-- Migration: Create playlists and playlist_tracks tables
-- T0296: Create Playlist Database Model

CREATE TABLE IF NOT EXISTS playlists (
    id BIGSERIAL PRIMARY KEY,
    user_id BIGINT NOT NULL REFERENCES users(id) ON DELETE CASCADE,
    title VARCHAR(200) NOT NULL,
    description TEXT,
    is_public BOOLEAN DEFAULT TRUE,
    cover_url VARCHAR(500),
    track_count INTEGER DEFAULT 0,
    created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
    updated_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP
);

CREATE TABLE IF NOT EXISTS playlist_tracks (
    id BIGSERIAL PRIMARY KEY,
    playlist_id BIGINT NOT NULL REFERENCES playlists(id) ON DELETE CASCADE,
    track_id BIGINT NOT NULL REFERENCES tracks(id) ON DELETE CASCADE,
    position INTEGER NOT NULL,
    added_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
    UNIQUE(playlist_id, track_id)
);

-- Indexes for performance
CREATE INDEX IF NOT EXISTS idx_playlists_user_id ON playlists(user_id);
CREATE INDEX IF NOT EXISTS idx_playlist_tracks_playlist_id ON playlist_tracks(playlist_id);
CREATE INDEX IF NOT EXISTS idx_playlist_tracks_track_id ON playlist_tracks(track_id);
CREATE INDEX IF NOT EXISTS idx_playlist_tracks_position ON playlist_tracks(playlist_id, position);