import 'package:comunic/lists/groups_list.dart';
import 'package:comunic/models/api_request.dart';
import 'package:comunic/models/group.dart';

/// Groups helper
///
/// @author Pierre HUBERT

const _APIGroupsMembershipLevelsMap = {
  "administrator": GroupMembershipLevel.ADMINISTRATOR,
  "moderator": GroupMembershipLevel.MODERATOR,
  "member": GroupMembershipLevel.MEMBER,
  "invited": GroupMembershipLevel.INVITED,
  "pending": GroupMembershipLevel.PENDING,
  "visitor": GroupMembershipLevel.VISITOR
};

const _APIGroupsVisibilityLevelsMap = {
  "open": GroupVisibilityLevel.OPEN,
  "private": GroupVisibilityLevel.PRIVATE,
  "secrete": GroupVisibilityLevel.SECRETE
};

const _APIGroupsRegistrationLevelsMap = {
  "open": GroupRegistrationLevel.OPEN,
  "moderated": GroupRegistrationLevel.MODERATED,
  "closed": GroupRegistrationLevel.CLOSED
};

const _APIGroupsPostsCreationLevelsMap = {
  "moderators": GroupPostCreationLevel.MODERATORS,
  "members": GroupPostCreationLevel.MEMBERS
};

final _groupsListCache = GroupsList();

class GroupsHelper {
  /// Download a list of groups information from the server
  Future<GroupsList> _downloadList(Set<int> groups) async {
    final response = await APIRequest(
      uri: "groups/get_multiple_info",
      needLogin: true,
      args: {"list": groups.join(",")},
    ).exec();

    if (response.code != 200) return null;

    final list = GroupsList();

    response
        .getObject()
        .forEach((k, d) => list[int.parse(k)] = _getGroupFromAPI(d));

    return list;
  }

  /// Get a list of groups from the server. In case of error, this method throws
  /// an exception
  Future<GroupsList> getListOrThrow(Set<int> groups,
      {bool force = false}) async {
    final list = await getList(groups, force: force);

    if (list == null) throw Exception("Could not get the list of groups!");

    return list;
  }

  /// Get a list of groups from the server
  Future<GroupsList> getList(Set<int> groups, {bool force = false}) async {
    final list = GroupsList();

    // Check which groups information to download
    final toDownload = Set<int>();
    groups.forEach((groupID) {
      if (_groupsListCache.containsKey(groupID))
        list[groupID] = _groupsListCache[groupID];
      else
        toDownload.add(groupID);
    });

    // Download required groups information
    if (toDownload.length > 0) {
      final downloaded = await _downloadList(toDownload);

      if (downloaded == null) return null;

      list.addAll(downloaded);
      _groupsListCache.addAll(downloaded);
    }

    return list;
  }

  /// Turn an API entry into a group object
  Group _getGroupFromAPI(Map<String, dynamic> map) {
    return Group(
        id: map["id"],
        name: map["name"],
        numberMembers: map["number_members"],
        membershipLevel: _APIGroupsMembershipLevelsMap[map["membership"]],
        visibilityLevel: _APIGroupsVisibilityLevelsMap[map["visibility"]],
        registrationLevel:
            _APIGroupsRegistrationLevelsMap[map["registration_level"]],
        postCreationLevel: _APIGroupsPostsCreationLevelsMap[map["posts_level"]],
        virtualDirectory: map["virtual_directory"],
        following: map["following"]);
  }
}