import { Router } from 'express';
import { z } from 'zod';
import { validate } from '../validate.js';
import { asyncWrap } from '../errors.js';
import * as conversations from '../../db/repos/conversations.js';
import * as messages from '../../db/repos/messages.js';
import * as agents from '../../db/repos/agents.js';
import { companionRegistry } from '../../ai/agent/tools/index.js';
import { runTurn } from '../../ai/agent/runtime.js';
import { makeCallModel, getAnthropicClient, DEFAULT_MODEL } from '../../ai/anthropic.js';

const COMPANION_SLUG = 'companion';

const SYSTEM = `You are the Void companion — a concise, helpful assistant embedded in a personal knowledge system.
Ground answers in the Void's content: call the context tool to see what the owner is looking at, and search/read before answering factual questions.
When the owner asks you to change something, use propose_change — it creates a draft they approve; you cannot apply changes directly. Be brief.`;

async function resolveConversation(space_id) {
  const agent = await agents.getBySlug(COMPANION_SLUG);
  const convo = await conversations.findOrCreateForSpace(space_id, agent.id, { kind: 'user', id: null });
  return { agent, convo };
}

function toAnthropicHistory(rows) {
  return rows
    .filter(m => m.role === 'user' || m.role === 'assistant')
    .map(m => ({ role: m.role, content: m.body }));
}

export const spacesScopedRouter = Router({ mergeParams: true });

spacesScopedRouter.get('/', asyncWrap(async (req, res) => {
  const { agent, convo } = await resolveConversation(req.params.space_id);
  const rows = await messages.listByConversation(convo.id);
  res.json({
    conversation_id: convo.id,
    agent: { id: agent.id, slug: agent.slug, name: agent.name },
    messages: rows
  });
}));

const turnSchema = z.object({
  text: z.string().min(1),
  view: z.object({ entityType: z.string(), entityId: z.string() }).partial().optional()
});

spacesScopedRouter.post('/turn',
  validate({ body: turnSchema }),
  asyncWrap(async (req, res) => {
    const { agent, convo } = await resolveConversation(req.params.space_id);
    const { text, view } = req.body;

    await messages.append(convo.id, { role: 'user', body: text });

    res.writeHead(200, {
      'Content-Type': 'text/event-stream',
      'Cache-Control': 'no-cache',
      Connection: 'keep-alive'
    });
    const send = (event, data) => res.write(`event: ${event}\ndata: ${JSON.stringify(data)}\n\n`);

    const callModel = req.app.locals.callModel
      || makeCallModel({ client: getAnthropicClient(), model: agent.model || DEFAULT_MODEL });

    const history = toAnthropicHistory(await messages.listByConversation(convo.id));

    let result;
    try {
      result = await runTurn({
        callModel,
        registry: companionRegistry,
        system: SYSTEM,
        messages: history,
        ctx: {
          agent: { kind: 'agent', id: agent.id, capabilities: agent.capabilities, scopes: agent.scopes },
          space_id: req.params.space_id,
          view: view ?? null,
          actor: req.actor
        },
        onEvent: (e) => send(e.type, e)
      });
    } catch (e) {
      send('error', { message: String(e?.message || e) });
      return res.end();
    }

    const assistant = await messages.append(convo.id, {
      role: 'assistant', body: result.text, agent_id: agent.id,
      metadata: { tool_trace: result.toolTrace, draft_ids: result.draftIds, usage: result.usage }
    });

    send('done', { assistant_message_id: assistant.id, draft_ids: result.draftIds, usage: result.usage });
    res.end();
  })
);