import type { IGrantedGroup, IUser } from '@growi/core';
import type { DeleteResult } from 'mongodb';
import mongoose, { type Model } from 'mongoose';

import type { PageActionOnGroupDelete } from '~/interfaces/user-group';
import type { ObjectIdLike } from '~/server/interfaces/mongoose-utils';
import type {
  UserGroupDocument,
  UserGroupModel,
} from '~/server/models/user-group';
import UserGroup from '~/server/models/user-group';
import {
  excludeTestIdsFromTargetIds,
  includesObjectIds,
} from '~/server/util/compare-objectId';
import loggerFactory from '~/utils/logger';

import type Crowi from '../crowi';
import type {
  UserGroupRelationDocument,
  UserGroupRelationModel,
} from '../models/user-group-relation';
import UserGroupRelation from '../models/user-group-relation';

const logger = loggerFactory('growi:service:UserGroupService');

export interface IUserGroupService {
  init(): Promise<void>;
  updateGroup(
    id: ObjectIdLike,
    name?: string,
    description?: string,
    parentId?: ObjectIdLike | null,
    forceUpdateParents?: boolean,
  ): Promise<UserGroupDocument>;
  removeCompletelyByRootGroupId(
    deleteRootGroupId: ObjectIdLike,
    action: string,
    user: IUser,
    transferToUserGroup?: IGrantedGroup,
  ): Promise<DeleteResult>;
  removeUserByUsername(
    userGroupId: ObjectIdLike,
    username: string,
  ): Promise<{ user: IUser; deletedGroupsCount: number }>;
}

/**
 * the service class of UserGroupService
 */
class UserGroupService implements IUserGroupService {
  crowi: Crowi;

  constructor(crowi: Crowi) {
    this.crowi = crowi;
  }

  async init(): Promise<void> {
    logger.debug('removing all invalid relations');
    return UserGroupRelation.removeAllInvalidRelations();
  }

  // ref: https://dev.growi.org/61b2cdabaa330ce7d8152844
  async updateGroup(
    id,
    name?: string,
    description?: string,
    parentId?: string | null,
    forceUpdateParents = false,
  ): Promise<UserGroupDocument> {
    const userGroup = await UserGroup.findById(id);
    if (userGroup == null) {
      throw new Error('The group does not exist');
    }

    // check if the new group name is available
    const isExist = (await UserGroup.countDocuments({ name })) > 0;
    if (userGroup.name !== name && isExist) {
      throw new Error('The group name is already taken');
    }

    if (name != null) {
      userGroup.name = name;
    }
    if (description != null) {
      userGroup.description = description;
    }

    // return when not update parent
    if (userGroup.parent === parentId) {
      return userGroup.save();
    }

    /*
     * Update parent
     */
    if (parentId === undefined) {
      // undefined will be ignored
      return userGroup.save();
    }

    // set parent to null and return when parentId is null
    if (parentId == null) {
      userGroup.parent = null;
      return userGroup.save();
    }

    const parent = await UserGroup.findById(parentId);

    if (parent == null) {
      // it should not be null
      throw Error('Parent group does not exist.');
    }

    /*
     * check if able to update parent or not
     */

    // throw if parent was in self and its descendants
    const descendantsWithTarget =
      await UserGroup.findGroupsWithDescendantsRecursively([userGroup]);
    if (
      includesObjectIds(
        descendantsWithTarget.map((d) => d._id),
        [parent._id],
      )
    ) {
      throw Error('It is not allowed to choose parent from descendant groups.');
    }

    // find users for comparison
    const [targetGroupUsers, parentGroupUsers] = await Promise.all([
      UserGroupRelation.findUserIdsByGroupId(userGroup._id),
      UserGroupRelation.findUserIdsByGroupId(parent._id),
    ]);
    const usersBelongsToTargetButNotParent = excludeTestIdsFromTargetIds(
      targetGroupUsers,
      parentGroupUsers,
    );

    // save if no users exist in both target and parent groups
    if (targetGroupUsers.length === 0 && parentGroupUsers.length === 0) {
      userGroup.parent = parent._id;
      return userGroup.save();
    }

    // add the target group's users to all ancestors
    if (forceUpdateParents) {
      const ancestorGroups =
        await UserGroup.findGroupsWithAncestorsRecursively(parent);
      const ancestorGroupIds = ancestorGroups.map((group) => group._id);

      await UserGroupRelation.createByGroupIdsAndUserIds(
        ancestorGroupIds,
        usersBelongsToTargetButNotParent,
      );
    }
    // throw if any of users in the target group is NOT included in the parent group
    else {
      const isUpdatable = usersBelongsToTargetButNotParent.length === 0;
      if (!isUpdatable) {
        throw Error(
          'The parent group does not contain the users in this group.',
        );
      }
    }

    userGroup.parent = parent._id;
    return userGroup.save();
  }

  async removeCompletelyByRootGroupId(
    deleteRootGroupId,
    action: PageActionOnGroupDelete,
    user,
    transferToUserGroup?: IGrantedGroup,
    userGroupModel: Model<UserGroupDocument> & UserGroupModel = UserGroup,
    userGroupRelationModel: Model<UserGroupRelationDocument> &
      UserGroupRelationModel = UserGroupRelation,
  ): Promise<DeleteResult> {
    const rootGroup = await userGroupModel.findById(deleteRootGroupId);
    if (rootGroup == null) {
      throw new Error(
        `UserGroup data does not exist. id: ${deleteRootGroupId}`,
      );
    }

    const groupsToDelete =
      await userGroupModel.findGroupsWithDescendantsRecursively([rootGroup]);

    // 1. update page & remove all groups
    await this.crowi.pageService.handlePrivatePagesForGroupsToDelete(
      groupsToDelete,
      action,
      transferToUserGroup,
      user,
    );
    // 2. remove all groups
    const deletedGroups = await userGroupModel.deleteMany({
      _id: { $in: groupsToDelete.map((g) => g._id) },
    });
    // 3. remove all relations
    await userGroupRelationModel.removeAllByUserGroups(groupsToDelete);

    return deletedGroups;
  }

  async removeUserByUsername(
    userGroupId: ObjectIdLike,
    username: string,
  ): Promise<{ user: IUser; deletedGroupsCount: number }> {
    const User = mongoose.model<IUser, { findUserByUsername }>('User');

    const [userGroup, user] = await Promise.all([
      UserGroup.findById(userGroupId),
      User.findUserByUsername(username),
    ]);

    const groupsOfRelationsToDelete =
      userGroup != null
        ? await UserGroup.findGroupsWithDescendantsRecursively([userGroup])
        : [];
    const relatedGroupIdsToDelete = groupsOfRelationsToDelete.map((g) => g._id);

    const deleteManyRes = await UserGroupRelation.deleteMany({
      relatedUser: user._id,
      relatedGroup: { $in: relatedGroupIdsToDelete },
    });

    return { user, deletedGroupsCount: deleteManyRes.deletedCount };
  }
}

export default UserGroupService;