import { h } from 'virtual-dom';
let _renderers = [];

const REPLACEMENTS = {
  'd-tracking': 'circle',
  'd-muted': 'times-circle',
  'd-regular': 'circle-o',
  'd-watching': 'exclamation-circle',
  'd-watching-first': 'dot-circle-o',
  'd-drop-expanded': 'caret-down',
  'd-drop-collapsed': 'caret-right',
  'd-unliked': 'heart-o',
  'd-liked': 'heart',
  'notification.mentioned': "at",
  'notification.group_mentioned': "at",
  'notification.quoted': "quote-right",
  'notification.replied': "reply",
  'notification.posted': "reply",
  'notification.edited': "pencil",
  'notification.liked': "heart",
  'notification.liked_2': "heart",
  'notification.liked_many': "heart",
  'notification.private_message': "envelope-o",
  'notification.invited_to_private_message': "envelope-o",
  'notification.invited_to_topic': "hand-o-right",
  'notification.invitee_accepted': "user",
  'notification.moved_post': "sign-out",
  'notification.linked': "link",
  'notification.granted_badge': "certificate",
  'notification.topic_reminder': "hand-o-right",
  'notification.watching_first_post': "dot-circle-o",
  'notification.group_message_summary': "group"
};

export function replaceIcon(source, destination) {
  REPLACEMENTS[source] = destination;
}

export function renderIcon(renderType, id, params) {
  for (let i=0; i<_renderers.length; i++) {
    let renderer = _renderers[i];
    let rendererForType = renderer[renderType];

    if (rendererForType) {
      const icon = { id, replacementId: REPLACEMENTS[id] };
      let result = rendererForType(icon, params || {});
      if (result) {
        return result;
      }
    }
  }
}

export function iconHTML(id, params) {
  return renderIcon('string', id, params);
}

export function iconNode(id, params) {
  return renderIcon('node', id, params);
}

// TODO: Improve how helpers are registered for vdom compliation
if (typeof Discourse !== "undefined") {
  Discourse.__widget_helpers.iconNode = iconNode;
}

export function registerIconRenderer(renderer) {
  _renderers.unshift(renderer);
}

// Support for font awesome icons
function faClasses(icon, params) {
  let classNames = `fa fa-${icon.replacementId || icon.id} d-icon d-icon-${icon.id}`;

  if (params) {
    if (params.modifier) { classNames += " fa-" + params.modifier; }
    if (params['class']) { classNames += ' ' + params['class']; }
  }
  return classNames;
}

// default resolver is font awesome
registerIconRenderer({
  name: 'font-awesome',

  string(icon, params) {
    let tagName = params.tagName || 'i';
    let html = `<${tagName} class='${faClasses(icon, params)}'`;
    if (params.title) { html += ` title='${I18n.t(params.title)}'`; }
    if (params.label) { html += " aria-hidden='true'"; }
    html += `></${tagName}>`;
    if (params.label) {
      html += `<span class='sr-only'>${params.label}</span>`;
    }
    return html;
  },

  node(icon, params) {
    let tagName = params.tagName || 'i';

    const properties = {
      className: faClasses(icon, params),
      attributes: { "aria-hidden": true }
    };

    if (params.title) { properties.attributes.title = params.title; }
    if (params.label) {
      return h(tagName, properties, h('span.sr-only', I18n.t(params.label)));
    } else {
      return h(tagName, properties);
    }
  }
});