/**
 * ControlPanel — DOM-based control panel (sliders, buttons, toggles) and event wiring.
 * Loaded as a plain script; class is defined on the global scope.
 */

/**
 * @typedef {Object} SimParams
 * @property {'single'|'double'} mode
 * @property {number} slitWidth       - in wavelength units
 * @property {number} slitSeparation  - in wavelength units
 * @property {number} wavelength      - in grid-cell units
 * @property {boolean} playing
 */

/**
 * Clamp simulation parameters to their valid ranges.
 * @param {SimParams} params
 * @returns {SimParams} A new object with clamped values.
 */
function clampParams(params) {
  return Object.assign({}, params, {
    slitWidth: Math.min(600, Math.max(1, params.slitWidth)),
    slitSeparation: Math.min(150, Math.max(10, params.slitSeparation)),
    wavelength: Math.min(40, Math.max(10, params.wavelength)),
    amplitude: Math.min(5.0, Math.max(0.01, params.amplitude)),
  });
}

class ControlPanel {
  constructor() {
    /** @type {SimParams} */
    this.params = {
      mode: 'double',
      slitWidth: 40,
      slitSeparation: 80,
      wavelength: 20,
      amplitude: 2.0,
      sourceWidth: 600,
      detectorPos: 330,
      waveNature: 'light',
      polarization: 'orthogonal',
      polarizer45: false,
      topSlitOpen: true,
      bottomSlitOpen: true,
      playing: false,
    };

    /** @type {function(SimParams): void} */
    this.onChange = null;

    /** @type {function(): void} */
    this.onReset = null;
  }

  /**
   * Build DOM elements inside the container and wire events.
   * @param {HTMLElement} container
   */
  init(container) {
    var self = this;

    // Root wrapper
    var wrapper = document.createElement('div');
    wrapper.style.cssText = 'display:flex;flex-wrap:wrap;align-items:center;gap:8px 12px;font-size:12px;color:#d0d4e8;';

    // --- Helper: create a labeled slider group ---
    function createSliderGroup(label, min, max, step, value) {
      var group = document.createElement('div');
      group.style.cssText = 'display:flex;align-items:center;gap:4px;background:rgba(255,255,255,0.04);padding:3px 8px;border-radius:6px;min-width:0;';

      var lbl = document.createElement('label');
      lbl.textContent = label;
      lbl.style.cssText = 'white-space:nowrap;color:#8899cc;font-size:11px;font-weight:500;';

      var input = document.createElement('input');
      input.type = 'range';
      input.min = String(min);
      input.max = String(max);
      input.step = String(step);
      input.value = String(value);
      input.style.cssText = 'width:80px;accent-color:#7b9fff;cursor:pointer;height:6px;touch-action:none;';

      var display = document.createElement('span');
      display.textContent = String(value);
      display.style.cssText = 'min-width:28px;text-align:right;font-variant-numeric:tabular-nums;color:#a0b0ff;font-size:11px;font-weight:600;';

      group.appendChild(lbl);
      group.appendChild(input);
      group.appendChild(display);
      return { group: group, input: input, display: display };
    }

    // --- Helper: create a styled button ---
    function createButton(text, bg) {
      var btn = document.createElement('button');
      btn.textContent = text;
      btn.style.cssText =
        'padding:8px 14px;border:none;border-radius:6px;cursor:pointer;font-size:11px;font-weight:700;color:#fff;background:' + bg + ';letter-spacing:0.3px;transition:all 0.15s;box-shadow:0 2px 8px rgba(0,0,0,0.3);touch-action:manipulation;min-height:36px;';
      btn.addEventListener('mouseenter', function () { btn.style.transform = 'scale(1.05)'; btn.style.boxShadow = '0 3px 12px rgba(0,0,0,0.4)'; });
      btn.addEventListener('mouseleave', function () { btn.style.transform = 'scale(1)'; btn.style.boxShadow = '0 2px 8px rgba(0,0,0,0.3)'; });
      return btn;
    }

    // ---- Mode toggle (single / double) ----
    var modeGroup = document.createElement('div');
    modeGroup.style.cssText = 'display:flex;align-items:center;gap:6px;';

    var modeLbl = document.createElement('label');
    modeLbl.textContent = 'Mode:';
    modeLbl.style.cssText = 'white-space:nowrap;color:#8899cc;font-size:12px;font-weight:500;';

    var modeSelect = document.createElement('select');
    modeSelect.style.cssText =
      'padding:6px 10px;border:1px solid rgba(100,140,255,0.25);border-radius:6px;background:rgba(255,255,255,0.06);color:#c0ccff;font-size:12px;cursor:pointer;font-weight:500;min-height:32px;';
    var optSingle = document.createElement('option');
    optSingle.value = 'single';
    optSingle.textContent = 'Single Slit';
    var optDouble = document.createElement('option');
    optDouble.value = 'double';
    optDouble.textContent = 'Double Slit';
    modeSelect.appendChild(optSingle);
    modeSelect.appendChild(optDouble);
    modeSelect.value = this.params.mode;

    modeGroup.appendChild(modeLbl);
    modeGroup.appendChild(modeSelect);

    // ---- Wave nature selector ----
    var waveGroup = document.createElement('div');
    waveGroup.style.cssText = 'display:flex;align-items:center;gap:6px;';
    var waveLbl = document.createElement('label');
    waveLbl.textContent = 'Wave:';
    waveLbl.style.cssText = 'white-space:nowrap;color:#8899cc;font-size:12px;font-weight:500;';
    var waveSelect = document.createElement('select');
    waveSelect.style.cssText = 'padding:6px 10px;border:1px solid rgba(100,140,255,0.25);border-radius:6px;background:rgba(255,255,255,0.06);color:#c0ccff;font-size:12px;cursor:pointer;font-weight:500;min-height:32px;';
    var optSound = document.createElement('option');
    optSound.value = 'sound'; optSound.textContent = 'Sound';
    var optLight = document.createElement('option');
    optLight.value = 'light'; optLight.textContent = 'Light';
    waveSelect.appendChild(optSound);
    waveSelect.appendChild(optLight);
    waveSelect.value = this.params.waveNature;
    waveGroup.appendChild(waveLbl);
    waveGroup.appendChild(waveSelect);

    // ---- Polarization selector (only visible for light + double slit) ----
    var polGroup = document.createElement('div');
    polGroup.style.cssText = 'display:flex;align-items:center;gap:6px;';
    var polLbl = document.createElement('label');
    polLbl.textContent = 'Polarization:';
    polLbl.style.cssText = 'white-space:nowrap;color:#8899cc;font-size:12px;font-weight:500;';
    var polSelect = document.createElement('select');
    polSelect.style.cssText = 'padding:6px 10px;border:1px solid rgba(100,140,255,0.25);border-radius:6px;background:rgba(255,255,255,0.06);color:#c0ccff;font-size:12px;cursor:pointer;font-weight:500;min-height:32px;';
    var optSamePol = document.createElement('option');
    optSamePol.value = 'same'; optSamePol.textContent = 'Same (∥)';
    var optOrthPol = document.createElement('option');
    optOrthPol.value = 'orthogonal'; optOrthPol.textContent = 'Orthogonal (⊥)';
    polSelect.appendChild(optSamePol);
    polSelect.appendChild(optOrthPol);
    polSelect.value = this.params.polarization;
    polGroup.appendChild(polLbl);
    polGroup.appendChild(polSelect);
    // Show only when light + double slit
    polGroup.style.display = (this.params.waveNature === 'light' && this.params.mode === 'double') ? 'flex' : 'none';

    // ---- 45° Polarizer toggle (only visible for orthogonal polarization) ----
    var pol45Group = document.createElement('div');
    pol45Group.style.cssText = 'display:flex;align-items:center;gap:6px;';
    var pol45Check = document.createElement('input');
    pol45Check.type = 'checkbox';
    pol45Check.checked = this.params.polarizer45;
    pol45Check.style.cssText = 'accent-color:#ffaa00;cursor:pointer;';
    var pol45Lbl = document.createElement('label');
    pol45Lbl.textContent = '45° Polarizer';
    pol45Lbl.style.cssText = 'white-space:nowrap;color:#ffcc44;cursor:pointer;font-size:12px;font-weight:500;';
    pol45Lbl.addEventListener('click', function() { pol45Check.click(); });
    pol45Group.appendChild(pol45Check);
    pol45Group.appendChild(pol45Lbl);
    pol45Group.style.display = (this.params.waveNature === 'light' && this.params.mode === 'double' && this.params.polarization === 'orthogonal') ? 'flex' : 'none';

    // ---- Slit open/close checkboxes (only in double-slit mode) ----
    var slitToggleGroup = document.createElement('div');
    slitToggleGroup.style.cssText = 'display:flex;align-items:center;gap:10px;';

    var topSlitCheck = document.createElement('input');
    topSlitCheck.type = 'checkbox';
    topSlitCheck.checked = this.params.topSlitOpen;
    topSlitCheck.style.cssText = 'accent-color:#ffcc00;cursor:pointer;';
    var topSlitLbl = document.createElement('label');
    topSlitLbl.textContent = 'Top Slit';
    topSlitLbl.style.cssText = 'white-space:nowrap;color:#8899cc;cursor:pointer;font-size:11px;font-weight:500;';
    topSlitLbl.addEventListener('click', function() { topSlitCheck.click(); });

    var bottomSlitCheck = document.createElement('input');
    bottomSlitCheck.type = 'checkbox';
    bottomSlitCheck.checked = this.params.bottomSlitOpen;
    bottomSlitCheck.style.cssText = 'accent-color:#00cc44;cursor:pointer;';
    var bottomSlitLbl = document.createElement('label');
    bottomSlitLbl.textContent = 'Bottom Slit';
    bottomSlitLbl.style.cssText = 'white-space:nowrap;color:#8899cc;cursor:pointer;font-size:11px;font-weight:500;';
    bottomSlitLbl.addEventListener('click', function() { bottomSlitCheck.click(); });

    slitToggleGroup.appendChild(topSlitCheck);
    slitToggleGroup.appendChild(topSlitLbl);
    slitToggleGroup.appendChild(bottomSlitCheck);
    slitToggleGroup.appendChild(bottomSlitLbl);
    slitToggleGroup.style.display = this.params.mode === 'double' ? 'flex' : 'none';

    // ---- Slit width slider ----
    var slitWidthCtrl = createSliderGroup('Slit Width:', 1, 600, 1, this.params.slitWidth);

    // ---- Slit separation slider (hidden in single mode) ----
    var slitSepCtrl = createSliderGroup('Separation:', 10, 150, 1, this.params.slitSeparation);
    this._sepGroup = slitSepCtrl.group;
    slitSepCtrl.group.style.display = this.params.mode === 'double' ? 'flex' : 'none';

    // ---- Wavelength slider ----
    var wavelengthCtrl = createSliderGroup('Wavelength (λ):', 10, 40, 1, this.params.wavelength);

    // ---- Amplitude slider ----
    var amplitudeCtrl = createSliderGroup('Amplitude:', 0.01, 5.0, 0.01, this.params.amplitude);

    // ---- Source width slider ----
    var sourceWidthCtrl = createSliderGroup('Source Width:', 1, 600, 1, this.params.sourceWidth);

    // ---- Detector position slider ----
    var detectorPosCtrl = createSliderGroup('Detector:', 50, 700, 1, this.params.detectorPos);

    // ---- Buttons ----
    var btnGroup = document.createElement('div');
    btnGroup.style.cssText = 'display:flex;align-items:center;gap:6px;margin-left:auto;';

    var startBtn = createButton('▶ Start', 'linear-gradient(135deg, #2e8b57, #3cb371)');
    var pauseBtn = createButton('⏸ Pause', 'linear-gradient(135deg, #cc7700, #e8a020)');
    var resetBtn = createButton('↺ Reset', 'linear-gradient(135deg, #c62828, #e53935)');
    var aboutBtn = createButton('ℹ About', 'linear-gradient(135deg, #4a5568, #6b7280)');

    btnGroup.appendChild(startBtn);
    btnGroup.appendChild(pauseBtn);
    btnGroup.appendChild(resetBtn);
    btnGroup.appendChild(aboutBtn);

    // ---- Assemble sliders into wrapper ----
    wrapper.appendChild(modeGroup);
    wrapper.appendChild(waveGroup);
    wrapper.appendChild(polGroup);
    wrapper.appendChild(pol45Group);
    wrapper.appendChild(slitToggleGroup);
    wrapper.appendChild(slitWidthCtrl.group);
    wrapper.appendChild(slitSepCtrl.group);
    wrapper.appendChild(wavelengthCtrl.group);
    wrapper.appendChild(amplitudeCtrl.group);
    wrapper.appendChild(sourceWidthCtrl.group);
    wrapper.appendChild(detectorPosCtrl.group);
    container.appendChild(wrapper);

    // ---- Put buttons in the always-visible buttons container ----
    var btnContainer = document.getElementById('control-buttons');
    if (btnContainer) {
      btnContainer.appendChild(startBtn);
      btnContainer.appendChild(pauseBtn);
      btnContainer.appendChild(resetBtn);
      btnContainer.appendChild(aboutBtn);
    } else {
      // Fallback: put buttons in the wrapper
      wrapper.appendChild(btnGroup);
    }

    // ---- Internal notify helper ----
    function notify() {
      self.params = clampParams(self.params);
      if (self.onChange) self.onChange(self.getParams());
    }

    // ---- Wire events ----

    // Helper to update polarization visibility
    function updatePolVisibility() {
      var isLightDouble = (self.params.waveNature === 'light' && self.params.mode === 'double');
      polGroup.style.display = isLightDouble ? 'flex' : 'none';
      pol45Group.style.display = (isLightDouble && self.params.polarization === 'orthogonal') ? 'flex' : 'none';
      slitToggleGroup.style.display = self.params.mode === 'double' ? 'flex' : 'none';
    }

    // Mode toggle
    modeSelect.addEventListener('change', function () {
      self.params.mode = modeSelect.value;
      slitSepCtrl.group.style.display = modeSelect.value === 'double' ? 'flex' : 'none';
      updatePolVisibility();
      notify();
    });

    // Wave nature
    waveSelect.addEventListener('change', function () {
      self.params.waveNature = waveSelect.value;
      updatePolVisibility();
      notify();
    });

    // Polarization
    polSelect.addEventListener('change', function () {
      self.params.polarization = polSelect.value;
      updatePolVisibility();
      notify();
    });

    // 45° Polarizer
    pol45Check.addEventListener('change', function () {
      self.params.polarizer45 = pol45Check.checked;
      notify();
    });

    // Top slit toggle
    topSlitCheck.addEventListener('change', function () {
      self.params.topSlitOpen = topSlitCheck.checked;
      notify();
    });

    // Bottom slit toggle
    bottomSlitCheck.addEventListener('change', function () {
      self.params.bottomSlitOpen = bottomSlitCheck.checked;
      notify();
    });

    // Slit width
    slitWidthCtrl.input.addEventListener('input', function () {
      var v = parseInt(slitWidthCtrl.input.value, 10);
      self.params.slitWidth = Math.min(600, Math.max(1, v));
      slitWidthCtrl.input.value = String(self.params.slitWidth);
      slitWidthCtrl.display.textContent = String(self.params.slitWidth);
      notify();
    });

    // Slit separation
    slitSepCtrl.input.addEventListener('input', function () {
      var v = parseInt(slitSepCtrl.input.value, 10);
      self.params.slitSeparation = Math.min(150, Math.max(10, v));
      slitSepCtrl.input.value = String(self.params.slitSeparation);
      slitSepCtrl.display.textContent = String(self.params.slitSeparation);
      notify();
    });

    // Wavelength
    wavelengthCtrl.input.addEventListener('input', function () {
      var v = parseInt(wavelengthCtrl.input.value, 10);
      self.params.wavelength = Math.min(40, Math.max(10, v));
      wavelengthCtrl.input.value = String(self.params.wavelength);
      wavelengthCtrl.display.textContent = String(self.params.wavelength);
      notify();
    });

    // Amplitude
    amplitudeCtrl.input.addEventListener('input', function () {
      var v = parseFloat(amplitudeCtrl.input.value);
      self.params.amplitude = Math.min(5.0, Math.max(0.01, v));
      amplitudeCtrl.input.value = String(self.params.amplitude);
      amplitudeCtrl.display.textContent = self.params.amplitude.toFixed(2);
      notify();
    });

    // Source width
    sourceWidthCtrl.input.addEventListener('input', function () {
      var v = parseInt(sourceWidthCtrl.input.value, 10);
      self.params.sourceWidth = Math.min(600, Math.max(1, v));
      sourceWidthCtrl.input.value = String(self.params.sourceWidth);
      sourceWidthCtrl.display.textContent = String(self.params.sourceWidth);
      notify();
    });

    // Detector position
    detectorPosCtrl.input.addEventListener('input', function () {
      var v = parseInt(detectorPosCtrl.input.value, 10);
      self.params.detectorPos = Math.min(700, Math.max(50, v));
      detectorPosCtrl.input.value = String(self.params.detectorPos);
      detectorPosCtrl.display.textContent = String(self.params.detectorPos);
      notify();
    });

    // Start
    startBtn.addEventListener('click', function () {
      self.params.playing = true;
      notify();
    });

    // Pause
    pauseBtn.addEventListener('click', function () {
      self.params.playing = false;
      notify();
    });

    // Reset
    resetBtn.addEventListener('click', function () {
      if (self.onReset) self.onReset();
    });

    // About
    aboutBtn.addEventListener('click', function () {
      var overlay = document.getElementById('about-overlay');
      if (overlay) overlay.style.display = 'flex';
    });
  }

  /**
   * Return a copy of the current parameters.
   * @returns {SimParams}
   */
  getParams() {
    return Object.assign({}, this.params);
  }
}

window.ControlPanel = ControlPanel;
window.clampParams = clampParams;