import { describe, it, expect, vi, beforeEach } from 'vitest';
import { api, ApiError, setUnauthorizedHandler } from '$api';

function mockFetch(status: number, body: unknown) {
	return vi.fn(
		async () =>
			new Response(JSON.stringify(body), {
				status,
				headers: { 'content-type': 'application/json' }
			})
	);
}

beforeEach(() => {
	document.cookie = 'csrftoken=abc';
});

describe('api client', () => {
	it('prepends the base URL and returns parsed JSON', async () => {
		vi.stubGlobal('fetch', mockFetch(200, { username: 'demo' }));
		const out = await api.get<{ username: string }>('/whoami/');
		expect(out).toEqual({ username: 'demo' });
		const url = (fetch as unknown as ReturnType<typeof vi.fn>).mock.calls[0][0];
		expect(String(url)).toContain('/api/whoami/');
	});

	it('throws ApiError carrying the backend detail on 4xx', async () => {
		vi.stubGlobal('fetch', mockFetch(400, { detail: 'Invalid credentials.' }));
		await expect(api.post('/login/', {})).rejects.toMatchObject({
			name: 'ApiError',
			status: 400,
			detail: 'Invalid credentials.'
		});
	});

	// The backend does not speak one error shape: DMR's response validator emits
	// `detail` as a list of {msg}, Pydantic bodies arrive as a bare list, and a
	// few endpoints use DRF-style field maps. Stringifying any of those yields
	// "[object Object]" in the UI, so each shape needs flattening.
	it('flattens a list-of-objects detail from DMR response validation', async () => {
		vi.stubGlobal(
			'fetch',
			mockFetch(422, { detail: [{ msg: 'Returned status code 400 is not specified', type: 'value_error' }] })
		);
		await expect(api.post('/register/', {})).rejects.toMatchObject({
			detail: 'Returned status code 400 is not specified'
		});
	});

	it('flattens a bare list body of Pydantic errors', async () => {
		vi.stubGlobal(
			'fetch',
			mockFetch(400, [
				{ msg: 'Username must be at least 3 characters', loc: ['username'] },
				{ msg: 'Invalid email format', loc: ['email'] }
			])
		);
		await expect(api.post('/register/', {})).rejects.toMatchObject({
			detail: 'Username must be at least 3 characters; Invalid email format'
		});
	});

	it('flattens a DRF-style field error map', async () => {
		vi.stubGlobal('fetch', mockFetch(400, { non_field_errors: ['Point already saved.'] }));
		await expect(api.post('/points/', {})).rejects.toMatchObject({
			detail: 'Point already saved.'
		});
	});

	it('never surfaces [object Object] for an unrecognised shape', async () => {
		vi.stubGlobal('fetch', mockFetch(400, { detail: { nested: { deep: true } } }));
		await expect(api.post('/register/', {})).rejects.toMatchObject({
			detail: 'Request failed (400)'
		});
	});

	it('invokes the unauthorized handler on 401', async () => {
		const handler = vi.fn();
		setUnauthorizedHandler(handler);
		vi.stubGlobal('fetch', mockFetch(401, { detail: 'Unauthorized' }));
		await expect(api.get('/whoami/')).rejects.toBeInstanceOf(ApiError);
		expect(handler).toHaveBeenCalledOnce();
	});
});