import Fastify, { type FastifyInstance } from 'fastify';
import { WebSocketServer, type WebSocket } from 'ws';
import { Store, StoreError, type ActiveRun, type PatchProjectInput, type PatchTaskInput } from '../store/index.js';
import type { Complexity } from '../model/complexity.js';
import { isComplexity } from '../model/complexity.js';
import type { TaskStatus } from '../model/status.js';
import type { Project, Autonomy } from '../model/types.js';
import { syncProject, hasTodoJson } from '../sync/todo-sync.js';
import { resolvedExecutorModels } from '../executor/models.js';
import { mergeBranch } from '../executor/merge.js';
import { git, removeWorktree } from '../executor/worktree.js';
import { resolveLogo, LOGO_MIME } from './logo.js';
import { createReadStream } from 'node:fs';
import { createUsageFetcher, type UsageInfo } from '../daemon/usage.js';

/** Project 出参：附加 hasTodoJson（<repoPath>/todo/todo.json 是否存在，每次序列化时算） */
function projectOut(p: Project): Project & { hasTodoJson: boolean } {
  return { ...p, hasTodoJson: hasTodoJson(p.repoPath) };
}

export interface ApiOptions {
  store: Store;
  logger?: boolean;
  /** Claude 订阅额度查询（测试注入；默认直连 OAuth usage API，60s 缓存） */
  getUsage?: () => Promise<UsageInfo | null>;
}

/**
 * REST + WebSocket API。所有写操作走 Store（带状态机守卫 / 审批闸）。
 * Store 的事件经 subscribe 广播到所有 WS 客户端，驱动看板实时刷新。
 */
export function buildServer(opts: ApiOptions): FastifyInstance {
  const { store } = opts;
  const app = Fastify({ logger: opts.logger ?? false });

  // Store 错误 → 400（业务校验），其余 → 500
  app.setErrorHandler((err, _req, reply) => {
    if (err instanceof StoreError) return reply.code(400).send({ error: err.message });
    app.log.error(err);
    return reply.code(500).send({ error: err.message ?? 'internal error' });
  });

  // ---------- Projects ----------
  app.get('/api/projects', () => store.listProjects().map(projectOut));

  app.post('/api/projects', (req) => {
    const b = req.body as Record<string, unknown>;
    if (!b?.name || !b?.repoPath) throw new StoreError('name 与 repoPath 必填');
    return projectOut(store.createProject({
      name: String(b.name), repoPath: String(b.repoPath),
      defaultBranch: b.defaultBranch ? String(b.defaultBranch) : undefined,
      verifyCmd: b.verifyCmd === undefined ? undefined : (b.verifyCmd === null ? null : String(b.verifyCmd)),
      autonomy: b.autonomy as never, model: b.model === undefined ? undefined : (b.model === null ? null : String(b.model)),
      concurrency: b.concurrency === undefined ? undefined : Number(b.concurrency),
      maxRetries: b.maxRetries === undefined ? undefined : Number(b.maxRetries),
      timeoutMs: b.timeoutMs === undefined ? undefined : Number(b.timeoutMs),
    }));
  });

  app.get('/api/projects/:id', (req) => {
    const { id } = req.params as { id: string };
    const p = store.getProject(id);
    if (!p) throw new StoreError(`项目不存在: ${id}`);
    return projectOut(p);
  });

  // 部分更新项目配置（校验在 Store.patchProject）
  app.patch('/api/projects/:id', (req) => {
    const { id } = req.params as { id: string };
    const b = (req.body ?? {}) as Record<string, unknown>;
    const patch: PatchProjectInput = {};
    if (b.autonomy !== undefined) patch.autonomy = b.autonomy as Autonomy;
    if (b.concurrency !== undefined) patch.concurrency = Number(b.concurrency);
    if (b.status !== undefined) patch.status = b.status as 'active' | 'paused';
    if (b.verifyCmd !== undefined) patch.verifyCmd = b.verifyCmd === null ? null : String(b.verifyCmd);
    if (b.model !== undefined) patch.model = b.model === null ? null : String(b.model);
    if (b.logo !== undefined) patch.logo = b.logo === null || b.logo === '' ? null : String(b.logo);
    if (b.maxRetries !== undefined) patch.maxRetries = Number(b.maxRetries);
    if (b.timeoutMs !== undefined) patch.timeoutMs = Number(b.timeoutMs);
    return projectOut(store.patchProject(id, patch));
  });

  // 项目重排序（侧栏拖动）：body { order: [projectId, ...] }
  app.post('/api/projects/reorder', (req) => {
    const b = (req.body ?? {}) as { order?: unknown };
    if (!Array.isArray(b.order)) throw new StoreError('order 必须是项目 id 数组');
    return store.reorderProjects(b.order.map(String)).map(projectOut);
  });

  // 项目 logo：仓库内文件 → 流式返回；外链头像 → 302；无 → 404（前端用首字母徽章兜底）
  app.get('/api/projects/:id/logo', async (req, reply) => {
    const { id } = req.params as { id: string };
    const p = store.getProject(id);
    if (!p) return reply.code(404).send();
    const r = await resolveLogo(p);
    if (!r) return reply.code(404).send();
    if (r.type === 'redirect') return reply.redirect(r.url);
    const ext = r.path.split('.').pop()?.toLowerCase() ?? '';
    reply.header('cache-control', 'no-cache').type(LOGO_MIME[ext] ?? 'application/octet-stream');
    return reply.send(createReadStream(r.path));
  });

  // 单向同步 <repoPath>/todo/todo.json → maestro（导入=首次同步，幂等）
  app.post('/api/projects/:id/sync', (req) => {
    const { id } = req.params as { id: string };
    return syncProject(store, id);
  });

  // ---------- Agents（每项目一条；active 来自 runs 表 status='started'，执行器 Phase 2 前通常为空） ----------
  // usage = Claude 订阅额度（执行 agent 烧的就是这个池子）；查询失败 → null，前端降级显示
  const getUsage = opts.getUsage ?? createUsageFetcher({ log: app.log });
  app.get('/api/agents', async () => {
    const runs = store.activeRuns();
    const byProject = new Map<string, ActiveRun[]>();
    for (const r of runs) {
      const list = byProject.get(r.projectId) ?? [];
      list.push(r);
      byProject.set(r.projectId, list);
    }
    const agents = store.listProjects().map((p) => ({
      projectId: p.id,
      projectName: p.name,
      autonomy: p.autonomy,
      concurrency: p.concurrency,
      status: p.status,
      scheduling: 'score',                       // 调度模式：score 优先（自身分+链条惯性+解锁加权）
      models: resolvedExecutorModels(p),         // 各复杂度实际使用的执行模型
      active: (byProject.get(p.id) ?? []).map((r) => ({
        runId: r.runId, taskId: r.taskId, taskTitle: r.taskTitle, kind: r.kind, startedAt: r.startedAt,
      })),
    }));
    return { totalActive: runs.length, agents, usage: await getUsage() };
  });

  // Claude 订阅额度（5 小时 + 周窗口）单独透传；查询失败 → null（前端/CLI 降级显示）
  app.get('/api/usage', async () => await getUsage());

  app.get('/api/projects/:id/tasks', (req) => {
    const { id } = req.params as { id: string };
    return store.listTasks(id);
  });

  app.get('/api/projects/:id/events', (req) => {
    const { id } = req.params as { id: string };
    return store.listEvents(id);
  });

  app.get('/api/projects/:id/next', (req) => {
    const { id } = req.params as { id: string };
    return store.nextExecutable(id) ?? { next: null };
  });

  // ---------- Tasks ----------
  app.post('/api/projects/:id/tasks', (req) => {
    const { id } = req.params as { id: string };
    const b = req.body as Record<string, unknown>;
    if (!b?.title) throw new StoreError('title 必填');
    if (!isComplexity(b.complexity)) throw new StoreError('complexity 必须是 hard|medium|easy');
    return store.createTask({
      projectId: id, title: String(b.title), complexity: b.complexity as Complexity,
      parentId: b.parentId ? String(b.parentId) : null,
      priority: b.priority === undefined ? undefined : Number(b.priority),
      deps: Array.isArray(b.deps) ? (b.deps as string[]) : undefined,
    });
  });

  app.get('/api/tasks/:id', (req) => {
    const { id } = req.params as { id: string };
    const t = store.getTask(id);
    if (!t) throw new StoreError(`任务不存在: ${id}`);
    return t;
  });

  // 部分更新任务（title/priority/complexity；complexity 重置逻辑在 Store.patchTask）
  app.patch('/api/tasks/:id', (req) => {
    const { id } = req.params as { id: string };
    const b = (req.body ?? {}) as Record<string, unknown>;
    const patch: PatchTaskInput = {};
    if (b.title !== undefined) patch.title = String(b.title);
    if (b.priority !== undefined) {
      const n = Number(b.priority);
      if (!Number.isFinite(n)) throw new StoreError('priority 必须是数字');
      patch.priority = n;
    }
    if (b.complexity !== undefined) {
      if (!isComplexity(b.complexity)) throw new StoreError('complexity 必须是 hard|medium|easy');
      patch.complexity = b.complexity;
    }
    return store.patchTask(id, patch);
  });

  app.get('/api/tasks/:id/children', (req) => {
    const { id } = req.params as { id: string };
    return store.childrenOf(id);
  });

  app.get('/api/tasks/:id/runs', (req) => {
    const { id } = req.params as { id: string };
    return store.listRuns(id);
  });

  // 单任务全量事件（升序）：归档详情的状态流转时间线
  app.get('/api/tasks/:id/events', (req) => {
    const { id } = req.params as { id: string };
    return store.listTaskEvents(id);
  });

  app.post('/api/tasks/:id/plan', (req) => {
    const { id } = req.params as { id: string };
    const b = req.body as { plan?: string };
    if (!b?.plan) throw new StoreError('plan 必填');
    return store.setPlan(id, b.plan);
  });

  app.post('/api/tasks/:id/spec', (req) => {
    const { id } = req.params as { id: string };
    const b = req.body as { spec?: string };
    if (!b?.spec) throw new StoreError('spec 必填');
    return store.setSpec(id, b.spec);
  });

  app.post('/api/tasks/:id/operations', (req) => {
    const { id } = req.params as { id: string };
    const b = req.body as { operations?: string };
    if (!b?.operations) throw new StoreError('operations 必填');
    return store.setOperations(id, b.operations);
  });

  app.post('/api/tasks/:id/transition', (req) => {
    const { id } = req.params as { id: string };
    const b = req.body as { to?: string; meta?: Record<string, unknown> };
    if (!b?.to) throw new StoreError('to 必填');
    return store.transition(id, b.to as TaskStatus, b.meta ?? {});
  });

  // 取消任务（transition → cancelled；状态机已守卫合法流转）
  app.post('/api/tasks/:id/cancel', (req) => {
    const { id } = req.params as { id: string };
    return store.transition(id, 'cancelled', { by: 'user' });
  });

  // 彻底删除任务及其子孙（不可恢复，cascade）
  app.delete('/api/tasks/:id', (req) => {
    const { id } = req.params as { id: string };
    return store.deleteTask(id);
  });

  // needs_attention 任务一键重投：重置重试基线 + 转 queued，让编排器下一轮重新领取
  app.post('/api/tasks/:id/requeue', (req) => {
    const { id } = req.params as { id: string };
    return store.requeueTask(id);
  });

  // 审批闸：accept / reject（reject 必带 reason）
  // exec 闸的 accept = 通过并合并（PR 闭环）：先 merge 再 decide；merge 失败 → 400，任务保留在审核闸。
  app.post('/api/tasks/:id/decide', async (req) => {
    const { id } = req.params as { id: string };
    const b = req.body as { action?: string; actor?: string; reason?: string | null; merge?: boolean };
    if (b?.action !== 'accept' && b?.action !== 'reject') throw new StoreError('action 必须是 accept|reject');

    const task = store.getTask(id);
    // merge:false = 仅通过不合并（逃生口：如目标分支正被用户工作区检出导致自动合并不可用）
    if (task && task.status === 'exec_review' && b.action === 'accept' && task.result?.branch && b.merge !== false) {
      const project = store.getProject(task.projectId);
      if (!project) throw new StoreError(`项目不存在: ${task.projectId}`);
      const { branch, worktree } = task.result;
      const mr = await mergeBranch(project.repoPath, branch, project.defaultBranch, task.id);
      if (!mr.ok) {
        // 自动合并失败（多为冲突）→ 建/复用最高优先级补救任务来完成合并，原任务留在审核闸
        const rem = store.ensureMergeRemediationTask(task.id, {
          branch, targetBranch: project.defaultBranch, conflictError: mr.error ?? '未知冲突',
        });
        throw new StoreError(`合并失败：${mr.error}（原任务保留在审核闸；已建最高优先级补救任务 ${rem.id}「${rem.title}」来完成合并）`);
      }

      store.decide(id, 'accept', b.actor ?? 'user', b.reason ?? null);
      // 合并产物记录：复用 prUrl 字段写 merged:<mergeCommit>
      store.setResult(id, { ...task.result, prUrl: `merged:${mr.mergeCommit}` });
      // 异步回收：执行 worktree + 已合并的任务分支（失败只记日志，不影响响应）
      void (async () => {
        try {
          if (worktree) await removeWorktree(project.repoPath, worktree);
        } catch (e) {
          app.log.error(`任务 ${id} 合并后清理 worktree 失败（不影响结果）：${(e as Error).message}`);
        }
        try {
          await git(project.repoPath, ['branch', '-d', branch]);
        } catch (e) {
          app.log.error(`任务 ${id} 合并后删除分支 ${branch} 失败（不影响结果）：${(e as Error).message}`);
        }
      })();
      return store.getTask(id);
    }

    // 非 exec 闸（或 reject / 无分支结果）：行为完全不变
    return store.decide(id, b.action, b.actor ?? 'user', b.reason ?? null);
  });

  // ---------- Approvals ----------
  app.get('/api/approvals', (req) => {
    const q = req.query as { projectId?: string };
    return store.pendingApprovals(q.projectId);
  });

  return app;
}

/** 在 Fastify 的底层 http server 上挂 WebSocket，把 Store 事件广播给所有客户端。 */
export function attachWebSocket(app: FastifyInstance, store: Store): WebSocketServer {
  const wss = new WebSocketServer({ server: app.server, path: '/ws' });
  const clients = new Set<WebSocket>();

  wss.on('connection', (ws) => {
    clients.add(ws);
    ws.on('close', () => clients.delete(ws));
    ws.on('error', () => clients.delete(ws));
  });

  store.subscribe((evt) => {
    const msg = JSON.stringify(evt);
    for (const ws of clients) {
      if (ws.readyState === ws.OPEN) ws.send(msg);
    }
  });

  return wss;
}