import 'package:comunic/lists/groups_list.dart';
import 'package:comunic/models/advanced_group_info.dart';
import 'package:comunic/models/api_request.dart';
import 'package:comunic/models/group.dart';
import 'package:comunic/utils/api_utils.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();

/// Callback for getting advanced user information
enum GetAdvancedInfoStatus { SUCCESS, ACCESS_DENIED }

class GetAdvancedInfoResult {
  final GetAdvancedInfoStatus status;
  final AdvancedGroupInfo info;

  GetAdvancedInfoResult(this.status, this.info) : assert(status != null);
}

/// Groups helper
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 (!force && _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;
  }

  /// Get information about a single group
  ///
  /// Throws in case of failure
  Future<Group> getSingle(int groupID, {bool force = false}) async {
    return (await getListOrThrow(Set<int>()..add(groupID), force: force))
        .values
        .first;
  }

  /// Get the list of groups of a user
  Future<Set<int>> getListUser() async =>
      (await APIRequest(uri: "groups/get_my_list", needLogin: true).exec())
          .assertOk()
          .getArray()
          .map((f) => cast<int>(f))
          .toSet();

  /// Perform a simple membership request
  Future<bool> _simpleMembershipRequest(int groupID, String uri,
          {Map<String, String> args}) async =>
      (await (APIRequest(uri: uri, needLogin: true)
                ..addInt("id", groupID)
                ..addArgs(args == null ? Map() : args))
              .exec())
          .isOK;

  /// Remove group membership
  Future<bool> removeMembership(int groupID) async =>
      _simpleMembershipRequest(groupID, "groups/remove_membership");

  /// Cancel membership request
  Future<bool> cancelRequest(int groupID) async =>
      _simpleMembershipRequest(groupID, "groups/cancel_request");

  /// Send a new membership request
  Future<bool> sendRequest(int groupID) async =>
      _simpleMembershipRequest(groupID, "groups/send_request");

  /// Respond to a group membership invitation
  Future<bool> respondInvitation(int groupID, bool accept) async =>
      _simpleMembershipRequest(groupID, "groups/respond_invitation", args: {
        "accept": accept ? "true" : "false",
      });

  /// Update group following status
  Future<bool> setFollowing(int groupID, bool follow) async =>
      (await (APIRequest(uri: "groups/set_following", needLogin: true)
                ..addInt("groupID", groupID)
                ..addBool("follow", follow))
              .exec())
          .isOK;

  /// Get advanced information about the user
  Future<GetAdvancedInfoResult> getAdvancedInfo(int groupID) async {
    // Get advanced information about the user
    final result =
        await (APIRequest(uri: "groups/get_advanced_info", needLogin: true)
              ..addInt("id", groupID))
            .exec();

    switch (result.code) {
      case 401:
        return GetAdvancedInfoResult(GetAdvancedInfoStatus.ACCESS_DENIED, null);

      case 200:
        return GetAdvancedInfoResult(GetAdvancedInfoStatus.SUCCESS,
            _getAdvancedGroupInfoFromAPI(result.getObject()));

      default:
        throw Exception("Could not get advanced group information!");
    }
  }

  /// Get group settings
  ///
  /// This function is currently a kind of alias, but it might
  /// change in the future
  ///
  /// Throws in case of error
  Future<AdvancedGroupInfo> getSettings(int groupID) async {
    final groupInfo = await getAdvancedInfo(groupID);

    if (groupInfo.status != GetAdvancedInfoStatus.SUCCESS)
      throw Exception("Could not get group information!");

    return groupInfo.info;
  }

  /// Turn an API entry into a group object
  Group _getGroupFromAPI(Map<String, dynamic> map) {
    return Group(
        id: map["id"],
        name: map["name"],
        iconURL: map["icon_url"],
        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"]);
  }

  /// Get advanced group information
  AdvancedGroupInfo _getAdvancedGroupInfoFromAPI(Map<String, dynamic> map) =>
      AdvancedGroupInfo(
        id: map["id"],
        name: map["name"],
        iconURL: map["icon_url"],
        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"],
        timeCreate: map["time_create"],
        description: map["description"],
        url: map["url"],
        likes: map["number_likes"],
        userLike: map["is_liking"],
      );
}