<?php
/**
 * 班级操行分管理系统 - 自动升级脚本
 * 
 * 读取 VERSION 文件确定目标版本，自动检测数据库当前版本，
 * 依次执行增量 SQL 升级脚本。
 */

// ===========================================
// 辅助函数
// ===========================================

// 版本升级列表（唯一数据源）
$UPGRADE_VERSIONS = [
    '1.0'   => __DIR__ . '/sql/upgrades/v1.0.sql',
    '1.1'   => __DIR__ . '/sql/upgrades/v1.1.sql',
    '1.2'   => __DIR__ . '/sql/upgrades/v1.2.sql',
    '1.3'   => __DIR__ . '/sql/upgrades/v1.3.sql',
    '1.4'   => __DIR__ . '/sql/upgrades/v1.4.sql',
    '1.5'   => __DIR__ . '/sql/upgrades/v1.5.sql',
    '1.6'   => __DIR__ . '/sql/upgrades/v1.6.sql',
    '1.7'   => __DIR__ . '/sql/upgrades/v1.7.sql',
    '1.8'   => __DIR__ . '/sql/upgrades/v1.8.sql',
    '2.0'   => __DIR__ . '/sql/upgrades/v2.0.sql',
    '2.0.1' => __DIR__ . '/sql/upgrades/v2.0.1.sql',
    '2.1'   => __DIR__ . '/sql/upgrades/v2.1.sql',
    '2.2'   => __DIR__ . '/sql/upgrades/v2.2.sql',
    '2.3'   => __DIR__ . '/sql/upgrades/v2.3.sql',
    '2.4'   => __DIR__ . '/sql/upgrades/v2.4.sql',
    '2.5'   => __DIR__ . '/sql/upgrades/v2.5.sql',
    '2.5.1' => __DIR__ . '/sql/upgrades/v2.5.1.sql',
    '2.6'   => __DIR__ . '/sql/upgrades/v2.6.sql',
    '2.7'   => __DIR__ . '/sql/upgrades/v2.7.sql',
    '2.8'   => __DIR__ . '/sql/upgrades/v2.8.sql',
];

/**
 * 读取 backend/.env 文件并解析数据库配置
 */
function readEnvConfig($envPath) {
    if (!file_exists($envPath)) {
        throw new RuntimeException('配置文件不存在: ' . $envPath);
    }

    $lines = file($envPath, FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES);
    $config = [];

    foreach ($lines as $line) {
        $line = trim($line);
        if ($line === '' || strpos($line, '#') === 0) {
            continue;
        }
        if (strpos($line, '=') !== false) {
            list($key, $value) = explode('=', $line, 2);
            $config[trim($key)] = trim($value);
        }
    }

    $required = ['DB_HOST', 'DB_PORT', 'DB_USER', 'DB_PASSWORD', 'DB_NAME'];
    foreach ($required as $key) {
        if (!isset($config[$key]) || $config[$key] === '') {
            throw new RuntimeException("缺少必要的数据库配置: {$key}");
        }
    }

    return $config;
}

/**
 * 检测数据库当前版本
 */
function detectCurrentVersion($pdo) {
    try {
        $stmt = $pdo->query("SELECT setting_value FROM system_settings WHERE setting_key = 'db_version'");
        $row = $stmt->fetch(PDO::FETCH_ASSOC);
        return $row ? $row['setting_value'] : '0.0.0';
    } catch (PDOException $e) {
        return '0.0.0';
    }
}

/**
 * 获取需要执行的升级步骤
 */
function getUpgradeSteps($currentVersion, $targetVersion) {
    global $UPGRADE_VERSIONS;

    $steps = [];
    foreach ($UPGRADE_VERSIONS as $version => $sqlFile) {
        if (version_compare($version, $currentVersion, '>') &&
            version_compare($version, $targetVersion, '<=')) {
            $steps[$version] = $sqlFile;
        }
    }

    uksort($steps, 'version_compare');
    return $steps;
}

/**
 * 执行 SQL 内容，处理包含 DELIMITER 的存储过程脚本
 *
 * DELIMITER 是 MySQL 客户端指令，MySQL 服务器不认识它，
 * 必须在客户端侧解析并拆分为独立的语句后逐条执行。
 */
function executeSqlContent($pdo, $sqlContent) {
    $sqlContent = trim($sqlContent);
    if ($sqlContent === '' || $sqlContent === '--') {
        return;
    }

    // 检查是否包含 DELIMITER 指令
    if (stripos($sqlContent, 'DELIMITER') !== false) {
        $lines = explode("\n", $sqlContent);
        $currentBlock = [];
        $inProcedure = false;
        $buffer = '';

        foreach ($lines as $line) {
            $trimmed = trim($line);

            // 跳过纯注释行（存储过程内部注释保留）
            if (!$inProcedure && (strpos($trimmed, '--') === 0 || strpos($trimmed, '#') === 0)) {
                continue;
            }

            if (strtoupper(substr($trimmed, 0, 12)) === 'DELIMITER $$') {
                // 开始存储过程定义
                $inProcedure = true;
                $currentBlock = [];
                continue;
            } elseif (strtoupper($trimmed) === 'DELIMITER ;') {
                // 执行累积的存储过程块
                if (!empty($currentBlock)) {
                    $procSql = trim(implode("\n", $currentBlock));
                    if ($procSql !== '') {
                        // 移除存储过程结尾的 $$ 定界符（发送给 MySQL 服务器时不需要）
                        $procSql = preg_replace('/\$\$\s*$/', '', $procSql);
                        $pdo->exec($procSql);
                    }
                }
                $inProcedure = false;
                $currentBlock = [];
                continue;
            } elseif (strtoupper(substr($trimmed, 0, 9)) === 'DELIMITER') {
                // 其他 DELIMITER 指令，跳过
                continue;
            }

            if ($inProcedure) {
                $currentBlock[] = $line;
            } else {
                // 普通 SQL，累积直到遇到分号
                if ($trimmed !== '') {
                    $buffer .= ($buffer !== '' ? ' ' : '') . $trimmed;

                    if (rtrim($buffer) !== '' && substr(rtrim($buffer), -1) === ';') {
                        $stmt = rtrim(rtrim($buffer), ';');
                        $stmt = trim($stmt);
                        if ($stmt !== '' && $stmt !== '--') {
                            $pdo->exec($stmt);
                        }
                        $buffer = '';
                    }
                }
            }
        }

        // 处理缓冲区中剩余的语句
        if ($buffer !== '') {
            $stmt = rtrim(rtrim($buffer), ';');
            $stmt = trim($stmt);
            if ($stmt !== '' && $stmt !== '--') {
                $pdo->exec($stmt);
            }
        }
    } else {
        // 无 DELIMITER，按分号+换行分割语句
        $statements = preg_split('/;\s*\n/', $sqlContent);
        foreach ($statements as $stmt) {
            $stmt = trim($stmt);
            if ($stmt !== '' && $stmt !== '--') {
                $pdo->exec($stmt);
            }
        }
    }
}

/**
 * 验证升级结果：检查版本号是否已正确更新
 *
 * @return array ['ok' => bool, 'message' => string]
 */
function verifyUpgrade($pdo, $expectedVersion) {
    // 检查 system_settings 表是否存在
    try {
        $check = $pdo->query("SELECT 1 FROM system_settings LIMIT 1");
    } catch (PDOException $e) {
        return ['ok' => false, 'message' => 'system_settings 表不存在，升级脚本可能未正确执行'];
    }

    // 检查版本号是否匹配
    $stmt = $pdo->prepare("SELECT setting_value FROM system_settings WHERE setting_key = 'db_version'");
    $stmt->execute();
    $row = $stmt->fetch(PDO::FETCH_ASSOC);

    if (!$row) {
        return ['ok' => false, 'message' => 'db_version 记录不存在'];
    }

    if ($row['setting_value'] !== $expectedVersion) {
        return ['ok' => false, 'message' => "版本号不匹配：期望 {$expectedVersion}，实际 {$row['setting_value']}"];
    }

    return ['ok' => true, 'message' => '验证通过'];
}

/**
 * 执行单个版本的升级 SQL（含验证与重试）
 *
 * @param PDO    $pdo       数据库连接
 * @param string $version   目标版本号
 * @param string $sqlFile   SQL 文件路径
 * @param int    $maxRetries 最大重试次数
 * @throws RuntimeException 升级失败时抛出
 */
function executeUpgrade($pdo, $version, $sqlFile, $maxRetries = 2) {
    if (!file_exists($sqlFile)) {
        throw new RuntimeException("SQL 文件不存在: {$sqlFile}");
    }

    $sql = file_get_contents($sqlFile);
    $isEmpty = (trim($sql) === '' || trim($sql) === '--');

    $lastError = null;

    for ($attempt = 1; $attempt <= $maxRetries; $attempt++) {
        try {
            if (!$isEmpty) {
                executeSqlContent($pdo, $sql);
            }

            // 更新版本号（使用预处理语句防止 SQL 注入）
            $stmt = $pdo->prepare(
                "INSERT INTO system_settings (setting_key, setting_value) VALUES ('db_version', :version)
                 ON DUPLICATE KEY UPDATE setting_value = :version"
            );
            $stmt->execute([':version' => $version]);

            // 验证版本号是否正确写入
            $verify = verifyUpgrade($pdo, $version);
            if ($verify['ok']) {
                return; // 成功
            }

            // 验证失败，准备重试
            $lastError = "升级验证失败: {$verify['message']}";
            if ($attempt < $maxRetries) {
                // 回滚版本号到升级前状态，以便重试
                $prevStmt = $pdo->prepare(
                    "UPDATE system_settings SET setting_value = :ver WHERE setting_key = 'db_version'"
                );
                // 获取升级前版本（从 getUpgradeSteps 推断，这里用 0.0.0 作为安全回退）
                $prevStmt->execute([':ver' => '0.0.0']);
                continue;
            }
        } catch (PDOException $e) {
            $lastError = "SQL 执行失败: " . $e->getMessage();
            if ($attempt < $maxRetries) {
                continue;
            }
        } catch (Exception $e) {
            $lastError = $e->getMessage();
            if ($attempt < $maxRetries) {
                continue;
            }
        }

        // 所有重试均失败
        break;
    }

    throw new RuntimeException("升级至 v{$version} 失败 (尝试 {$maxRetries} 次): {$lastError}");
}

// ===========================================
// 主逻辑
// ===========================================

// POST 模式：执行单个升级步骤（依次执行）
if ($_SERVER['REQUEST_METHOD'] === 'POST' && ($_GET['action'] ?? '') === 'step') {
    header('Content-Type: application/json; charset=utf-8');

    $stepVersion = $_GET['version'] ?? '';
    if (empty($stepVersion)) {
        http_response_code(400);
        echo json_encode(['success' => false, 'error' => '缺少版本号参数']);
        exit();
    }

    try {
        $envPath = __DIR__ . '/backend/.env';
        $config = readEnvConfig($envPath);

        $dsn = "mysql:host={$config['DB_HOST']};port={$config['DB_PORT']};dbname={$config['DB_NAME']};charset=utf8mb4";
        $pdo = new PDO($dsn, $config['DB_USER'], $config['DB_PASSWORD'], [
            PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION
        ]);

        // 获取该版本对应的 SQL 文件
        if (!isset($UPGRADE_VERSIONS[$stepVersion])) {
            throw new RuntimeException("未知版本: {$stepVersion}");
        }

        $sqlFile = $UPGRADE_VERSIONS[$stepVersion];
        $shortFile = basename($sqlFile);

        executeUpgrade($pdo, $stepVersion, $sqlFile);

        // 重新检测当前版本
        $newVersion = detectCurrentVersion($pdo);

        echo json_encode([
            'success' => true,
            'version' => $stepVersion,
            'message' => "升级至 v{$stepVersion} 成功 ({$shortFile})",
            'current' => $newVersion
        ]);
    } catch (Exception $e) {
        http_response_code(500);
        echo json_encode([
            'success' => false,
            'version' => $stepVersion,
            'error' => "升级至 v{$stepVersion} 失败: " . $e->getMessage()
        ]);
    }
    exit();
}

// POST 模式：执行升级（AJAX 请求）
if ($_SERVER['REQUEST_METHOD'] === 'POST' && ($_GET['action'] ?? '') === 'execute') {
    header('Content-Type: application/json; charset=utf-8');

    $upgradeLog = [];
    $currentVersion = '未知';
    $targetVersion = '未知';

    try {
        $envPath = __DIR__ . '/backend/.env';
        $config = readEnvConfig($envPath);

        $dsn = "mysql:host={$config['DB_HOST']};port={$config['DB_PORT']};dbname={$config['DB_NAME']};charset=utf8mb4";
        $pdo = new PDO($dsn, $config['DB_USER'], $config['DB_PASSWORD'], [
            PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION
        ]);

        $currentVersion = detectCurrentVersion($pdo);

        $versionFile = __DIR__ . '/VERSION';
        if (!file_exists($versionFile)) {
            throw new RuntimeException('VERSION 文件不存在');
        }
        $targetVersion = trim(file_get_contents($versionFile));

        $upgradeSteps = getUpgradeSteps($currentVersion, $targetVersion);

        if (empty($upgradeSteps)) {
            echo json_encode([
                'success' => true,
                'current' => $currentVersion,
                'target' => $targetVersion,
                'steps' => [['version' => '', 'status' => 'uptodate', 'message' => '数据库已是最新版本，无需升级。']]
            ]);
            exit();
        }

        $pdo->beginTransaction();
        try {
            foreach ($upgradeSteps as $version => $sqlFile) {
                $shortFile = basename($sqlFile);
                try {
                    executeUpgrade($pdo, $version, $sqlFile);
                    $upgradeLog[] = [
                        'version' => $version,
                        'status' => 'success',
                        'message' => "升级至 v{$version} 成功 ({$shortFile})"
                    ];
                } catch (Exception $e) {
                    $upgradeLog[] = [
                        'version' => $version,
                        'status' => 'error',
                        'message' => "升级至 v{$version} 失败 ({$shortFile}): " . $e->getMessage()
                    ];
                    throw $e;
                }
            }
            $pdo->commit();
        } catch (Exception $e) {
            $pdo->rollBack();
            throw $e;
        }

        echo json_encode([
            'success' => true,
            'current' => $currentVersion,
            'target' => $targetVersion,
            'steps' => $upgradeLog
        ]);
    } catch (Exception $e) {
        http_response_code(500);
        echo json_encode([
            'success' => false,
            'current' => $currentVersion,
            'target' => $targetVersion,
            'steps' => $upgradeLog,
            'error' => $e->getMessage()
        ]);
    }
    exit();
}

// GET 模式：显示升级信息页面
$currentVersion = '未知';
$targetVersion = '未知';
$upgradeSteps = [];
$hasError = false;
$errorMessage = '';
$isUpToDate = false;

try {
    $envPath = __DIR__ . '/backend/.env';
    $config = readEnvConfig($envPath);

    $dsn = "mysql:host={$config['DB_HOST']};port={$config['DB_PORT']};dbname={$config['DB_NAME']};charset=utf8mb4";
    $pdo = new PDO($dsn, $config['DB_USER'], $config['DB_PASSWORD'], [
        PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION
    ]);

    $currentVersion = detectCurrentVersion($pdo);

    $versionFile = __DIR__ . '/VERSION';
    if (!file_exists($versionFile)) {
        throw new RuntimeException('VERSION 文件不存在: ' . $versionFile);
    }
    $targetVersion = trim(file_get_contents($versionFile));

    $upgradeSteps = getUpgradeSteps($currentVersion, $targetVersion);
    $isUpToDate = empty($upgradeSteps);
} catch (Exception $e) {
    $hasError = true;
    $errorMessage = $e->getMessage();
}

?>
<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>系统升级 - 班级操行分管理系统</title>
    <style>
        * { margin: 0; padding: 0; box-sizing: border-box; }
        body {
            font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
            background: #f5f7fa;
            color: #333;
            line-height: 1.6;
            padding: 20px;
        }
        .container {
            max-width: 720px;
            margin: 40px auto;
            background: #fff;
            border-radius: 8px;
            box-shadow: 0 2px 12px rgba(0,0,0,0.08);
            overflow: hidden;
        }
        .header {
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            color: #fff;
            padding: 24px 32px;
        }
        .header h1 { font-size: 20px; font-weight: 600; }
        .header p { font-size: 13px; opacity: 0.85; margin-top: 4px; }
        .content { padding: 24px 32px; }
        .info-row {
            display: flex;
            justify-content: space-between;
            padding: 10px 0;
            border-bottom: 1px solid #f0f0f0;
            font-size: 14px;
        }
        .info-row:last-child { border-bottom: none; }
        .info-label { color: #888; }
        .info-value { font-weight: 600; }
        .section-title {
            font-size: 15px;
            font-weight: 600;
            margin: 20px 0 12px;
            color: #444;
        }
        .step {
            display: flex;
            align-items: flex-start;
            padding: 10px 12px;
            margin-bottom: 8px;
            border-radius: 6px;
            font-size: 14px;
            background: #fafafa;
            border-left: 3px solid #ddd;
        }
        .step.success { border-left-color: #52c41a; background: #f6ffed; }
        .step.error { border-left-color: #ff4d4f; background: #fff2f0; }
        .step.pending { border-left-color: #faad14; background: #fffbe6; }
        .step-icon { margin-right: 10px; font-size: 16px; flex-shrink: 0; }
        .step.success .step-icon { color: #52c41a; }
        .step.error .step-icon { color: #ff4d4f; }
        .step.pending .step-icon { color: #faad14; }
        .step-message { word-break: break-all; }
        .error-box {
            background: #fff2f0;
            border: 1px solid #ffccc7;
            border-radius: 6px;
            padding: 12px 16px;
            margin-top: 16px;
            color: #cf1322;
            font-size: 13px;
            word-break: break-all;
        }
        .warning-box {
            background: #fffbe6;
            border: 1px solid #ffe58f;
            border-radius: 6px;
            padding: 12px 16px;
            margin-top: 16px;
            color: #ad6800;
            font-size: 13px;
        }
        .btn-upgrade {
            display: inline-block;
            padding: 10px 32px;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            color: #fff;
            border: none;
            border-radius: 6px;
            font-size: 15px;
            font-weight: 500;
            cursor: pointer;
            margin-top: 20px;
            transition: opacity 0.2s;
        }
        .btn-upgrade:hover { opacity: 0.9; }
        .btn-upgrade:disabled {
            opacity: 0.6;
            cursor: not-allowed;
        }
        .btn-upgrade.loading {
            opacity: 0.7;
            cursor: wait;
        }
        .action-area {
            text-align: center;
            margin-top: 16px;
        }
        .result-area {
            margin-top: 16px;
        }
        .footer {
            text-align: center;
            padding: 16px 32px;
            border-top: 1px solid #f0f0f0;
            color: #aaa;
            font-size: 12px;
        }
        .success-box {
            background: #f6ffed;
            border: 1px solid #b7eb8f;
            border-radius: 6px;
            padding: 16px;
            margin-top: 16px;
            text-align: center;
            color: #389e0d;
            font-size: 14px;
        }
    </style>
</head>
<body>
    <div class="container">
        <div class="header">
            <h1>班级操行分管理系统 - 数据库升级</h1>
            <p>自动检测版本并执行增量升级</p>
        </div>
        <div class="content">
            <div class="info-row">
                <span class="info-label">当前数据库版本</span>
                <span class="info-value" id="currentVersion"><?php echo htmlspecialchars($currentVersion); ?></span>
            </div>
            <div class="info-row">
                <span class="info-label">目标版本</span>
                <span class="info-value" id="targetVersion"><?php echo htmlspecialchars($targetVersion); ?></span>
            </div>

            <?php if ($hasError): ?>
            <div class="error-box">
                <strong>错误：</strong><?php echo htmlspecialchars($errorMessage); ?>
            </div>
            <?php if ($hasError && strpos($errorMessage, '配置文件不存在') !== false): ?>
            <div class="warning-box">
                <strong>💡 解决方法：</strong><br>
                1. 进入 <code>backend/</code> 目录<br>
                2. 复制配置模板：<code>cp .env.example .env</code><br>
                3. 编辑 <code>.env</code> 文件，填入实际的数据库连接信息<br>
                4. 刷新此页面
            </div>
            <?php endif; ?>
            <?php elseif ($isUpToDate): ?>
            <div class="success-box">
                ✓ 数据库已是最新版本，无需升级。
            </div>
            <?php else: ?>
            <div class="section-title">待执行升级步骤</div>
            <?php foreach ($upgradeSteps as $version => $sqlFile): ?>
            <div class="step pending" id="step-<?php echo htmlspecialchars($version); ?>">
                <span class="step-icon">○</span>
                <span class="step-message">升级至 v<?php echo htmlspecialchars($version); ?> (<?php echo htmlspecialchars(basename($sqlFile)); ?>)</span>
            </div>
            <?php endforeach; ?>

            <div class="warning-box">
                ⚠️ 升级前请确保已备份数据库，升级过程中请勿关闭页面。
            </div>

            <div class="action-area">
                <button class="btn-upgrade" id="btnUpgrade" onclick="executeUpgrade()">立即升级</button>
            </div>

            <div class="result-area" id="resultArea" style="display:none;"></div>
            <?php endif; ?>
        </div>
        <div class="footer">
            班级操行分管理系统 v<?php echo htmlspecialchars($targetVersion); ?>
        </div>
    </div>

    <?php if (!$hasError && !$isUpToDate): ?>
    <script>
    function escapeHtml(str) {
        if (typeof str !== 'string') return '';
        var div = document.createElement('div');
        div.appendChild(document.createTextNode(str));
        return div.innerHTML;
    }

    function executeUpgrade() {
        var btn = document.getElementById('btnUpgrade');
        var resultArea = document.getElementById('resultArea');

        btn.disabled = true;
        btn.classList.add('loading');
        btn.textContent = '升级中...';
        resultArea.style.display = 'none';

        // 收集所有待执行步骤
        var steps = [];
        <?php foreach ($upgradeSteps as $version => $sqlFile): ?>
        steps.push('<?php echo htmlspecialchars($version); ?>');
        <?php endforeach; ?>

        var currentIndex = 0;

        function executeNextStep() {
            if (currentIndex >= steps.length) {
                btn.classList.remove('loading');
                btn.textContent = '升级完成';
                resultArea.style.display = 'block';
                resultArea.innerHTML = '<div class="success-box">✓ 升级成功！数据库已更新至最新版本<br><br><small style="color:#888">建议升级完成后删除 upgrade.php 文件</small></div>';
                return;
            }

            var version = steps[currentIndex];
            fetch('?action=step&version=' + encodeURIComponent(version), { method: 'POST' })
                .then(function(r) { return r.json(); })
                .then(function(data) {
                    var el = document.getElementById('step-' + version);
                    if (el) {
                        el.className = 'step ' + (data.success ? 'success' : 'error');
                        el.querySelector('.step-icon').textContent = data.success ? '✓' : '✗';
                    }

                    if (data.success) {
                        currentIndex++;
                        executeNextStep();
                    } else {
                        btn.classList.remove('loading');
                        btn.textContent = '升级失败';
                        btn.disabled = false;
                        resultArea.style.display = 'block';
                        resultArea.innerHTML = '<div class="error-box"><strong>升级失败：</strong>' + escapeHtml(data.error || '未知错误') + '</div>';
                    }
                })
                .catch(function(err) {
                    var el = document.getElementById('step-' + version);
                    if (el) {
                        el.className = 'step error';
                        el.querySelector('.step-icon').textContent = '✗';
                    }
                    btn.classList.remove('loading');
                    btn.disabled = false;
                    btn.textContent = '立即升级';
                    resultArea.style.display = 'block';
                    resultArea.innerHTML = '<div class="error-box"><strong>请求失败：</strong>' + escapeHtml(err.message) + '</div>';
                });
        }

        executeNextStep();
    }
    </script>
    <?php endif; ?>
</body>
</html>