/*
Copyright 2017 Vector Creations Ltd
Copyright 2017, 2018 New Vector Ltd
Copyright 2019 - 2022 The Matrix.org Foundation C.I.C.

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 React, { ReactNode } from "react";
import { Store } from 'flux/utils';
import { MatrixError } from "matrix-js-sdk/src/http-api";
import { logger } from "matrix-js-sdk/src/logger";
import { ViewRoom as ViewRoomEvent } from "@matrix-org/analytics-events/types/typescript/ViewRoom";
import { JoinedRoom as JoinedRoomEvent } from "@matrix-org/analytics-events/types/typescript/JoinedRoom";
import { JoinRule } from "matrix-js-sdk/src/@types/partials";
import { Room } from "matrix-js-sdk/src/models/room";
import { ClientEvent } from "matrix-js-sdk/src/client";
import { MatrixEvent } from "matrix-js-sdk/src/models/event";
import { Optional } from "matrix-events-sdk";

import dis from '../dispatcher/dispatcher';
import { MatrixClientPeg } from '../MatrixClientPeg';
import Modal from '../Modal';
import { _t } from '../languageHandler';
import { getCachedRoomIDForAlias, storeRoomAliasInCache } from '../RoomAliasCache';
import { ActionPayload } from "../dispatcher/payloads";
import { Action } from "../dispatcher/actions";
import { retry } from "../utils/promise";
import { TimelineRenderingType } from "../contexts/RoomContext";
import { PosthogAnalytics } from "../PosthogAnalytics";
import { ViewRoomPayload } from "../dispatcher/payloads/ViewRoomPayload";
import DMRoomMap from "../utils/DMRoomMap";
import SpaceStore from "./spaces/SpaceStore";
import { isMetaSpace, MetaSpace } from "./spaces";
import { JoinRoomPayload } from "../dispatcher/payloads/JoinRoomPayload";
import { JoinRoomReadyPayload } from "../dispatcher/payloads/JoinRoomReadyPayload";
import { JoinRoomErrorPayload } from "../dispatcher/payloads/JoinRoomErrorPayload";
import { ViewRoomErrorPayload } from "../dispatcher/payloads/ViewRoomErrorPayload";
import ErrorDialog from "../components/views/dialogs/ErrorDialog";
import { ActiveRoomChangedPayload } from "../dispatcher/payloads/ActiveRoomChangedPayload";

const NUM_JOIN_RETRY = 5;

const INITIAL_STATE = {
    // Whether we're joining the currently viewed room (see isJoining())
    joining: false,
    // Any error that has occurred during joining
    joinError: null as Error,
    // The room ID of the room currently being viewed
    roomId: null as string,

    // The event to scroll to when the room is first viewed
    initialEventId: null as string,
    initialEventPixelOffset: null as number,
    // Whether to highlight the initial event
    isInitialEventHighlighted: false,
    // whether to scroll `event_id` into view
    initialEventScrollIntoView: true,

    // The room alias of the room (or null if not originally specified in view_room)
    roomAlias: null as string,
    // Whether the current room is loading
    roomLoading: false,
    // Any error that has occurred during loading
    roomLoadError: null as MatrixError,

    replyingToEvent: null as MatrixEvent,

    shouldPeek: false,

    viaServers: [] as string[],

    wasContextSwitch: false,
};

type Listener = (isActive: boolean) => void;

/**
 * A class for storing application state for RoomView. This is the RoomView's interface
*  with a subset of the js-sdk.
 *  ```
 */
export class RoomViewStore extends Store<ActionPayload> {
    // Important: This cannot be a dynamic getter (lazily-constructed instance) because
    // otherwise we'll miss view_room dispatches during startup, breaking relaunches of
    // the app. We need to eagerly create the instance.
    public static readonly instance = new RoomViewStore();

    private state = INITIAL_STATE; // initialize state

    // Keep these out of state to avoid causing excessive/recursive updates
    private roomIdActivityListeners: Record<string, Listener[]> = {};

    public constructor() {
        super(dis);
    }

    public addRoomListener(roomId: string, fn: Listener): void {
        if (!this.roomIdActivityListeners[roomId]) this.roomIdActivityListeners[roomId] = [];
        this.roomIdActivityListeners[roomId].push(fn);
    }

    public removeRoomListener(roomId: string, fn: Listener): void {
        if (this.roomIdActivityListeners[roomId]) {
            const i = this.roomIdActivityListeners[roomId].indexOf(fn);
            if (i > -1) {
                this.roomIdActivityListeners[roomId].splice(i, 1);
            }
        } else {
            logger.warn("Unregistering unrecognised listener (roomId=" + roomId + ")");
        }
    }

    private emitForRoom(roomId: string, isActive: boolean): void {
        if (!this.roomIdActivityListeners[roomId]) return;

        for (const fn of this.roomIdActivityListeners[roomId]) {
            fn.call(null, isActive);
        }
    }

    private setState(newState: Partial<typeof INITIAL_STATE>): void {
        // If values haven't changed, there's nothing to do.
        // This only tries a shallow comparison, so unchanged objects will slip
        // through, but that's probably okay for now.
        let stateChanged = false;
        for (const key of Object.keys(newState)) {
            if (this.state[key] !== newState[key]) {
                stateChanged = true;
                break;
            }
        }
        if (!stateChanged) {
            return;
        }

        const lastRoomId = this.state.roomId;
        this.state = Object.assign(this.state, newState);
        if (lastRoomId !== this.state.roomId) {
            if (lastRoomId) this.emitForRoom(lastRoomId, false);
            if (this.state.roomId) this.emitForRoom(this.state.roomId, true);

            // Fired so we can reduce dependency on event emitters to this store, which is relatively
            // central to the application and can easily cause import cycles.
            dis.dispatch<ActiveRoomChangedPayload>({
                action: Action.ActiveRoomChanged,
                oldRoomId: lastRoomId,
                newRoomId: this.state.roomId,
            });
        }

        this.__emitChange();
    }

    protected __onDispatch(payload): void { // eslint-disable-line @typescript-eslint/naming-convention
        switch (payload.action) {
            // view_room:
            //      - room_alias:   '#somealias:matrix.org'
            //      - room_id:      '!roomid123:matrix.org'
            //      - event_id:     '$213456782:matrix.org'
            //      - event_offset: 100
            //      - highlighted:  true
            case Action.ViewRoom:
                this.viewRoom(payload);
                break;
            // for these events blank out the roomId as we are no longer in the RoomView
            case 'view_welcome_page':
            case Action.ViewHomePage:
                this.setState({
                    roomId: null,
                    roomAlias: null,
                    viaServers: [],
                    wasContextSwitch: false,
                });
                break;
            case Action.ViewRoomError:
                this.viewRoomError(payload);
                break;
            case 'will_join':
                this.setState({
                    joining: true,
                });
                break;
            case 'cancel_join':
                this.setState({
                    joining: false,
                });
                break;
            // join_room:
            //      - opts: options for joinRoom
            case Action.JoinRoom:
                this.joinRoom(payload);
                break;
            case Action.JoinRoomError:
                this.joinRoomError(payload);
                break;
            case Action.JoinRoomReady: {
                if (this.state.roomId === payload.roomId) {
                    this.setState({ shouldPeek: false });
                }

                const cli = MatrixClientPeg.get();

                const updateMetrics = () => {
                    const room = cli.getRoom(payload.roomId);
                    const numMembers = room.getJoinedMemberCount();
                    const roomSize = numMembers > 1000 ? "MoreThanAThousand"
                        : numMembers > 100 ? "OneHundredAndOneToAThousand"
                            : numMembers > 10 ? "ElevenToOneHundred"
                                : numMembers > 2 ? "ThreeToTen"
                                    : numMembers > 1 ? "Two"
                                        : "One";

                    PosthogAnalytics.instance.trackEvent<JoinedRoomEvent>({
                        eventName: "JoinedRoom",
                        trigger: payload.metricsTrigger,
                        roomSize,
                        isDM: !!DMRoomMap.shared().getUserIdForRoomId(room.roomId),
                        isSpace: room.isSpaceRoom(),
                    });

                    cli.off(ClientEvent.Room, updateMetrics);
                };

                if (cli.getRoom(payload.roomId)) {
                    updateMetrics();
                } else {
                    cli.on(ClientEvent.Room, updateMetrics);
                }

                break;
            }
            case 'on_client_not_viable':
            case Action.OnLoggedOut:
                this.reset();
                break;
            case 'reply_to_event':
                // If currently viewed room does not match the room in which we wish to reply then change rooms
                // this can happen when performing a search across all rooms. Persist the data from this event for
                // both room and search timeline rendering types, search will get auto-closed by RoomView at this time.
                if ([TimelineRenderingType.Room, TimelineRenderingType.Search].includes(payload.context)) {
                    if (payload.event && payload.event.getRoomId() !== this.state.roomId) {
                        dis.dispatch<ViewRoomPayload>({
                            action: Action.ViewRoom,
                            room_id: payload.event.getRoomId(),
                            replyingToEvent: payload.event,
                            metricsTrigger: undefined, // room doesn't change
                        });
                    } else {
                        this.setState({
                            replyingToEvent: payload.event,
                        });
                    }
                }
                break;
        }
    }

    private async viewRoom(payload: ViewRoomPayload): Promise<void> {
        if (payload.room_id) {
            if (payload.metricsTrigger !== null && payload.room_id !== this.state.roomId) {
                let activeSpace: ViewRoomEvent["activeSpace"];
                if (SpaceStore.instance.activeSpace === MetaSpace.Home) {
                    activeSpace = "Home";
                } else if (isMetaSpace(SpaceStore.instance.activeSpace)) {
                    activeSpace = "Meta";
                } else {
                    activeSpace = SpaceStore.instance.activeSpaceRoom.getJoinRule() === JoinRule.Public
                        ? "Public"
                        : "Private";
                }

                PosthogAnalytics.instance.trackEvent<ViewRoomEvent>({
                    eventName: "ViewRoom",
                    trigger: payload.metricsTrigger,
                    viaKeyboard: payload.metricsViaKeyboard,
                    isDM: !!DMRoomMap.shared().getUserIdForRoomId(payload.room_id),
                    isSpace: MatrixClientPeg.get().getRoom(payload.room_id)?.isSpaceRoom(),
                    activeSpace,
                });
            }

            const newState = {
                roomId: payload.room_id,
                roomAlias: payload.room_alias,
                initialEventId: payload.event_id,
                isInitialEventHighlighted: payload.highlighted,
                initialEventScrollIntoView: payload.scroll_into_view ?? true,
                roomLoading: false,
                roomLoadError: null,
                // should peek by default
                shouldPeek: payload.should_peek === undefined ? true : payload.should_peek,
                // have we sent a join request for this room and are waiting for a response?
                joining: payload.joining || false,
                // Reset replyingToEvent because we don't want cross-room because bad UX
                replyingToEvent: null,
                viaServers: payload.via_servers,
                wasContextSwitch: payload.context_switch,
            };

            // Allow being given an event to be replied to when switching rooms but sanity check its for this room
            if (payload.replyingToEvent?.getRoomId() === payload.room_id) {
                newState.replyingToEvent = payload.replyingToEvent;
            } else if (this.state.roomId === payload.room_id) {
                // if the room isn't being changed, e.g visiting a permalink then maintain replyingToEvent
                newState.replyingToEvent = this.state.replyingToEvent;
            }

            this.setState(newState);

            if (payload.auto_join) {
                dis.dispatch<JoinRoomPayload>({
                    ...payload,
                    action: Action.JoinRoom,
                    roomId: payload.room_id,
                    metricsTrigger: payload.metricsTrigger as JoinRoomPayload["metricsTrigger"],
                });
            }
        } else if (payload.room_alias) {
            // Try the room alias to room ID navigation cache first to avoid
            // blocking room navigation on the homeserver.
            let roomId = getCachedRoomIDForAlias(payload.room_alias);
            if (!roomId) {
                // Room alias cache miss, so let's ask the homeserver. Resolve the alias
                // and then do a second dispatch with the room ID acquired.
                this.setState({
                    roomId: null,
                    initialEventId: null,
                    initialEventPixelOffset: null,
                    isInitialEventHighlighted: null,
                    initialEventScrollIntoView: true,
                    roomAlias: payload.room_alias,
                    roomLoading: true,
                    roomLoadError: null,
                    viaServers: payload.via_servers,
                    wasContextSwitch: payload.context_switch,
                });
                try {
                    const result = await MatrixClientPeg.get().getRoomIdForAlias(payload.room_alias);
                    storeRoomAliasInCache(payload.room_alias, result.room_id);
                    roomId = result.room_id;
                } catch (err) {
                    logger.error("RVS failed to get room id for alias: ", err);
                    dis.dispatch<ViewRoomErrorPayload>({
                        action: Action.ViewRoomError,
                        room_id: null,
                        room_alias: payload.room_alias,
                        err,
                    });
                    return;
                }
            }

            // Re-fire the payload with the newly found room_id
            dis.dispatch({
                ...payload,
                room_id: roomId,
            });
        }
    }

    private viewRoomError(payload: ViewRoomErrorPayload): void {
        this.setState({
            roomId: payload.room_id,
            roomAlias: payload.room_alias,
            roomLoading: false,
            roomLoadError: payload.err,
        });
    }

    private async joinRoom(payload: JoinRoomPayload): Promise<void> {
        this.setState({
            joining: true,
        });

        const cli = MatrixClientPeg.get();
        // take a copy of roomAlias & roomId as they may change by the time the join is complete
        const { roomAlias, roomId } = this.state;
        const address = roomAlias || roomId;
        const viaServers = this.state.viaServers || [];
        try {
            await retry<Room, MatrixError>(() => cli.joinRoom(address, {
                viaServers,
                ...(payload.opts || {}),
            }), NUM_JOIN_RETRY, (err) => {
                // if we received a Gateway timeout then retry
                return err.httpStatus === 504;
            });

            // We do *not* clear the 'joining' flag because the Room object and/or our 'joined' member event may not
            // have come down the sync stream yet, and that's the point at which we'd consider the user joined to the
            // room.
            dis.dispatch<JoinRoomReadyPayload>({
                action: Action.JoinRoomReady,
                roomId,
                metricsTrigger: payload.metricsTrigger,
            });
        } catch (err) {
            dis.dispatch({
                action: Action.JoinRoomError,
                roomId,
                err,
            });
        }
    }

    private getInvitingUserId(roomId: string): string {
        const cli = MatrixClientPeg.get();
        const room = cli.getRoom(roomId);
        if (room?.getMyMembership() === "invite") {
            const myMember = room.getMember(cli.getUserId());
            const inviteEvent = myMember ? myMember.events.member : null;
            return inviteEvent && inviteEvent.getSender();
        }
    }

    public showJoinRoomError(err: MatrixError, roomId: string): void {
        let description: ReactNode = err.message ? err.message : JSON.stringify(err);
        logger.log("Failed to join room:", description);

        if (err.name === "ConnectionError") {
            description = _t("There was an error joining.");
        } else if (err.errcode === 'M_INCOMPATIBLE_ROOM_VERSION') {
            description = <div>
                { _t("Sorry, your homeserver is too old to participate here.") }<br />
                { _t("Please contact your homeserver administrator.") }
            </div>;
        } else if (err.httpStatus === 404) {
            const invitingUserId = this.getInvitingUserId(roomId);
            // only provide a better error message for invites
            if (invitingUserId) {
                // if the inviting user is on the same HS, there can only be one cause: they left.
                if (invitingUserId.endsWith(`:${MatrixClientPeg.get().getDomain()}`)) {
                    description = _t("The person who invited you has already left.");
                } else {
                    description = _t("The person who invited you has already left, or their server is offline.");
                }
            }
        }

        Modal.createDialog(ErrorDialog, {
            title: _t("Failed to join"),
            description,
        });
    }

    private joinRoomError(payload: JoinRoomErrorPayload): void {
        this.setState({
            joining: false,
            joinError: payload.err,
        });
        this.showJoinRoomError(payload.err, payload.roomId);
    }

    public reset(): void {
        this.state = Object.assign({}, INITIAL_STATE);
    }

    // The room ID of the room currently being viewed
    public getRoomId(): Optional<string> {
        return this.state.roomId;
    }

    // The event to scroll to when the room is first viewed
    public getInitialEventId(): Optional<string> {
        return this.state.initialEventId;
    }

    // Whether to highlight the initial event
    public isInitialEventHighlighted(): boolean {
        return this.state.isInitialEventHighlighted;
    }

    // Whether to avoid jumping to the initial event
    public initialEventScrollIntoView(): boolean {
        return this.state.initialEventScrollIntoView;
    }

    // The room alias of the room (or null if not originally specified in view_room)
    public getRoomAlias(): Optional<string> {
        return this.state.roomAlias;
    }

    // Whether the current room is loading (true whilst resolving an alias)
    public isRoomLoading(): boolean {
        return this.state.roomLoading;
    }

    // Any error that has occurred during loading
    public getRoomLoadError(): Optional<MatrixError> {
        return this.state.roomLoadError;
    }

    // True if we're expecting the user to be joined to the room currently being
    // viewed. Note that this is left true after the join request has finished,
    // since we should still consider a join to be in progress until the room
    // & member events come down the sync.
    //
    // This flag remains true after the room has been successfully joined,
    // (this store doesn't listen for the appropriate member events)
    // so you should always observe the joined state from the member event
    // if a room object is present.
    // ie. The correct logic is:
    // if (room) {
    //     if (myMember.membership == 'joined') {
    //         // user is joined to the room
    //     } else {
    //         // Not joined
    //     }
    // } else {
    //     if (RoomViewStore.instance.isJoining()) {
    //         // show spinner
    //     } else {
    //         // show join prompt
    //     }
    // }
    public isJoining(): boolean {
        return this.state.joining;
    }

    // Any error that has occurred during joining
    public getJoinError(): Optional<Error> {
        return this.state.joinError;
    }

    // The mxEvent if one is currently being replied to/quoted
    public getQuotingEvent(): Optional<MatrixEvent> {
        return this.state.replyingToEvent;
    }

    public shouldPeek(): boolean {
        return this.state.shouldPeek;
    }

    public getWasContextSwitch(): boolean {
        return this.state.wasContextSwitch;
    }
}
