<?php
/**
 * Centrale Caching Laag voor Fociz
 * Biedt een supersnelle database- én in-memory transiënte cache voor externe API-aanroepen (Microsoft Graph, Jira Cloud).
 */

require_once __DIR__ . '/../config/database.php';

function ensure_app_cache_table(?PDO $db = null): void {
    static $ensured = false;
    if ($ensured) return;

    try {
        $pdo = $db ?: get_db_connection();
        $pdo->exec("
            CREATE TABLE IF NOT EXISTS `app_cache` (
                `cache_key` VARCHAR(128) NOT NULL PRIMARY KEY,
                `cache_value` MEDIUMTEXT NOT NULL,
                `expires_at` INT UNSIGNED NOT NULL,
                INDEX `idx_app_cache_expires` (`expires_at`)
            ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
        ");
        $ensured = true;
    } catch (Throwable $e) {
        error_log("ensure_app_cache_table error: " . $e->getMessage());
    }
}

/**
 * Haalt een item op uit de cache.
 * Controleert eerst het runtime statisch geheugen, vervolgens MariaDB.
 */
function fociz_cache_get(string $key, $default = null) {
    static $memoryCache = [];

    $now = time();

    // 1. Runtime memory check (0ms)
    if (isset($memoryCache[$key])) {
        if ($memoryCache[$key]['expires_at'] > $now) {
            return $memoryCache[$key]['value'];
        }
        unset($memoryCache[$key]);
    }

    // 2. Database check (< 0.5ms)
    try {
        $db = get_db_connection();
        ensure_app_cache_table($db);

        $stmt = $db->prepare("SELECT cache_value, expires_at FROM app_cache WHERE cache_key = ?");
        $stmt->execute([$key]);
        $row = $stmt->fetch();

        if ($row) {
            if ((int)$row['expires_at'] > $now) {
                $decoded = json_decode($row['cache_value'], true);
                $val = ($decoded !== null || $row['cache_value'] === 'null') ? $decoded : $row['cache_value'];
                $memoryCache[$key] = [
                    'value' => $val,
                    'expires_at' => (int)$row['expires_at']
                ];
                return $val;
            } else {
                // Verlopen item direct opruimen
                $del = $db->prepare("DELETE FROM app_cache WHERE cache_key = ?");
                $del->execute([$key]);
            }
        }
    } catch (Throwable $e) {
        error_log("fociz_cache_get error for {$key}: " . $e->getMessage());
    }

    return $default;
}

/**
 * Slaat een item op in de cache met een bepaalde levensduur in seconden.
 */
function fociz_cache_set(string $key, $value, int $ttlSeconds = 60): bool {
    static $memoryCache = [];

    $now = time();
    $expiresAt = $now + max(1, $ttlSeconds);

    // 1. Sla op in runtime memory
    $memoryCache[$key] = [
        'value' => $value,
        'expires_at' => $expiresAt
    ];

    // 2. Sla op in database
    try {
        $db = get_db_connection();
        ensure_app_cache_table($db);

        $valToStore = is_string($value) ? $value : json_encode($value, JSON_UNESCAPED_UNICODE);

        $stmt = $db->prepare("
            INSERT INTO app_cache (cache_key, cache_value, expires_at)
            VALUES (?, ?, ?)
            ON DUPLICATE KEY UPDATE 
                cache_value = VALUES(cache_value), 
                expires_at = VALUES(expires_at)
        ");
        return $stmt->execute([$key, $valToStore, $expiresAt]);
    } catch (Throwable $e) {
        error_log("fociz_cache_set error for {$key}: " . $e->getMessage());
        return false;
    }
}

/**
 * Verwijdert een specifiek item uit de cache.
 */
function fociz_cache_delete(string $key): bool {
    try {
        $db = get_db_connection();
        ensure_app_cache_table($db);
        $stmt = $db->prepare("DELETE FROM app_cache WHERE cache_key = ?");
        return $stmt->execute([$key]);
    } catch (Throwable $e) {
        return false;
    }
}

/**
 * Verwijdert alle items met een bepaald voorvoegsel (bijv. 'ms_events_1_')
 */
function fociz_cache_delete_pattern(string $prefix): bool {
    try {
        $db = get_db_connection();
        ensure_app_cache_table($db);
        $stmt = $db->prepare("DELETE FROM app_cache WHERE cache_key LIKE ?");
        return $stmt->execute([$prefix . '%']);
    } catch (Throwable $e) {
        return false;
    }
}