forskjeller.naiv.no/public/bolig/app.js

// Formateringshjelpere — norsk locale
function fmtKr(n) {
  return Math.round(n).toLocaleString('nb-NO') + '\u202fkr';
}

function fmtShort(n) {
  if (n >= 1e6) return (n / 1e6).toFixed(1).replace('.', ',') + '\u202fM';
  if (n >= 1e3) return Math.round(n / 1e3) + '\u202fk';
  return Math.round(n);
}

function getData() {
  const pA = +document.getElementById('priceA').value;
  const pB = +document.getElementById('priceB').value;
  const g = +document.getElementById('growth').value / 100;
  const Y = +document.getElementById('yrs').value;

  // Lån = 85 % av kjøpspris (forenklet avdragsfritt)
  const loanA = pA * 0.85;
  const loanB = pB * 0.85;

  const labels = [], valA = [], valB = [], valGaps = [];
  const eqA = [], eqB = [], eqGaps = [];

  for (let y = 0; y <= Y; y++) {
    labels.push(y === 0 ? 'I dag' : (y % 5 === 0 || Y <= 10 || y === Y) ? 'År ' + y : '');
    const a = pA * Math.pow(1 + g, y);
    const b = pB * Math.pow(1 + g, y);
    valA.push(a);
    valB.push(b);
    valGaps.push(b - a);
    eqA.push(a - loanA);
    eqB.push(b - loanB);
    eqGaps.push((b - loanB) - (a - loanA));
  }

  return { pA, pB, g, Y, loanA, loanB, labels, valA, valB, valGaps, eqA, eqB, eqGaps };
}

const GRID_COLOR = 'rgba(0,0,0,0.06)';
const TICK_COLOR = '#8a857e';

function baseOpts() {
  return {
    responsive: true, maintainAspectRatio: false,
    plugins: {
      legend: { display: false },
      tooltip: {
        callbacks: { label: c => ' ' + fmtKr(c.parsed.y) },
        backgroundColor: '#1a1714',
        titleColor: '#f5f2eb',
        bodyColor: 'rgba(245,242,235,0.7)',
        padding: 10,
        cornerRadius: 4,
        titleFont: { family: 'DM Sans', size: 12 },
        bodyFont: { family: 'DM Sans', size: 12 }
      }
    },
    scales: {
      x: {
        ticks: { color: TICK_COLOR, font: { size: 11, family: 'DM Sans' }, autoSkip: false, maxRotation: 0 },
        grid: { display: false },
        border: { color: 'rgba(0,0,0,0.1)' }
      },
      y: {
        ticks: { color: TICK_COLOR, font: { size: 11, family: 'DM Sans' }, callback: v => fmtShort(v) },
        grid: { color: GRID_COLOR },
        border: { dash: [3, 3], color: 'transparent' }
      }
    }
  };
}

// Diagram 1: Boligverdi over tid
const chart1 = new Chart(document.getElementById('chart1'), {
  type: 'line',
  data: { labels: [], datasets: [
    { data: [], borderColor: '#1a4a8a', backgroundColor: 'rgba(26,74,138,0.07)', fill: true, tension: 0.35, pointRadius: 0, borderWidth: 2 },
    { data: [], borderColor: '#c0392b', backgroundColor: 'rgba(192,57,43,0.07)', fill: true, tension: 0.35, pointRadius: 0, borderWidth: 2 }
  ]},
  options: baseOpts()
});

// Diagram 2: Verdidifferanse
const chart2 = new Chart(document.getElementById('chart2'), {
  type: 'line',
  data: { labels: [], datasets: [
    { data: [], borderColor: '#4a3a8a', backgroundColor: 'rgba(74,58,138,0.1)', fill: true, tension: 0.35, pointRadius: 0, borderWidth: 2 }
  ]},
  options: baseOpts()
});

// Diagram 3: Egenkapitalvekst (A, B, gap)
const chart3 = new Chart(document.getElementById('chart3'), {
  type: 'line',
  data: { labels: [], datasets: [
    { data: [], borderColor: '#1a4a8a', backgroundColor: 'rgba(26,74,138,0.07)', fill: true, tension: 0.35, pointRadius: 0, borderWidth: 2 },
    { data: [], borderColor: '#c0392b', backgroundColor: 'rgba(192,57,43,0.07)', fill: true, tension: 0.35, pointRadius: 0, borderWidth: 2 },
    { data: [], borderColor: '#4a3a8a', backgroundColor: 'rgba(74,58,138,0.1)', fill: true, tension: 0.35, pointRadius: 0, borderWidth: 2, borderDash: [6, 4] }
  ]},
  options: baseOpts()
});

// SIKKERHETSNOTAT: Alle verdier er beregnet fra numeriske slider-verdier.
// Ingen bruker-tekstinput brukes i DOM-oppdateringer.
function update() {
  const { pA, pB, g, Y, loanA, loanB, labels, valA, valB, valGaps, eqA, eqB, eqGaps } = getData();

  // Slider-visning
  document.querySelectorAll('.yr-lbl').forEach(el => el.textContent = Y);
  document.getElementById('priceA-out').textContent = Math.round(pA).toLocaleString('nb-NO') + '\u202fkr';
  document.getElementById('priceB-out').textContent = Math.round(pB).toLocaleString('nb-NO') + '\u202fkr';
  document.getElementById('growth-out').textContent = (g * 100).toLocaleString('nb-NO', { minimumFractionDigits: 1 }) + '\u202f%';
  document.getElementById('yrs-out').textContent = Y + '\u202får';

  // Statistikkort
  document.getElementById('st-valA').textContent = fmtKr(valA[Y]);
  document.getElementById('st-subA').textContent = 'EK: ' + fmtKr(eqA[Y]);
  document.getElementById('st-valB').textContent = fmtKr(valB[Y]);
  document.getElementById('st-subB').textContent = 'EK: ' + fmtKr(eqB[Y]);
  document.getElementById('st-valdiff').textContent = fmtKr(valGaps[Y]);
  document.getElementById('st-valdiff-sub').textContent = 'var ' + fmtKr(pB - pA) + ' ved start';
  document.getElementById('st-eqdiff').textContent = fmtKr(eqGaps[Y]);
  const startEqGap = (pB * 0.15) - (pA * 0.15);
  document.getElementById('st-eqdiff-sub').textContent = 'var ' + fmtKr(startEqGap) + ' ved start';

  // Banner
  document.getElementById('banner-gap').textContent = fmtKr(eqGaps[Y]);

  // Innsikt — bruker DOM-metoder for sikkerhet
  const insightEl = document.getElementById('insight');
  insightEl.textContent = '';
  const growthPct = (g * 100).toLocaleString('nb-NO', { minimumFractionDigits: 1 });
  const parts = [
    { text: 'Begge boligene steg ' + growthPct + ' % i året. Men B-eieren har ' },
    { text: fmtKr(eqGaps[Y]), bold: true },
    { text: ' mer i egenkapital — fordi gjeldsgraden forsterker forskjellen.' }
  ];
  parts.forEach(p => {
    if (p.bold) {
      const strong = document.createElement('strong');
      strong.textContent = p.text;
      insightEl.appendChild(strong);
    } else {
      insightEl.appendChild(document.createTextNode(p.text));
    }
  });

  // Diagram 1: Boligverdi
  chart1.data.labels = labels;
  chart1.data.datasets[0].data = valA;
  chart1.data.datasets[1].data = valB;
  chart1.update('none');

  // Diagram 2: Verdidifferanse
  chart2.data.labels = labels;
  chart2.data.datasets[0].data = valGaps;
  chart2.update('none');

  // Diagram 3: Egenkapital
  chart3.data.labels = labels;
  chart3.data.datasets[0].data = eqA;
  chart3.data.datasets[1].data = eqB;
  chart3.data.datasets[2].data = eqGaps;
  chart3.update('none');
}

['priceA', 'priceB', 'growth', 'yrs'].forEach(id =>
  document.getElementById(id).addEventListener('input', update)
);
update();