/**
 * Regression tests for the realtime reliability patch (TSK-0224):
 *   (a) polling fallback claims a task even when its SSE event is lost;
 *   (b) parseSSEBuffer accepts CRLF frames and joins multiple data: lines;
 *   (c) delivered-but-unacked messages stay visible in the inbox;
 *   (d) discovery self-heal falls back when the configured URL is dead.
 */
import { describe, it, expect, beforeEach, afterEach } from 'vitest';
import { mkdtempSync, rmSync } from 'fs';
import { tmpdir } from 'os';
import { join } from 'path';
import { init } from '../src/cli/commands/init.js';
import { workAgent } from '../src/cli/commands/work.js';
import { parseSSEBuffer } from '../src/cli/commands/watch.js';
import { startServer } from '../src/server/index.js';
import { createMessage, listInbox, getMessage } from '../src/core/services/messageService.js';
import { probeServer, resolveReachableServerUrl } from '../src/discovery.js';
import type { Task } from '../src/core/schema.js';

// ─── (a) polling fallback: claim despite a lost SSE event ────────────────────

describe('work — polling fallback (lost SSE event)', () => {
  let cwd: string;
  let server: Awaited<ReturnType<typeof startServer>>;
  const realFetch = globalThis.fetch;

  beforeEach(async () => {
    cwd = mkdtempSync(join(tmpdir(), 'ah-poll-'));
    init(cwd, { projectName: 'poll-test', yes: true });
    server = await startServer(cwd, { host: '127.0.0.1', port: 0 });

    // Suppress the SSE channel: /events returns an open stream that never
    // delivers a frame. Every other request passes through to the real server.
    globalThis.fetch = (async (input: RequestInfo | URL, init?: RequestInit) => {
      const url = typeof input === 'string' ? input : input instanceof URL ? input.toString() : input.url;
      if (url.endsWith('/events')) {
        const stream = new ReadableStream<Uint8Array>({
          start(controller) {
            init?.signal?.addEventListener('abort', () => {
              try {
                controller.close();
              } catch {
                /* already closed */
              }
            });
            // Never enqueue: the SSE frame is "lost".
          },
        });
        return new Response(stream, { status: 200, headers: { 'Content-Type': 'text/event-stream' } });
      }
      return realFetch(input, init);
    }) as typeof fetch;
  });

  afterEach(async () => {
    globalThis.fetch = realFetch;
    await server.app.close().catch(() => undefined);
    rmSync(cwd, { recursive: true, force: true });
  });

  it('claims a task via the polling fallback when its SSE event never arrives', async () => {
    const workDone = workAgent({
      serverUrl: server.url,
      projectCwd: cwd,
      agent: 'kimi',
      role: 'implementer',
      timeoutSec: 8,
      pollIntervalMs: 100,
    });

    // Delegate a task after the wait started. The SSE event is swallowed by the
    // stub above, so only the polling fallback can notice it.
    await new Promise((r) => setTimeout(r, 300));
    await realFetch(`${server.url}/tasks`, {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ title: 'kimi: claimed via polling', role: 'implementer' }),
    });

    await workDone; // must resolve via the poll, long before the 8s timeout

    const tasks = (await realFetch(`${server.url}/tasks`).then((r) => r.json())) as Task[];
    const mine = tasks.find((t) => (t.title ?? '').startsWith('kimi:'));
    expect(mine).toBeDefined();
    expect(mine?.status).toBe('in_progress');
    expect(mine?.assignedTo).toBe('kimi');
  }, 10000);
});

// ─── (b) CRLF-tolerant SSE parser ────────────────────────────────────────────

describe('parseSSEBuffer — CRLF + multi-line data', () => {
  it('parses CRLF-framed events', () => {
    const buf = 'data: {"type":"task","action":"created","id":"TSK-0001"}\r\n\r\n';
    const { events, remaining } = parseSSEBuffer(buf);
    expect(events).toHaveLength(1);
    expect(events[0].id).toBe('TSK-0001');
    expect(remaining).toBe('');
  });

  it('parses mixed LF/CRLF frames and CRLF keepalives', () => {
    const buf =
      ':\r\n\r\n' +
      'data: {"type":"memory","action":"created","id":"MEM-001"}\n\n' +
      'data: {"type":"decision","action":"created","id":"DEC-001"}\r\n\r\n';
    const { events, remaining } = parseSSEBuffer(buf);
    expect(events).toHaveLength(2);
    expect(events[0].id).toBe('MEM-001');
    expect(events[1].id).toBe('DEC-001');
    expect(remaining).toBe('');
  });

  it('joins multiple data: lines of one event with a newline', () => {
    const buf = 'data: {"type":"task",\r\ndata: "id":"TSK-0002"}\r\n\r\n';
    const { events } = parseSSEBuffer(buf);
    expect(events).toHaveLength(1);
    expect(events[0].type).toBe('task');
    expect(events[0].id).toBe('TSK-0002');
  });

  it('keeps an incomplete CRLF tail in `remaining`', () => {
    const buf = 'data: {"type":"task","id":"TSK-0001"}\r\n\r\ndata: {"type":"deci';
    const { events, remaining } = parseSSEBuffer(buf);
    expect(events).toHaveLength(1);
    expect(remaining).toBe('data: {"type":"deci');
  });
});

// ─── (c) delivered-unacked messages stay visible ─────────────────────────────

describe('message semantics — delivered stays visible until explicit ack/read', () => {
  let cwd: string;

  beforeEach(() => {
    cwd = mkdtempSync(join(tmpdir(), 'ah-msg-vis-'));
    init(cwd, { projectName: 'msg-vis', yes: true });
  });

  afterEach(() => {
    rmSync(cwd, { recursive: true, force: true });
  });

  it('a surfaced (delivered) message stays in the default inbox and never re-wakes', () => {
    const msg = createMessage(cwd, { from: 'claude', to: 'kimi', text: 'look at this' });

    // The work-loop drain path: fetch unread. First call surfaces it and flips
    // it to delivered; nothing marks it read.
    const first = listInbox(cwd, 'kimi', { unreadOnly: true });
    expect(first).toHaveLength(1);
    expect(first[0].status).toBe('delivered');
    expect(getMessage(cwd, msg.id).message.status).toBe('delivered');

    // No spin: the unread-filtered wake check is empty on the next pass…
    expect(listInbox(cwd, 'kimi', { unreadOnly: true })).toHaveLength(0);

    // …but the info stays visible in the default inbox until explicit ack/read.
    const inbox = listInbox(cwd, 'kimi');
    expect(inbox.map((m) => m.id)).toContain(msg.id);
    expect(inbox.find((m) => m.id === msg.id)?.status).toBe('delivered');
  });
});

// ─── (d) discovery self-heal ─────────────────────────────────────────────────

describe('discovery self-heal — stale configured URL', () => {
  let cwd: string;
  let server: Awaited<ReturnType<typeof startServer>>;

  beforeEach(async () => {
    cwd = mkdtempSync(join(tmpdir(), 'ah-heal-'));
    init(cwd, { projectName: 'heal-test', yes: true });
    server = await startServer(cwd, { host: '127.0.0.1', port: 0 });
  });

  afterEach(async () => {
    await server.app.close().catch(() => undefined);
    rmSync(cwd, { recursive: true, force: true });
  });

  it('falls back to the discovered URL when the configured one is dead', async () => {
    const discovered = await resolveReachableServerUrl('http://127.0.0.1:1', {
      discover: async () => server.url,
    });
    expect(discovered).toBe(server.url);
  });

  it('keeps the configured URL when it answers (discovery not consulted)', async () => {
    let discoverCalled = false;
    const resolved = await resolveReachableServerUrl(server.url, {
      discover: async () => {
        discoverCalled = true;
        return 'http://example.invalid:9';
      },
    });
    expect(resolved).toBe(server.url);
    expect(discoverCalled).toBe(false);
  });

  it('returns undefined when the configured URL is dead and nothing is discovered', async () => {
    const resolved = await resolveReachableServerUrl('http://127.0.0.1:1', {
      discover: async () => undefined,
    });
    expect(resolved).toBeUndefined();
  });

  it('probeServer distinguishes a live server from a dead one', async () => {
    expect(await probeServer(server.url)).toBe(true);
    expect(await probeServer('http://127.0.0.1:1', 300)).toBe(false);
  });
});