import 'dotenv/config';
import split2 from 'split2';
import { from as copyFrom } from 'pg-copy-streams';
import { createReadStream } from 'node:fs';
import { Transform, type TransformCallback } from 'node:stream';
import { pipeline } from 'node:stream/promises';
import { fileURLToPath } from 'node:url';
import { getPool, close } from './index.js';

const FIXTURE = fileURLToPath(new URL('./fixtures/notes.jsonl', import.meta.url));

const COLUMNS = ['id', 'text', 'x', 'y', 'author', 'color'] as const;

type Column = typeof COLUMNS[number];

const DEFAULTS: Partial<Record<Column, unknown>> = { x: 0, y: 0, color: 'yellow' };

const csvField = (value: unknown): string => {
  if (value === null || value === undefined) return '';
  return `"${String(value).replaceAll('"', '""')}"`;
};

const toCsvRows = (): Transform => new Transform({
  writableObjectMode: true,
  transform(line: string, _encoding: BufferEncoding, callback: TransformCallback) {
    if (line.trim().length === 0) {
      callback();
      return;
    }

    let note: Record<string, unknown>;
    try {
      note = JSON.parse(line) as Record<string, unknown>;
    } catch {
      callback(new Error(`Fixture contains a malformed JSON line: ${line.slice(0, 80)}`));
      return;
    }

    const row = COLUMNS.map((col) => csvField(note[col] ?? DEFAULTS[col]));
    callback(null, `${row.join(',')}\n`);
  },
});

const run = async (): Promise<void> => {
  const client = await getPool().connect();

  try {
    await client.query('BEGIN');

    // COPY has no ON CONFLICT, so land the fixture in a temp table first and
    // let a single INSERT ... SELECT apply the existing idempotency.
    await client.query(
      'CREATE TEMP TABLE notes_import (LIKE notes INCLUDING DEFAULTS) ON COMMIT DROP'
    );

    const copy = client.query(
      copyFrom(`COPY notes_import (${COLUMNS.join(', ')}) FROM STDIN WITH (FORMAT csv)`)
    );

    await pipeline(createReadStream(FIXTURE), split2(), toCsvRows(), copy);

    const { rowCount: staged } = await client.query('SELECT 1 FROM notes_import');
    const { rowCount: inserted } = await client.query(
      `INSERT INTO notes (${COLUMNS.join(', ')})
       SELECT ${COLUMNS.join(', ')} FROM notes_import
       ON CONFLICT (id) DO NOTHING`
    );

    await client.query('COMMIT');

    console.log(`Seed complete — ${inserted} notes inserted (${(staged ?? 0) - (inserted ?? 0)} already existed).`);
  } catch (err) {
    await client.query('ROLLBACK').catch(() => {});
    console.error('Seed failed:', err instanceof Error ? err.message : err);
    process.exitCode = 1;
  } finally {
    client.release();
    await close();
  }
};

run();