// Regression for issue #97: a hot reload that swaps WsClientAdapter's
// underlying socket (binding-signature change → `await this.close()` then
// `await this.open()`) leaves the OLD socket's `'close'` event scheduled to
// fire AFTER the new socket has already been assigned to `this.socket`.
// Without a guard in the close handler that event would null out
// `this.socket`, drop `connected`, and schedule an unwanted reconnect — on a
// single-connection backend that kicks duplicates, this snowballed into a
// reconnect storm. The fix is a one-line identity check; these tests pin it.
//
// We mock `@snowluma/websocket` (its native addon isn't built in a plain
// checkout, mirroring the comment in adapter-reload-state-machine.test.ts)
// with a minimal EventEmitter-backed fake whose `'open'` / `'close'` events
// are driven explicitly by the test — this is exactly the lifecycle the
// adapter's connect() wires up to. Both the class and the instances registry
// live inside `vi.hoisted` so they are constructed BEFORE `vi.mock` runs.

import { beforeEach, describe, expect, it, vi } from 'vitest';

const { FakeWebSocket, instances } = vi.hoisted(() => {
    // eslint-disable-next-line @typescript-eslint/no-require-imports
    const { EventEmitter } = require('node:events') as typeof import('node:events');
    const instances: FakeWebSocket[] = [];

    class FakeWebSocket extends EventEmitter {
        // 1 = OPEN, 2 = CLOSING, 3 = CLOSED — matches @snowluma/websocket.
        public readyState = 1;
        public closeArgs?: { code: number; reason: string };
        public readonly url: string;

        constructor(url: string, _opts: unknown) {
            super();

            if (url.includes('throw-sync')) {
                throw new Error('invalid websocket url');
            }

            this.url = url;
            instances.push(this);
        }

        close(code = 1000, reason = 'normal'): void {
            if (this.readyState === 3 || this.readyState === 2) {
                return;
            }

            this.readyState = 2;
            this.closeArgs = { code, reason };
            // Crucially DO NOT auto-emit 'close' here — real WebSockets emit it
            // only after the underlying net socket actually ends, which is the
            // deferred delivery that creates the race. Tests trigger it
            // explicitly via simulateClose() below.
        }

        send(_payload: string, cb?: (err?: Error | null) => void): void {
            cb?.(null);
        }

        simulateOpen(): void {
            this.emit('open');
        }

        simulateClose(): void {
            this.readyState = 3;
            this.emit('close');
        }
    }

    return { FakeWebSocket, instances };
});

vi.mock('@snowluma/websocket', () => ({ WebSocket: FakeWebSocket }));

// Imports below resolve through the vi.mock above.
import { WsClientAdapter } from '../src/network/ws-client-adapter';
import type { NetworkAdapterContext } from '../src/network/adapter';
import type { WsClientNetwork } from '../src/types';

function ctx(): NetworkAdapterContext {
    return {
        uin: '10001',
        api: { processStreamRequest: async () => {} } as never,
        buildLifecycleEvent: () => ({}),
        buildHeartbeatEvent: () => ({}),
    };
}

function cfg(over: Partial<WsClientNetwork> = {}): WsClientNetwork {
    return {
        enabled: true,
        url: 'ws://127.0.0.1:8080/',
        role: 'Universal',
        reconnectIntervalMs: 1000,
        ...over,
    } as WsClientNetwork;
}

describe('WsClientAdapter — stale-socket close guard (issue #97)', () => {
    beforeEach(() => {
        instances.length = 0;
    });

    it('rolls back enabled state when socket construction throws synchronously', () => {
        const adapter = new WsClientAdapter('ws', cfg({ url: 'ws://throw-sync/' }), ctx());

        expect(() => adapter.open()).toThrow('invalid websocket url');
        expect(adapter.isActive).toBe(false);
        expect(adapter.describeManagedStatus()).toMatchObject({
            status: 'degraded',
            lastError: 'invalid websocket url',
        });
    });

    it('closes the socket but waits for an in-flight inbound action to drain', async () => {
        let finishAction!: () => void;
        const actionGate = new Promise<void>((resolve) => {
            finishAction = resolve;
        });
        const gatedCtx: NetworkAdapterContext = {
            ...ctx(),
            api: { processStreamRequest: vi.fn(() => actionGate) } as never,
        };
        const adapter = new WsClientAdapter('ws', cfg(), gatedCtx);
        adapter.open();
        const socket = instances[0];
        socket.emit('message', Buffer.from('{"action":"get_status"}'));

        let closed = false;
        const closing = adapter.close().then(() => {
            closed = true;
        });
        await Promise.resolve();
        expect(socket.readyState).toBe(2);
        expect(closed).toBe(false);

        finishAction();
        await closing;
        expect(closed).toBe(true);
    });

    it('records and drops a valid action after API quiesce', async () => {
        const processStreamRequest = vi.fn(async () => {});
        const traceQuiescedStreamRequest = vi.fn();
        const quiescedCtx: NetworkAdapterContext = {
            ...ctx(),
            api: {
                isAcceptingActions: false,
                processStreamRequest,
                traceQuiescedStreamRequest,
            } as never,
        };
        const adapter = new WsClientAdapter('ws', cfg(), quiescedCtx);
        adapter.open();
        const socket = instances[0];
        const raw = Buffer.from(
            JSON.stringify({
                action: 'get_status',
                params: { detail: 'complete' },
            }),
        );

        socket.emit('message', raw);

        expect(traceQuiescedStreamRequest).toHaveBeenCalledWith(raw.toString('utf8'));
        expect(processStreamRequest).not.toHaveBeenCalled();
        await adapter.close();
    });

    it('ignores the close event from a socket replaced by a hot reload', async () => {
        vi.useFakeTimers();

        try {
            const adapter = new WsClientAdapter('ws', cfg(), ctx());
            adapter.open();
            expect(instances).toHaveLength(1);
            const a = instances[0];
            a.simulateOpen();

            // Hot reload with a binding-signature change (different URL). The base
            // class drives `await this.close()` then `await this.open()`; the close
            // handler on socket A has NOT yet fired (real flow: WebSocket.close()
            // schedules the close frame + a deferred 'close' event).
            await adapter.reload(cfg({ url: 'ws://127.0.0.1:8081/' }));
            expect(instances).toHaveLength(2);
            const b = instances[1];
            expect(b).not.toBe(a);

            // Delayed 'close' from the stale socket arrives now.
            a.simulateClose();

            // Pre-fix behavior: the close handler would null `this.socket`, drop
            // `connected`, and scheduleReconnect → after the interval a third
            // socket would appear. Post-fix: the guard short-circuits.
            vi.advanceTimersByTime(10_000);
            expect(instances).toHaveLength(2);

            // The new socket is still the current connection: simulate its 'open'
            // and the adapter reports 'ok' / '已连接' (only reachable when
            // `this.socket` is non-null AND `connected` is true).
            b.simulateOpen();
            const status = adapter.describeStatus();
            expect(status.status).toBe('ok');
            expect(status.detail).toBe('已连接');
        } finally {
            vi.useRealTimers();
        }
    });

    it('still drives reconnect when the CURRENT socket closes unexpectedly', () => {
        vi.useFakeTimers();

        try {
            const adapter = new WsClientAdapter('ws', cfg(), ctx());
            adapter.open();
            const a = instances[0];
            a.simulateOpen();

            // The current socket dies on its own (no close() / no reload). The
            // handler must still null state and schedule the reconnect — the
            // guard only suppresses STALE events, not real ones.
            a.simulateClose();

            vi.advanceTimersByTime(1500);
            expect(instances).toHaveLength(2); // reconnect spun up a new socket
            const status = adapter.describeStatus();
            expect(status.status).toBe('warn');
        } finally {
            vi.useRealTimers();
        }
    });

    it('does not reconnect when adapter.close() races with an in-flight close event', () => {
        vi.useFakeTimers();

        try {
            const adapter = new WsClientAdapter('ws', cfg(), ctx());
            adapter.open();
            const a = instances[0];
            a.simulateOpen();

            // User-driven close (e.g. config disabled): close() flips
            // explicitlyClosed=true and detaches `this.socket = null`
            // synchronously. The deferred 'close' event from A then fires; the
            // guard sees `this.socket !== socket` (this.socket is already null)
            // and short-circuits — even though the explicitlyClosed flag would
            // also have done so, the guard is the FIRST line of defence and
            // matches the issue's exact stated invariant.
            adapter.close();
            a.simulateClose();

            vi.advanceTimersByTime(10_000);
            expect(instances).toHaveLength(1); // no reconnect, no new socket
            const status = adapter.describeStatus();
            expect(status.status).toBe('disabled');
        } finally {
            vi.useRealTimers();
        }
    });
});