import { afterEach, describe, expect, it } from 'vitest';
import {
    createLogger,
    currentRequestId,
    getLogLevel,
    nextRequestId,
    renderTraceBytes,
    runWithoutRequestContext,
    runWithRequestId,
    runWithTraceRequest,
    setLogLevel,
} from '../src/logger';

const originalLevel = getLogLevel();

afterEach(() => {
    setLogLevel(originalLevel);
});

describe('TRACE diagnostics contract', () => {
    it('renders every byte as continuous lowercase hexadecimal', () => {
        expect(renderTraceBytes(new Uint8Array())).toBe('');
        expect(renderTraceBytes(new Uint8Array([0x00, 0x01, 0x0f, 0x10, 0xff]))).toBe('00010f10ff');
    });

    it('renders only the addressed Uint8Array view', () => {
        const backing = new Uint8Array([0xaa, 0x00, 0x0f, 0xff, 0xbb]);

        expect(renderTraceBytes(backing.subarray(1, 4))).toBe('000fff');
        expect(renderTraceBytes(Buffer.from(backing.buffer).subarray(2, 4))).toBe('0fff');
    });

    it('does not render bytes while TRACE is disabled', () => {
        setLogLevel('info');
        let rendered = false;

        createLogger('Trace.Contract').trace(() => {
            rendered = true;
            return ['body=%s', renderTraceBytes(new Uint8Array([0xff]))];
        });

        expect(rendered).toBe(false);
    });

    it('creates distinct request contexts that survive asynchronous work', async () => {
        setLogLevel('info');
        const beforeDisabled = nextRequestId();
        expect(runWithTraceRequest(() => currentRequestId())).toBeUndefined();
        const afterDisabled = nextRequestId();
        expect(afterDisabled).toBe(beforeDisabled + 1);

        setLogLevel('trace');
        const observeContext = () =>
            runWithTraceRequest(async () => {
                const before = currentRequestId();
                await Promise.resolve();
                const after = currentRequestId();
                expect(after).toBe(before);
                return after;
            });

        const first = await observeContext();
        expect(currentRequestId()).toBeUndefined();
        const second = await observeContext();
        expect(currentRequestId()).toBeUndefined();

        expect(first).toEqual(expect.any(Number));
        expect(first).toBeGreaterThan(0);
        expect(second).toEqual(expect.any(Number));
        expect(second).toBeGreaterThan(0);
        expect(second).not.toBe(first);
    });

    it('allocates once for nested TRACE contexts and reuses the request id', () => {
        setLogLevel('trace');
        const before = nextRequestId();

        const observed = runWithTraceRequest(() => {
            const outer = currentRequestId();
            const inner = runWithTraceRequest(() => currentRequestId());
            return { outer, inner };
        });

        const after = nextRequestId();
        expect(observed.outer).toEqual(expect.any(Number));
        expect(observed.inner).toBe(observed.outer);
        expect(observed.outer).toBe(before + 1);
        expect(after).toBe(before + 2);
        expect(currentRequestId()).toBeUndefined();
    });

    it('detaches long-lived resources from the current request context', async () => {
        await runWithRequestId(4243, async () => {
            expect(currentRequestId()).toBe(4243);
            const detached = await runWithoutRequestContext(async () => {
                expect(currentRequestId()).toBeUndefined();
                await Promise.resolve();
                return currentRequestId();
            });
            expect(detached).toBeUndefined();
            expect(currentRequestId()).toBe(4243);
        });
        expect(currentRequestId()).toBeUndefined();
    });

    it('reuses an existing request context even while TRACE is disabled', async () => {
        setLogLevel('info');

        await runWithRequestId(4242, async () => {
            const observed = await runWithTraceRequest(async () => {
                await Promise.resolve();
                return currentRequestId();
            });
            expect(observed).toBe(4242);
        });
    });
});