/*---------------------------------------------------------------------------------------------
 *  Copyright (c) Microsoft Corporation. All rights reserved.
 *  Licensed under the MIT License. See License.txt in the project root for license information.
 *--------------------------------------------------------------------------------------------*/

import { ThemeIcon } from '../../../../vs/platform/theme/common/themeService';
import {
  getIconRegistry,
  IconContribution,
  IconFontContribution,
} from '../../../../vs/platform/theme/common/iconRegistry';
import { asCSSPropertyValue, asCSSUrl } from '../../../../vs/base/browser/dom';
import { Event, Emitter } from '../../../../vs/base/common/event';

export interface IIconsStyleSheet {
  getCSS(): string;
  readonly onDidChange: Event<void>;
}

export function getIconsStyleSheet(): IIconsStyleSheet {
  const onDidChangeEmmiter = new Emitter<void>();
  const iconRegistry = getIconRegistry();
  iconRegistry.onDidChange(() => onDidChangeEmmiter.fire());

  return {
    onDidChange: onDidChangeEmmiter.event,
    getCSS() {
      const usedFontIds: { [id: string]: IconFontContribution } = {};
      const formatIconRule = (
        contribution: IconContribution
      ): string | undefined => {
        let definition = contribution.defaults;
        while (ThemeIcon.isThemeIcon(definition)) {
          const c = iconRegistry.getIcon(definition.id);
          if (!c) {
            return undefined;
          }
          definition = c.defaults;
        }
        const fontId = definition.fontId;
        if (fontId) {
          const fontContribution = iconRegistry.getIconFont(fontId);
          if (fontContribution) {
            usedFontIds[fontId] = fontContribution;
            return `.codicon-${contribution.id}:before { content: '${
              definition.fontCharacter
            }'; font-family: ${asCSSPropertyValue(fontId)}; }`;
          }
        }
        return `.codicon-${contribution.id}:before { content: '${definition.fontCharacter}'; }`;
      };

      const rules = [];
      for (let contribution of iconRegistry.getIcons()) {
        const rule = formatIconRule(contribution);
        if (rule) {
          rules.push(rule);
        }
      }
      for (let id in usedFontIds) {
        const fontContribution = usedFontIds[id];
        const src = fontContribution.definition.src
          .map((l) => `${asCSSUrl(l.location)} format('${l.format}')`)
          .join(', ');
        rules.push(
          `@font-face { src: ${src}; font-family: ${asCSSPropertyValue(id)}; }`
        );
      }
      return rules.join('\n');
    },
  };
}