<?php
/**
 * Radio state — per-user persistence for station choice + volume.
 *
 * Storage: per-user, in `wp_usermeta` under key `radio_state`. A small
 * associative array. Picked user_meta over site-wide options so each
 * admin remembers their own preferred station — matches Buddy's
 * per-user model and the WordPress mental model.
 */

if ( ! defined( 'ABSPATH' ) ) { exit; }

const RADIO_META_KEY = 'radio_state';

/**
 * Default state for a fresh listener. Used the first time a user
 * visits a Radio-rendering page.
 *
 * @return array { station_id, volume, theme, last_played_at }
 */
function radio_default_state() {
    return array(
        'station_id'      => radio_default_station_id(),  // Groove Salad
        'volume'          => 0.6,                          // 60% — comfortable default
        'theme'           => 'auto',                       // auto = match site admin colour scheme
        'last_played_at'  => 0,
    );
}

/**
 * Fetch the current user's state, falling back to defaults and
 * persisting them on first read so a baseline exists for AJAX patches.
 *
 * @param int $user_id Optional. Defaults to current user.
 * @return array
 */
function radio_get_state( $user_id = 0 ) {
    $user_id = $user_id ? (int) $user_id : get_current_user_id();
    if ( ! $user_id ) { return radio_default_state(); }

    $state = get_user_meta( $user_id, RADIO_META_KEY, true );
    if ( ! is_array( $state ) || empty( $state ) ) {
        $state = radio_default_state();
        update_user_meta( $user_id, RADIO_META_KEY, $state );
    }

    // Merge any newly-introduced default keys forward without trampling
    // existing user values.
    $state = array_merge( radio_default_state(), $state );

    // Validate station — if it's been removed from stations.php, fall
    // back to the default rather than rendering a dead choice.
    if ( ! radio_find_station( $state['station_id'] ) ) {
        $state['station_id'] = radio_default_station_id();
    }

    // Clamp volume to [0, 1].
    $state['volume'] = max( 0.0, min( 1.0, (float) $state['volume'] ) );

    return $state;
}

/**
 * Apply a partial update to the current user's state. Only keys in
 * `radio_default_state()` are persisted; everything else is dropped.
 *
 * @param array $patch
 * @param int   $user_id Optional. Defaults to current user.
 * @return array  The new state.
 */
function radio_update_state( array $patch, $user_id = 0 ) {
    $user_id = $user_id ? (int) $user_id : get_current_user_id();
    if ( ! $user_id ) { return radio_default_state(); }

    $state    = radio_get_state( $user_id );
    $allowed  = array_keys( radio_default_state() );
    $filtered = array_intersect_key( $patch, array_flip( $allowed ) );

    if ( isset( $filtered['station_id'] ) ) {
        $filtered['station_id'] = sanitize_key( $filtered['station_id'] );
        if ( ! radio_find_station( $filtered['station_id'] ) ) {
            unset( $filtered['station_id'] );
        }
    }
    if ( isset( $filtered['volume'] ) ) {
        $filtered['volume'] = max( 0.0, min( 1.0, (float) $filtered['volume'] ) );
    }
    if ( isset( $filtered['theme'] ) ) {
        $filtered['theme'] = in_array( $filtered['theme'], array( 'auto', 'light', 'dark' ), true ) ? $filtered['theme'] : 'auto';
    }

    $new_state = array_merge( $state, $filtered );
    $new_state['last_played_at'] = time();

    update_user_meta( $user_id, RADIO_META_KEY, $new_state );
    return $new_state;
}