import { createHash, randomUUID } from 'node:crypto';
import { resolve } from 'node:path';
import type {
  AgentBrowserBounds,
  AgentBrowserCdpEventPage,
  AgentBrowserCdpResult,
  AgentBrowserErrorCode,
  AgentBrowserPayloadChunk,
  AgentBrowserPayloadRef,
  AgentBrowserSnapshot,
  AgentBrowserState,
} from '../../shared/agent-browser';
import type {
  AgentBrowserAdapter,
  AgentBrowserViewPort,
  PortListener,
} from './adapter';
import { AgentBrowserCdpGuard } from './cdp-guard';
import { AgentBrowserEventBuffer } from './event-buffer';
import { AgentBrowserFault } from './fault';
import { AgentBrowserPayloadStore } from './payload-store';

const CDP_PROTOCOL_VERSION = '1.3';
const INLINE_RESULT_BYTES = 64 * 1024;
const MAX_WAIT_MS = 5_000;
const DEFAULT_CDP_TIMEOUT_MS = 10_000;
const MAX_CDP_TIMEOUT_MS = 30_000;
const OPEN_TIMEOUT_MS = 30_000;
const RENDERER_PRIME_URL = 'about:blank';
const ENABLED_DOMAINS = ['Runtime.enable', 'Log.enable', 'Network.enable', 'Page.enable'] as const;
const STREAM_ISSUING_METHODS = new Set([
  'Fetch.takeResponseBodyAsStream',
  'Network.loadNetworkResource',
  'Page.printToPDF',
  'Tracing.tracingComplete',
]);

interface BrowserRecord {
  browserId: string;
  projectId: string;
  projectPath: string;
  partition: string;
  view: AgentBrowserViewPort;
  state: AgentBrowserState;
  generation: number;
  url: string;
  title: string;
  visible: boolean;
  bounds: AgentBrowserBounds | null;
  error?: {
    code: AgentBrowserErrorCode;
    message: string;
  };
  eventBuffer: AgentBrowserEventBuffer;
  childSessions: Set<string>;
  ioHandles: Set<string>;
  webContentsListeners: Array<{ event: string; listener: PortListener }>;
  debuggerListeners: Array<{
    event: 'message' | 'detach';
    listener: PortListener;
  }>;
  interruptWaiters: Set<(fault: AgentBrowserFault) => void>;
}

export interface AgentBrowserOpenInput {
  projectId: string;
  projectPath: string;
  url: string;
  bounds?: AgentBrowserBounds;
  visible?: boolean;
}

export interface AgentBrowserPresentInput {
  projectPath: string;
  visible: boolean;
  bounds?: AgentBrowserBounds;
}

export interface AgentBrowserNavigateInput {
  projectPath: string;
  action: 'url' | 'back' | 'forward' | 'reload';
  url?: string;
}

export interface AgentBrowserSendCdpInput {
  projectPath: string;
  method: string;
  params?: Record<string, unknown>;
  sessionRef?: string;
  timeoutMs?: number;
}

export interface AgentBrowserReadEventsInput {
  projectPath: string;
  after?: number;
  methods?: string[];
  limit?: number;
  waitMs?: number;
}

export interface AgentBrowserReadPayloadInput {
  projectPath: string;
  handle: string;
  offset?: number;
  maxBytes?: number;
}

export interface AgentBrowserModuleOptions {
  payloadStore?: AgentBrowserPayloadStore;
  cdpGuard?: AgentBrowserCdpGuard;
}

export function agentBrowserPartition(projectPath: string): string {
  const normalized = normalizePath(projectPath);
  const key = createHash('sha256').update(normalized).digest('hex').slice(0, 32);
  return `persist:niancode-agent-browser:${key}`;
}

export class AgentBrowserModule {
  private readonly payloadStore: AgentBrowserPayloadStore;
  private readonly cdpGuard: AgentBrowserCdpGuard;
  private readonly eventWaiters = new Set<() => void>();
  private readonly commandCancellers = new Set<(fault: AgentBrowserFault) => void>();
  private record: BrowserRecord | null = null;
  private commandTail: Promise<void> = Promise.resolve();
  private lifecycleBarrier: Promise<void> = Promise.resolve();
  private queueEpoch = 0;
  private generation = 0;
  private disposed = false;

  constructor(
    private readonly adapter: AgentBrowserAdapter,
    options: AgentBrowserModuleOptions = {},
  ) {
    this.payloadStore = options.payloadStore ?? new AgentBrowserPayloadStore();
    this.cdpGuard = options.cdpGuard ?? new AgentBrowserCdpGuard();
  }

  async getSnapshot(projectPath?: string): Promise<AgentBrowserSnapshot> {
    if (!this.record) return this.closedSnapshot();
    if (projectPath) this.assertProject(this.record, projectPath);
    return this.snapshot(this.record);
  }

  open(input: AgentBrowserOpenInput): Promise<AgentBrowserSnapshot> {
    return this.serialize(async () => {
      this.assertAvailable();
      const projectPath = normalizeRequiredPath(input.projectPath);
      const targetUrl = normalizeUrl(input.url);
      const bounds = input.bounds ? normalizeBounds(input.bounds) : null;

      if (this.record && !samePath(this.record.projectPath, projectPath)) {
        await this.closeInternal();
      }
      if (this.record) {
        const record = this.record;
        if (record.state === 'suspended_devtools') {
          throw new AgentBrowserFault(
            'DEVTOOLS_CONFLICT',
            '请先关闭当前页面的原生 DevTools。',
            true,
            record.generation,
          );
        }
        if (record.state !== 'attached') {
          await this.closeInternal();
        }
      }
      if (this.record) {
        const record = this.record;
        if (bounds) {
          this.applyPresentation(record, input.visible ?? true, bounds);
        }
        if (record.url !== targetUrl || record.error) {
          await this.navigateTo(record, targetUrl);
        }
        return this.snapshot(record);
      }

      const view = this.adapter.createView(agentBrowserPartition(projectPath));
      const record: BrowserRecord = {
        browserId: randomUUID(),
        projectId: input.projectId,
        projectPath,
        partition: agentBrowserPartition(projectPath),
        view,
        state: 'opening',
        generation: ++this.generation,
        url: targetUrl,
        title: '',
        visible: Boolean(bounds) && (input.visible ?? true),
        bounds,
        eventBuffer: new AgentBrowserEventBuffer(),
        childSessions: new Set(),
        ioHandles: new Set(),
        webContentsListeners: [],
        debuggerListeners: [],
        interruptWaiters: new Set(),
      };
      this.record = record;

      this.registerListeners(record);
      record.view.webContents.denyWindowOpen();
      if (bounds) record.view.setBounds(bounds);
      record.view.setVisible(record.visible);
      this.adapter.mount(record.view);

      try {
        await this.runWhileActive(
          record,
          record.view.webContents.loadURL(RENDERER_PRIME_URL),
          OPEN_TIMEOUT_MS,
        );
        await this.runWhileActive(
          record,
          this.attachDebugger(record, false),
          OPEN_TIMEOUT_MS,
        );
      } catch (error) {
        await this.closeInternal(record);
        throw toFault(
          error,
          'ATTACH_FAILED',
          '无法连接开发浏览器调试协议。',
          true,
          record.generation,
        );
      }

      try {
        await this.loadPageUntilReady(record, targetUrl);
        try {
          record.view.webContents.navigationHistory.clear();
        } catch {
          // The first real page remains usable if Chromium history is unavailable.
        }
      } catch (error) {
        await this.closeInternal(record);
        throw toFault(
          error,
          'CDP_PROTOCOL_ERROR',
          '页面加载失败。',
          true,
          record.generation,
        );
      }
      this.refreshMetadata(record);
      return this.snapshot(record);
    });
  }

  present(input: AgentBrowserPresentInput): Promise<AgentBrowserSnapshot> {
    return this.serialize(async () => {
      const record = this.requireRecord(input.projectPath);
      if (input.visible && !input.bounds) {
        throw new AgentBrowserFault(
          'VIEWPORT_NOT_READY',
          '显示开发浏览器时必须提供当前显示区域。',
          true,
          record.generation,
        );
      }
      const bounds = input.bounds ? normalizeBounds(input.bounds) : record.bounds;
      this.applyPresentation(record, input.visible, bounds);
      return this.snapshot(record);
    });
  }

  navigate(input: AgentBrowserNavigateInput): Promise<AgentBrowserSnapshot> {
    return this.serialize(async () => {
      const record = this.requireAttached(input.projectPath);
      const navigation = record.view.webContents.navigationHistory;
      if (input.action === 'url') {
        if (!input.url) {
          throw new AgentBrowserFault('INVALID_URL', '缺少网页地址。', false);
        }
        await this.navigateTo(record, normalizeUrl(input.url));
      } else if (input.action === 'back') {
        if (navigation.canGoBack()) navigation.goBack();
      } else if (input.action === 'forward') {
        if (navigation.canGoForward()) navigation.goForward();
      } else {
        record.view.webContents.reload();
      }
      this.refreshMetadata(record);
      return this.snapshot(record);
    });
  }

  sendCdp(input: AgentBrowserSendCdpInput): Promise<AgentBrowserCdpResult> {
    const timeoutMs = normalizeTimeout(input.timeoutMs);
    return this.serializeWithTimeout(async () => {
      const record = this.requireAttached(input.projectPath);
      const method = input.method.trim();
      if (!method) {
        throw new AgentBrowserFault('INVALID_REQUEST', 'CDP method 不能为空。', false);
      }
      this.cdpGuard.assertAllowed(
        method,
        input.params,
        input.sessionRef,
        record.childSessions,
        record.ioHandles,
      );

      let result: unknown;
      try {
        result = await record.view.webContents.debugger.sendCommand(
          method,
          input.params,
          input.sessionRef,
        );
      } catch (error) {
        throw toFault(
          error,
          'CDP_PROTOCOL_ERROR',
          `CDP method ${method} 执行失败。`,
          true,
          record.generation,
        );
      }
      if (
        record !== this.record
        || record.state !== 'attached'
        || record.generation !== this.generation
      ) {
        throw new AgentBrowserFault(
          'CLOSED',
          'CDP 命令完成前开发浏览器已关闭或切换。',
          true,
          record.generation,
          'unknown',
        );
      }
      this.captureIoHandles(method, result, record);
      if (method === 'IO.close' && typeof input.params?.handle === 'string') {
        record.ioHandles.delete(input.params.handle);
      }
      if (method === 'IO.read' && isRecord(result) && result.eof === true
        && typeof input.params?.handle === 'string') {
        record.ioHandles.delete(input.params.handle);
      }
      return this.encodeResult(result);
    }, timeoutMs);
  }

  async readEvents(input: AgentBrowserReadEventsInput): Promise<AgentBrowserCdpEventPage> {
    let record = this.requirePresented(input.projectPath);
    const after = normalizeNonNegativeInteger(input.after, 0, 'after');
    const limit = normalizeIntegerRange(input.limit, 100, 1, 200, 'limit');
    const waitMs = normalizeIntegerRange(input.waitMs, 0, 0, MAX_WAIT_MS, 'waitMs');
    if (after > record.eventBuffer.cursor) {
      throw new AgentBrowserFault(
        'INVALID_REQUEST',
        '事件游标超出当前浏览器事件范围。',
        false,
        record.generation,
      );
    }

    let page = record.eventBuffer.read(after, input.methods, limit);
    if (
      page.events.length > 0
      || page.gap
      || waitMs === 0
      || page.nextCursor < record.eventBuffer.cursor
    ) {
      return page;
    }

    const cursorBeforeWait = record.eventBuffer.cursor;
    await this.waitForEvent(waitMs, () => {
      const current = this.record;
      return !current
        || current !== record
        || current.eventBuffer.cursor !== cursorBeforeWait;
    });
    record = this.requirePresented(input.projectPath);
    page = record.eventBuffer.read(page.nextCursor, input.methods, limit);
    return page;
  }

  async readPayload(input: AgentBrowserReadPayloadInput): Promise<AgentBrowserPayloadChunk> {
    this.requirePresented(input.projectPath);
    return this.payloadStore.read(input.handle, input.offset, input.maxBytes);
  }

  async close(projectPath?: string): Promise<AgentBrowserSnapshot> {
    if (this.record && projectPath) this.assertProject(this.record, projectPath);
    this.preemptCommands('开发浏览器已关闭。');
    await this.closeInternal();
    return this.closedSnapshot();
  }

  async resetProfile(projectPath: string): Promise<AgentBrowserSnapshot> {
    const normalized = normalizeRequiredPath(projectPath);
    if (this.record) this.assertProject(this.record, normalized);
    this.preemptCommands('开发浏览器数据正在重置。');
    const previousBarrier = this.lifecycleBarrier;
    let releaseBarrier: (() => void) | undefined;
    const barrier = new Promise<void>((resolvePromise) => {
      releaseBarrier = resolvePromise;
    });
    this.lifecycleBarrier = barrier;
    try {
      await previousBarrier;
      await this.closeInternal();
      await this.adapter.resetPartition(agentBrowserPartition(normalized));
      return this.closedSnapshot();
    } finally {
      releaseBarrier?.();
    }
  }

  async dispose(): Promise<void> {
    if (this.disposed) return;
    this.disposed = true;
    this.preemptCommands('开发浏览器模块已关闭。');
    await this.closeInternal();
    this.payloadStore.clear();
  }

  private async attachDebugger(record: BrowserRecord, reattach: boolean): Promise<void> {
    if (record !== this.record || record.view.webContents.isDestroyed()) {
      throw new AgentBrowserFault(
        'TARGET_GONE',
        '开发浏览器页面已关闭。',
        true,
        record.generation,
      );
    }
    const port = record.view.webContents.debugger;
    const needsAttach = !port.isAttached();
    if (reattach && needsAttach) {
      record.generation = ++this.generation;
      record.childSessions.clear();
      record.ioHandles.clear();
    }
    record.state = 'attaching';
    record.error = undefined;
    if (needsAttach) port.attach(CDP_PROTOCOL_VERSION);

    for (const method of ENABLED_DOMAINS) {
      await port.sendCommand(method);
    }
    await port.sendCommand('Target.setAutoAttach', {
      autoAttach: true,
      waitForDebuggerOnStart: false,
      flatten: true,
    });
    if (record !== this.record || record.view.webContents.isDestroyed()) {
      throw new AgentBrowserFault(
        'CLOSED',
        '开发浏览器调试器连接完成前页面已关闭或切换。',
        true,
        record.generation,
        'unknown',
      );
    }
    record.state = 'attached';
    record.error = undefined;
  }

  private registerListeners(record: BrowserRecord): void {
    const contents = record.view.webContents;
    const onDebuggerMessage: PortListener = (
      _event,
      methodValue,
      params,
      sessionRefValue,
    ) => {
      if (record !== this.record || typeof methodValue !== 'string') return;
      const sessionRef = typeof sessionRefValue === 'string' ? sessionRefValue : undefined;
      this.updateTargetScope(record, methodValue, params);
      this.captureIoHandles(methodValue, params, record);
      this.appendEvent(record, methodValue, params, sessionRef);
    };
    const onDebuggerDetach: PortListener = (_event, reasonValue) => {
      if (record !== this.record || record.state === 'closing' || record.state === 'crashed') {
        return;
      }
      record.eventBuffer.markGap('debugger-detached');
      record.childSessions.clear();
      record.ioHandles.clear();
      const devToolsOpen = !contents.isDestroyed() && contents.isDevToolsOpened();
      record.state = devToolsOpen ? 'suspended_devtools' : 'detached_fault';
      record.error = {
        code: devToolsOpen ? 'DEVTOOLS_CONFLICT' : 'DEBUGGER_BUSY',
        message: devToolsOpen
          ? '原生 DevTools 正在使用当前页面调试器。'
          : `开发浏览器调试器已断开：${String(reasonValue ?? 'unknown')}`,
      };
      this.notifyEventWaiters();
    };
    this.addDebuggerListener(record, 'message', onDebuggerMessage);
    this.addDebuggerListener(record, 'detach', onDebuggerDetach);

    this.addWebContentsListener(record, 'did-navigate', (_event, urlValue) => {
      if (typeof urlValue === 'string') record.url = urlValue;
      this.refreshMetadata(record);
    });
    this.addWebContentsListener(record, 'did-navigate-in-page', (_event, urlValue) => {
      if (typeof urlValue === 'string') record.url = urlValue;
      this.refreshMetadata(record);
    });
    this.addWebContentsListener(record, 'page-title-updated', (_event, titleValue) => {
      if (typeof titleValue === 'string') record.title = titleValue;
    });
    this.addWebContentsListener(record, 'devtools-opened', () => {
      if (record !== this.record || record.state === 'closing') return;
      record.state = 'suspended_devtools';
      record.error = {
        code: 'DEVTOOLS_CONFLICT',
        message: '原生 DevTools 已打开，智能体调试暂时暂停。',
      };
    });
    this.addWebContentsListener(record, 'devtools-closed', () => {
      if (record !== this.record || record.state === 'closing' || record.state === 'crashed') {
        return;
      }
      void this.serialize(async () => {
        if (record !== this.record || record.view.webContents.isDestroyed()) return;
        try {
          await this.runWhileActive(
            record,
            this.attachDebugger(record, true),
            OPEN_TIMEOUT_MS,
          );
        } catch (error) {
          if (record !== this.record || record.view.webContents.isDestroyed()) return;
          record.state = 'detached_fault';
          const fault = toFault(
            error,
            'ATTACH_FAILED',
            '关闭 DevTools 后无法恢复智能体调试。',
            true,
            record.generation,
          );
          record.error = { code: fault.code, message: fault.message };
        }
      }).catch(() => undefined);
    });
    this.addWebContentsListener(record, 'render-process-gone', () => {
      if (record !== this.record || record.state === 'closing') return;
      record.state = 'crashed';
      record.error = {
        code: 'RENDERER_CRASHED',
        message: '开发浏览器页面进程已退出。',
      };
      record.eventBuffer.markGap('view-recreated');
      record.childSessions.clear();
      record.ioHandles.clear();
      this.notifyEventWaiters();
    });
    this.addWebContentsListener(record, 'destroyed', () => {
      if (record !== this.record || record.state === 'closing') return;
      record.state = 'crashed';
      record.error = {
        code: 'TARGET_GONE',
        message: '开发浏览器页面已关闭。',
      };
      record.eventBuffer.markGap('view-recreated');
      this.notifyEventWaiters();
    });
  }

  private appendEvent(
    record: BrowserRecord,
    method: string,
    params: unknown,
    sessionRef?: string,
  ): void {
    const base = {
      generation: record.generation,
      timestamp: Date.now(),
      method,
      ...(sessionRef ? { sessionRef } : {}),
    };
    let eventParams = params;
    let payload: AgentBrowserPayloadRef | undefined;
    try {
      const bytes = Buffer.byteLength(JSON.stringify({ ...base, params }));
      if (bytes > INLINE_RESULT_BYTES) {
        payload = this.payloadStore.putJson(params);
        eventParams = undefined;
      }
    } catch {
      eventParams = { omitted: true, reason: 'payload-too-large-or-invalid' };
    }
    record.eventBuffer.push({
      ...base,
      ...(eventParams === undefined ? {} : { params: eventParams }),
      ...(payload ? { payload } : {}),
    });
    this.notifyEventWaiters();
  }

  private updateTargetScope(record: BrowserRecord, method: string, params: unknown): void {
    if (!isRecord(params)) return;
    if (method === 'Target.attachedToTarget' && typeof params.sessionId === 'string') {
      record.childSessions.add(params.sessionId);
    } else if (
      method === 'Target.detachedFromTarget'
      && typeof params.sessionId === 'string'
    ) {
      record.childSessions.delete(params.sessionId);
    }
  }

  private captureIoHandles(method: string, value: unknown, record: BrowserRecord): void {
    if (!STREAM_ISSUING_METHODS.has(method)) return;
    collectStringFields(value, 'stream', record.ioHandles);
  }

  private encodeResult(result: unknown): AgentBrowserCdpResult {
    let byteLength: number;
    try {
      byteLength = Buffer.byteLength(JSON.stringify(result) ?? 'null');
    } catch {
      throw new AgentBrowserFault(
        'CDP_PROTOCOL_ERROR',
        'CDP 返回了无法序列化的数据。',
        false,
      );
    }
    return byteLength > INLINE_RESULT_BYTES
      ? this.payloadStore.putJson(result)
      : { kind: 'inline', value: result };
  }

  private applyPresentation(
    record: BrowserRecord,
    visible: boolean,
    bounds: AgentBrowserBounds | null,
  ): void {
    if (bounds) {
      record.view.setBounds(bounds);
      record.bounds = bounds;
    }
    record.view.setVisible(visible);
    record.visible = visible;
  }

  private async navigateTo(record: BrowserRecord, targetUrl: string): Promise<void> {
    try {
      await this.loadPageUntilReady(record, targetUrl);
      record.url = targetUrl;
      record.error = undefined;
    } catch (error) {
      throw toFault(
        error,
        'CDP_PROTOCOL_ERROR',
        '页面导航失败。',
        true,
        record.generation,
      );
    }
  }

  private async loadPageUntilReady(
    record: BrowserRecord,
    targetUrl: string,
  ): Promise<void> {
    const contents = record.view.webContents;
    await new Promise<void>((resolvePromise, rejectPromise) => {
      let settled = false;
      let timer: ReturnType<typeof setTimeout> | undefined;
      let interrupt: ((fault: AgentBrowserFault) => void) | undefined;
      const cleanup = () => {
        this.removeWebContentsListener(record, 'dom-ready', onDomReady);
        this.removeWebContentsListener(record, 'did-fail-load', onDidFailLoad);
        if (timer) clearTimeout(timer);
        if (interrupt) record.interruptWaiters.delete(interrupt);
      };
      const succeed = () => {
        if (settled) return;
        settled = true;
        cleanup();
        resolvePromise();
      };
      const fail = (error: unknown) => {
        if (settled) return;
        settled = true;
        cleanup();
        rejectPromise(error);
      };
      const onDomReady: PortListener = () => {
        succeed();
      };
      const onDidFailLoad: PortListener = (
        _event,
        errorCodeValue,
        errorDescriptionValue,
        _validatedUrl,
        isMainFrameValue,
      ) => {
        if (isMainFrameValue === false) return;
        if (
          errorCodeValue === -3
          || errorDescriptionValue === 'ERR_ABORTED'
        ) {
          return;
        }
        fail(new Error(
          typeof errorDescriptionValue === 'string' && errorDescriptionValue
            ? errorDescriptionValue
            : '页面加载失败。',
        ));
      };
      interrupt = fail;

      this.addWebContentsListener(record, 'dom-ready', onDomReady);
      this.addWebContentsListener(record, 'did-fail-load', onDidFailLoad);
      record.interruptWaiters.add(interrupt);
      timer = setTimeout(() => {
        fail(new AgentBrowserFault(
          'CDP_TIMEOUT',
          `开发浏览器操作在 ${OPEN_TIMEOUT_MS}ms 内未完成。`,
          true,
          record.generation,
          'unknown',
        ));
      }, OPEN_TIMEOUT_MS);

      try {
        contents.loadURL(targetUrl).then(succeed, (error: unknown) => {
          if (!isNavigationAbort(error)) fail(error);
        });
      } catch (error) {
        fail(error);
      }
    });
  }

  private refreshMetadata(record: BrowserRecord): void {
    if (record.view.webContents.isDestroyed()) return;
    record.url = safeUrl(record.view, record.url);
    try {
      record.title = record.view.webContents.getTitle();
    } catch {
      // Metadata is best effort while a navigation is committing.
    }
  }

  private snapshot(record: BrowserRecord): AgentBrowserSnapshot {
    this.refreshMetadata(record);
    const contents = record.view.webContents;
    let canGoBack = false;
    let canGoForward = false;
    if (!contents.isDestroyed()) {
      try {
        canGoBack = contents.navigationHistory.canGoBack();
        canGoForward = contents.navigationHistory.canGoForward();
      } catch {
        // Navigation state can disappear while the renderer is crashing.
      }
    }
    return {
      browserId: record.browserId,
      projectId: record.projectId,
      projectPath: record.projectPath,
      state: record.state,
      generation: record.generation,
      url: record.url,
      title: record.title,
      visible: record.visible,
      bounds: record.bounds,
      canGoBack,
      canGoForward,
      eventCursor: record.eventBuffer.cursor,
      ...(record.error ? { error: record.error } : {}),
    };
  }

  private closedSnapshot(): AgentBrowserSnapshot {
    return {
      browserId: null,
      projectId: null,
      projectPath: null,
      state: 'closed',
      generation: this.generation,
      url: '',
      title: '',
      visible: false,
      bounds: null,
      canGoBack: false,
      canGoForward: false,
      eventCursor: 0,
    };
  }

  private requireRecord(projectPath: string): BrowserRecord {
    this.assertAvailable();
    const record = this.record;
    if (!record) {
      throw new AgentBrowserFault('BROWSER_NOT_OPEN', '开发浏览器尚未打开。', true);
    }
    this.assertProject(record, projectPath);
    return record;
  }

  private requireAttached(projectPath: string): BrowserRecord {
    const record = this.requirePresented(projectPath);
    if (record.state === 'suspended_devtools') {
      throw new AgentBrowserFault(
        'DEVTOOLS_CONFLICT',
        '请先关闭当前页面的原生 DevTools。',
        true,
        record.generation,
      );
    }
    if (record.state === 'crashed') {
      throw new AgentBrowserFault(
        'RENDERER_CRASHED',
        '开发浏览器页面进程已退出。',
        true,
        record.generation,
      );
    }
    if (record.state !== 'attached' || !record.view.webContents.debugger.isAttached()) {
      throw new AgentBrowserFault(
        'DEBUGGER_BUSY',
        '开发浏览器调试器尚未就绪。',
        true,
        record.generation,
      );
    }
    return record;
  }

  private requirePresented(projectPath: string): BrowserRecord {
    const record = this.requireRecord(projectPath);
    if (!record.visible || !record.bounds) {
      throw new AgentBrowserFault(
        'VIEWPORT_NOT_READY',
        '开发浏览器已收起，智能体调试已暂停。',
        true,
        record.generation,
      );
    }
    return record;
  }

  private assertProject(record: BrowserRecord, projectPath: string): void {
    if (!samePath(record.projectPath, normalizeRequiredPath(projectPath))) {
      throw new AgentBrowserFault(
        'PROJECT_MISMATCH',
        '智能体只能访问当前项目的开发浏览器。',
        false,
        record.generation,
      );
    }
  }

  private assertAvailable(): void {
    if (this.disposed) {
      throw new AgentBrowserFault('CLOSED', '开发浏览器模块已关闭。', false);
    }
  }

  private async closeInternal(expected?: BrowserRecord): Promise<void> {
    const record = expected ?? this.record;
    if (!record) {
      this.notifyEventWaiters();
      return;
    }
    if (expected && this.record !== expected) return;
    record.state = 'closing';
    this.removeListeners(record);
    this.record = null;
    const interrupted = new AgentBrowserFault(
      'CLOSED',
      '开发浏览器已关闭。',
      true,
      record.generation,
      'unknown',
    );
    for (const interrupt of record.interruptWaiters) interrupt(interrupted);
    record.interruptWaiters.clear();
    try {
      if (record.view.webContents.debugger.isAttached()) {
        record.view.webContents.debugger.detach();
      }
    } catch {
      // The renderer may already be gone.
    }
    try {
      record.view.setVisible(false);
    } catch {
      // Native view teardown is best effort during app shutdown.
    }
    this.adapter.unmount(record.view);
    this.adapter.destroy(record.view);
    record.childSessions.clear();
    record.ioHandles.clear();
    record.eventBuffer.clear();
    this.payloadStore.clear();
    this.notifyEventWaiters();
  }

  private addWebContentsListener(
    record: BrowserRecord,
    event: string,
    listener: PortListener,
  ): void {
    record.view.webContents.on(event, listener);
    record.webContentsListeners.push({ event, listener });
  }

  private addDebuggerListener(
    record: BrowserRecord,
    event: 'message' | 'detach',
    listener: PortListener,
  ): void {
    record.view.webContents.debugger.on(event, listener);
    record.debuggerListeners.push({ event, listener });
  }

  private removeWebContentsListener(
    record: BrowserRecord,
    event: string,
    listener: PortListener,
  ): void {
    record.view.webContents.removeListener(event, listener);
    const index = record.webContentsListeners.findIndex(
      (entry) => entry.event === event && entry.listener === listener,
    );
    if (index >= 0) record.webContentsListeners.splice(index, 1);
  }

  private removeListeners(record: BrowserRecord): void {
    for (const { event, listener } of record.webContentsListeners) {
      record.view.webContents.removeListener(event, listener);
    }
    for (const { event, listener } of record.debuggerListeners) {
      record.view.webContents.debugger.removeListener(event, listener);
    }
    record.webContentsListeners.length = 0;
    record.debuggerListeners.length = 0;
  }

  private serialize<T>(operation: () => Promise<T>): Promise<T> {
    const epoch = this.queueEpoch;
    const barrier = this.lifecycleBarrier;
    let resolveCaller: (value: T) => void;
    let rejectCaller: (reason: unknown) => void;
    let callerSettled = false;
    const caller = new Promise<T>((resolvePromise, rejectPromise) => {
      resolveCaller = resolvePromise;
      rejectCaller = rejectPromise;
    });
    const cancelCaller = (fault: AgentBrowserFault) => {
      if (callerSettled) return;
      callerSettled = true;
      rejectCaller(fault);
    };
    this.commandCancellers.add(cancelCaller);

    const execution = this.commandTail.then(async () => {
      try {
        await barrier;
        if (callerSettled) return;
        if (epoch !== this.queueEpoch) {
          throw new AgentBrowserFault(
            'CLOSED',
            '开发浏览器操作已被新的生命周期取代。',
            true,
            this.record?.generation,
            'unknown',
          );
        }
        const value = await operation();
        if (!callerSettled) {
          callerSettled = true;
          this.commandCancellers.delete(cancelCaller);
          resolveCaller(value);
        }
      } catch (error) {
        if (!callerSettled) {
          callerSettled = true;
          this.commandCancellers.delete(cancelCaller);
          rejectCaller(error);
        }
      }
    });
    this.commandTail = execution.then(
      () => undefined,
      () => undefined,
    );
    return caller;
  }

  private serializeWithTimeout<T>(
    operation: () => Promise<T>,
    timeoutMs: number,
  ): Promise<T> {
    const epoch = this.queueEpoch;
    const barrier = this.lifecycleBarrier;
    let resolveCaller: (value: T) => void;
    let rejectCaller: (reason: unknown) => void;
    let callerSettled = false;
    const generation = this.record?.generation;
    let timer: ReturnType<typeof setTimeout> | undefined;
    const caller = new Promise<T>((resolvePromise, rejectPromise) => {
      resolveCaller = resolvePromise;
      rejectCaller = rejectPromise;
    });
    const cancelCaller = (fault: AgentBrowserFault) => {
      if (callerSettled) return;
      callerSettled = true;
      if (timer) clearTimeout(timer);
      rejectCaller(fault);
    };
    this.commandCancellers.add(cancelCaller);
    timer = setTimeout(() => {
      if (callerSettled) return;
      callerSettled = true;
      this.commandCancellers.delete(cancelCaller);
      rejectCaller(new AgentBrowserFault(
        'CDP_TIMEOUT',
        `CDP 命令在 ${timeoutMs}ms 内未完成，执行结果未知。`,
        true,
        generation,
        'unknown',
      ));
      this.preemptCommands('CDP 命令超时，开发浏览器已关闭。');
      void this.closeInternal().catch(() => undefined);
    }, timeoutMs);

    const execution = this.commandTail.then(async () => {
      await barrier;
      if (callerSettled || epoch !== this.queueEpoch) return;
      try {
        const value = await operation();
        if (!callerSettled) {
          callerSettled = true;
          this.commandCancellers.delete(cancelCaller);
          if (timer) clearTimeout(timer);
          resolveCaller(value);
        }
      } catch (error) {
        if (!callerSettled) {
          callerSettled = true;
          this.commandCancellers.delete(cancelCaller);
          if (timer) clearTimeout(timer);
          rejectCaller(error);
        }
      }
    });
    this.commandTail = execution.then(
      () => undefined,
      () => undefined,
    );
    return caller;
  }

  private preemptCommands(message: string): void {
    this.queueEpoch += 1;
    this.commandTail = Promise.resolve();
    const fault = new AgentBrowserFault(
      'CLOSED',
      message,
      true,
      this.record?.generation,
      'unknown',
    );
    const cancellers = [...this.commandCancellers];
    this.commandCancellers.clear();
    for (const cancel of cancellers) cancel(fault);
  }

  private async runWhileActive<T>(
    record: BrowserRecord,
    operation: Promise<T>,
    timeoutMs: number,
  ): Promise<T> {
    if (record !== this.record) {
      throw new AgentBrowserFault(
        'CLOSED',
        '开发浏览器已关闭或切换。',
        true,
        record.generation,
        'unknown',
      );
    }

    let settled = false;
    let timer: ReturnType<typeof setTimeout> | undefined;
    let interrupt: ((fault: AgentBrowserFault) => void) | undefined;
    const result = new Promise<T>((resolvePromise, rejectPromise) => {
      interrupt = (fault) => {
        if (settled) return;
        settled = true;
        rejectPromise(fault);
      };
      record.interruptWaiters.add(interrupt);
      timer = setTimeout(() => {
        if (settled) return;
        settled = true;
        rejectPromise(new AgentBrowserFault(
          'CDP_TIMEOUT',
          `开发浏览器操作在 ${timeoutMs}ms 内未完成。`,
          true,
          record.generation,
          'unknown',
        ));
      }, timeoutMs);
      operation.then(
        (value) => {
          if (settled) return;
          settled = true;
          if (record !== this.record) {
            rejectPromise(new AgentBrowserFault(
              'CLOSED',
              '开发浏览器操作完成前页面已关闭或切换。',
              true,
              record.generation,
              'unknown',
            ));
            return;
          }
          resolvePromise(value);
        },
        (error: unknown) => {
          if (settled) return;
          settled = true;
          rejectPromise(error);
        },
      );
    });

    try {
      return await result;
    } finally {
      if (timer) clearTimeout(timer);
      if (interrupt) record.interruptWaiters.delete(interrupt);
    }
  }

  private async waitForEvent(waitMs: number, changed: () => boolean): Promise<void> {
    if (changed()) return;
    let wake: (() => void) | undefined;
    const eventPromise = new Promise<void>((resolvePromise) => {
      wake = resolvePromise;
      this.eventWaiters.add(resolvePromise);
    });
    if (changed()) wake?.();
    let timer: ReturnType<typeof setTimeout> | undefined;
    try {
      await Promise.race([
        eventPromise,
        new Promise<void>((resolvePromise) => {
          timer = setTimeout(resolvePromise, waitMs);
        }),
      ]);
    } finally {
      if (timer) clearTimeout(timer);
      if (wake) this.eventWaiters.delete(wake);
    }
  }

  private notifyEventWaiters(): void {
    const waiters = [...this.eventWaiters];
    this.eventWaiters.clear();
    for (const wake of waiters) wake();
  }
}

function normalizeRequiredPath(projectPath: string): string {
  if (!projectPath.trim()) {
    throw new AgentBrowserFault('INVALID_REQUEST', '项目目录不能为空。', false);
  }
  return resolve(projectPath);
}

function normalizePath(projectPath: string): string {
  const normalized = resolve(projectPath);
  return process.platform === 'win32' ? normalized.toLocaleLowerCase('en-US') : normalized;
}

function samePath(left: string, right: string): boolean {
  return normalizePath(left) === normalizePath(right);
}

function normalizeUrl(value: string): string {
  let url: URL;
  try {
    url = new URL(value);
  } catch {
    throw new AgentBrowserFault('INVALID_URL', '网页地址格式无效。', false);
  }
  if (url.protocol !== 'http:' && url.protocol !== 'https:') {
    throw new AgentBrowserFault(
      'INVALID_URL',
      '开发浏览器只允许打开 HTTP 或 HTTPS 地址。',
      false,
    );
  }
  return url.toString();
}

function normalizeBounds(bounds: AgentBrowserBounds): AgentBrowserBounds {
  const normalized = {
    x: Math.trunc(bounds.x),
    y: Math.trunc(bounds.y),
    width: Math.trunc(bounds.width),
    height: Math.trunc(bounds.height),
  };
  if (
    !Object.values(normalized).every(Number.isFinite)
    || normalized.width < 1
    || normalized.height < 1
  ) {
    throw new AgentBrowserFault(
      'VIEWPORT_NOT_READY',
      '开发浏览器显示区域无效。',
      true,
    );
  }
  return normalized;
}

function normalizeTimeout(value?: number): number {
  if (value === undefined) return DEFAULT_CDP_TIMEOUT_MS;
  if (!Number.isFinite(value) || value < 1) {
    throw new AgentBrowserFault('INVALID_REQUEST', 'CDP timeoutMs 无效。', false);
  }
  return Math.min(Math.trunc(value), MAX_CDP_TIMEOUT_MS);
}

function normalizeNonNegativeInteger(
  value: number | undefined,
  fallback: number,
  field: string,
): number {
  if (value === undefined) return fallback;
  if (!Number.isFinite(value) || value < 0) {
    throw new AgentBrowserFault('INVALID_REQUEST', `${field} 无效。`, false);
  }
  return Math.trunc(value);
}

function normalizeIntegerRange(
  value: number | undefined,
  fallback: number,
  min: number,
  max: number,
  field: string,
): number {
  const normalized = normalizeNonNegativeInteger(value, fallback, field);
  if (normalized < min) {
    throw new AgentBrowserFault('INVALID_REQUEST', `${field} 无效。`, false);
  }
  return Math.min(normalized, max);
}

function safeUrl(view: AgentBrowserViewPort, fallback: string): string {
  try {
    return view.webContents.getURL() || fallback;
  } catch {
    return fallback;
  }
}

function toFault(
  error: unknown,
  code: AgentBrowserErrorCode,
  fallbackMessage: string,
  retryable: boolean,
  generation?: number,
): AgentBrowserFault {
  if (error instanceof AgentBrowserFault) return error;
  return new AgentBrowserFault(
    code,
    errorMessage(error, fallbackMessage),
    retryable,
    generation,
  );
}

function errorMessage(error: unknown, fallback: string): string {
  return error instanceof Error && error.message ? error.message : fallback;
}

function isNavigationAbort(error: unknown): boolean {
  if (isRecord(error) && error.code === -3) return true;
  const message = error instanceof Error ? error.message : String(error ?? '');
  return message.includes('ERR_ABORTED');
}

function isRecord(value: unknown): value is Record<string, unknown> {
  return Boolean(value && typeof value === 'object' && !Array.isArray(value));
}

function collectStringFields(value: unknown, field: string, output: Set<string>): void {
  if (Array.isArray(value)) {
    for (const item of value) collectStringFields(item, field, output);
    return;
  }
  if (!isRecord(value)) return;
  for (const [key, nested] of Object.entries(value)) {
    if (key === field && typeof nested === 'string') output.add(nested);
    else collectStringFields(nested, field, output);
  }
}