import { strictEqual, rejects } from 'node:assert/strict';
import test from 'node:test';

import { cacheableFetch } from './functions';

type FetchMock = typeof fetch;

const withFixedNow = async <T>(now: number, fn: () => Promise<T>) => {
  const originalNow = Date.now;
  Date.now = () => now;

  try {
    return await fn();
  } finally {
    Date.now = originalNow;
  }
};

test('cacheableFetch reuses cached response before expiry', async () => {
  const originalFetch = globalThis.fetch;
  const fixedNow = Date.now();
  const futureExpires = new Date(fixedNow + 60_000).toUTCString();
  let calls = 0;

  globalThis.fetch = (async () => {
    calls += 1;
    return new Response(JSON.stringify({ ok: true, call: calls }), {
      status: 200,
      headers: { Expires: futureExpires }
    });
  }) as FetchMock;

  try {
    await withFixedNow(fixedNow, async () => {
      const first = await cacheableFetch<{ ok: boolean; call: number }>('https://example.test/cache-1');
      const second = await cacheableFetch<{ ok: boolean; call: number }>('https://example.test/cache-1');
      const third = await cacheableFetch<{ ok: boolean; call: number }>('https://example.test/cache-1');

      strictEqual(calls, 1);
      strictEqual(first.call, 1);
      strictEqual(second.call, 1);
      strictEqual(third.call, 1);
    });
  } finally {
    globalThis.fetch = originalFetch;
  }
});

test('cacheableFetch does not share cache across different urls', async () => {
  const originalFetch = globalThis.fetch;
  const fixedNow = Date.now();
  const futureExpires = new Date(fixedNow + 60_000).toUTCString();
  let calls = 0;

  globalThis.fetch = (async () => {
    calls += 1;
    return new Response(JSON.stringify({ ok: true, call: calls }), {
      status: 200,
      headers: { Expires: futureExpires }
    });
  }) as FetchMock;

  try {
    await withFixedNow(fixedNow, async () => {
      const first = await cacheableFetch<{ ok: boolean; call: number }>('https://example.test/cache-4');
      const second = await cacheableFetch<{ ok: boolean; call: number }>('https://example.test/cache-5');

      strictEqual(calls, 2);
      strictEqual(first.call, 1);
      strictEqual(second.call, 2);
    });
  } finally {
    globalThis.fetch = originalFetch;
  }
});

test('cacheableFetch refetches after expiry', async () => {
  const originalFetch = globalThis.fetch;
  const fixedNow = Date.now();
  const pastExpires = new Date(fixedNow - 60_000).toUTCString();
  let calls = 0;

  globalThis.fetch = (async () => {
    calls += 1;
    return new Response(JSON.stringify({ ok: true, call: calls }), {
      status: 200,
      headers: { Expires: pastExpires }
    });
  }) as FetchMock;

  try {
    await withFixedNow(fixedNow, async () => {
      const first = await cacheableFetch<{ ok: boolean; call: number }>('https://example.test/cache-2');
      const second = await cacheableFetch<{ ok: boolean; call: number }>('https://example.test/cache-2');

      strictEqual(calls, 2);
      strictEqual(first.call, 1);
      strictEqual(second.call, 2);
    });
  } finally {
    globalThis.fetch = originalFetch;
  }
});

test('cacheableFetch does not cache failed responses', async () => {
  const originalFetch = globalThis.fetch;
  const fixedNow = Date.now();
  const futureExpires = new Date(fixedNow + 60_000).toUTCString();
  let calls = 0;

  globalThis.fetch = (async () => {
    calls += 1;

    if (calls === 1) {
      return new Response(JSON.stringify({ error: 'boom' }), {
        status: 500,
        headers: { Expires: futureExpires }
      });
    }

    return new Response(JSON.stringify({ ok: true, call: calls }), {
      status: 200,
      headers: { Expires: futureExpires }
    });
  }) as FetchMock;

  try {
    await withFixedNow(fixedNow, async () => {
      await rejects(() => cacheableFetch('https://example.test/cache-3'));
      const result = await cacheableFetch<{ ok: boolean; call: number }>('https://example.test/cache-3');

      strictEqual(calls, 2);
      strictEqual(result.call, 2);
    });
  } finally {
    globalThis.fetch = originalFetch;
  }
});