/**
 * Legacy system (MySQL `oapi`) → tehran-taj (PostgreSQL) data import.
 *
 * The rules live in docs/DATA-MIGRATION-MAP.md; every step cites its section.
 *
 * Usage (from apps/api):
 *
 *   npx ts-node --transpile-only scripts/legacy-import/index.ts \
 *     --source  "mysql://user:pass@127.0.0.1:3307/oapi" \
 *     --target  "postgresql://user:pass@localhost:5432/goldbank_import_test" \
 *     [--images "F:/legacy/storage" --upload-dir "./storage/uploads"] \
 *     [--only customers,ledger] [--report ./legacy-import-report.md] --yes
 *
 * Safety:
 *  - The source is only read. Point it at a COPY of production anyway.
 *  - --target is required and never taken from .env, so the dev database is
 *    never written by accident. Without --yes nothing is written; a target
 *    whose name does not contain "import" or "staging" also needs
 *    --confirm-db=<its exact name>.
 *  - Re-runnable: every written row is recorded in legacy_import.id_map, so a
 *    second run updates instead of duplicating, and a run that stops half way
 *    is finished by running it again.
 *  - Never writes Customer/Product accounting* columns, ProductVariant.imageId,
 *    or the Accounting* tables, and never deletes a ProductImage.
 *  - Writes go straight through Prisma, not through the API services, so no
 *    SMS is sent and nothing is queued to the accounting software.
 */
import { writeFileSync } from 'node:fs';
import { resolve } from 'node:path';
import { PrismaClient } from '@prisma/client';
import { IdMap, makeContext, openSource, type Ctx, type Options } from './lib/context';
import { admins, branches, cities, customers, experts, roles, workshops } from './steps/people';
import { brands, categories, products, variants } from './steps/catalog';
import { favorites, ledger, orders, preOrders } from './steps/commerce';
import { reconcile, reconcileSales } from './steps/reconcile';

/** Order matters: each step reads the ids the earlier ones mapped. */
const STEPS: [string, (ctx: Ctx) => Promise<void>][] = [
  ['cities', cities],
  ['roles', roles],
  ['branches', branches],
  ['admins', admins],
  ['experts', experts],
  ['workshops', workshops],
  ['customers', customers],
  ['brands', brands],
  ['categories', categories],
  ['products', products],
  ['variants', variants],
  ['orders', orders],
  ['ledger', ledger],
  ['favorites', favorites],
  ['preorders', preOrders],
  ['reconcile', reconcile],
  ['reconcile-sales', reconcileSales],
];

const ENTITIES = [
  'city', 'ut', 'branch', 'admin', 'expert', 'workshop', 'customer', 'file', 'brand', 'category',
  'product', 'pimage', 'variant', 'order', 'orderitem', 'ledger', 'preorder',
];

/** Columns the prep migrations added; the import refuses to run without them. */
const REQUIRED = [
  ['Customer', 'nationalCode'], ['Customer', 'birthDate'], ['Customer', 'cityNameRaw'],
  ['Customer', 'verificationRejectionReason'], ['CustomerFavorite', 'customerId'],
];

function parseArgs(argv: string[]) {
  const a = new Map<string, string>();
  for (let i = 0; i < argv.length; i++) {
    const k = argv[i];
    if (!k.startsWith('--')) continue;
    const eq = k.indexOf('=');
    if (eq > 0) a.set(k.slice(2, eq), k.slice(eq + 1));
    else if (argv[i + 1] && !argv[i + 1].startsWith('--')) a.set(k.slice(2), argv[++i]);
    else a.set(k.slice(2), 'true');
  }
  return a;
}

const fail = (msg: string): never => {
  console.error(`\n✖ ${msg}\n`);
  process.exit(1);
};

async function main() {
  const a = parseArgs(process.argv.slice(2));
  const opt: Options = {
    sourceUrl: a.get('source') ?? fail('--source <mysql url> is required'),
    targetUrl: a.get('target') ?? fail('--target <postgres url> is required (never read from .env)'),
    imagesDir: a.get('images'),
    uploadDir: a.get('upload-dir'),
    only: a.get('only') ? new Set(a.get('only')!.split(',').map((s) => s.trim())) : undefined,
    reportPath: resolve(a.get('report') ?? 'legacy-import-report.md'),
  };
  if (opt.imagesDir && !opt.uploadDir) fail('--images needs --upload-dir (the target UPLOAD_DIR)');
  if (opt.only) for (const s of opt.only) if (!STEPS.some(([n]) => n === s)) fail(`unknown step "${s}"`);

  const db = new PrismaClient({ datasources: { db: { url: opt.targetUrl } } });
  const src = openSource(opt.sourceUrl);

  try {
    /* preflight — read only */
    const [{ db: dbName }] = await db.$queryRawUnsafe<{ db: string }[]>('SELECT current_database() AS db');
    const [srcInfo] = await (await src.query('SELECT DATABASE() AS db, VERSION() AS v'))[0] as { db: string; v: string }[];
    const missing: string[] = [];
    for (const [t, c] of REQUIRED) {
      const [{ n }] = await db.$queryRawUnsafe<{ n: bigint }[]>(
        `SELECT COUNT(*) AS n FROM information_schema.columns WHERE table_schema = 'public' AND table_name = $1 AND column_name = $2`, t, c,
      );
      if (Number(n) === 0) missing.push(`${t}.${c}`);
    }
    const counts = {
      customers: await db.customer.count(),
      products: await db.product.count(),
      ledger: await db.ledgerEntry.count(),
    };
    console.log(`source  mysql ${srcInfo.v} · database ${srcInfo.db}`);
    console.log(`target  postgres · database ${dbName} · ${counts.customers} customers, ${counts.products} products, ${counts.ledger} ledger entries`);
    if (missing.length) fail(`target is missing ${missing.join(', ')} — apply the prep migrations first`);

    if (a.get('yes') !== 'true') {
      console.log('\nNothing written. Re-run with --yes to import.');
      return;
    }
    if (!/import|staging/i.test(dbName) && a.get('confirm-db') !== dbName) {
      fail(`"${dbName}" does not look like a test or staging copy. To write to it anyway add --confirm-db=${dbName}`);
    }

    /* run */
    await IdMap.ensureSchema(db);
    const ctx = makeContext(opt, src, db);
    for (const e of ENTITIES) await ctx.map.load(e);

    for (const [name, step] of STEPS) {
      if (opt.only && !opt.only.has(name)) continue;
      const t0 = Date.now();
      process.stdout.write(`▸ ${name} … `);
      await step(ctx);
      console.log(`${((Date.now() - t0) / 1000).toFixed(1)}s`);
    }

    const md = ctx.report.render([
      `- started: ${ctx.report.startedAt.toISOString()} · finished: ${new Date().toISOString()}`,
      `- source: \`${srcInfo.db}\` (MySQL ${srcInfo.v}) · target: \`${dbName}\``,
      `- steps: ${opt.only ? [...opt.only].join(', ') : 'all'}`,
      `- images: ${opt.imagesDir ? `${opt.imagesDir} → ${opt.uploadDir}` : 'not copied (no --images)'}`,
    ]);
    writeFileSync(opt.reportPath, md);
    console.log(`\nreport: ${opt.reportPath}`);
  } finally {
    await src.end();
    await db.$disconnect();
  }
}

main().catch((e) => {
  console.error(e);
  process.exit(1);
});