"use strict";
/**
 * @module models/room
 */
var EventEmitter = require("events").EventEmitter;

var RoomState = require("./room-state");
var RoomSummary = require("./room-summary");
var utils = require("../utils");

/**
 * Construct a new Room.
 * @constructor
 * @param {string} roomId Required. The ID of this room.
 * @param {*} storageToken Optional. The token which a data store can use
 * to remember the state of the room. What this means is dependent on the store
 * implementation.
 * @prop {string} roomId The ID of this room.
 * @prop {string} name The human-readable display name for this room.
 * @prop {Array<MatrixEvent>} timeline The ordered list of message events for
 * this room.
 * @prop {RoomState} oldState The state of the room at the time of the oldest
 * event in the timeline.
 * @prop {RoomState} currentState The state of the room at the time of the
 * newest event in the timeline.
 * @prop {RoomSummary} summary The room summary.
 * @prop {*} storageToken A token which a data store can use to remember
 * the state of the room.
 */
function Room(roomId, storageToken) {
    this.roomId = roomId;
    this.name = roomId;
    this.timeline = [];
    this.oldState = new RoomState(roomId);
    this.currentState = new RoomState(roomId);
    this.summary = null;
    this.storageToken = storageToken;
    this._redactions = [];
}
utils.inherits(Room, EventEmitter);

/**
 * Get a member from the current room state.
 * @param {string} userId The user ID of the member.
 * @return {RoomMember} The member or <code>null</code>.
 */
 Room.prototype.getMember = function(userId) {
    var member = this.currentState.members[userId];
    if (!member) {
        return null;
    }
    return member;
 };

/**
 * Get a list of members whose membership state is "join".
 * @return {RoomMember[]} A list of currently joined members.
 */
 Room.prototype.getJoinedMembers = function() {
    return this.getMembersWithMemership("join");
 };

/**
 * Get a list of members with given membership state.
 * @param {string} membership The membership state.
 * @return {RoomMember[]} A list of members with the given membership state.
 */
 Room.prototype.getMembersWithMemership = function(membership) {
    return utils.filter(this.currentState.getMembers(), function(m) {
        return m.membership === membership;
    });
 };

 /**
 * Check if the given user_id has the given membership state.
 * @param {string} userId The user ID to check.
 * @param {string} membership The membership e.g. <code>'join'</code>
 * @return {boolean} True if this user_id has the given membership state.
 */
 Room.prototype.hasMembershipState = function(userId, membership) {
    return utils.filter(this.currentState.getMembers(), function(m) {
        return m.membership === membership && m.userId === userId;
    }).length > 0;
 };

/**
 * Add some events to this room's timeline. Will fire "Room.timeline" for
 * each event added.
 * @param {MatrixEvent[]} events A list of events to add.
 * @param {boolean} toStartOfTimeline True to add these events to the start
 * (oldest) instead of the end (newest) of the timeline. If true, the oldest
 * event will be the <b>last</b> element of 'events'.
 * @fires module:client~MatrixClient#event:"Room.timeline"
 */
Room.prototype.addEventsToTimeline = function(events, toStartOfTimeline) {
    var stateContext = toStartOfTimeline ? this.oldState : this.currentState;

    function checkForRedaction(redactEvent) {
        return function(e) {
            return e.getId() === redactEvent.event.redacts;
        };
    }

    for (var i = 0; i < events.length; i++) {
        if (toStartOfTimeline && this._redactions.indexOf(events[i].getId()) >= 0) {
            continue; // do not add the redacted event.
        }

        setEventMetadata(events[i], stateContext, toStartOfTimeline);
        // modify state
        if (events[i].isState()) {
            stateContext.setStateEvents([events[i]]);
            // it is possible that the act of setting the state event means we
            // can set more metadata (specifically sender/target props), so try
            // it again if the prop wasn't previously set.
            if (!events[i].sender) {
                setEventMetadata(events[i], stateContext, toStartOfTimeline);
            }
        }
        if (events[i].getType() === "m.room.redaction") {
            // try to remove the element
            var removed = utils.removeElement(
                this.timeline, checkForRedaction(events[i])
            );
            if (!removed && toStartOfTimeline) {
                // redactions will trickle in BEFORE the event redacted so make
                // a note of the redacted event; we'll check it later.
                this._redactions.push(events[i].event.redacts);
            }
            // NB: We continue to add the redaction event to the timeline so clients
            // can say "so and so redacted an event" if they wish to.
        }

        // TODO: pass through filter to see if this should be added to the timeline.
        if (toStartOfTimeline) {
            this.timeline.unshift(events[i]);
        }
        else {
            this.timeline.push(events[i]);
        }
        this.emit("Room.timeline", events[i], this, Boolean(toStartOfTimeline));
    }
};

/**
 * Add some events to this room. This can include state events, message
 * events and typing notifications. These events are treated as "live" so
 * they will go to the end of the timeline.
 * @param {MatrixEvent[]} events A list of events to add.
 * @param {string} duplicateStrategy Optional. Applies to events in the
 * timeline only. If this is not specified, no duplicate suppression is
 * performed (this improves performance). If this is 'replace' then if a
 * duplicate is encountered, the event passed to this function will replace the
 * existing event in the timeline. If this is 'ignore', then the event passed to
 * this function will be ignored entirely, preserving the existing event in the
 * timeline. Events are identical based on their event ID <b>only</b>.
 * @throws If <code>duplicateStrategy</code> is not falsey, 'replace' or 'ignore'.
 */
Room.prototype.addEvents = function(events, duplicateStrategy) {
    if (duplicateStrategy && ["replace", "ignore"].indexOf(duplicateStrategy) === -1) {
        throw new Error("duplicateStrategy MUST be either 'replace' or 'ignore'");
    }
    for (var i = 0; i < events.length; i++) {
        if (events[i].getType() === "m.typing") {
            this.currentState.setTypingEvent(events[i]);
        }
        else {
            if (duplicateStrategy) {
                // is there a duplicate?
                var shouldIgnore = false;
                for (var j = 0; j < this.timeline.length; j++) {
                    if (this.timeline[j].getId() === events[i].getId()) {
                        if (duplicateStrategy === "replace") {
                            // still need to set the right metadata on this event
                            setEventMetadata(
                                events[i],
                                this.currentState,
                                false
                            );
                            this.timeline[j] = events[i];
                            // skip the insert so we don't add this event twice.
                            // Don't break in case we replace multiple events.
                            shouldIgnore = true;
                        }
                        else if (duplicateStrategy === "ignore") {
                            shouldIgnore = true;
                            break; // stop searching, we're skipping the insert
                        }
                    }
                }
                if (shouldIgnore) {
                    continue; // skip the insertion of this event.
                }
            }
            // TODO: We should have a filter to say "only add state event
            // types X Y Z to the timeline".
            this.addEventsToTimeline([events[i]]);
        }
    }
};

/**
 * Recalculate various aspects of the room, including the room name and
 * room summary. Call this any time the room's current state is modified.
 * May fire "Room.name" if the room name is updated.
 * @param {string} userId The client's user ID.
 * @fires module:client~MatrixClient#event:"Room.name"
 */
Room.prototype.recalculate = function(userId) {
    var oldName = this.name;
    this.name = calculateRoomName(this, userId);
    this.summary = new RoomSummary(this.roomId, {
        title: this.name
    });

    if (oldName !== this.name) {
        this.emit("Room.name", this);
    }
};

function setEventMetadata(event, stateContext, toStartOfTimeline) {
    // set sender and target properties
    event.sender = stateContext.getSentinelMember(
        event.getSender()
    );
    if (event.getType() === "m.room.member") {
        event.target = stateContext.getSentinelMember(
            event.getStateKey()
        );
    }
    if (event.isState()) {
        // room state has no concept of 'old' or 'current', but we want the
        // room state to regress back to previous values if toStartOfTimeline
        // is set, which means inspecting prev_content if it exists. This
        // is done by toggling the forwardLooking flag.
        if (toStartOfTimeline) {
            event.forwardLooking = false;
        }
    }
}

/**
 * This is an internal method. Calculates the name of the room from the current
 * room state.
 * @param {Room} room The matrix room.
 * @param {string} userId The client's user ID. Used to filter room members
 * correctly.
 * @return {string} The calculated room name.
 */
function calculateRoomName(room, userId) {
    // check for an alias, if any. for now, assume first alias is the
    // official one.
    var alias;
    var mRoomAliases = room.currentState.getStateEvents("m.room.aliases")[0];
    if (mRoomAliases && utils.isArray(mRoomAliases.getContent().aliases)) {
        alias = mRoomAliases.getContent().aliases[0];
    }

    var mRoomName = room.currentState.getStateEvents('m.room.name', '');
    if (mRoomName) {
        return mRoomName.getContent().name + (false && alias ? " (" + alias + ")" : "");
    }
    else if (alias) {
        return alias;
    }
    else {
        // get members that are NOT ourselves and are actually in the room.
        var members = utils.filter(room.currentState.getMembers(), function(m) {
            return (m.userId !== userId && m.membership !== "leave");
        });
        // TODO: Localisation
        if (members.length === 0) {
            var memberList = utils.filter(room.currentState.getMembers(), function(m) {
                return (m.membership !== "leave");
            });
            if (memberList.length === 1) {
                // we exist, but no one else... self-chat or invite.
                if (memberList[0].membership === "invite") {
                    return "Room Invite";
                }
                else {
                    return userId;
                }
            }
            else {
                // there really isn't anyone in this room...
                return "?";
            }
        }
        else if (members.length === 1) {
            return members[0].name;
        }
        else if (members.length === 2) {
            return (
                members[0].name + " and " + members[1].name
            );
        }
        else {
            return (
                members[0].name + " and " + (members.length - 1) + " others"
            );
        }
    }
}

/**
 * The Room class.
 */
module.exports = Room;

/**
 * Fires whenever the timeline in a room is updated.
 * @event module:client~MatrixClient#"Room.timeline"
 * @param {MatrixEvent} event The matrix event which caused this event to fire.
 * @param {Room} room The room whose Room.timeline was updated.
 * @param {boolean} toStartOfTimeline True if this event was added to the start
 * (beginning; oldest) of the timeline e.g. due to pagination.
 * @example
 * matrixClient.on("Room.timeline", function(event, room, toStartOfTimeline){
 *   if (toStartOfTimeline) {
 *     var messageToAppend = room.timeline[room.timeline.length - 1];
 *   }
 * });
 */

/**
 * Fires whenever the name of a room is updated.
 * @event module:client~MatrixClient#"Room.name"
 * @param {Room} room The room whose Room.name was updated.
 * @example
 * matrixClient.on("Room.name", function(room){
 *   var newName = room.name;
 * });
 */