import {CCApi} from '../../common/api.js';
import {parseUrl} from '../../common/commonUtils.js';

export var avatars = {
  isFilterSetUp: false,
  privateForums: [],

  // Gets a list of private forums. If it is already cached, the cached list is
  // returned; otherwise it is also computed and cached.
  getPrivateForums() {
    return new Promise((resolve, reject) => {
      if (this.isFilterSetUp) return resolve(this.privateForums);

      if (!document.documentElement.hasAttribute('data-startup'))
        return reject('[threadListAvatars] Couldn\'t get startup data.');

      var startupData =
          JSON.parse(document.documentElement.getAttribute('data-startup'));
      var forums = startupData?.['1']?.['2'];
      if (forums === undefined)
        return reject(
            '[threadListAvatars] Couldn\'t retrieve forums from startup data.');

      for (var f of forums) {
        var forumId = f?.['2']?.['1']?.['1'];
        var forumVisibility = f?.['2']?.['18'];
        if (forumId === undefined || forumVisibility === undefined) {
          console.warn(
              '[threadListAvatars] Coudln\'t retrieve forum id and/or forum visibility for the following forum:',
              f);
          continue;
        }

        // forumVisibility's value 1 means "PUBLIC".
        if (forumVisibility != 1) this.privateForums.push(forumId);
      }

      // Forum 51488989 is marked as public but it is in fact private.
      this.privateForums.push('51488989');

      this.isFilterSetUp = true;
      return resolve(this.privateForums);
    });
  },

  // Some threads belong to private forums, and this feature will not be able to
  // get its avatars since it makes an anonymomus call to get the contents of
  // the thread.
  //
  // This function returns whether avatars should be retrieved depending on if
  // the thread belongs to a known private forum.
  shouldRetrieveAvatars(thread) {
    return this.getPrivateForums().then(privateForums => {
      return !privateForums.includes(thread.forum);
    });
  },

  // Get an object with the author of the thread and an array of the first |num|
  // replies from the thread |thread|.
  getFirstMessages(thread, num = 15) {
    return CCApi(
               'ViewThread', {
                 1: thread.forum,
                 2: thread.thread,
                 // options
                 3: {
                   // pagination
                   1: {
                     2: num,  // maxNum
                   },
                   3: true,    // withMessages
                   5: true,    // withUserProfile
                   10: false,  // withPromotedMessages
                   16: false,  // withThreadNotes
                   18: true,   // sendNewThreadIfMoved
                 }
               },
               // |authentication| is false because otherwise this would mark
               // the thread as read as a side effect, and that would mark all
               // threads in the list as read.
               //
               // Due to the fact that we have to call this endpoint
               // anonymously, this means we can't retrieve information about
               // threads in private forums.
               /* authentication = */ false)
        .then(data => {
          var numMessages = data?.['1']?.['8'];
          if (numMessages === undefined)
            throw new Error(
                'Request to view thread doesn\'t include the number of messages');

          var messages = numMessages == 0 ? [] : data?.['1']['3'];
          if (messages === undefined)
            throw new Error(
                'numMessages was ' + numMessages +
                ' but the response didn\'t include any message.');

          var author = data?.['1']?.['4'];
          if (author === undefined)
            throw new Error(
                'Author isn\'t included in the ViewThread response.');

          return {
            messages,
            author,
          };
        });
  },

  // Get a list of at most |num| avatars for thread |thread|
  getVisibleAvatars(thread, num = 3) {
    return this.shouldRetrieveAvatars(thread).then(shouldRetrieve => {
      if (!shouldRetrieve) {
        console.debug('[threadListAvatars] Skipping thread', thread);
        return [];
      }

      return this.getFirstMessages(thread).then(result => {
        var messages = result.messages;
        var author = result.author;

        var avatarUrls = [];

        var authorUrl = author?.['1']?.['2'];
        if (authorUrl !== undefined) avatarUrls.push(authorUrl);

        for (var m of messages) {
          var url = m?.['3']?.['1']?.['2'];

          if (url === undefined) continue;
          if (!avatarUrls.includes(url)) avatarUrls.push(url);
          if (avatarUrls.length == 3) break;
        }

        return avatarUrls;
      });
    });
  },

  // Inject avatars for thread summary (thread item) |node| in a thread list.
  inject(node) {
    var header = node.querySelector(
        'ec-thread-summary .main-header .panel-description a.header');
    if (header === null) {
      console.error(
          '[threadListAvatars] Header is not present in the thread item\'s DOM.');
      return;
    }

    var thread = parseUrl(header.href);
    if (thread === false) {
      console.error('[threadListAvatars] Thread\'s link cannot be parsed.');
      return;
    }

    this.getVisibleAvatars(thread)
        .then(avatarUrls => {
          var avatarsContainer = document.createElement('div');
          avatarsContainer.classList.add('TWPT-avatars');

          var count = Math.floor(Math.random() * 4);

          for (var i = 0; i < avatarUrls.length; ++i) {
            var avatar = document.createElement('div');
            avatar.classList.add('TWPT-avatar');
            avatar.style.backgroundImage = 'url(\'' + avatarUrls[i] + '\')';
            avatarsContainer.appendChild(avatar);
          }

          header.appendChild(avatarsContainer);
        })
        .catch(err => {
          console.error(
              '[threadListAvatars] Could not retrieve avatars for thread',
              thread, err);
        });
  },
};