/**
 * The design panel.
 *
 * Every control is generated from the style schema the server sends, so the editor offers exactly
 * what the server accepts – nothing more, nothing less. Adding a property on the server makes it
 * appear here without touching this file.
 */
import { devices, effectiveStyle, hoverStyle, setStyle, resetStyleDevice, clearStyle } from './editor-model.js';

export const GROUPS = {
  text: 'Typografie',
  background: 'Hintergrund',
  spacing: 'Abstand',
  size: 'Größe',
  border: 'Rahmen',
  layout: 'Layout',
  effect: 'Wirkung',
};

const UNITS = ['px', 'rem', 'em', '%', 'vw', 'vh', 'ch'];

/** Splits "18.5rem" into its number and its unit; an empty value yields empty parts. */
function splitLength(value) {
  const match = /^(-?\d+(?:\.\d+)?)(px|rem|em|%|vw|vh|ch)$/.exec(value ?? '');
  if (match) return { number: match[1], unit: match[2] };
  return { number: value === '0' ? '0' : '', unit: 'px' };
}

function element(tag, className, text) {
  const node = document.createElement(tag);
  if (className) node.className = className;
  if (text !== undefined) node.textContent = text;
  return node;
}

export function createDesignPanel({ schema, onChange, getBlock, getDevice, getSelection, getHistory }) {
  const change = mutate => { getHistory().change(mutate); onChange(); };

  /** One labelled row with a reset button that appears as soon as this device has an own value. */
  const row = (id, labelText, control, { own, inherited, onReset }) => {
    const wrap = element('div', 'design-row' + (own ? ' design-own' : ''));
    const head = element('div', 'design-row-head');
    const label = element('label', null, labelText);
    label.htmlFor = id;
    head.append(label);
    if (own) {
      const reset = element('button', 'text-button design-reset-one', '⟲');
      reset.type = 'button';
      reset.title = 'Auf geerbten Wert zurücksetzen';
      reset.setAttribute('aria-label', `${labelText} zurücksetzen`);
      reset.addEventListener('click', onReset);
      head.append(reset);
    }
    wrap.append(head, control);
    if (!own && inherited) wrap.append(element('p', 'design-inherited', inherited));
    return wrap;
  };

  const colorControl = (id, value, apply) => {
    const wrap = element('div', 'color-control');
    const picker = document.createElement('input');
    picker.type = 'color';
    picker.id = id;
    picker.value = /^#[0-9a-fA-F]{6}$/.test(value ?? '') ? value : '#000000';
    const text = document.createElement('input');
    text.type = 'text';
    text.className = 'color-text';
    text.value = value ?? '';
    text.placeholder = '#1a2b3c';
    text.setAttribute('aria-label', 'Farbwert oder Palettenname');
    const palette = document.createElement('select');
    palette.className = 'color-palette';
    palette.setAttribute('aria-label', 'Farbe aus der Palette');
    palette.append(new Option('Palette …', ''));
    for (const color of schema.colors) palette.append(new Option(`${color.name} (${color.value})`, `@${color.key}`));
    palette.value = (value ?? '').startsWith('@') ? value : '';

    picker.addEventListener('input', () => { text.value = picker.value; apply(picker.value); });
    text.addEventListener('change', () => apply(text.value.trim()));
    palette.addEventListener('change', () => { if (palette.value) { text.value = palette.value; apply(palette.value); } });
    wrap.append(picker, text, palette);
    return wrap;
  };

  const lengthControl = (id, value, apply, placeholder) => {
    const wrap = element('div', 'length-control');
    const parts = splitLength(value);
    const number = document.createElement('input');
    number.type = 'number';
    number.id = id;
    number.step = 'any';
    number.value = parts.number;
    number.placeholder = placeholder ?? 'erbt';
    const unit = document.createElement('select');
    unit.setAttribute('aria-label', 'Einheit');
    for (const name of UNITS) unit.append(new Option(name, name));
    unit.value = parts.unit;
    const push = () => apply(number.value === '' ? '' : `${number.value}${unit.value}`);
    number.addEventListener('change', push);
    unit.addEventListener('change', () => { if (number.value !== '') push(); });
    wrap.append(number, unit);
    return wrap;
  };

  const numberControl = (id, value, property, apply) => {
    const wrap = element('div', 'number-control');
    const slider = document.createElement('input');
    slider.type = 'range';
    slider.min = property.min; slider.max = property.max; slider.step = property.step;
    slider.value = value ?? property.min;
    slider.setAttribute('aria-label', `${property.label} Schieberegler`);
    const exact = document.createElement('input');
    exact.type = 'number';
    exact.id = id;
    exact.min = property.min; exact.max = property.max; exact.step = property.step;
    exact.value = value ?? '';
    exact.placeholder = 'erbt';
    slider.addEventListener('input', () => { exact.value = slider.value; });
    slider.addEventListener('change', () => apply(slider.value));
    exact.addEventListener('change', () => { slider.value = exact.value; apply(exact.value); });
    wrap.append(slider, exact);
    return wrap;
  };

  const choiceControl = (id, value, property, apply, inheritedLabel) => {
    const select = document.createElement('select');
    select.id = id;
    select.append(new Option(`Übernehmen: ${inheritedLabel}`, ''));
    for (const [key, label] of Object.entries(property.values)) select.append(new Option(label, key));
    select.value = value ?? '';
    select.addEventListener('change', () => apply(select.value));
    return select;
  };

  const fontControl = (id, value, apply, inheritedLabel) => {
    const select = document.createElement('select');
    select.id = id;
    select.append(new Option(`Übernehmen: ${inheritedLabel}`, ''));
    for (const font of schema.fonts) select.append(new Option(`${font.name}${font.family ? ` · ${font.family}` : ''}`, font.key));
    select.value = value ?? '';
    select.addEventListener('change', () => apply(select.value));
    return select;
  };

  /** Four inputs for padding, margin, border width and corners. */
  const sideControl = (key, block, deviceName, property) => {
    const grid = element('div', 'side-control');
    const parts = property.corners ? schema.corners : schema.sides;
    for (const [side, label] of Object.entries(parts)) {
      const cell = element('div', 'side-cell');
      const id = `style-${key}-${side}`;
      const caption = element('label', null, label);
      caption.htmlFor = id;
      const current = effectiveStyle(block, deviceName, key, side);
      const control = lengthControl(id, current.source === deviceName ? current.value : '', value => {
        change(doc => setStyle(doc, getSelection(), deviceName, key, value, { side }));
      }, current.value ? String(current.value) : 'erbt');
      if (current.value && current.source !== deviceName) control.classList.add('is-inherited');
      cell.append(caption, control);
      grid.append(cell);
    }
    const all = element('button', 'text-button side-all', 'Alle Seiten gleich setzen');
    all.type = 'button';
    all.addEventListener('click', () => {
      const first = grid.querySelector('input[type=number]');
      const unit = grid.querySelector('select');
      if (first?.value === '') return;
      change(doc => {
        for (const side of Object.keys(parts)) setStyle(doc, getSelection(), deviceName, key, `${first.value}${unit.value}`, { side });
      });
    });
    const wrap = element('div', 'side-wrap');
    wrap.append(grid, all);
    return wrap;
  };

  /** Renders the whole panel for one block into the given container. */
  return function render(panel) {
    const block = getBlock();
    const deviceName = getDevice();
    if (!block) return;

    const scope = element('p', 'design-scope');
    scope.textContent = `${devices[deviceName]} · ${deviceName === 'desktop' ? 'Basis für alle Geräte' : deviceName === 'tablet' ? 'bis 1024 px, gilt auch für Mobil' : 'bis 767 px'}`;
    panel.append(scope);
    panel.append(element('p', 'field-help', 'Leere Felder erben vom größeren Gerät und zuletzt vom Theme. Werte mit eigenem Wert sind hervorgehoben und lassen sich einzeln zurücksetzen.'));

    for (const [group, groupLabel] of Object.entries(GROUPS)) {
      const properties = Object.entries(schema.properties).filter(([, p]) => p.group === group);
      if (properties.length === 0) continue;
      const details = element('details', 'design-group');
      if (group === 'text' || group === 'spacing') details.open = true;
      details.append(element('summary', null, groupLabel));
      const body = element('div', 'design-group-body');

      for (const [key, property] of properties) {
        const id = `style-${key}`;
        const current = effectiveStyle(block, deviceName, key);
        const own = block.style?.[deviceName]?.[key] !== undefined;
        const apply = value => change(doc => setStyle(doc, getSelection(), deviceName, key, value));
        const onReset = () => change(doc => setStyle(doc, getSelection(), deviceName, key, ''));
        const inheritedText = current.value !== undefined && !own
          ? `Erbt ${describe(property, current.value)} von ${devices[current.source]}`
          : 'Theme-Standard';

        let control;
        if (property.sides || property.corners) {
          body.append(element('p', 'design-group-label', property.label), sideControl(key, block, deviceName, property));
          continue;
        }
        if (property.type === 'color') control = colorControl(id, own ? current.value : '', apply);
        else if (property.type === 'length' || property.type === 'length-auto') control = lengthControl(id, own ? current.value : '', apply, current.value ? String(current.value) : 'erbt');
        else if (property.type === 'number') control = numberControl(id, own ? current.value : '', property, apply);
        else if (property.type === 'choice') control = choiceControl(id, own ? current.value : '', property, apply, inheritedText);
        else if (property.type === 'font') control = fontControl(id, own ? current.value : '', apply, inheritedText);
        else continue; // media properties are set through the media library

        body.append(row(id, property.label, control, { own, inherited: inheritedText, onReset }));

        if (schema.hoverable.includes(key)) {
          const hoverId = `${id}-hover`;
          const hoverValue = hoverStyle(block, deviceName, key);
          const hoverApply = value => change(doc => setStyle(doc, getSelection(), deviceName, key, value, { hover: true }));
          const hoverControl = property.type === 'color'
            ? colorControl(hoverId, hoverValue ?? '', hoverApply)
            : property.type === 'number'
              ? numberControl(hoverId, hoverValue ?? '', property, hoverApply)
              : lengthControl(hoverId, hoverValue ?? '', hoverApply, 'kein Hover');
          body.append(row(hoverId, `${property.label} beim Überfahren`, hoverControl, {
            own: hoverValue !== undefined,
            inherited: 'Kein eigener Hover-Wert',
            onReset: () => hoverApply(''),
          }));
        }
      }
      details.append(body);
      panel.append(details);
    }

    const actions = element('div', 'design-actions');
    const resetDevice = element('button', 'secondary', `${devices[deviceName]} zurücksetzen`);
    resetDevice.type = 'button';
    resetDevice.addEventListener('click', () => change(doc => resetStyleDevice(doc, getSelection(), deviceName)));
    const resetAll = element('button', 'secondary danger-text', 'Gesamte Gestaltung entfernen');
    resetAll.type = 'button';
    resetAll.addEventListener('click', () => change(doc => clearStyle(doc, getSelection())));
    actions.append(resetDevice, resetAll);
    panel.append(actions);
  };

  function describe(property, value) {
    if (property.type === 'choice') return property.values[value] ?? value;
    return String(value);
  }
}