import { FastifyInstance, FastifyReply } from 'fastify';
import { createTask, listTasks, getTask, claimTask, doneTask, reviewTask, cancelTask, reopenTask, assignTask } from '../core/services/taskService.js';
import { getTaskActivity } from '../core/services/activityService.js';
import { createHandoff, listHandoffs, getHandoff } from '../core/services/handoffService.js';
import { createDecision, listDecisions } from '../core/services/decisionService.js';
import { addMemory, searchMemory, listMemory } from '../core/services/memoryService.js';
import { getStatus, updateStatus } from '../core/services/statusService.js';
import { autoDelegate, suggestDelegation } from '../core/services/delegateService.js';
import { loadConfig } from '../core/config.js';
import { renderBoardHtml } from './board.js';
import { renderTeamHtml } from './team.js';
import { eventBus, emitChange } from './events.js';
import type { AgentHubEvent } from './events.js';
import type { Task, Handoff, Decision, Memory } from '../core/schema.js';

function notFound(reply: FastifyReply, resource: string) {
  return reply.status(404).send({ error: `${resource} not found` });
}

function badRequest(reply: FastifyReply, message: string) {
  return reply.status(400).send({ error: message });
}

export async function registerRoutes(app: FastifyInstance, cwd: string): Promise<void> {
  // Static, self-contained Trello-like board. Polls /tasks, /handoffs and
  // /decisions on the same origin; no build step, no deps. Cached once — the
  // markup is constant, only the data it fetches changes.
  const boardHtml = renderBoardHtml(loadConfig(cwd).projectName);
  app.get('/board', async (_request, reply) => reply.type('text/html; charset=utf-8').send(boardHtml));

  // Team hierarchy page: roles tree with per-agent free/busy state.
  app.get('/team', async (_request, reply) => {
    const teamHtml = renderTeamHtml(cwd);
    return reply.type('text/html; charset=utf-8').send(teamHtml);
  });

  // ─── Server-Sent Events ──────────────────────────────────────────────────
  // GET /events?role=<role>
  //
  // Keeps the connection open and streams JSON-encoded AgentHubEvent objects
  // as SSE data lines. Sends a keepalive comment (": \n\n") every 25 s so
  // proxies and clients detect the connection is still alive.
  //
  // Optional ?role= filter: tasks whose role doesn't match are dropped
  // server-side. All handoff / decision / memory events are always forwarded.
  //
  // Both REST mutations and direct local-CLI writes emit events: REST routes
  // publish via emitChange(), and the filesystem watcher (fsWatch.ts) observes
  // the entity directories and emits for any other write. A shared dedup cache
  // (events.ts) ensures each change is delivered exactly once.
  app.get('/events', async (request, reply) => {
    const { role } = request.query as { role?: string };

    // Take full control of the raw response so Fastify doesn't interfere.
    reply.hijack();

    const raw = reply.raw;
    raw.writeHead(200, {
      'Content-Type': 'text/event-stream',
      'Cache-Control': 'no-cache',
      Connection: 'keep-alive',
    });
    raw.flushHeaders();

    const listener = (event: AgentHubEvent) => {
      // Server-side role filter: skip tasks that belong to a different role.
      // Handoffs, decisions and memory always pass through.
      if (role && event.type === 'task' && event.role !== undefined && event.role !== role) {
        return;
      }
      raw.write(`data: ${JSON.stringify(event)}\n\n`);
    };

    eventBus.on('change', listener);

    const keepAliveTimer = setInterval(() => {
      raw.write(':\n\n');
    }, 25_000);

    // Clean up when the client disconnects (or the server closes).
    request.raw.on('close', () => {
      clearInterval(keepAliveTimer);
      eventBus.off('change', listener);
    });
  });

  // ─── Presence ──────────────────────────────────────────────────────────────
  // POST /announce { agent, role?, action? } — an agent reports in on connect.
  // Ephemeral: broadcast to SSE subscribers only, nothing is written to disk.
  app.post('/announce', async (request, reply) => {
    const { agent, role, action } = request.body as { agent?: string; role?: string; action?: string };
    if (!agent) return badRequest(reply, 'agent is required');
    const ev: AgentHubEvent = {
      type: 'agent',
      action: action === 'left' ? 'left' : 'joined',
      id: agent,
      role,
    };
    eventBus.publish(ev);
    return { ok: true, agent, action: ev.action };
  });

  // ─── Status ──────────────────────────────────────────────────────────────
  app.get('/status', async () => ({ body: getStatus(cwd) }));
  app.post('/status/update', async () => ({ body: updateStatus(cwd) }));

  // ─── Tasks ───────────────────────────────────────────────────────────────
  app.get('/tasks', async (request) => {
    const { status, role } = request.query as { status?: string; role?: string };
    return listTasks(cwd, { status, role });
  });

  app.post('/tasks', async (request, reply) => {
    let task: Task;
    try {
      task = createTask(cwd, request.body as Partial<Task>);
    } catch (err) {
      return badRequest(reply, err instanceof Error ? err.message : 'Invalid task');
    }
    emitChange(
      {
        type: 'task',
        action: 'created',
        id: task.id,
        title: task.title,
        status: task.status,
        role: task.role,
        assignedTo: task.assignedTo,
      },
      task.updatedAt,
    );
    return task;
  });

  app.get('/tasks/:id', async (request, reply) => {
    const { id } = request.params as { id: string };
    try {
      const { task, body } = getTask(cwd, id);
      return { task, body };
    } catch {
      return notFound(reply, 'Task');
    }
  });

  app.get('/tasks/:id/activity', async (request, reply) => {
    const { id } = request.params as { id: string };
    try {
      return getTaskActivity(cwd, id);
    } catch {
      return notFound(reply, 'Task');
    }
  });

  app.patch('/tasks/:id', async (request, reply) => {
    const { id } = request.params as { id: string };
    const patch = request.body as Partial<Task>;

    // Assign without claiming: address an open task to an agent (no status
    // change). Fires task/updated so a waiting `agenthub work` auto-claims it.
    if (patch.assignedTo !== undefined && patch.status === undefined) {
      const assigned = assignTask(cwd, id, patch.assignedTo);
      emitChange(
        {
          type: 'task',
          action: 'updated',
          id: assigned.id,
          title: assigned.title,
          status: assigned.status,
          role: assigned.role,
          assignedTo: assigned.assignedTo,
        },
        assigned.updatedAt,
      );
      return assigned;
    }

    let task: Task;
    switch (patch.status) {
      case 'in_progress':
        if (!patch.assignedTo) return badRequest(reply, 'assignedTo is required to claim a task (in_progress)');
        task = claimTask(cwd, id, patch.assignedTo);
        break;
      case 'done':
        task = doneTask(cwd, id, {
          doneBy: patch.doneBy as string | undefined,
          doneTokens: patch.doneTokens as number | undefined,
          doneDuration: patch.doneDuration as number | undefined,
        });
        break;
      case 'review':
        task = reviewTask(cwd, id);
        break;
      case 'cancelled':
        task = cancelTask(cwd, id);
        break;
      case 'open':
        task = reopenTask(cwd, id);
        break;
      default:
        return badRequest(reply, 'Unsupported patch: status must be one of open, in_progress, review, done, cancelled');
    }

    emitChange(
      {
        type: 'task',
        action: 'updated',
        id: task.id,
        title: task.title,
        status: task.status,
        role: task.role,
        assignedTo: task.assignedTo,
      },
      task.updatedAt,
    );
    return task;
  });

  // ─── Handoffs ────────────────────────────────────────────────────────────
  app.get('/handoffs', async () => listHandoffs(cwd));
  app.post('/handoffs', async (request, reply) => {
    let handoff: Handoff;
    try {
      handoff = createHandoff(cwd, request.body as Partial<Handoff>);
    } catch (err) {
      return badRequest(reply, err instanceof Error ? err.message : 'Invalid handoff');
    }
    emitChange(
      {
        type: 'handoff',
        action: 'created',
        id: handoff.id,
        title: handoff.summary,
        role: handoff.toRole,
        assignedTo: handoff.toAgent,
      },
      handoff.createdAt,
    );
    return handoff;
  });
  app.get('/handoffs/:id', async (request, reply) => {
    const { id } = request.params as { id: string };
    try {
      const { handoff, body } = getHandoff(cwd, id);
      return { handoff, body };
    } catch {
      return notFound(reply, 'Handoff');
    }
  });

  // ─── Decisions ───────────────────────────────────────────────────────────
  app.get('/decisions', async () => listDecisions(cwd));
  app.post('/decisions', async (request, reply) => {
    let decision: Decision;
    try {
      decision = createDecision(cwd, request.body as Partial<Decision>);
    } catch (err) {
      return badRequest(reply, err instanceof Error ? err.message : 'Invalid decision');
    }
    emitChange(
      {
        type: 'decision',
        action: 'created',
        id: decision.id,
        title: decision.title,
      },
      decision.updatedAt,
    );
    return decision;
  });

  // ─── Memory ──────────────────────────────────────────────────────────────
  app.get('/memory', async () => listMemory(cwd));
  app.post('/memory', async (request, reply) => {
    let memory: Memory;
    try {
      memory = addMemory(cwd, request.body as Partial<Memory>);
    } catch (err) {
      return badRequest(reply, err instanceof Error ? err.message : 'Invalid memory');
    }
    emitChange(
      {
        type: 'memory',
        action: 'created',
        id: memory.id,
        title: memory.title,
      },
      memory.updatedAt,
    );
    return memory;
  });
  app.get('/memory/search', async (request) => {
    const { q } = request.query as { q: string };
    return searchMemory(cwd, q ?? '');
  });

  // ─── Delegate ────────────────────────────────────────────────────────────
  app.post('/delegate', async (request) => {
    const { auto } = request.query as { auto?: string };
    const config = loadConfig(cwd);
    const suggestion = suggestDelegation(cwd);
    if (!suggestion) return { suggestion: null };
    const shouldAuto = auto === 'true' || config.delegationMode === 'auto';
    if (shouldAuto) {
      const handoff = autoDelegate(cwd);
      return { suggestion, handoff };
    }
    return { suggestion };
  });
}