<?php
namespace Zadex\Theme;

defined('ABSPATH') || exit;

/**
 * Picks the published theme template that applies to the current request for a location
 * (header, footer, single, archive, search, 404).
 *
 * The best template is the one whose conditions score highest (Conditions::matches); ties go to the most
 * recently modified template. Results are cached per request and location. Filter `zadex/theme/template_id`
 * (int|null $id, string $type) can override the choice (return 0/null to disable the location).
 */
final class Resolver
{
    /** @var array<string, int|null> */
    private static array $cache = [];

    /** Context override (tests, editor preview); null = the current WordPress request. */
    private static ?array $context = null;

    public static function for_location(string $type): ?int
    {
        if (array_key_exists($type, self::$cache)) {
            return self::$cache[$type];
        }
        $id = in_array($type, TemplatePost::locations(), true) ? self::find($type) : null;
        $filtered = apply_filters('zadex/theme/template_id', $id, $type);
        $id = is_numeric($filtered) && (int) $filtered > 0 ? (int) $filtered : null;
        self::$cache[$type] = $id;
        return $id;
    }

    /** @var array<string, int[]> */
    private static array $all_cache = [];

    /**
     * Every published template of a type whose conditions match the request, best score first (ties: most
     * recently modified). Used for fragments that can apply several times per page (popups). Filter
     * `zadex/theme/matching_ids` (int[] $ids, string $type).
     *
     * @return int[]
     */
    public static function matching(string $type): array
    {
        if (isset(self::$all_cache[$type])) {
            return self::$all_cache[$type];
        }
        $scored = [];
        $order = 0;
        $ids = self::published($type);
        $context = $ids ? (self::$context ?? Conditions::context()) : [];
        foreach ($ids as $id) {
            $score = Conditions::matches(TemplatePost::conditions((int) $id), $context);
            if ($score > 0) {
                $scored[] = [(int) $id, $score, $order++];
            }
        }
        usort($scored, static fn(array $a, array $b): int => $b[1] <=> $a[1] ?: $a[2] <=> $b[2]);
        $ids = array_map(static fn(array $s): int => $s[0], $scored);
        $filtered = apply_filters('zadex/theme/matching_ids', $ids, $type);
        $ids = is_array($filtered) ? array_values(array_unique(array_filter(array_map('intval', $filtered), static fn(int $i): bool => $i > 0))) : $ids;
        self::$all_cache[$type] = $ids;
        return $ids;
    }

    /** @return int[] published template ids of a type, most recently modified first */
    private static function published(string $type): array
    {
        $ids = get_posts([
            'post_type'        => TemplatePost::POST_TYPE,
            'post_status'      => 'publish',
            'numberposts'      => 200,
            'fields'           => 'ids',
            'orderby'          => 'modified',
            'order'            => 'DESC',
            // phpcs:disable WordPress.DB.SlowDBQuery.slow_db_query_meta_key, WordPress.DB.SlowDBQuery.slow_db_query_meta_value -- templates are identified by their type meta; bounded query, result cached per request.
            'meta_key'         => TemplatePost::META_TYPE,
            'meta_value'       => $type,
            // phpcs:enable WordPress.DB.SlowDBQuery.slow_db_query_meta_key, WordPress.DB.SlowDBQuery.slow_db_query_meta_value
            'no_found_rows'    => true,
        ]);
        return is_array($ids) ? array_map('intval', $ids) : [];
    }

    /** Drops the per-request cache (tests, or after the main query changed). */
    public static function reset(?array $context = null): void
    {
        self::$cache = [];
        self::$all_cache = [];
        self::$context = $context;
    }

    private static function find(string $type): ?int
    {
        $ids = get_posts([
            'post_type'        => TemplatePost::POST_TYPE,
            'post_status'      => 'publish',
            'numberposts'      => 200,
            'fields'           => 'ids',
            'orderby'          => 'modified',
            'order'            => 'DESC',
            // phpcs:disable WordPress.DB.SlowDBQuery.slow_db_query_meta_key, WordPress.DB.SlowDBQuery.slow_db_query_meta_value -- templates are identified by their type meta; bounded query, result cached per request.
            'meta_key'         => TemplatePost::META_TYPE,
            'meta_value'       => $type,
            // phpcs:enable WordPress.DB.SlowDBQuery.slow_db_query_meta_key, WordPress.DB.SlowDBQuery.slow_db_query_meta_value
            'no_found_rows'    => true,
        ]);
        if (!$ids) {
            return null;
        }
        $context = self::$context ?? Conditions::context();
        $best = null;
        $best_score = 0;
        foreach ($ids as $id) {
            $score = Conditions::matches(TemplatePost::conditions((int) $id), $context);
            if ($score > $best_score) {
                $best = (int) $id;
                $best_score = $score;
            }
        }
        return $best;
    }
}