<?php
declare(strict_types=1);

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

function tetrisEnsureSchema(): void
{
    static $ready = false;
    if ($ready) {
        return;
    }

    db()->exec(
        "CREATE TABLE IF NOT EXISTS tetris_scores (
            id INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
            player_name VARCHAR(32) NOT NULL,
            score INT UNSIGNED NOT NULL DEFAULT 0,
            lines_cleared INT UNSIGNED NOT NULL DEFAULT 0,
            level_reached INT UNSIGNED NOT NULL DEFAULT 1,
            duration_seconds INT UNSIGNED NOT NULL DEFAULT 0,
            client_signature VARCHAR(64) DEFAULT NULL,
            created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
            INDEX idx_score_order (score DESC, lines_cleared DESC, level_reached DESC, duration_seconds ASC)
        ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci"
    );

    $ready = true;
}

function tetrisNormalizePlayerName(string $name): string
{
    $name = trim(preg_replace('/\s+/', ' ', $name) ?? '');
    return function_exists('mb_substr') ? mb_substr($name, 0, 32) : substr($name, 0, 32);
}

function tetrisFetchTopScores(int $limit = 10): array
{
    tetrisEnsureSchema();
    $limit = max(1, min(100, $limit));
    $stmt = db()->query(
        "SELECT id, player_name, score, lines_cleared, level_reached, duration_seconds, created_at
         FROM tetris_scores
         ORDER BY score DESC, lines_cleared DESC, level_reached DESC, duration_seconds ASC, id ASC
         LIMIT {$limit}"
    );

    return $stmt->fetchAll() ?: [];
}

function tetrisFetchRecentScores(int $limit = 8): array
{
    tetrisEnsureSchema();
    $limit = max(1, min(100, $limit));
    $stmt = db()->query(
        "SELECT id, player_name, score, lines_cleared, level_reached, duration_seconds, created_at
         FROM tetris_scores
         ORDER BY id DESC
         LIMIT {$limit}"
    );

    return $stmt->fetchAll() ?: [];
}

function tetrisFetchScore(int $id): ?array
{
    tetrisEnsureSchema();
    $stmt = db()->prepare(
        'SELECT id, player_name, score, lines_cleared, level_reached, duration_seconds, created_at
         FROM tetris_scores
         WHERE id = :id
         LIMIT 1'
    );
    $stmt->bindValue(':id', $id, PDO::PARAM_INT);
    $stmt->execute();
    $score = $stmt->fetch();

    return $score ?: null;
}

function tetrisFetchScoreRank(int $id): ?int
{
    $score = tetrisFetchScore($id);
    if (!$score) {
        return null;
    }

    $stmt = db()->prepare(
        'SELECT COUNT(*) + 1 AS score_rank
         FROM tetris_scores
         WHERE score > :score
            OR (score = :score AND lines_cleared > :lines)
            OR (score = :score AND lines_cleared = :lines AND level_reached > :level)
            OR (score = :score AND lines_cleared = :lines AND level_reached = :level AND duration_seconds < :duration)
            OR (score = :score AND lines_cleared = :lines AND level_reached = :level AND duration_seconds = :duration AND id < :id)'
    );
    $stmt->bindValue(':score', (int) $score['score'], PDO::PARAM_INT);
    $stmt->bindValue(':lines', (int) $score['lines_cleared'], PDO::PARAM_INT);
    $stmt->bindValue(':level', (int) $score['level_reached'], PDO::PARAM_INT);
    $stmt->bindValue(':duration', (int) $score['duration_seconds'], PDO::PARAM_INT);
    $stmt->bindValue(':id', (int) $score['id'], PDO::PARAM_INT);
    $stmt->execute();

    return (int) ($stmt->fetchColumn() ?: 1);
}

function tetrisInsertScore(array $input): array
{
    tetrisEnsureSchema();

    $playerName = tetrisNormalizePlayerName((string) ($input['player_name'] ?? ''));
    $score = (int) ($input['score'] ?? 0);
    $lines = (int) ($input['lines_cleared'] ?? 0);
    $level = (int) ($input['level_reached'] ?? 1);
    $duration = (int) ($input['duration_seconds'] ?? 0);
    $clientSignature = trim((string) ($input['client_signature'] ?? ''));

    $playerLength = function_exists('mb_strlen') ? mb_strlen($playerName) : strlen($playerName);

    if ($playerName === '' || $playerLength < 2) {
        throw new InvalidArgumentException('Enter a player name with at least 2 characters.');
    }

    if (!preg_match('/^[\p{L}\p{N} ._\-]+$/u', $playerName)) {
        throw new InvalidArgumentException('Use letters, numbers, spaces, dots, dashes, or underscores in the player name.');
    }

    if ($score < 0 || $score > 9999999) {
        throw new InvalidArgumentException('Score is outside the allowed range.');
    }

    if ($lines < 0 || $lines > 9999) {
        throw new InvalidArgumentException('Lines cleared is outside the allowed range.');
    }

    if ($level < 1 || $level > 999) {
        throw new InvalidArgumentException('Level is outside the allowed range.');
    }

    if ($duration < 0 || $duration > 86400) {
        throw new InvalidArgumentException('Duration is outside the allowed range.');
    }

    if ($score === 0 && $lines === 0) {
        throw new InvalidArgumentException('Play a round before submitting a score.');
    }

    $stmt = db()->prepare(
        'INSERT INTO tetris_scores (player_name, score, lines_cleared, level_reached, duration_seconds, client_signature)
         VALUES (:player_name, :score, :lines_cleared, :level_reached, :duration_seconds, :client_signature)'
    );
    $stmt->bindValue(':player_name', $playerName, PDO::PARAM_STR);
    $stmt->bindValue(':score', $score, PDO::PARAM_INT);
    $stmt->bindValue(':lines_cleared', $lines, PDO::PARAM_INT);
    $stmt->bindValue(':level_reached', $level, PDO::PARAM_INT);
    $stmt->bindValue(':duration_seconds', $duration, PDO::PARAM_INT);
    $safeSignature = $clientSignature !== '' ? (function_exists('mb_substr') ? mb_substr($clientSignature, 0, 64) : substr($clientSignature, 0, 64)) : null;
    $stmt->bindValue(':client_signature', $safeSignature, $safeSignature !== null ? PDO::PARAM_STR : PDO::PARAM_NULL);
    $stmt->execute();

    $id = (int) db()->lastInsertId();

    return [
        'score' => tetrisFetchScore($id),
        'rank' => tetrisFetchScoreRank($id),
    ];
}