import { afterEach, describe, expect, it, vi } from 'vitest';
import { createMetricsRefresh } from '../../src/lib/ui/metrics-refresh.js';

afterEach(() => vi.useRealTimers());
const totals = { observed: 0, active: 0, idle: 0, unknown: 0, playerHours: 0 };
const report = (days: number) => ({
    days,
    now: 1000,
    since: 0,
    summary: totals,
    points: [],
    maps: [],
    servers: [],
    scope: { game: null, map: null, timeZone: 'UTC' },
    scopeOptions: { games: [], maps: [] },
    registeredServerCount: 0,
    firstRetainedSampleAt: null,
    latestSampleAt: null,
    scopeFirstSampleAt: null,
    scopeLatestSampleAt: null,
    previous: {
        since: -1000,
        until: 0,
        summary: totals,
        firstSampleAt: null,
        lastSampleAt: null,
        partialHistory: true
    },
    heatmap: { timeZone: 'UTC', cells: [] },
    pooledPressure: { value: null, fullMapHours: 0, knownMapHours: 0, coveredMaps: 0, totalMaps: 0 }
});
function setup(fetcher: typeof fetch) {
    let query = 'days=7';
    const onData = vi.fn(),
        onError = vi.fn(),
        onLoading = vi.fn();
    return {
        ...createMetricsRefresh({
            getQuery: () => query,
            onData,
            onError,
            onLoading,
            fetcher,
            timeoutMs: 100
        }),
        onData,
        onError,
        onLoading,
        setQuery: (value: string) => {
            query = value;
        }
    };
}

describe('metrics background refresh', () => {
    it('keeps the previous report after failure and accepts a successful retry', async () => {
        const fetcher = vi
            .fn()
            .mockResolvedValueOnce(new Response('', { status: 503 }))
            .mockResolvedValueOnce(Response.json(report(7)));
        const refresh = setup(fetcher);
        await refresh.refresh();
        expect(refresh.onData).not.toHaveBeenCalled();
        expect(refresh.onError).toHaveBeenLastCalledWith('Report refresh failed (503).');
        await refresh.refresh();
        expect(refresh.onData).toHaveBeenLastCalledWith(report(7));
        expect(refresh.onError).toHaveBeenLastCalledWith(null);
        expect(refresh.onLoading).toHaveBeenLastCalledWith(false);
    });

    it('coalesces duplicate requests and ignores old replies even when transport ignores abort', async () => {
        const resolve: ((r: Response) => void)[] = [];
        const fetcher = vi.fn(() => new Promise<Response>((done) => resolve.push(done)));
        const refresh = setup(fetcher);
        const old = refresh.refresh();
        expect(refresh.refresh()).toBe(old);
        expect(fetcher).toHaveBeenCalledTimes(1);
        refresh.setQuery('days=1');
        const next = refresh.refresh();
        resolve[1](Response.json(report(1)));
        await next;
        resolve[0](Response.json(report(7)));
        await old;
        expect(refresh.onData).toHaveBeenCalledTimes(1);
        expect(refresh.onData).toHaveBeenLastCalledWith(report(1));
    });

    it('preserves the report when an HTTP success lacks the expanded report contract', async () => {
        const fetcher = vi
            .fn()
            .mockResolvedValueOnce(Response.json({ ...report(7), heatmap: null }))
            .mockResolvedValueOnce(
                Response.json({
                    ...report(7),
                    scope: { game: null, map: null, timeZone: 'Invalid/Zone' }
                })
            )
            .mockResolvedValueOnce(Response.json(report(7)));
        const refresh = setup(fetcher);
        await refresh.refresh();
        await refresh.refresh();
        expect(refresh.onData).not.toHaveBeenCalled();
        expect(refresh.onError).toHaveBeenLastCalledWith('The metrics response was incomplete.');
        await refresh.refresh();
        expect(refresh.onData).toHaveBeenCalledTimes(1);
    });

    it('suppresses errors from a cancelled request', async () => {
        let reject!: (error: Error) => void;
        const refresh = setup(
            vi.fn(
                () =>
                    new Promise<Response>((_, fail) => {
                        reject = fail;
                    })
            )
        );
        const pending = refresh.refresh();
        refresh.cancel();
        reject(new Error('Obsolete response'));
        await pending;
        expect(refresh.onData).not.toHaveBeenCalled();
        expect(refresh.onError.mock.calls).toEqual([[null]]);
        expect(refresh.onLoading).toHaveBeenLastCalledWith(false);
    });

    it('times out with retry feedback and clears loading', async () => {
        vi.useFakeTimers();
        const fetcher = vi.fn(
            (_input, init) =>
                new Promise<Response>((_, reject) => {
                    init?.signal?.addEventListener('abort', () => reject(new Error('aborted')));
                })
        ) as typeof fetch;
        const refresh = setup(fetcher);
        const pending = refresh.refresh();
        await vi.advanceTimersByTimeAsync(100);
        await pending;
        expect(refresh.onError).toHaveBeenLastCalledWith('Report refresh timed out. Try again.');
        expect(refresh.onLoading).toHaveBeenLastCalledWith(false);
    });
});