<?php

declare(strict_types=1);

header('Content-Type: application/json; charset=utf-8');
header('Access-Control-Allow-Origin: *');
header('Access-Control-Allow-Methods: GET, POST, OPTIONS');
header('Access-Control-Allow-Headers: Content-Type');

if ($_SERVER['REQUEST_METHOD'] === 'OPTIONS') {
    http_response_code(204);
    exit;
}

$dataDir = __DIR__ . DIRECTORY_SEPARATOR . 'data';
$dataFile = $dataDir . DIRECTORY_SEPARATOR . 'lobbies.json';

if (!is_dir($dataDir)) {
    mkdir($dataDir, 0777, true);
}

if (!file_exists($dataFile)) {
    file_put_contents($dataFile, "{}\n");
}

function respond(array $payload, int $status = 200): void
{
    http_response_code($status);
    echo json_encode($payload, JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES);
    exit;
}

function read_body(): array
{
    $raw = file_get_contents('php://input');
    if ($raw === false || trim($raw) === '') {
        return [];
    }

    $decoded = json_decode($raw, true);
    return is_array($decoded) ? $decoded : [];
}

function clean_name(mixed $value, int $maxLength = 40): string
{
    $name = trim((string) $value);
    $name = preg_replace('/\s+/', ' ', $name) ?? '';
    return substr($name, 0, $maxLength);
}

function clean_scores(mixed $value): array
{
    if (!is_array($value)) {
        return [];
    }

    return array_slice(array_map(static function ($score): int {
        return max(0, min(100, (int) $score));
    }, $value), 0, 3);
}

function clean_countries(mixed $value): array
{
    if (!is_array($value)) {
        return [];
    }

    return array_slice(array_map(static function ($country): string {
        return clean_name($country, 80);
    }, $value), 0, 3);
}

function with_lobbies(callable $callback, bool $write = false): mixed
{
    global $dataFile;

    $handle = fopen($dataFile, 'c+');
    if ($handle === false) {
        respond(['ok' => false, 'error' => 'Could not open data file.'], 500);
    }

    flock($handle, $write ? LOCK_EX : LOCK_SH);
    rewind($handle);
    $raw = stream_get_contents($handle);
    $lobbies = json_decode($raw ?: '{}', true);
    if (!is_array($lobbies)) {
        $lobbies = [];
    }

    $result = $callback($lobbies);

    if ($write) {
        rewind($handle);
        ftruncate($handle, 0);
        fwrite($handle, json_encode($lobbies, JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES) . "\n");
        fflush($handle);
    }

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

    return $result;
}

function ensure_lobby(array &$lobbies, string $lobbyName): array
{
    if (!isset($lobbies[$lobbyName]) || !is_array($lobbies[$lobbyName])) {
        $lobbies[$lobbyName] = [
            'name' => $lobbyName,
            'players' => [],
            'leaderboard' => [],
        ];
    }

    $lobbies[$lobbyName]['players'] = array_values($lobbies[$lobbyName]['players'] ?? []);
    $lobbies[$lobbyName]['leaderboard'] = array_values($lobbies[$lobbyName]['leaderboard'] ?? []);

    return $lobbies[$lobbyName];
}

$action = $_GET['action'] ?? '';
$body = read_body();

if ($action === 'createLobby') {
    $lobbyName = clean_name($body['lobbyName'] ?? '');
    if ($lobbyName === '') {
        respond(['ok' => false, 'error' => 'Lobby name is required.'], 400);
    }

    $lobby = with_lobbies(static function (array &$lobbies) use ($lobbyName): array {
        return ensure_lobby($lobbies, $lobbyName);
    }, true);

    respond(['ok' => true, 'lobby' => ['name' => $lobby['name']]]);
}

if ($action === 'joinLobby') {
    $lobbyName = clean_name($body['lobbyName'] ?? '');
    $playerName = clean_name($body['playerName'] ?? '', 24);
    if ($lobbyName === '' || $playerName === '') {
        respond(['ok' => false, 'error' => 'Lobby name and player name are required.'], 400);
    }

    $lobby = with_lobbies(static function (array &$lobbies) use ($lobbyName, $playerName): array {
        ensure_lobby($lobbies, $lobbyName);
        if (!in_array($playerName, $lobbies[$lobbyName]['players'], true)) {
            $lobbies[$lobbyName]['players'][] = $playerName;
        }
        return $lobbies[$lobbyName];
    }, true);

    respond(['ok' => true, 'lobby' => ['name' => $lobby['name'], 'players' => $lobby['players']]]);
}

if ($action === 'leaveLobby') {
    $lobbyName = clean_name($body['lobbyName'] ?? '');
    $playerName = clean_name($body['playerName'] ?? '', 24);

    with_lobbies(static function (array &$lobbies) use ($lobbyName, $playerName): void {
        if ($lobbyName === '' || $playerName === '' || !isset($lobbies[$lobbyName])) {
            return;
        }

        $lobbies[$lobbyName]['players'] = array_values(array_filter(
            $lobbies[$lobbyName]['players'] ?? [],
            static fn ($name): bool => $name !== $playerName,
        ));
    }, true);

    respond(['ok' => true]);
}

if ($action === 'submitScore') {
    $lobbyName = clean_name($body['lobbyName'] ?? '');
    $playerName = clean_name($body['playerName'] ?? '', 24);
    if ($lobbyName === '' || $playerName === '') {
        respond(['ok' => false, 'error' => 'Lobby name and player name are required.'], 400);
    }

    $entry = [
        'playerName' => $playerName,
        'totalScore' => max(0, min(300, (int) ($body['totalScore'] ?? 0))),
        'scores' => clean_scores($body['scores'] ?? []),
        'countries' => clean_countries($body['countries'] ?? []),
        'date' => gmdate('c'),
    ];

    with_lobbies(static function (array &$lobbies) use ($lobbyName, $playerName, $entry): void {
        ensure_lobby($lobbies, $lobbyName);
        if (!in_array($playerName, $lobbies[$lobbyName]['players'], true)) {
            $lobbies[$lobbyName]['players'][] = $playerName;
        }

        $lobbies[$lobbyName]['leaderboard'][] = $entry;
        usort(
            $lobbies[$lobbyName]['leaderboard'],
            static fn (array $a, array $b): int => ($b['totalScore'] ?? 0) <=> ($a['totalScore'] ?? 0),
        );
        $lobbies[$lobbyName]['leaderboard'] = array_slice($lobbies[$lobbyName]['leaderboard'], 0, 20);
    }, true);

    respond(['ok' => true, 'entry' => $entry]);
}

if ($action === 'getLeaderboard') {
    $lobbyName = clean_name($_GET['lobbyName'] ?? '');
    if ($lobbyName === '') {
        respond(['ok' => false, 'error' => 'Lobby name is required.'], 400);
    }

    $leaderboard = with_lobbies(static function (array &$lobbies) use ($lobbyName): array {
        return $lobbies[$lobbyName]['leaderboard'] ?? [];
    });

    respond(['ok' => true, 'leaderboard' => $leaderboard]);
}

if ($action === 'getLobby') {
    $lobbyName = clean_name($_GET['lobbyName'] ?? '');
    if ($lobbyName === '') {
        respond(['ok' => false, 'error' => 'Lobby name is required.'], 400);
    }

    $lobby = with_lobbies(static function (array &$lobbies) use ($lobbyName): array {
        if (!isset($lobbies[$lobbyName])) {
            return ['name' => $lobbyName, 'players' => []];
        }

        return [
            'name' => $lobbies[$lobbyName]['name'] ?? $lobbyName,
            'players' => array_values($lobbies[$lobbyName]['players'] ?? []),
        ];
    });

    respond(['ok' => true, 'lobby' => $lobby]);
}

respond(['ok' => false, 'error' => 'Unknown action.'], 404);