import type { FastifyInstance } from 'fastify';
import { z } from 'zod';
import type { Sql } from '../db.js';
import type { Broker } from '@boocode/server/broker';
import type { WsFrame } from '@boocode/server/ws-frames';

const SendBody = z.object({
  content: z.string().min(1).max(64_000),
  chat_id: z.string().uuid(),
});

interface InferenceApi {
  enqueue: (sessionId: string, chatId: string, assistantId: string, user: string) => void;
  cancel: (sessionId: string, chatId: string) => Promise<boolean>;
  hasActive: (chatId: string) => boolean;
}

export function registerMessageRoutes(
  app: FastifyInstance,
  sql: Sql,
  broker: Broker,
  inference: InferenceApi,
): void {
  // POST /api/sessions/:sessionId/messages — send a user message + kick off inference
  app.post<{ Params: { sessionId: string } }>(
    '/api/sessions/:sessionId/messages',
    async (req, reply) => {
      const parsed = SendBody.safeParse(req.body);
      if (!parsed.success) {
        reply.code(400);
        return { error: 'invalid body', details: parsed.error.flatten() };
      }

      const sessionId = req.params.sessionId;
      const { content, chat_id: chatId } = parsed.data;

      // Validate session exists
      const sessionRows = await sql<{ id: string }[]>`
        SELECT id FROM sessions WHERE id = ${sessionId}
      `;
      if (sessionRows.length === 0) {
        reply.code(404);
        return { error: 'session not found' };
      }

      // Validate chat belongs to session and is open
      const chatRows = await sql<{ id: string; session_id: string }[]>`
        SELECT id, session_id FROM chats WHERE id = ${chatId} AND session_id = ${sessionId} AND status = 'open'
      `;
      if (chatRows.length === 0) {
        reply.code(404);
        return { error: 'chat not found or not open in this session' };
      }

      // Reject if inference is already running on this chat
      if (inference.hasActive(chatId)) {
        reply.code(409);
        return { error: 'inference already running on this chat' };
      }

      // Create user message + streaming assistant row in a transaction
      const result = await sql.begin(async (tx) => {
        const [userMsg] = await tx<{ id: string }[]>`
          INSERT INTO messages (session_id, chat_id, role, content, status, created_at)
          VALUES (${sessionId}, ${chatId}, 'user', ${content}, 'complete', clock_timestamp())
          RETURNING id
        `;
        const [assistantMsg] = await tx<{ id: string }[]>`
          INSERT INTO messages (session_id, chat_id, role, content, status, created_at)
          VALUES (${sessionId}, ${chatId}, 'assistant', '', 'streaming', clock_timestamp())
          RETURNING id
        `;
        await tx`UPDATE sessions SET updated_at = clock_timestamp() WHERE id = ${sessionId}`;
        await tx`UPDATE chats SET updated_at = clock_timestamp() WHERE id = ${chatId}`;
        return { user_message_id: userMsg!.id, assistant_message_id: assistantMsg!.id };
      });

      // Publish user message frames so WS subscribers see it immediately
      broker.publishFrame(sessionId, {
        type: 'message_started',
        message_id: result.user_message_id,
        chat_id: chatId,
        role: 'user',
      } as unknown as WsFrame);
      broker.publishFrame(sessionId, {
        type: 'delta',
        message_id: result.user_message_id,
        chat_id: chatId,
        content,
      } as unknown as WsFrame);
      broker.publishFrame(sessionId, {
        type: 'message_complete',
        message_id: result.user_message_id,
        chat_id: chatId,
      } as unknown as WsFrame);

      // Enqueue inference — the runner will stream assistant deltas via broker
      inference.enqueue(sessionId, chatId, result.assistant_message_id, 'default');

      reply.code(202);
      return result;
    },
  );

  // POST /api/sessions/:sessionId/stop — cancel active inference
  app.post<{ Params: { sessionId: string } }>(
    '/api/sessions/:sessionId/stop',
    async (req, reply) => {
      const sessionId = req.params.sessionId;

      // Find active chats in this session
      const chats = await sql<{ id: string }[]>`
        SELECT id FROM chats WHERE session_id = ${sessionId} AND status = 'open'
      `;
      let cancelled = false;
      for (const chat of chats) {
        if (inference.hasActive(chat.id)) {
          cancelled = await inference.cancel(sessionId, chat.id);
          break;
        }
      }

      return { cancelled };
    },
  );
}