<?php
declare(strict_types=1);

header('Content-Type: application/json; charset=utf-8');
header('Cache-Control: no-store, no-cache, must-revalidate, max-age=0');

require_once __DIR__ . '/../db/config.php';
require_once __DIR__ . '/../db/migrate.php';

run_migrations();

try {
    $method = strtoupper((string) ($_SERVER['REQUEST_METHOD'] ?? 'GET'));

    if ($method === 'GET') {
        listScores((int) ($_GET['limit'] ?? 10));
    }

    if ($method !== 'POST') {
        jsonResponse(['success' => false, 'error' => 'Method not allowed.'], 405);
    }

    $raw = file_get_contents('php://input');
    $payload = json_decode($raw ?: '[]', true);
    if (!is_array($payload)) {
        jsonResponse(['success' => false, 'error' => 'Invalid JSON payload.'], 400);
    }

    $action = (string) ($payload['action'] ?? '');
    if ($action === 'save_score') {
        saveScore($payload);
    }

    if ($action === 'list_scores') {
        listScores((int) ($payload['limit'] ?? 10));
    }

    jsonResponse(['success' => false, 'error' => 'Unknown action.'], 422);
} catch (Throwable $exception) {
    error_log('Scoreboard API error: ' . $exception->getMessage());
    jsonResponse(['success' => false, 'error' => 'Scoreboard is temporarily unavailable.'], 500);
}

function saveScore(array $payload): void
{
    $playerName = normalizePlayerName((string) ($payload['player_name'] ?? ''));
    $score = max(0, (int) ($payload['score'] ?? 0));
    $linesCleared = max(0, (int) ($payload['lines'] ?? 0));
    $level = max(1, (int) ($payload['level'] ?? 1));
    $piecesPlaced = max(0, (int) ($payload['pieces_placed'] ?? 0));
    $durationSeconds = max(0, (int) ($payload['duration_seconds'] ?? 0));
    $roomCode = normalizeRoomCode((string) ($payload['room_code'] ?? ''));
    $mode = $roomCode !== '' ? 'multiplayer' : 'solo';

    $pdo = db();
    $insert = $pdo->prepare(
        'INSERT INTO tetris_scores (player_name, score, lines_cleared, level, pieces_placed, duration_seconds, mode, room_code) '
        . 'VALUES (:player_name, :score, :lines_cleared, :level, :pieces_placed, :duration_seconds, :mode, :room_code)'
    );
    $insert->bindValue(':player_name', $playerName, PDO::PARAM_STR);
    $insert->bindValue(':score', $score, PDO::PARAM_INT);
    $insert->bindValue(':lines_cleared', $linesCleared, PDO::PARAM_INT);
    $insert->bindValue(':level', $level, PDO::PARAM_INT);
    $insert->bindValue(':pieces_placed', $piecesPlaced, PDO::PARAM_INT);
    $insert->bindValue(':duration_seconds', $durationSeconds, PDO::PARAM_INT);
    $insert->bindValue(':mode', $mode, PDO::PARAM_STR);
    if ($roomCode === '') {
        $insert->bindValue(':room_code', null, PDO::PARAM_NULL);
    } else {
        $insert->bindValue(':room_code', $roomCode, PDO::PARAM_STR);
    }
    $insert->execute();

    $scoreId = (int) $pdo->lastInsertId();

    $placementQuery = $pdo->prepare(
        'SELECT COUNT(*) FROM tetris_scores WHERE '
        . 'score > :score '
        . 'OR (score = :score AND lines_cleared > :lines_cleared) '
        . 'OR (score = :score AND lines_cleared = :lines_cleared AND level > :level) '
        . 'OR (score = :score AND lines_cleared = :lines_cleared AND level = :level AND duration_seconds < :duration_seconds) '
        . 'OR (score = :score AND lines_cleared = :lines_cleared AND level = :level AND duration_seconds = :duration_seconds AND id < :score_id)'
    );
    $placementQuery->bindValue(':score', $score, PDO::PARAM_INT);
    $placementQuery->bindValue(':lines_cleared', $linesCleared, PDO::PARAM_INT);
    $placementQuery->bindValue(':level', $level, PDO::PARAM_INT);
    $placementQuery->bindValue(':duration_seconds', $durationSeconds, PDO::PARAM_INT);
    $placementQuery->bindValue(':score_id', $scoreId, PDO::PARAM_INT);
    $placementQuery->execute();
    $placement = ((int) $placementQuery->fetchColumn()) + 1;

    jsonResponse([
        'success' => true,
        'entry' => [
            'id' => $scoreId,
            'player_name' => $playerName,
            'score' => $score,
            'lines' => $linesCleared,
            'level' => $level,
            'pieces_placed' => $piecesPlaced,
            'duration_seconds' => $durationSeconds,
            'mode' => $mode,
            'room_code' => $roomCode !== '' ? $roomCode : null,
        ],
        'placement' => $placement,
    ]);
}

function listScores(int $limit = 10): void
{
    $limit = max(1, min(25, $limit));

    $pdo = db();
    $stmt = $pdo->prepare(
        'SELECT id, player_name, score, lines_cleared, level, pieces_placed, duration_seconds, mode, room_code, created_at '
        . 'FROM tetris_scores '
        . 'ORDER BY score DESC, lines_cleared DESC, level DESC, duration_seconds ASC, id ASC '
        . 'LIMIT :limit'
    );
    $stmt->bindValue(':limit', $limit, PDO::PARAM_INT);
    $stmt->execute();

    $scores = [];
    foreach ($stmt->fetchAll() as $row) {
        $scores[] = [
            'id' => (int) $row['id'],
            'player_name' => (string) $row['player_name'],
            'score' => (int) $row['score'],
            'lines' => (int) $row['lines_cleared'],
            'level' => (int) $row['level'],
            'pieces_placed' => (int) $row['pieces_placed'],
            'duration_seconds' => (int) $row['duration_seconds'],
            'mode' => (string) $row['mode'],
            'room_code' => $row['room_code'] !== null ? (string) $row['room_code'] : null,
            'created_at' => (string) $row['created_at'],
        ];
    }

    jsonResponse([
        'success' => true,
        'scores' => $scores,
        'limit' => $limit,
    ]);
}

function normalizePlayerName(string $value): string
{
    $value = trim(preg_replace('/\s+/', ' ', $value) ?? '');
    $value = preg_replace('/[^\p{L}\p{N} ._\-]/u', '', $value) ?? '';
    if ($value === '') {
        return 'Player';
    }

    if (function_exists('mb_substr')) {
        return mb_substr($value, 0, 48);
    }

    return substr($value, 0, 48);
}

function normalizeRoomCode(string $value): string
{
    $value = strtoupper(trim($value));
    $value = preg_replace('/[^A-Z0-9]/', '', $value) ?? '';
    return substr($value, 0, 8);
}

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