const express = require('express');
const db = require('../db');
const { streamCompletion } = require('../lib/llm');
const router = express.Router();

// GET /api/models — list all
router.get('/', (req, res) => {
  try {
    const rows = db.prepare('SELECT * FROM models ORDER BY id').all();
    res.json(rows);
  } catch (err) {
    console.error('[models] list error:', err.message);
    res.status(500).json({ error: err.message });
  }
});

// POST /api/models — create
router.post('/', (req, res) => {
  const { name, api_base, api_key, provider, is_default_main, is_default_fork, is_default_exam } = req.body;
  if (!name || !api_base || !provider) {
    return res.status(400).json({ error: 'name, api_base, and provider are required' });
  }

  try {
    const info = db.prepare(`
      INSERT INTO models (name, api_base, api_key, provider, is_default_main, is_default_fork, is_default_exam)
      VALUES (?, ?, ?, ?, ?, ?, ?)
    `).run(
      name,
      api_base,
      api_key || '',
      provider,
      is_default_main ? 1 : 0,
      is_default_fork ? 1 : 0,
      is_default_exam ? 1 : 0
    );

    // If setting a default flag, unset others for that role
    const newId = info.lastInsertRowid;
    if (is_default_main) unsetOtherDefaults(newId, 'is_default_main');
    if (is_default_fork) unsetOtherDefaults(newId, 'is_default_fork');
    if (is_default_exam) unsetOtherDefaults(newId, 'is_default_exam');

    const row = db.prepare('SELECT * FROM models WHERE id = ?').get(newId);
    res.status(201).json(row);
  } catch (err) {
    console.error('[models] create error:', err.message);
    res.status(500).json({ error: err.message });
  }
});

// PUT /api/models/:id — update
router.put('/:id', (req, res) => {
  const id = parseInt(req.params.id, 10);
  if (Number.isNaN(id)) {
    return res.status(400).json({ error: 'Invalid model id' });
  }

  const { name, api_base, api_key, provider, is_default_main, is_default_fork, is_default_exam } = req.body;

  try {
    const existing = db.prepare('SELECT * FROM models WHERE id = ?').get(id);
    if (!existing) {
      return res.status(404).json({ error: 'Model not found' });
    }

    db.prepare(`
      UPDATE models SET
        name = COALESCE(?, name),
        api_base = COALESCE(?, api_base),
        api_key = ?,
        provider = COALESCE(?, provider),
        is_default_main = COALESCE(?, is_default_main),
        is_default_fork = COALESCE(?, is_default_fork),
        is_default_exam = COALESCE(?, is_default_exam)
      WHERE id = ?
    `).run(
      name ?? null,
      api_base ?? null,
      api_key !== undefined ? (api_key === null ? '' : api_key) : null,
      provider ?? null,
      is_default_main !== undefined ? (is_default_main ? 1 : 0) : null,
      is_default_fork !== undefined ? (is_default_fork ? 1 : 0) : null,
      is_default_exam !== undefined ? (is_default_exam ? 1 : 0) : null,
      id
    );

    if (is_default_main) unsetOtherDefaults(id, 'is_default_main');
    if (is_default_fork) unsetOtherDefaults(id, 'is_default_fork');
    if (is_default_exam) unsetOtherDefaults(id, 'is_default_exam');

    const row = db.prepare('SELECT * FROM models WHERE id = ?').get(id);
    res.json(row);
  } catch (err) {
    console.error('[models] update error:', err.message);
    res.status(500).json({ error: err.message });
  }
});

// DELETE /api/models/:id
router.delete('/:id', (req, res) => {
  const id = parseInt(req.params.id, 10);
  if (Number.isNaN(id)) {
    return res.status(400).json({ error: 'Invalid model id' });
  }

  try {
    // Reject if conversations reference this model
    const convCount = db.prepare('SELECT COUNT(*) as count FROM conversations WHERE model_id = ?').get(id);
    if (convCount.count > 0) {
      return res.status(409).json({ error: 'Cannot delete model referenced by conversations' });
    }

    const info = db.prepare('DELETE FROM models WHERE id = ?').run(id);
    if (info.changes === 0) {
      return res.status(404).json({ error: 'Model not found' });
    }

    res.json({ deleted: true });
  } catch (err) {
    console.error('[models] delete error:', err.message);
    res.status(500).json({ error: err.message });
  }
});

// POST /api/models/:id/test — send "di hola" and return latency
router.post('/:id/test', async (req, res) => {
  const id = parseInt(req.params.id, 10);
  if (Number.isNaN(id)) {
    return res.status(400).json({ error: 'Invalid model id' });
  }

  try {
    const model = db.prepare('SELECT * FROM models WHERE id = ?').get(id);
    if (!model) {
      return res.status(404).json({ error: 'Model not found' });
    }

    const start = Date.now();
    let fullText = '';

    for await (const chunk of streamCompletion(model, [{ role: 'user', content: 'di hola' }], '')) {
      if (chunk.error) {
        return res.status(502).json({ error: chunk.error });
      }
      if (chunk.done) {
        fullText = chunk.fullText;
      }
    }

    const latency = Date.now() - start;
    res.json({ latency_ms: latency, response: fullText.trim() });
  } catch (err) {
    console.error('[models] test error:', err.message);
    res.status(500).json({ error: err.message });
  }
});

function unsetOtherDefaults(exceptId, column) {
  db.prepare(`UPDATE models SET ${column} = 0 WHERE id != ?`).run(exceptId);
}

module.exports = router;