<?php

declare(strict_types=1);

// File-based per-IP rate limiting for hosting without Redis. Ported from the
// PSA order system (includes/functions.php rateLimitEvaluate). State lives
// under storage/ratelimit/ and is therefore not web-readable.

function manageRateLimitClientIp(): string
{
    $ip = trim((string) ($_SERVER["REMOTE_ADDR"] ?? ""));

    return $ip !== "" ? $ip : "unknown";
}

function manageRateLimitStatePath(string $name): string
{
    $name = preg_replace("/[^a-z0-9_-]/", "", strtolower($name)) ?? "";
    if ($name === "") {
        $name = "default";
    }

    return manageStorageDir() . "ratelimit" . DIRECTORY_SEPARATOR . $name . ".json";
}

/**
 * @return bool true while under the limit; increments the counter when $consume
 */
function manageRateLimitEvaluate(
    string $name,
    int $maxAttempts,
    int $windowSeconds,
    bool $consume,
): bool {
    if ($maxAttempts < 1 || $windowSeconds < 1) {
        return true;
    }

    $path = manageRateLimitStatePath($name);
    $dir = dirname($path);
    if (!is_dir($dir) && !@mkdir($dir, 02775, true) && !is_dir($dir)) {
        // Without usable state the limiter must not lock anybody out.
        return true;
    }
    @chmod($dir, 02775);

    $handle = fopen($path, "c+");
    if ($handle === false) {
        return true;
    }

    if (!flock($handle, LOCK_EX)) {
        fclose($handle);
        return true;
    }

    rewind($handle);
    $raw = stream_get_contents($handle);
    $data = [];
    if (is_string($raw) && trim($raw) !== "") {
        $decoded = json_decode($raw, true);
        if (is_array($decoded)) {
            $data = $decoded;
        }
    }

    $now = time();
    $ip = manageRateLimitClientIp();

    foreach ($data as $key => $entry) {
        if (!is_array($entry)) {
            unset($data[$key]);
            continue;
        }
        if ($now - (int) ($entry["w"] ?? 0) > $windowSeconds * 2) {
            unset($data[$key]);
        }
    }

    $entry = isset($data[$ip]) && is_array($data[$ip]) ? $data[$ip] : null;
    $windowStart = (int) ($entry["w"] ?? $now);
    $count = (int) ($entry["c"] ?? 0);

    if ($entry === null || $now - $windowStart > $windowSeconds) {
        $windowStart = $now;
        $count = 0;
    }

    if ($count >= $maxAttempts) {
        flock($handle, LOCK_UN);
        fclose($handle);
        return false;
    }

    if ($consume) {
        $data[$ip] = ["w" => $windowStart, "c" => $count + 1];
        $payload = json_encode($data, JSON_UNESCAPED_UNICODE);
        if ($payload !== false) {
            ftruncate($handle, 0);
            rewind($handle);
            fwrite($handle, $payload);
            fflush($handle);
            @chmod($path, 0660);
        }
    }

    flock($handle, LOCK_UN);
    fclose($handle);

    return true;
}

function manageRateLimitTryConsume(string $name, int $maxAttempts, int $windowSeconds): bool
{
    return manageRateLimitEvaluate($name, $maxAttempts, $windowSeconds, true);
}

function manageRateLimitClearIp(string $name): void
{
    $path = manageRateLimitStatePath($name);
    if (!is_file($path)) {
        return;
    }

    $handle = fopen($path, "c+");
    if ($handle === false) {
        return;
    }
    if (!flock($handle, LOCK_EX)) {
        fclose($handle);
        return;
    }

    rewind($handle);
    $raw = stream_get_contents($handle);
    $data = is_string($raw) && trim($raw) !== "" ? json_decode($raw, true) : [];
    if (is_array($data)) {
        unset($data[manageRateLimitClientIp()]);
        $payload = json_encode($data, JSON_UNESCAPED_UNICODE);
        if ($payload !== false) {
            ftruncate($handle, 0);
            rewind($handle);
            fwrite($handle, $payload);
            fflush($handle);
        }
    }

    flock($handle, LOCK_UN);
    fclose($handle);
}

function manageLoginIsRateLimited(): bool
{
    return !manageRateLimitEvaluate(
        "admin-login",
        (int) MANAGE_LOGIN_RATE_LIMIT_MAX,
        (int) MANAGE_LOGIN_RATE_LIMIT_WINDOW,
        false,
    );
}

function manageLoginRecordFailure(): void
{
    manageRateLimitTryConsume(
        "admin-login",
        (int) MANAGE_LOGIN_RATE_LIMIT_MAX,
        (int) MANAGE_LOGIN_RATE_LIMIT_WINDOW,
    );
}

function manageLoginClearRateLimit(): void
{
    manageRateLimitClearIp("admin-login");
}