import { pbkdf2Sync, randomBytes } from 'node:crypto';
import { existsSync } from 'node:fs';
import { rm } from 'node:fs/promises';
import { isAbsolute, join, relative, resolve } from 'node:path';
import { loadEnvFile } from 'node:process';
import { buildSeedOperations, createDatabase, relationalTables } from '../database.mjs';
import { createBaseDatabase } from '../src/data/base.mjs';
import { createSeedDatabase } from '../src/data/seed.mjs';
import { CURRENT_SCHEMA_VERSION } from '../src/database/version.mjs';

const root = resolve(process.cwd());
const envPath = join(root, '.env');
if (existsSync(envPath)) loadEnvFile(envPath);

const options = new Set(process.argv.slice(2));
if (options.has('--mysql') && options.has('--sqlite')) throw new Error('不能同时指定 --mysql 和 --sqlite');
const configuredClient = options.has('--mysql') ? 'mysql' : options.has('--sqlite') ? 'sqlite' : process.env.DATABASE_CLIENT;
const client = String(configuredClient || (process.env.NODE_ENV === 'production' ? 'mysql' : 'sqlite')).toLowerCase();
if (!['sqlite', 'mysql'].includes(client)) throw new Error(`不支持的 DATABASE_CLIENT：${client}`);
process.env.DATABASE_CLIENT = client;
const force = options.has('--force');
const initializeEmpty = options.has('--empty');

function hashPassword(password, salt = randomBytes(16).toString('hex')) {
  const hash = pbkdf2Sync(password, salt, 120000, 32, 'sha256').toString('hex');
  return `${salt}:${hash}`;
}

const createTargetState = () => initializeEmpty
  ? createBaseDatabase({
      nowIso: () => new Date().toISOString(),
      hashPassword,
      initialAdmin: {
        username: process.env.INITIAL_ADMIN_USERNAME,
        password: process.env.INITIAL_ADMIN_PASSWORD,
        displayName: process.env.INITIAL_ADMIN_DISPLAY_NAME
      }
    })
  : createSeedDatabase({ nowIso: () => new Date().toISOString(), hashPassword });

async function prepareSqlite() {
  const databasePath = resolve(process.env.SQLITE_PATH || join(root, 'data', 'exam.sqlite'));
  const relativePath = relative(root, databasePath);
  if (!relativePath || relativePath.startsWith('..') || isAbsolute(relativePath)) {
    throw new Error('拒绝覆盖工作区以外的 SQLite 数据库');
  }
  await rm(databasePath, { force: true });
  await rm(`${databasePath}-shm`, { force: true });
  await rm(`${databasePath}-wal`, { force: true });
  process.env.SQLITE_PATH = databasePath;
  return databasePath;
}

function mysqlPoolOptions(mysql) {
  if (process.env.DATABASE_URL) return mysql.createPool(process.env.DATABASE_URL);
  if (!process.env.MYSQL_HOST || !process.env.MYSQL_USER || !process.env.MYSQL_DATABASE) {
    throw new Error('MySQL 配置不完整：请在 .env 设置 DATABASE_URL，或 MYSQL_HOST、MYSQL_USER、MYSQL_DATABASE');
  }
  return mysql.createPool({
    host: process.env.MYSQL_HOST,
    port: Number(process.env.MYSQL_PORT || 3306),
    user: process.env.MYSQL_USER,
    password: process.env.MYSQL_PASSWORD || '',
    database: process.env.MYSQL_DATABASE,
    waitForConnections: true,
    connectionLimit: 2,
    charset: 'utf8mb4',
    timezone: 'Z',
    enableKeepAlive: true
  });
}

const mysqlBusinessTables = [
  'schools', 'school_classes', 'candidate_profiles', 'notices', 'exams', 'exam_subjects',
  'registrations', 'registration_subjects', 'exam_arrangement_plans', 'admit_cards', 'admit_card_subjects',
  'results', 'test_centers', 'test_rooms', 'center_change_requests', 'center_change_rooms',
  'candidate_account_batches', 'candidate_account_batch_items', 'workflow_instances', 'workflow_actions', 'admission_records', 'audit_logs'
];

async function prepareMysql() {
  const { default: mysql } = await import('mysql2/promise');
  const pool = mysqlPoolOptions(mysql);
  let connection;
  try {
    connection = await pool.getConnection();
    const [[databaseRow]] = await connection.query('SELECT DATABASE() AS name');
    const databaseName = String(databaseRow?.name || '');
    if (!databaseName || ['mysql', 'information_schema', 'performance_schema', 'sys'].includes(databaseName.toLowerCase())) {
      throw new Error(`拒绝向系统数据库导入测试数据：${databaseName || '未选择数据库'}`);
    }

    const [tableRows] = await connection.query(`
      SELECT TABLE_NAME FROM information_schema.TABLES
      WHERE TABLE_SCHEMA = DATABASE() AND TABLE_TYPE = 'BASE TABLE'
    `);
    const existingTables = new Set(tableRows.map(row => row.TABLE_NAME));
    const existingAppTables = relationalTables.filter(table => existingTables.has(table));
    if (!existingAppTables.length) return { location: `MySQL database ${databaseName}`, initialized: false };
    if (existingAppTables.length !== relationalTables.length) {
      const missing = relationalTables.filter(table => !existingTables.has(table));
      throw new Error(`MySQL 数据库结构不完整，缺少：${missing.join(', ')}。请先使用空数据库启动一次应用完成建表`);
    }

    const [metadataRows] = await connection.query('SELECT schema_version FROM schema_metadata WHERE id = 1');
    if (Number(metadataRows[0]?.schema_version) !== CURRENT_SCHEMA_VERSION) {
      throw new Error(`MySQL 数据库结构版本不是 v${CURRENT_SCHEMA_VERSION}（当前 ${metadataRows[0]?.schema_version ?? '未知'}），请先完成结构初始化`);
    }

    const [examPartitionRows] = await connection.query(
      'SELECT candidates_table, admissions_table, results_table, centers_table FROM exam_data_partitions'
    );
    const [schoolPartitionRows] = await connection.query('SELECT students_table FROM school_student_partitions');
    const dynamicPartitionTables = [
      ...examPartitionRows.flatMap(row => [row.candidates_table, row.admissions_table, row.results_table, row.centers_table]),
      ...schoolPartitionRows.map(row => row.students_table)
    ];
    if (dynamicPartitionTables.some(table => !/^[a-z][a-z0-9_]{0,63}$/.test(table))) {
      throw new Error('分表登记中存在非法表名，拒绝替换测试数据');
    }

    const nonEmpty = [];
    for (const table of mysqlBusinessTables) {
      const [[row]] = await connection.query(`SELECT COUNT(*) AS count FROM \`${table}\``);
      if (Number(row.count) > 0) nonEmpty.push(`${table}=${row.count}`);
    }
    const [[userRow]] = await connection.query('SELECT COUNT(*) AS count FROM users');
    if (Number(userRow.count) > 1) nonEmpty.push(`users=${userRow.count}`);
    let recognizedTestData = false;
    if (initializeEmpty && nonEmpty.length) {
      const [[bulkUsers]] = await connection.query("SELECT COUNT(*) AS count FROM users WHERE id LIKE 'usr_bulk_%'");
      const [[testSchools]] = await connection.query("SELECT COUNT(*) AS count FROM schools WHERE id IN ('school_hz1', 'school_hz3', 'school_hz5', 'school_hz7', 'school_hz9')");
      recognizedTestData = Number(bulkUsers.count) >= 1100 && Number(testSchools.count) === 5;
    }
    if (nonEmpty.length && !force && !recognizedTestData) {
      const forceCommand = initializeEmpty
        ? 'npm run initialize-system:mysql -- --force'
        : 'npm run seed-test-data:mysql -- --force';
      throw new Error(
        `MySQL 数据库 ${databaseName} 已有业务数据（${nonEmpty.slice(0, 8).join(', ')}${nonEmpty.length > 8 ? ', ...' : ''}）。` +
        `如确认这是可覆盖的测试库，请运行 ${forceCommand}`
      );
    }
    if (nonEmpty.length) {
      console.warn(`[${recognizedTestData ? 'test-data cleanup' : 'force'}] Replacing existing business data in MySQL database ${databaseName}`);
    } else {
      console.log(`Preparing empty MySQL database ${databaseName} for ${initializeEmpty ? 'system initialization' : 'test data'}`);
    }

    const state = createTargetState();
    await connection.query('SET FOREIGN_KEY_CHECKS = 0');
    await connection.beginTransaction();
    try {
      // 先移除考试，使归档成绩保护触发器在清理 results 时不再命中。
      const clearOrder = ['exams', ...[...relationalTables].reverse().filter(table => !['schema_metadata', 'exams'].includes(table))];
      for (const table of clearOrder) await connection.query(`DELETE FROM \`${table}\``);
      for (const operation of buildSeedOperations(state)) await connection.execute(operation.sql, operation.params);
      await connection.commit();
    } catch (error) {
      await connection.rollback();
      throw error;
    } finally {
      await connection.query('SET FOREIGN_KEY_CHECKS = 1');
    }
    for (const table of dynamicPartitionTables) await connection.query(`DROP TABLE IF EXISTS \`${table}\``);
    return { location: `MySQL database ${databaseName}`, initialized: true };
  } finally {
    connection?.release();
    await pool.end();
  }
}

let location;
let mysqlAlreadyImported = false;
if (client === 'sqlite') {
  location = await prepareSqlite();
} else {
  const prepared = await prepareMysql();
  location = prepared.location;
  mysqlAlreadyImported = prepared.initialized;
}
const database = await createDatabase({
  root,
  seed: createTargetState
});
const state = await database.read();
await database.close();

const pending = state.registrations.filter(item => item.status === 'pending').length;
const rejected = state.registrations.filter(item => item.status === 'rejected').length;
const unpaid = state.registrations.filter(item => item.status === 'approved' && item.paymentStatus === 'unpaid').length;
const paid = state.registrations.filter(item => item.status === 'approved' && item.paymentStatus === 'paid').length;
if (initializeEmpty) {
  console.log(`Initialized empty system in ${location}${mysqlAlreadyImported ? ' (transactional replace)' : ''}`);
  console.log(`${state.users.length} initial administrator, ${state.schools.length} schools, ${state.candidateProfiles.length} candidates, ${state.registrations.length} registrations`);
} else {
  console.log(`Imported test data into ${location}${mysqlAlreadyImported ? ' (transactional replace)' : ''}`);
  console.log(`${state.schools.filter(item => item.isSourceSchool).length} source schools, ${state.schools.filter(item => item.isAdmissionSchool).length} admission schools, ${state.candidateProfiles.length} candidates, ${state.registrations.length} registrations`);
  console.log(`pending ${pending}, rejected ${rejected}, approved/unpaid ${unpaid}, approved/paid ${paid}`);
  console.log(`${state.results.length} published subject scores, ${state.admissionRecords.filter(item => item.kind === 'preference' && Number(item.payload?.round || 1) === 1).length} first-round preferences`);
  console.log(`arrangement plans ${state.arrangementPlans.length}, admit cards ${state.registrations.filter(item => item.admitCard).length}`);
  console.log('all predefined test account passwords: 12345678');
}