const { Router } = require('express');
const settings = require('../config/settings');
const fs = require('fs');

const router = Router();

router.get('/', (req, res) => {
  res.json(settings.load());
});

router.patch('/', (req, res) => {
  const { recentEpisodeLimit, semanticLimit, scoreThreshold } = req.body;
  const updates = {};

  if (recentEpisodeLimit !== undefined) {
    const val = Number(recentEpisodeLimit);
    if (!Number.isInteger(val) || val < 1 || val > 20)
      return res.status(400).json({ error: 'recentEpisodeLimit must be 1–20' });
    updates.recentEpisodeLimit = val;
  }

  if (semanticLimit !== undefined) {
    const val = Number(semanticLimit);
    if (!Number.isInteger(val) || val < 1 || val > 20)
      return res.status(400).json({ error: 'semanticLimit must be 1–20' });
    updates.semanticLimit = val;
  }

  if (scoreThreshold !== undefined) {
    const val = Number(scoreThreshold);
    if (isNaN(val) || val < 0 || val > 1)
      return res.status(400).json({ error: 'scoreThreshold must be 0–1' });
    updates.scoreThreshold = val;
  }

  if (req.body.modelsFolderPath !== undefined) {
    const val = req.body.modelsFolderPath.trim();
    if (!val) return res.status(400).json({ error: 'modelsFolderPath cannot be empty' });
    // Verify the path exists and is readable
    try {
        fs.readdirSync(val);
    } catch {
        return res.status(400).json({ error: `Path not accessible: ${val}` });
    }
    updates.modelsFolderPath = val;
  }

  if (req.body.temperature !== undefined) {
    const val = Number(req.body.temperature);
    if (isNaN(val) || val < 0 || val > 2)
        return res.status(400).json({ error: 'temperature must be 0–2' });
    updates.temperature = val;
  }

  if (req.body.repeatPenalty !== undefined) {
  const val = Number(req.body.repeatPenalty);
  if (isNaN(val) || val < 1 || val > 2)
    return res.status(400).json({ error: 'repeatPenalty must be 1–2' });
  updates.repeatPenalty = val;
}

if (req.body.topP !== undefined) {
  const val = Number(req.body.topP);
  if (isNaN(val) || val < 0 || val > 1)
    return res.status(400).json({ error: 'topP must be 0–1' });
  updates.topP = val;
}

if (req.body.topK !== undefined) {
  const val = Number(req.body.topK);
  if (!Number.isInteger(val) || val < 1 || val > 100)
    return res.status(400).json({ error: 'topK must be 1–100' });
  updates.topK = val;
}

if (req.body.systemPrompt !== undefined) {
  const val = req.body.systemPrompt;
  if (typeof val !== 'string') 
    return res.status(400).json({ error: 'systemPrompt must be a string' });
  updates.systemPrompt = val.trim() || null; // null reverts to default
}

  res.json(settings.save(updates));
});

module.exports = router;