key,value) VALUES('db_version','1');
            INSERT INTO meta(key,value) VALUES('schema_hash','$current_hash');
            INSERT INTO meta(key,value) VALUES('created_at',datetime('now'));
            COMMIT;"
        return
    fi
    [[ $stored_version == "1" ]] || { echo "FEHLER: DB-Version '$stored_version' != 1" >&2; exit 3; }
    [[ $stored_hash == "$current_hash" ]] || {
        echo "FEHLER: Schema-Hash-Mismatch" >&2
        echo "  gespeichert: $stored_hash" >&2
        echo "  berechnet  : $current_hash" >&2
        exit 4
    }
}
init_db

# =========================================================================
# HELFER
# =========================================================================
sql_escape() { printf '%s' "$1" | sed "s/'/''/g"; }
trim() {
    local s="$1"
    s="${s%$'\r'}"
    s="${s#"${s%%[![:space:]]*}"}"
    s="${s%"${s##*[![:space:]]}"}"
    printf '%s' "$s"
}
ask() {
    local prompt="$1" default="${2-}" ans
    if [[ -n $default ]]; then
        IFS= read -r -p "$prompt [$default]: " ans || exit 1
        trim "${ans:-$default}"
    else
        IFS= read -r -p "$prompt: " ans || exit 1
        trim "$ans"
    fi
}

# =========================================================================
# GET-OR-CREATE — eine Verbindung, atomar; setzt SEL_*-Globale
# =========================================================================
get_or_create_artist() {
    local name="$1" esc result
    esc=$(sql_escape "$name")
    result=$(sqlite3 -batch -separator "$SEP" "$DB_PATH" "
        INSERT OR IGNORE INTO artists(name) VALUES('$esc');
        SELECT id, name FROM artists WHERE name='$esc';")
    [[ -n $result ]] || { echo "FEHLER: Artist '$name' nicht lesbar" >&2; exit 6; }
    IFS=$SEP read -r SEL_ARTIST_ID SEL_ARTIST_NAME <<<"$result"
}
get_or_create_album() {
    local artist_id="$1" name="$2" esc result
    [[ -n $artist_id ]] || { echo "FEHLER: get_or_create_album ohne artist_id" >&2; exit 6; }
    esc=$(sql_escape "$name")
    result=$(sqlite3 -batch -separator "$SEP" "$DB_PATH" "
        INSERT OR IGNORE INTO albums(artist_id, name) VALUES($artist_id, '$esc');
        SELECT id, name FROM albums
         WHERE artist_id=$artist_id AND name='$esc';")
    [[ -n $result ]] || { echo "FEHLER: Album '$name' nicht lesbar" >&2; exit 6; }
    IFS=$SEP read -r SEL_ALBUM_ID SEL_ALBUM_NAME <<<"$result"
}

# =========================================================================
# ARTIST-AUSWAHL — setzt SEL_*; UI auf stderr
# =========================================================================
select_artist() {
    SEL_ARTIST_ID=""; SEL_ARTIST_NAME=""
    local query="" name choice row i
    local -a rows
    while :; do
        rows=()
        if [[ -n $query ]]; then
            mapfile -t rows < <(sqlite3 -batch -separator "$SEP" "$DB_PATH" \
                "SELECT id, name FROM artists
                 WHERE name LIKE '%$(sql_escape "$query")%'
                 ORDER BY name COLLATE NOCASE;")
        else
            mapfile -t rows < <(sqlite3 -batch -separator "$SEP" "$DB_PATH" \
                "SELECT id, name FROM artists ORDER BY name COLLATE NOCASE;")
        fi

        echo >&2
        echo "=== Artists${query:+ passend zu \"$query\"} ===" >&2

        if (( ${#rows[@]} == 0 )); then
            if [[ -z $query ]]; then
                echo "  (noch keine Artists in der Datenbank)" >&2
                echo "  → neuen Artist anlegen:" >&2
                name=$(ask "neuer Artist")
                [[ -n $name ]] || { echo "  leerer Name." >&2; continue; }
                get_or_create_artist "$name"
                return
            else
                echo "  (keine Treffer für \"$query\")" >&2
                echo "  n) neu anlegen als \"$query\" (Name editierbar)" >&2
                echo "  s) neue Suche (leer = alle)" >&2
            fi
        else
            i=1
            for row in "${rows[@]}"; do
                echo "  $i) ${row#*"$SEP"}" >&2
                i=$((i+1))
            done
            echo "  s) Suche · n) neuer Artist · oder Namen eintippen" >&2
        fi

        IFS= read -r -p "> " choice || exit 1
        choice=$(trim "$choice")

        case "$choice" in
            "") continue ;;
            s|S) query=$(ask "Suchbegriff (leer = alle)"); continue ;;
            n|N)
                name=$(ask "neuer Artist" "$query")
                [[ -n $name ]] || { echo "  leerer Name." >&2; continue; }
                get_or_create_artist "$name"
                return
                ;;
        esac
        if [[ $choice =~ ^[0-9]+$ ]] && (( choice >= 1 && choice <= ${#rows[@]} )); then
            IFS=$SEP read -r SEL_ARTIST_ID SEL_ARTIST_NAME <<<"${rows[$((choice-1))]}"
            return
        fi
        query="$choice"
    done
}

# =========================================================================
# ALBUM-AUSWAHL — analog
# =========================================================================
select_album() {
    local artist_id="$1"
    [[ -n $artist_id ]] || { echo "FEHLER: select_album ohne artist_id" >&2; exit 6; }
    SEL_ALBUM_ID=""; SEL_ALBUM_NAME=""
    local query="" name choice row i
    local -a rows
    while :; do
        rows=()
        if [[ -n $query ]]; then
            mapfile -t rows < <(sqlite3 -batch -separator "$SEP" "$DB_PATH" \
                "SELECT id, name FROM albums
                 WHERE artist_id=$artist_id
                   AND name LIKE '%$(sql_escape "$query")%'
                 ORDER BY name COLLATE NOCASE;")
        else
            mapfile -t rows < <(sqlite3 -batch -separator "$SEP" "$DB_PATH" \
                "SELECT id, name FROM albums
                 WHERE artist_id=$artist_id ORDER BY name COLLATE NOCASE;")
        fi

        echo >&2
        echo "=== Alben für Artist #$artist_id${query:+ passend zu \"$query\"} ===" >&2

        if (( ${#rows[@]} == 0 )); then
            if [[ -z $query ]]; then
                echo "  (dieser Artist hat noch keine Alben)" >&2
                echo "  → neues Album anlegen:" >&2
                name=$(ask "neues Album")
                [[ -n $name ]] || { echo "  leerer Name." >&2; continue; }
                get_or_create_album "$artist_id" "$name"
                return
            else
                echo "  (keine Treffer für \"$query\")" >&2
                echo "  n) neu anlegen als \"$query\" (Name editierbar)" >&2
                echo "  s) neue Suche (leer = alle)" >&2
            fi
        else
            i=1
            for row in "${rows[@]}"; do
                echo "  $i) ${row#*"$SEP"}" >&2
                i=$((i+1))
            done
            echo "  s) Suche · n) neues Album · oder Namen eintippen" >&2
        fi

        IFS= read -r -p "> " choice || exit 1
        choice=$(trim "$choice")

        case "$choice" in
            "") continue ;;
            s|S) query=$(ask "Suchbegriff (leer = alle)"); continue ;;
            n|N)
                name=$(ask "neues Album" "$query")
                [[ -n $name ]] || { echo "  leerer Name." >&2; continue; }
                get_or_create_album "$artist_id" "$name"
                return
                ;;
        esac
        if [[ $choice =~ ^[0-9]+$ ]] && (( choice >= 1 && choice <= ${#rows[@]} )); then
            IFS=$SEP read -r SEL_ALBUM_ID SEL_ALBUM_NAME <<<"${rows[$((choice-1))]}"
            return
        fi
        query="$choice"
    done
}

# =========================================================================
# URL-VORSCHAU
# =========================================================================
echo >&2
echo "Prüfe URL …" >&2
yt_title=$(yt-dlp --skip-download --no-playlist \
    --print '%(title)s' -- "$youtube_url" 2>/dev/null || true)
echo "  Titel : ${yt_title:-(nicht abrufbar)}" >&2
echo "  URL   : $youtube_url" >&2
echo "  Norm  : $norm_url" >&2

# =========================================================================
# DB-CHECK
# =========================================================================
existing=$(sqlite3 -batch -separator "$SEP" "$DB_PATH" "
    SELECT s.id, s.title, ar.name, al.name, s.file_path, s.downloaded_at
    FROM songs s
    JOIN albums al ON al.id = s.album_id
    JOIN artists ar ON ar.id = al.artist_id
    WHERE s.youtube_url = '$(sql_escape "$norm_url")'
       OR s.youtube_url = '$(sql_escape "$youtube_url")';")

if [[ -n $existing ]]; then
    IFS=$SEP read -r song_id t art alb path ts <<<"$existing"

    if [[ $path == /* ]]; then
        display_path="$path"
    else
        display_path="$MUSIC_ROOT/$path"
    fi

    echo >&2
    echo "Bereits vorhanden:" >&2
    echo "  $art — $alb — $t" >&2
    echo "  Datei : $display_path" >&2
    echo "  Wann  : $ts" >&2
    IFS= read -r -p "Neu laden (r) oder abbrechen (a)? [r/a] " choice || exit 1
    case "$choice" in
        r|R)
            sqlite3 -batch "$DB_PATH" "PRAGMA foreign_keys=ON;
                DELETE FROM songs WHERE id=$song_id;"
            echo "  → alter DB-Eintrag entfernt (Datei: $display_path)" >&2
            ;;
        *) echo "Abgebrochen." >&2; exit 0 ;;
    esac
else
    if [[ -z $yt_title ]]; then
        IFS= read -r -p "Titel nicht abrufbar. Trotzdem fortfahren? [y/N] " ok
        [[ $ok =~ ^[Yy] ]] || exit 1
    fi
fi

# =========================================================================
# HAUPTFLUSS
# =========================================================================
song_name=$(ask "Songtitel")
[[ -n $song_name ]] || { echo "Titel erforderlich" >&2; exit 1; }

select_artist
artist_id="$SEL_ARTIST_ID"
artist_name="$SEL_ARTIST_NAME"
[[ -n $artist_id ]] || { echo "FEHLER: kein Artist gewählt" >&2; exit 6; }

select_album "$artist_id"
album_id="$SEL_ALBUM_ID"
album_name="$SEL_ALBUM_NAME"
[[ -n $album_id ]] || { echo "FEHLER: kein Album gewählt" >&2; exit 6; }

dup=$(sqlite3 -batch "$DB_PATH" "SELECT id FROM songs
    WHERE album_id=$album_id AND title='$(sql_escape "$song_name")';")
[[ -z $dup ]] || echo "WARNUNG: Song existiert bereits (id=$dup)" >&2

# =========================================================================
# DATEINAMEN SANITIZEN — nur für die Platte, DB-Namen bleiben raw
# =========================================================================
safe_song=${song_name//\//-}
safe_artist=${artist_name//\//-}
safe_album=${album_name//\//-}

for _comp in "$safe_artist" "$safe_album" "$safe_song"; do
    if [[ -z $_comp || $_comp == "." || $_comp == ".." ]]; then
        echo "FEHLER: unzulässiger Name '$_comp' (nach Sanitizing)" >&2
        exit 7
    fi
done
unset _comp

# =========================================================================
# DOWNLOAD
# =========================================================================
work_dir=$(mktemp -d)
trap 'rm -rf "$work_dir"' EXIT

yt-dlp \
    -f 'ba[acodec^=flac]/ba[acodec^=opus]/ba' \
    --extract-audio --audio-format best --audio-quality 0 \
    --no-embed-metadata --no-write-info-json \
    --no-write-thumbnail --no-write-description \
    --no-playlist \
    -o "$work_dir/%(id)s.%(ext)s" \
    -- "$youtube_url"

src=$(find "$work_dir" -maxdepth 1 -type f \
    \( -name '*.flac' -o -name '*.opus' -o -name '*.mp3' \
       -o -name '*.ogg'  -o -name '*.m4a' \) \
    -print -quit)
[[ -n $src && -f $src ]] || { echo "keine Audiodatei erzeugt" >&2; exit 2; }
ext=${src##*.}

# =========================================================================
# TAGGING
# =========================================================================
case "$ext" in
    flac)
        metaflac --set-tag="ARTIST=$artist_name" \
                 --set-tag="ALBUM=$album_name"   \
                 --set-tag="TITLE=$song_name"    "$src"
        ;;
    mp3)
        eyed3 --artist "$artist_name" --album "$album_name" \
              --title "$song_name" -- "$src"
        ;;
    opus|ogg|m4a)
        ffmpeg -y -loglevel error -i "$src" -c copy \
            -metadata artist="$artist_name" \
            -metadata album="$album_name"   \
            -metadata title="$song_name"    \
            "${src%.*}.tagged.$ext"
        mv -- "${src%.*}.tagged.$ext" "$src"
        ;;
esac

# =========================================================================
# VERSCHIEBEN — relativer Pfad in DB, absoluter Pfad auf Platte
# =========================================================================
rel_path="${safe_artist}/${safe_album}/${safe_song}.${ext}"
dest="$MUSIC_ROOT/$rel_path"
mkdir -p "$(dirname "$dest")"
mv -v -- "$src" "$dest" >&2

# =========================================================================
# IN DB SCHREIBEN
# =========================================================================
sqlite3 -batch "$DB_PATH" "PRAGMA foreign_keys=ON;
    INSERT INTO songs(album_id, title, youtube_url, file_path, format)
    VALUES($album_id,
           '$(sql_escape "$song_name")',
           '$(sql_escape "$norm_url")',
           '$(sql_escape "$rel_path")',
           '$ext');"

echo >&2
echo "fertig: $dest" >&2
echo "  DB-Pfad: $rel_path (relativ zu \$MUSIC_ROOT)" >&2
echo "  Artist #$artist_id $artist_name" >&2
echo "  Album  #$album_id  $album_name" >&2
echo "  Titel  $song_name" >&2
NIX_SCRIPT
)"