import type { AgentBrowserService } from '../api/context';
import type { CodingConversationService } from './conversation-service';
import type { CodingConversationRuntime } from './contracts';
import { OPEN_WORK_PROMPT, type WorkPreviewResult } from '../../shared/coding-work-preview';
import { codingRecovery } from '../../shared/coding-recovery';
import type { AgentBrowserSnapshot } from '../../shared/agent-browser';

type Project = { id: string; path: string };
type Attempt = {
  requestId: string;
  conversationId?: string;
  submitted?: boolean;
  runId?: string;
  submittedAt?: number;
  result?: WorkPreviewResult;
};

/** Only probe a known loopback work address; never scan ports or follow redirects. */
export async function workPageResponds(address: string): Promise<boolean> {
  try {
    const url = new URL(address);
    if (!['http:', 'https:'].includes(url.protocol)
      || !['localhost', '127.0.0.1', '[::1]'].includes(url.hostname)
      || url.username || url.password) return false;
    const response = await fetch(url, { redirect: 'manual', signal: AbortSignal.timeout(2_000) });
    await response.body?.cancel();
    return response.ok;
  } catch {
    return false;
  }
}

export class CodingWorkPreviewService {
  private readonly attempts = new Map<string, Attempt>();
  private readonly flights = new Map<string, Promise<WorkPreviewResult>>();
  // Native views are disposable during background sleep; the running project
  // server and its verified address have a separate lifetime.
  private readonly pages = new Map<string, { path: string; url: string }>();

  constructor(private readonly deps: {
    browser: Pick<AgentBrowserService, 'getSnapshot' | 'open'>;
    conversations: Pick<CodingConversationService, 'getConversation' | 'listConversations' | 'createConversation' | 'getSnapshot' | 'acceptPrompt'>;
    runtime: Pick<CodingConversationRuntime, 'getDiagnostics'>;
    ensureActive(project: Project): Promise<void>;
    responds?(url: string): Promise<boolean>;
  }) {}

  remember(project: Project, snapshot: AgentBrowserSnapshot): void {
    if (snapshot.projectId !== project.id || !snapshot.url || !snapshot.browserId
      || snapshot.state !== 'attached' || snapshot.error) return;
    this.pages.delete(project.id);
    if (this.pages.size >= 100) this.pages.delete(this.pages.keys().next().value!);
    this.pages.set(project.id, { path: project.path, url: snapshot.url });
    this.attempts.delete(project.id);
    // A successful manual/Agent open supersedes a slow older startup check.
    this.flights.delete(project.id);
  }

  async ensure(project: Project, requestId: string, conversationId?: string): Promise<WorkPreviewResult> {
    await this.deps.ensureActive(project);
    // Serialize browser checks as well as prompt submission for each project.
    const existing = this.flights.get(project.id);
    if (existing) return existing;
    const flight = this.check(project, requestId, conversationId);
    this.flights.set(project.id, flight);
    try { return await flight; }
    finally { if (this.flights.get(project.id) === flight) this.flights.delete(project.id); }
  }

  private async check(project: Project, requestId: string, conversationId?: string): Promise<WorkPreviewResult> {
    const { browser, conversations } = this.deps;
    const snapshot = await browser.getSnapshot(project.path);
    const responds = this.deps.responds ?? workPageResponds;
    const remembered = this.pages.get(project.id);
    const address = snapshot.projectId === project.id && snapshot.url
      ? snapshot.url
      : remembered?.path === project.path ? remembered.url : undefined;
    if (address && await responds(address)) {
      await this.deps.ensureActive(project);
      const ready = snapshot.projectId === project.id && snapshot.url === address
        && snapshot.browserId && snapshot.state === 'attached' && !snapshot.error
        ? snapshot
        : await browser.open({ projectId: project.id, projectPath: project.path, url: address, visible: false });
      await this.deps.ensureActive(project);
      this.remember(project, ready);
      return { status: 'ready', browser: ready };
    }
    if (this.pages.has(project.id) && this.pages.get(project.id) !== remembered) return this.check(project, requestId, conversationId);
    this.pages.delete(project.id);
    await this.deps.ensureActive(project);
    let attempt = this.attempts.get(project.id);
    if (attempt?.submitted && attempt.conversationId) {
      const current = await conversations.getSnapshot(attempt.conversationId);
      if (this.pages.has(project.id)) return this.check(project, requestId, conversationId);
      if (!['idle', 'error'].includes(current.run.status)) {
        return { status: 'starting', conversation: await conversations.getConversation(attempt.conversationId) };
      }
      if (attempt.runId && current.run.runId !== attempt.runId && Date.now() - attempt.submittedAt! < 15_000) {
        return { status: 'starting', conversation: await conversations.getConversation(attempt.conversationId) };
      }
      // The accepted action settled without opening a reachable work page.
      const errorCode = current.run.error?.code;
      attempt.result ??= { status: 'failed', errorCode, message: codingRecovery(errorCode, true).message };
    }
    if (attempt?.result && attempt.requestId === requestId) return attempt.result;
    if (!attempt || attempt.result || attempt.requestId !== requestId) {
      attempt = { requestId, conversationId };
      // Keep only a bounded number of inactive project attempts.
      if (this.attempts.size >= 100) this.attempts.delete(this.attempts.keys().next().value!);
      this.attempts.set(project.id, attempt);
    }

    const list = await conversations.listConversations(project.id);
    const projectIds = new Set(list.map(({ id }) => id));
    const busy = this.deps.runtime.getDiagnostics().workers.some((worker) => (
      projectIds.has(worker.conversationId) && ['starting', 'queued', 'running'].includes(worker.stage)
    ));
    if (busy) return { status: 'waiting' };
    let conversation = attempt.conversationId
      ? await conversations.getConversation(attempt.conversationId)
      : list.find((item) => !item.archivedAt);
    await this.deps.ensureActive(project);
    conversation ??= await conversations.createConversation({ projectId: project.id, title: '新对话' });
    attempt.conversationId = conversation.id;
    const current = await conversations.getSnapshot(conversation.id);
    if (this.pages.has(project.id)) return this.check(project, requestId, conversationId);
    if (!['idle', 'error'].includes(current.run.status)) return { status: 'waiting', conversation };
    await this.deps.ensureActive(project);
    // Mark before dispatch: uncertain acceptance must never cause automatic resubmission.
    attempt.submitted = true;
    attempt.submittedAt = Date.now();
    try {
      const acceptance = await conversations.acceptPrompt({
        conversationId: conversation.id,
        clientRequestId: `work-preview-${attempt.requestId}`,
        mode: 'prompt',
        text: OPEN_WORK_PROMPT,
      });
      attempt.runId = acceptance.runId;
    } catch (error) {
      const errorCode = error && typeof error === 'object' && 'code' in error && typeof error.code === 'string'
        ? error.code : 'CODING_REQUEST_UNCERTAIN';
      attempt.result = { status: 'failed', conversation, errorCode, message: codingRecovery(errorCode, true).message };
      return attempt.result;
    }
    return { status: 'starting', conversation };
  }
}