/**
 * V3: 为 ai_providers 表添加 visibility 列（public/private）
 *
 * 背景：
 *   - 管理员可发布 public provider，全员可用
 *   - 普通用户（teacher/student 等）可创建 private provider，仅本人可见
 *
 * 缺失列清单：
 *   - ai_providers.visibility        (可见性：public | private，默认 private)
 *   - 索引 ai_provider_visibility_idx (visibility)
 *   - 索引 ai_provider_created_by_idx (created_by)
 *
 * 注意：默认值设为 'private'，保证历史记录不会意外对全员公开。
 *      管理员可在 UI 中将需要共享的 provider 改为 public。
 */
require("dotenv/config");
const mysql = require("mysql2/promise");

const ALTER_OPERATIONS = [
  {
    table: "ai_providers",
    description: "添加 visibility 列（public/private 可见性）",
    sql: [
      "ALTER TABLE `ai_providers` ADD COLUMN `visibility` ENUM('public','private') NOT NULL DEFAULT 'private' AFTER `is_default`",
      "ALTER TABLE `ai_providers` ADD INDEX `ai_provider_visibility_idx` (`visibility`)",
      "ALTER TABLE `ai_providers` ADD INDEX `ai_provider_created_by_idx` (`created_by`)",
    ],
  },
];

async function columnExists(conn, table, column) {
  const [rows] = await conn.execute(
    `SELECT COLUMN_NAME FROM information_schema.COLUMNS
     WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME = ? AND COLUMN_NAME = ?`,
    [table, column],
  );
  return rows.length > 0;
}

async function indexExists(conn, table, indexName) {
  const [rows] = await conn.execute(
    `SELECT INDEX_NAME FROM information_schema.STATISTICS
     WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME = ? AND INDEX_NAME = ?
     LIMIT 1`,
    [table, indexName],
  );
  return rows.length > 0;
}

async function main() {
  const conn = await mysql.createConnection({ uri: process.env.DATABASE_URL });
  console.log("✅ 已连接数据库\n");

  for (const op of ALTER_OPERATIONS) {
    console.log(`${"=".repeat(60)}`);
    console.log(`表: ${op.table} — ${op.description}`);
    console.log("=".repeat(60));

    for (const sql of op.sql) {
      try {
        const isColumn = sql.includes("ADD COLUMN");
        const isIndex = sql.includes("ADD INDEX");

        if (isColumn) {
          const match = sql.match(/ADD COLUMN `(\w+)`/);
          if (match && await columnExists(conn, op.table, match[1])) {
            console.log(`  ⏭️  跳过已存在的列: ${match[1]}`);
            continue;
          }
        } else if (isIndex) {
          const match = sql.match(/ADD INDEX `(\w+)`/);
          if (match && await indexExists(conn, op.table, match[1])) {
            console.log(`  ⏭️  跳过已存在的索引: ${match[1]}`);
            continue;
          }
        }

        await conn.execute(sql);
        console.log(`  ✅ 执行成功: ${sql.slice(0, 100)}...`);
      } catch (err) {
        if (err.code === "ER_DUP_FIELDNAME" || err.code === "ER_DUP_KEYNAME" || err.errno === 1060 || err.errno === 1061) {
          console.log(`  ⏭️  已存在，跳过: ${err.message}`);
        } else {
          console.error(`  ❌ 执行失败: ${err.message}`);
          console.error(`     SQL: ${sql}`);
        }
      }
    }
    console.log("");
  }

  // 验证最终列结构
  console.log(`${"=".repeat(60)}`);
  console.log("最终验证 — 检查 visibility 列是否已添加");
  console.log("=".repeat(60));

  const checks = [
    ["ai_providers", "visibility"],
  ];

  let allOk = true;
  for (const [table, col] of checks) {
    const exists = await columnExists(conn, table, col);
    const status = exists ? "✅" : "❌";
    if (!exists) allOk = false;
    console.log(`  ${status} ${table}.${col}`);
  }

  console.log(allOk ? "\n✅ visibility 列已就绪" : "\n❌ 仍有缺失列，请检查错误");

  await conn.end();
  process.exitCode = allOk ? 0 : 1;
}

main().catch((err) => {
  console.error("致命错误:", err);
  process.exit(1);
});