<?php
// api.php — весь бэкенд одним файлом с роутингом по ?action=. Никакого
// фреймворка не нужно на 4 маленьких эндпоинта.
require __DIR__ . '/db.php';
header('Content-Type: application/json; charset=utf-8');

$pdo = get_db();
$action = $_GET['action'] ?? '';

function read_json_body(): array {
    $data = json_decode(file_get_contents('php://input'), true);
    return is_array($data) ? $data : [];
}

function top5(PDO $pdo, string $level): array {
    $stmt = $pdo->prepare('
        SELECT s.move_count, s.source, s.created_at, u.name
        FROM solutions s JOIN users u ON u.id = s.user_id
        WHERE s.level_name = ?
        ORDER BY s.move_count ASC
        LIMIT 5
    ');
    $stmt->execute([$level]);
    return $stmt->fetchAll(PDO::FETCH_ASSOC);
}

switch ($action) {

    case 'whoami': {
        $u = current_user($pdo);
        echo json_encode($u ? ['name' => $u['name'], 'lastLevel' => (int)$u['last_level']] : ['name' => null, 'lastLevel' => 0]);
        break;
    }

    case 'save_progress': {
        $u = current_user($pdo);
        if (!$u) { http_response_code(401); echo json_encode(['error' => 'no user']); break; }
        $body = read_json_body();
        $level = (int)($body['level'] ?? -1);
        if ($level < 0) { http_response_code(400); echo json_encode(['error' => 'bad level']); break; }
        $pdo->prepare('UPDATE users SET last_level = ? WHERE id = ?')->execute([$level, $u['id']]);
        echo json_encode(['ok' => true]);
        break;
    }

    case 'set_name': {
        $body = read_json_body();
        $name = trim(mb_substr((string)($body['name'] ?? ''), 0, 40));
        if ($name === '') { http_response_code(400); echo json_encode(['error' => 'empty name']); break; }
        $u = current_user($pdo);
        if ($u) {
            $pdo->prepare('UPDATE users SET name = ? WHERE id = ?')->execute([$name, $u['id']]);
        } else {
            $token = bin2hex(random_bytes(16));
            $pdo->prepare('INSERT INTO users (token, name, created_at) VALUES (?, ?, ?)')
                ->execute([$token, $name, time()]);
            setcookie('sokoban_token', $token, time() + 60*60*24*365, '/', '', false, true);
        }
        echo json_encode(['name' => $name]);
        break;
    }

    case 'top': {
        $level = (string)($_GET['level'] ?? '');
        echo json_encode($level === '' ? [] : top5($pdo, $level));
        break;
    }

    case 'best': {
        $level = (string)($_GET['level'] ?? '');
        $stmt = $pdo->prepare('SELECT moves FROM solutions WHERE level_name = ? ORDER BY move_count ASC LIMIT 1');
        $stmt->execute([$level]);
        $row = $stmt->fetch(PDO::FETCH_ASSOC);
        echo json_encode($row ? ['moves' => json_decode($row['moves'])] : null);
        break;
    }

    case 'submit': {
        $u = current_user($pdo);
        if (!$u) { http_response_code(401); echo json_encode(['error' => 'no user']); break; }

        $body = read_json_body();
        $level = (string)($body['level'] ?? '');
        $moves = $body['moves'] ?? null;
        $source = ($body['source'] ?? 'player') === 'solver' ? 'solver' : 'player';

        if ($level === '' || !is_array($moves) || !count($moves) || count($moves) > 20000) {
            http_response_code(400); echo json_encode(['error' => 'bad payload']); break;
        }
        // каждый ход — пара из {-1,0,1}, ничего больше сюда залететь не должно
        foreach ($moves as $m) {
            if (!is_array($m) || count($m) !== 2 || !in_array($m[0], [-1,0,1], true) || !in_array($m[1], [-1,0,1], true)) {
                http_response_code(400); echo json_encode(['error' => 'bad move']); break 2;
            }
        }

        $moveKey = md5(implode('|', array_map(function($m) { return $m[0] . ',' . $m[1]; }, $moves)));
        try {
            $pdo->prepare('INSERT INTO solutions (level_name, user_id, moves, move_count, move_key, source, created_at) VALUES (?, ?, ?, ?, ?, ?, ?)')
                ->execute([$level, $u['id'], json_encode($moves), count($moves), $moveKey, $source, time()]);
        } catch (PDOException $e) {
            // UNIQUE(level_name, move_key) — та же последовательность уже есть, не ошибка
        }

        // держим только топ-5 по числу ходов на уровень
        $pdo->prepare('
            DELETE FROM solutions WHERE level_name = ? AND id NOT IN (
                SELECT id FROM solutions WHERE level_name = ? ORDER BY move_count ASC LIMIT 5
            )
        ')->execute([$level, $level]);

        echo json_encode(top5($pdo, $level));
        break;
    }

    default:
        http_response_code(404);
        echo json_encode(['error' => 'unknown action']);
}