<?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 AUTO_INCREMENT PRIMARY KEY,
            player_name VARCHAR(24) 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,
            created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
            INDEX idx_score (score DESC, lines_cleared DESC),
            INDEX idx_created_at (created_at DESC)
        ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci"
    );

    $ready = true;
}

function tetrisFetchLeaderboard(int $limit = 10): array
{
    tetrisEnsureSchema();
    $stmt = db()->prepare(
        'SELECT id, player_name, score, lines_cleared, level_reached, duration_seconds, created_at
         FROM tetris_scores
         ORDER BY score DESC, lines_cleared DESC, duration_seconds ASC, id ASC
         LIMIT :limit'
    );
    $stmt->bindValue(':limit', $limit, PDO::PARAM_INT);
    $stmt->execute();

    return $stmt->fetchAll();
}

function tetrisFetchRecent(int $limit = 8): array
{
    tetrisEnsureSchema();
    $stmt = db()->prepare(
        'SELECT id, player_name, score, lines_cleared, level_reached, duration_seconds, created_at
         FROM tetris_scores
         ORDER BY created_at DESC, id DESC
         LIMIT :limit'
    );
    $stmt->bindValue(':limit', $limit, PDO::PARAM_INT);
    $stmt->execute();

    return $stmt->fetchAll();
}

function tetrisFetchScoreById(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 tetrisFetchBestScore(): ?array
{
    $scores = tetrisFetchLeaderboard(1);
    return $scores[0] ?? null;
}

function tetrisSaveScore(array $input): int
{
    tetrisEnsureSchema();

    $name = trim((string) ($input['player_name'] ?? ''));
    if ($name === '') {
        throw new InvalidArgumentException('Enter your name to save the run.');
    }
    $nameLength = function_exists('mb_strlen') ? mb_strlen($name) : strlen($name);
    if ($nameLength > 24) {
        throw new InvalidArgumentException('Name must be 24 characters or fewer.');
    }
    if (!preg_match('/^[\p{L}\p{N} _.-]+$/u', $name)) {
        throw new InvalidArgumentException('Use letters, numbers, spaces, dots, dashes, or underscores only.');
    }

    $score = max(0, min(999999, (int) ($input['score'] ?? 0)));
    $lines = max(0, min(9999, (int) ($input['lines_cleared'] ?? 0)));
    $level = max(1, min(999, (int) ($input['level_reached'] ?? 1)));
    $duration = max(0, min(86400, (int) ($input['duration_seconds'] ?? 0)));

    if ($score === 0 && $lines === 0) {
        throw new InvalidArgumentException('Finish a run before saving to the leaderboard.');
    }

    $stmt = db()->prepare(
        'INSERT INTO tetris_scores (player_name, score, lines_cleared, level_reached, duration_seconds)
         VALUES (:player_name, :score, :lines_cleared, :level_reached, :duration_seconds)'
    );
    $stmt->bindValue(':player_name', $name, 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);
    $stmt->execute();

    return (int) db()->lastInsertId();
}