const express = require('express');
const fs = require('fs');
const path = require('path');
const sass = require('sass');

const app = express();
const BASE = __dirname;
const DATA_FILE = path.join(BASE, 'data', 'responses.json');
const CSV_FILE  = path.join(BASE, 'data', 'responses.csv');

// Compile SCSS on startup
try {
  const cssDir = path.join(BASE, 'public', 'css');
  fs.mkdirSync(cssDir, { recursive: true });
  const result = sass.compile(path.join(BASE, 'src', 'styles', 'main.scss'), { style: 'compressed' });
  fs.writeFileSync(path.join(cssDir, 'main.css'), result.css);
  console.log('SCSS compiled successfully');
} catch (err) {
  console.error('SCSS compile error:', err.message);
}

// Ensure data directory & files exist (data/ is gitignored, so a fresh clone has neither)
fs.mkdirSync(path.dirname(DATA_FILE), { recursive: true });
if (!fs.existsSync(DATA_FILE)) fs.writeFileSync(DATA_FILE, JSON.stringify([], null, 2));
if (!fs.existsSync(CSV_FILE))  fs.writeFileSync(CSV_FILE, buildCSVHeader() + '\n');

// ──────────────────────────────────────────
// CSV helpers
// ──────────────────────────────────────────
function csvEscape(val) {
  const s = String(val ?? '');
  if (s.includes(',') || s.includes('"') || s.includes('\n')) {
    return '"' + s.replace(/"/g, '""') + '"';
  }
  return s;
}

function buildCSVHeader() {
  const cols = ['timestamp', 'grade'];
  for (let i = 1; i <= 15; i++) cols.push(`case_${i}_likert`);
  for (let i = 1; i <= 15; i++) cols.push(`case_${i}_order`);
  for (let i = 1; i <= 15; i++) cols.push(`case_${i}_ms`);
  cols.push('ahp_w_stability','ahp_w_revenue','ahp_w_capital','ahp_w_plan','ahp_w_social');
  cols.push('ahp_lambda_max','ahp_CI','ahp_CR','ahp_cr_warning');
  for (let i = 1; i <= 15; i++) cols.push(`match_case_${i}`);
  cols.push('post_q1','post_q2','post_q3','post_q4','open_response');
  return cols.join(',');
}

function buildCSVRow(payload) {
  const fields = [];

  fields.push(payload.meta.timestamp, csvEscape(payload.meta.grade));

  // Case judgments ordered by case_id 1-15
  const byCase = {};
  (payload.intuitive_judgments || []).forEach(j => { byCase[j.case_id] = j; });
  for (let i = 1; i <= 15; i++) fields.push(byCase[i]?.judgment ?? '');
  for (let i = 1; i <= 15; i++) fields.push(byCase[i]?.presented_order ?? '');
  for (let i = 1; i <= 15; i++) fields.push(byCase[i]?.response_time_ms ?? '');

  // AHP
  const ahp = payload.ahp || {};
  (ahp.weights || [0,0,0,0,0]).forEach(w => fields.push(Number(w).toFixed(4)));
  fields.push(Number(ahp.lambda_max).toFixed(4));
  fields.push(Number(ahp.CI).toFixed(4));
  fields.push(Number(ahp.CR).toFixed(4));
  fields.push(ahp.cr_warning_shown ? 1 : 0);

  // Match by case_id
  const matchByCase = {};
  (payload.comparison || []).forEach(c => { matchByCase[c.case_id] = c.match; });
  for (let i = 1; i <= 15; i++) {
    const m = matchByCase[i];
    fields.push(m === true ? 1 : m === false ? 0 : '');
  }

  // Post survey
  const ps = payload.post_survey || {};
  fields.push(ps.q1 ?? '', ps.q2 ?? '', ps.q3 ?? '', ps.q4 ?? '');
  fields.push(csvEscape(ps.open_response ?? ''));

  return fields.join(',');
}

// ──────────────────────────────────────────
// Routes
// ──────────────────────────────────────────
app.use(express.json({ limit: '1mb' }));
app.use(express.static(path.join(BASE, 'public')));

app.post('/api/submit', (req, res) => {
  try {
    // Save JSON
    const data = JSON.parse(fs.readFileSync(DATA_FILE, 'utf8'));
    const submission = { ...req.body, server_timestamp: Date.now() };
    data.push(submission);
    fs.writeFileSync(DATA_FILE, JSON.stringify(data, null, 2));

    // Append CSV row
    const row = buildCSVRow(submission);
    fs.appendFileSync(CSV_FILE, row + '\n');

    res.json({ success: true, id: data.length });
  } catch (err) {
    console.error('Submit error:', err);
    res.status(500).json({ error: err.message });
  }
});

app.get('/api/responses', (req, res) => {
  try {
    res.json(JSON.parse(fs.readFileSync(DATA_FILE, 'utf8')));
  } catch (err) {
    res.status(500).json({ error: err.message });
  }
});

const PORT = process.env.PORT || 3000;
app.listen(PORT, () => console.log(`Server running at http://localhost:${PORT}`));