/*
Copyright 2015, 2016 OpenMarket Ltd

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

import MatrixClientPeg from './MatrixClientPeg';
import Promise from 'bluebird';

/**
 * Given a room object, return the alias we should use for it,
 * if any. This could be the canonical alias if one exists, otherwise
 * an alias selected arbitrarily but deterministically from the list
 * of aliases. Otherwise return null;
 */
export function getDisplayAliasForRoom(room) {
    return room.getCanonicalAlias() || room.getAliases()[0];
}

/**
 * If the room contains only two members including the logged-in user,
 * return the other one. Otherwise, return null.
 */
export function getOnlyOtherMember(room, myUserId) {

    if (room.currentState.getJoinedMemberCount() === 2) {
        return room.getJoinedMembers().filter(function(m) {
            return m.userId !== myUserId;
        })[0];
    }

    return null;
}

function _isConfCallRoom(room, myUserId, conferenceHandler) {
    if (!conferenceHandler) return false;

    const myMembership = room.getMyMembership();
    if (myMembership != "join") {
        return false;
    }

    const otherMember = getOnlyOtherMember(room, myUserId);
    if (!otherMember) {
        return false;
    }

    if (conferenceHandler.isConferenceUser(otherMember.userId)) {
        return true;
    }

    return false;
}

// Cache whether a room is a conference call. Assumes that rooms will always
// either will or will not be a conference call room.
const isConfCallRoomCache = {
    // $roomId: bool
};

export function isConfCallRoom(room, myUserId, conferenceHandler) {
    if (isConfCallRoomCache[room.roomId] !== undefined) {
        return isConfCallRoomCache[room.roomId];
    }

    const result = _isConfCallRoom(room, myUserId, conferenceHandler);

    isConfCallRoomCache[room.roomId] = result;

    return result;
}

export function looksLikeDirectMessageRoom(room, myUserId) {
    const myMembership = room.getMyMembership();
    const me = room.getMember(myUserId);

    if (myMembership == "join" || myMembership === "ban" || (me && me.isKicked())) {
        // Used to split rooms via tags
        const tagNames = Object.keys(room.tags);
        // Used for 1:1 direct chats
        // Show 1:1 chats in seperate "Direct Messages" section as long as they haven't
        // been moved to a different tag section
        const totalMemberCount = room.currentState.getJoinedMemberCount() +
            room.currentState.getInvitedMemberCount();
        if (totalMemberCount === 2 && !tagNames.length) {
            return true;
        }
    }
    return false;
}

export function guessAndSetDMRoom(room, isDirect) {
    let newTarget;
    if (isDirect) {
        const guessedUserId = guessDMRoomTargetId(
            room, MatrixClientPeg.get().getUserId()
        );
        newTarget = guessedUserId;
    } else {
        newTarget = null;
    }

    return setDMRoom(room.roomId, newTarget);
}

/**
 * Marks or unmarks the given room as being as a DM room.
 * @param {string} roomId The ID of the room to modify
 * @param {string} userId The user ID of the desired DM
                   room target user or null to un-mark
                   this room as a DM room
 * @returns {object} A promise
 */
export function setDMRoom(roomId, userId) {
    if (MatrixClientPeg.get().isGuest()) {
        return Promise.resolve();
    }

    const mDirectEvent = MatrixClientPeg.get().getAccountData('m.direct');
    let dmRoomMap = {};

    if (mDirectEvent !== undefined) dmRoomMap = mDirectEvent.getContent();

    // remove it from the lists of any others users
    // (it can only be a DM room for one person)
    for (const thisUserId of Object.keys(dmRoomMap)) {
        const roomList = dmRoomMap[thisUserId];

        if (thisUserId != userId) {
            const indexOfRoom = roomList.indexOf(roomId);
            if (indexOfRoom > -1) {
                roomList.splice(indexOfRoom, 1);
            }
        }
    }

    // now add it, if it's not already there
    if (userId) {
        const roomList = dmRoomMap[userId] || [];
        if (roomList.indexOf(roomId) == -1) {
            roomList.push(roomId);
        }
        dmRoomMap[userId] = roomList;
    }


    return MatrixClientPeg.get().setAccountData('m.direct', dmRoomMap);
}

/**
 * Given a room, estimate which of its members is likely to
 * be the target if the room were a DM room and return that user.
 */
function guessDMRoomTargetId(room, myUserId) {
    let oldestTs;
    let oldestUser;

    // Pick the joined user who's been here longest (and isn't us),
    for (const user of room.getJoinedMembers()) {
        if (user.userId == myUserId) continue;

        if (oldestTs === undefined || (user.events.member && user.events.member.getTs() < oldestTs)) {
            oldestUser = user;
            oldestTs = user.events.member.getTs();
        }
    }
    if (oldestUser) return oldestUser;

    // if there are no joined members other than us, use the oldest member
    for (const user of room.currentState.getMembers()) {
        if (user.userId == myUserId) continue;

        if (oldestTs === undefined || (user.events.member && user.events.member.getTs() < oldestTs)) {
            oldestUser = user;
            oldestTs = user.events.member.getTs();
        }
    }

    if (oldestUser === undefined) return myUserId;
    return oldestUser;
}