/**
 * 历史汇率数据播种脚本
 * 运行方式: npx tsx scripts/seed-historical-rates.ts
 *
 * 功能：解析 scripts/rates.csv，将历史汇率数据分批 upsert 到 exchange_rates_history 表。
 * 特性：
 *   - 自动剔除 BOM 头 (\uFEFF)
 *   - 按 500 条/批次批量写入
 *   - 联合唯一约束 (fromCurrency, toCurrency, fetchTime) 确保幂等性
 */

import * as fs from 'fs';
import * as path from 'path';
import { db } from '@/db';
import { exchangeRatesHistory } from '@/db/schema';
import { sql } from 'drizzle-orm';

const BATCH_SIZE = 500;

function parseCsv(filePath: string): typeof exchangeRatesHistory.$inferInsert[] {
  const raw = fs.readFileSync(filePath, 'utf-8');
  const content = raw.replace(/^\uFEFF/, '');
  const lines = content.split('\n').filter(line => line.trim().length > 0);

  // 剔除表头
  const header = lines[0];
  if (!header) {
    throw new Error('CSV file is empty');
  }

  const records: typeof exchangeRatesHistory.$inferInsert[] = [];
  for (let i = 1; i < lines.length; i++) {
    const line = lines[i].replace(/^\uFEFF/, '').trim();
    if (!line) continue;

    const parts = line.split(',');
    if (parts.length < 4) {
      console.warn(`Skipping malformed line ${i + 1}: ${line}`);
      continue;
    }

    const [fromCurrency, toCurrency, rateStr, fetchTimeStr] = parts;

    const rate = parseFloat(rateStr.trim());
    if (isNaN(rate)) {
      console.warn(`Skipping line ${i + 1} with invalid rate: ${rateStr}`);
      continue;
    }

    const fetchTime = new Date(fetchTimeStr.trim());
    if (isNaN(fetchTime.getTime())) {
      console.warn(`Skipping line ${i + 1} with invalid date: ${fetchTimeStr}`);
      continue;
    }

    records.push({
      fromCurrency: fromCurrency.trim(),
      toCurrency: toCurrency.trim(),
      rate: rate.toString(),
      fetchTime,
    });
  }

  return records;
}

async function seed() {
  const csvPath = path.join(__dirname, 'rates.csv');

  if (!fs.existsSync(csvPath)) {
    console.error(`CSV file not found: ${csvPath}`);
    process.exit(1);
  }

  console.log(`Reading CSV from: ${csvPath}`);
  const records = parseCsv(csvPath);
  console.log(`Parsed ${records.length} valid records.`);

  const batches: typeof exchangeRatesHistory.$inferInsert[][] = [];
  for (let i = 0; i < records.length; i += BATCH_SIZE) {
    batches.push(records.slice(i, i + BATCH_SIZE));
  }

  let totalUpserted = 0;
  for (let i = 0; i < batches.length; i++) {
    const batch = batches[i];
    await db
      .insert(exchangeRatesHistory)
      .values(batch)
      .onConflictDoUpdate({
        target: [exchangeRatesHistory.fromCurrency, exchangeRatesHistory.toCurrency, exchangeRatesHistory.fetchTime],
        set: { rate: sql`EXCLUDED.rate` },
      });
    totalUpserted += batch.length;
    console.log(`Batch ${i + 1}/${batches.length}: ${batch.length} records processed (${totalUpserted}/${records.length} total).`);
  }

  console.log(`Seed complete. Total records processed: ${totalUpserted}`);
}

seed().catch((err) => {
  console.error('Seed failed:', err);
  process.exit(1);
});