import { describe, expect, it } from 'bun:test';
import { mergeDataSeries } from './chart-data-transformers';

type PricePoint = {
  date: string;
  price: number;
};

describe('mergeDataSeries', () => {
  it('normalizes intraday timestamps onto the same trading day', () => {
    const merged = mergeDataSeries<PricePoint>([
      {
        id: 'stock',
        data: [
          { date: '2026-03-10T21:00:00.000Z', price: 100 },
          { date: '2026-03-11T21:00:00.000Z', price: 101 }
        ]
      },
      {
        id: 'sp500',
        data: [
          { date: '2026-03-10', price: 5000 },
          { date: '2026-03-11', price: 5050 }
        ]
      }
    ]);

    expect(merged).toEqual([
      { date: '2026-03-10', stock: 100, sp500: 5000 },
      { date: '2026-03-11', stock: 101, sp500: 5050 }
    ]);
  });

  it('fills a comparison series from the nearest prior trading day when dates are missing', () => {
    const merged = mergeDataSeries<PricePoint>([
      {
        id: 'stock',
        data: [
          { date: '2026-03-10', price: 100 },
          { date: '2026-03-11', price: 103 },
          { date: '2026-03-12', price: 104 }
        ]
      },
      {
        id: 'sp500',
        data: [
          { date: '2026-03-10', price: 5000 },
          { date: '2026-03-12', price: 5060 }
        ]
      }
    ]);

    expect(merged).toEqual([
      { date: '2026-03-10', stock: 100, sp500: 5000 },
      { date: '2026-03-11', stock: 103, sp500: 5000 },
      { date: '2026-03-12', stock: 104, sp500: 5060 }
    ]);
  });

  it('does not backfill dates before a series first appears', () => {
    const merged = mergeDataSeries<PricePoint>([
      {
        id: 'stock',
        data: [
          { date: '2026-03-10', price: 100 },
          { date: '2026-03-11', price: 103 }
        ]
      },
      {
        id: 'sp500',
        data: [
          { date: '2026-03-11', price: 5000 }
        ]
      }
    ]);

    expect(merged).toEqual([
      { date: '2026-03-10', stock: 100 },
      { date: '2026-03-11', stock: 103, sp500: 5000 }
    ]);
  });
});