/*
Copyright 2019, 2020 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, {createRef} from 'react';
import PropTypes from 'prop-types';
import {_t} from "../../../languageHandler";
import sdk from "../../../index";
import MatrixClientPeg from "../../../MatrixClientPeg";
import {makeUserPermalink} from "../../../utils/permalinks/Permalinks";
import DMRoomMap from "../../../utils/DMRoomMap";
import {RoomMember} from "matrix-js-sdk/lib/matrix";
import * as humanize from "humanize";
import SdkConfig from "../../../SdkConfig";
import {getHttpUriForMxc} from "matrix-js-sdk/lib/content-repo";

// TODO: [TravisR] Make this generic for all kinds of invites

const INITIAL_ROOMS_SHOWN = 3; // Number of rooms to show at first
const INCREMENT_ROOMS_SHOWN = 5; // Number of rooms to add when 'show more' is clicked

// This is the interface that is expected by various components in this file. It is a bit
// awkward because it also matches the RoomMember class from the js-sdk with some extra support
// for 3PIDs/email addresses.
//
// Dev note: In order to allow us to compile the app correctly, this needs to be a class
// even though FlowJS supports interfaces. It just means that we "extend" rather than "implement"
// in the classes, at least until TypeScript saves us.
class Member {
    /**
     * The display name of this Member. For users this should be their profile's display
     * name or user ID if none set. For 3PIDs this should be the 3PID address (email).
     */
    get name(): string { throw new Error("Member class not implemented"); }

    /**
     * The ID of this Member. For users this should be their user ID. For 3PIDs this should
     * be the 3PID address (email).
     */
    get userId(): string { throw new Error("Member class not implemented"); }

    /**
     * Gets the MXC URL of this Member's avatar. For users this should be their profile's
     * avatar MXC URL or null if none set. For 3PIDs this should always be null.
     */
    getMxcAvatarUrl(): string { throw new Error("Member class not implemented"); }
}

class DirectoryMember extends Member {
    _userId: string;
    _displayName: string;
    _avatarUrl: string;

    constructor(userDirResult: {user_id: string, display_name: string, avatar_url: string}) {
        super();
        this._userId = userDirResult.user_id;
        this._displayName = userDirResult.display_name;
        this._avatarUrl = userDirResult.avatar_url;
    }

    // These next class members are for the Member interface
    get name(): string {
        return this._displayName || this._userId;
    }

    get userId(): string {
        return this._userId;
    }

    getMxcAvatarUrl(): string {
        return this._avatarUrl;
    }
}

class DMUserTile extends React.PureComponent {
    static propTypes = {
        member: PropTypes.object.isRequired, // Should be a Member (see interface above)
        onRemove: PropTypes.func.isRequired, // takes 1 argument, the member being removed
    };

    _onRemove = (e) => {
        // Stop the browser from highlighting text
        e.preventDefault();
        e.stopPropagation();

        this.props.onRemove(this.props.member);
    };

    render() {
        const BaseAvatar = sdk.getComponent("views.avatars.BaseAvatar");
        const AccessibleButton = sdk.getComponent("elements.AccessibleButton");

        const avatarSize = 20;
        const avatar = this.props.member.isEmail
            ? <img
                className='mx_DMInviteDialog_userTile_avatar'
                src={require("../../../../res/img/icon-email-pill-avatar.svg")}
                width={avatarSize} height={avatarSize} />
            : <BaseAvatar
                className='mx_DMInviteDialog_userTile_avatar'
                url={getHttpUriForMxc(
                    MatrixClientPeg.get().getHomeserverUrl(), this.props.member.getMxcAvatarUrl(),
                    avatarSize, avatarSize, "crop")}
                name={this.props.member.name}
                idName={this.props.member.userId}
                width={avatarSize}
                height={avatarSize} />;

        return (
            <span className='mx_DMInviteDialog_userTile'>
                <span className='mx_DMInviteDialog_userTile_pill'>
                    {avatar}
                    <span className='mx_DMInviteDialog_userTile_name'>{this.props.member.name}</span>
                </span>
                <AccessibleButton
                    className='mx_DMInviteDialog_userTile_remove'
                    onClick={this._onRemove}
                >
                    <img src={require("../../../../res/img/icon-pill-remove.svg")} alt={_t('Remove')} width={8} height={8} />
                </AccessibleButton>
            </span>
        );
    }
}

class DMRoomTile extends React.PureComponent {
    static propTypes = {
        member: PropTypes.object.isRequired, // Should be a Member (see interface above)
        lastActiveTs: PropTypes.number,
        onToggle: PropTypes.func.isRequired, // takes 1 argument, the member being toggled
        highlightWord: PropTypes.string,
        isSelected: PropTypes.bool,
    };

    _onClick = (e) => {
        // Stop the browser from highlighting text
        e.preventDefault();
        e.stopPropagation();

        this.props.onToggle(this.props.member);
    };

    _highlightName(str: string) {
        if (!this.props.highlightWord) return str;

        // We convert things to lowercase for index searching, but pull substrings from
        // the submitted text to preserve case. Note: we don't need to htmlEntities the
        // string because React will safely encode the text for us.
        const lowerStr = str.toLowerCase();
        const filterStr = this.props.highlightWord.toLowerCase();

        const result = [];

        let i = 0;
        let ii;
        while ((ii = lowerStr.indexOf(filterStr, i)) >= 0) {
            // Push any text we missed (first bit/middle of text)
            if (ii > i) {
                // Push any text we aren't highlighting (middle of text match, or beginning of text)
                result.push(<span key={i + 'begin'}>{str.substring(i, ii)}</span>);
            }

            i = ii; // copy over ii only if we have a match (to preserve i for end-of-text matching)

            // Highlight the word the user entered
            const substr = str.substring(i, filterStr.length + i);
            result.push(<span className='mx_DMInviteDialog_roomTile_highlight' key={i + 'bold'}>{substr}</span>);
            i += substr.length;
        }

        // Push any text we missed (end of text)
        if (i < (str.length - 1)) {
            result.push(<span key={i + 'end'}>{str.substring(i)}</span>);
        }

        return result;
    }

    render() {
        const BaseAvatar = sdk.getComponent("views.avatars.BaseAvatar");

        let timestamp = null;
        if (this.props.lastActiveTs) {
            // TODO: [TravisR] Figure out how to i18n this
            // `humanize` wants seconds for a timestamp, so divide by 1000
            const humanTs = humanize.relativeTime(this.props.lastActiveTs / 1000);
            timestamp = <span className='mx_DMInviteDialog_roomTile_time'>{humanTs}</span>;
        }

        const avatarSize = 36;
        const avatar = this.props.member.isEmail
            ? <img
                src={require("../../../../res/img/icon-email-pill-avatar.svg")}
                width={avatarSize} height={avatarSize} />
            : <BaseAvatar
                url={getHttpUriForMxc(
                    MatrixClientPeg.get().getHomeserverUrl(), this.props.member.getMxcAvatarUrl(),
                    avatarSize, avatarSize, "crop")}
                name={this.props.member.name}
                idName={this.props.member.userId}
                width={avatarSize}
                height={avatarSize} />;

        let checkmark = null;
        if (this.props.isSelected) {
            // To reduce flickering we put the 'selected' room tile above the real avatar
            checkmark = <div className='mx_DMInviteDialog_roomTile_selected' />;
        }

        // To reduce flickering we put the checkmark on top of the actual avatar (prevents
        // the browser from reloading the image source when the avatar remounts).
        const stackedAvatar = (
            <span className='mx_DMInviteDialog_roomTile_avatarStack'>
                {avatar}
                {checkmark}
            </span>
        );

        return (
            <div className='mx_DMInviteDialog_roomTile' onClick={this._onClick}>
                {stackedAvatar}
                <span className='mx_DMInviteDialog_roomTile_name'>{this._highlightName(this.props.member.name)}</span>
                <span className='mx_DMInviteDialog_roomTile_userId'>{this._highlightName(this.props.member.userId)}</span>
                {timestamp}
            </div>
        );
    }
}

export default class DMInviteDialog extends React.PureComponent {
    static propTypes = {
        // Takes an array of user IDs/emails to invite.
        onFinished: PropTypes.func.isRequired,
    };

    _debounceTimer: number = null;
    _editorRef: any = null;

    constructor() {
        super();

        this.state = {
            targets: [], // array of Member objects (see interface above)
            filterText: "",
            recents: this._buildRecents(),
            numRecentsShown: INITIAL_ROOMS_SHOWN,
            suggestions: this._buildSuggestions(),
            numSuggestionsShown: INITIAL_ROOMS_SHOWN,
            serverResultsMixin: [], // { user: DirectoryMember, userId: string }[], like recents and suggestions
        };

        this._editorRef = createRef();
    }

    _buildRecents(): {userId: string, user: RoomMember, lastActive: number} {
        const rooms = DMRoomMap.shared().getUniqueRoomsWithIndividuals();
        const recents = [];
        for (const userId in rooms) {
            const room = rooms[userId];
            const member = room.getMember(userId);
            if (!member) continue; // just skip people who don't have memberships for some reason

            const lastEventTs = room.timeline && room.timeline.length
                ? room.timeline[room.timeline.length - 1].getTs()
                : 0;
            if (!lastEventTs) continue; // something weird is going on with this room

            recents.push({userId, user: member, lastActive: lastEventTs});
        }

        // Sort the recents by last active to save us time later
        recents.sort((a, b) => b.lastActive - a.lastActive);

        return recents;
    }

    _buildSuggestions(): {userId: string, user: RoomMember} {
        const maxConsideredMembers = 200;
        const client = MatrixClientPeg.get();
        const excludedUserIds = [client.getUserId(), SdkConfig.get()['welcomeUserId']];
        const joinedRooms = client.getRooms()
            .filter(r => r.getMyMembership() === 'join')
            .filter(r => r.getJoinedMemberCount() <= maxConsideredMembers);

        // Generates { userId: {member, rooms[]} }
        const memberRooms = joinedRooms.reduce((members, room) => {
            const joinedMembers = room.getJoinedMembers().filter(u => !excludedUserIds.includes(u.userId));
            for (const member of joinedMembers) {
                if (!members[member.userId]) {
                    members[member.userId] = {
                        member: member,
                        // Track the room size of the 'picked' member so we can use the profile of
                        // the smallest room (likely a DM).
                        pickedMemberRoomSize: room.getJoinedMemberCount(),
                        rooms: [],
                    };
                }

                members[member.userId].rooms.push(room);

                if (room.getJoinedMemberCount() < members[member.userId].pickedMemberRoomSize) {
                    members[member.userId].member = member;
                    members[member.userId].pickedMemberRoomSize = room.getJoinedMemberCount();
                }
            }
            return members;
        }, {});

        // Generates { userId: {member, numRooms, score} }
        const memberScores = Object.values(memberRooms).reduce((scores, entry) => {
            const numMembersTotal = entry.rooms.reduce((c, r) => c + r.getJoinedMemberCount(), 0);
            const maxRange = maxConsideredMembers * entry.rooms.length;
            scores[entry.member.userId] = {
                member: entry.member,
                numRooms: entry.rooms.length,
                score: Math.max(0, Math.pow(1 - (numMembersTotal / maxRange), 5)),
            };
            return scores;
        }, {});

        const members = Object.values(memberScores);
        members.sort((a, b) => {
            if (a.score === b.score) {
                if (a.numRooms === b.numRooms) {
                    return a.member.userId.localeCompare(b.member.userId);
                }

                return b.numRooms - a.numRooms;
            }
            return b.score - a.score;
        });
        return members.map(m => ({userId: m.member.userId, user: m.member}));
    }

    _startDm = () => {
        this.props.onFinished(this.state.targets.map(t => t.userId));
    };

    _cancel = () => {
        this.props.onFinished([]);
    };

    _updateFilter = (e) => {
        const term = e.target.value;
        this.setState({filterText: term});

        // Debounce server lookups to reduce spam. We don't clear the existing server
        // results because they might still be vaguely accurate, likewise for races which
        // could happen here.
        if (this._debounceTimer) {
            clearTimeout(this._debounceTimer);
        }
        this._debounceTimer = setTimeout(() => {
            MatrixClientPeg.get().searchUserDirectory({term}).then(r => {
                if (term !== this.state.filterText) {
                    // Discard the results - we were probably too slow on the server-side to make
                    // these results useful. This is a race we want to avoid because we could overwrite
                    // more accurate results.
                    return;
                }
                this.setState({
                    serverResultsMixin: r.results.map(u => ({
                        userId: u.user_id,
                        user: new DirectoryMember(u),
                    })),
                });
            }).catch(e => {
                console.error("Error searching user directory:");
                console.error(e);
                this.setState({serverResultsMixin: []}); // clear results because it's moderately fatal
            });
        }, 150); // 150ms debounce (human reaction time + some)
    };

    _showMoreRecents = () => {
        this.setState({numRecentsShown: this.state.numRecentsShown + INCREMENT_ROOMS_SHOWN});
    };

    _showMoreSuggestions = () => {
        this.setState({numSuggestionsShown: this.state.numSuggestionsShown + INCREMENT_ROOMS_SHOWN});
    };

    _toggleMember = (member: Member) => {
        const targets = this.state.targets.map(t => t); // cheap clone for mutation
        const idx = targets.indexOf(member);
        if (idx >= 0) targets.splice(idx, 1);
        else targets.push(member);
        this.setState({targets});
    };

    _removeMember = (member: Member) => {
        const targets = this.state.targets.map(t => t); // cheap clone for mutation
        const idx = targets.indexOf(member);
        if (idx >= 0) {
            targets.splice(idx, 1);
            this.setState({targets});
        }
    };

    _onClickInputArea = (e) => {
        // Stop the browser from highlighting text
        e.preventDefault();
        e.stopPropagation();

        if (this._editorRef && this._editorRef.current) {
            this._editorRef.current.focus();
        }
    };

    _renderSection(kind: "recents"|"suggestions") {
        let sourceMembers = kind === 'recents' ? this.state.recents : this.state.suggestions;
        let showNum = kind === 'recents' ? this.state.numRecentsShown : this.state.numSuggestionsShown;
        const showMoreFn = kind === 'recents' ? this._showMoreRecents.bind(this) : this._showMoreSuggestions.bind(this);
        const lastActive = (m) => kind === 'recents' ? m.lastActive : null;
        const sectionName = kind === 'recents' ? _t("Recent Conversations") : _t("Suggestions");

        // Mix in the server results if we have any, but only if we're searching
        if (this.state.filterText && this.state.serverResultsMixin && kind === 'suggestions') {
            // only pick out the server results that aren't already covered though
            const uniqueServerResults = this.state.serverResultsMixin
                .filter(u => !sourceMembers.some(m => m.userId === u.userId));

            sourceMembers = sourceMembers.concat(uniqueServerResults);
        }

        // Hide the section if there's nothing to filter by
        if (!sourceMembers || sourceMembers.length === 0) return null;

        // Do some simple filtering on the input before going much further. If we get no results, say so.
        if (this.state.filterText) {
            const filterBy = this.state.filterText.toLowerCase();
            sourceMembers = sourceMembers
                .filter(m => m.user.name.toLowerCase().includes(filterBy) || m.userId.toLowerCase().includes(filterBy));

            if (sourceMembers.length === 0) {
                return (
                    <div className='mx_DMInviteDialog_section'>
                        <h3>{sectionName}</h3>
                        <p>{_t("No results")}</p>
                    </div>
                );
            }
        }

        // If we're going to hide one member behind 'show more', just use up the space of the button
        // with the member's tile instead.
        if (showNum === sourceMembers.length - 1) showNum++;

        // .slice() will return an incomplete array but won't error on us if we go too far
        const toRender = sourceMembers.slice(0, showNum);
        const hasMore = toRender.length < sourceMembers.length;

        const AccessibleButton = sdk.getComponent("elements.AccessibleButton");
        let showMore = null;
        if (hasMore) {
            showMore = (
                <AccessibleButton onClick={showMoreFn} kind="link">
                    {_t("Show more")}
                </AccessibleButton>
            );
        }

        const tiles = toRender.map(r => (
            <DMRoomTile
                member={r.user}
                lastActiveTs={lastActive(r)}
                key={r.userId}
                onToggle={this._toggleMember}
                highlightWord={this.state.filterText}
                isSelected={this.state.targets.some(t => t.userId === r.userId)}
            />
        ));
        return (
            <div className='mx_DMInviteDialog_section'>
                <h3>{sectionName}</h3>
                {tiles}
                {showMore}
            </div>
        );
    }

    _renderEditor() {
        const targets = this.state.targets.map(t => (
            <DMUserTile member={t} onRemove={this._removeMember} key={t.userId} />
        ));
        const input = (
            <textarea
                key={"input"}
                rows={1}
                onChange={this._updateFilter}
                defaultValue={this.state.filterText}
                ref={this._editorRef}
            />
        );
        return (
            <div className='mx_DMInviteDialog_editor' onClick={this._onClickInputArea}>
                {targets}
                {input}
            </div>
        );
    }

    render() {
        const BaseDialog = sdk.getComponent('views.dialogs.BaseDialog');
        const AccessibleButton = sdk.getComponent("elements.AccessibleButton");

        const userId = MatrixClientPeg.get().getUserId();
        return (
            <BaseDialog
                className='mx_DMInviteDialog'
                hasCancel={true}
                onFinished={this._cancel}
                title={_t("Direct Messages")}
            >
                <div className='mx_DMInviteDialog_content'>
                    <p>
                        {_t(
                            "If you can't find someone, ask them for their username, or share your " +
                            "username (%(userId)s) or <a>profile link</a>.",
                            {userId},
                            {a: (sub) => <a href={makeUserPermalink(userId)} rel="noopener" target="_blank">{sub}</a>},
                        )}
                    </p>
                    <div className='mx_DMInviteDialog_addressBar'>
                        {this._renderEditor()}
                        <AccessibleButton
                            kind="primary"
                            onClick={this._startDm}
                            className='mx_DMInviteDialog_goButton'
                        >
                            {_t("Go")}
                        </AccessibleButton>
                    </div>
                    {this._renderSection('recents')}
                    {this._renderSection('suggestions')}
                </div>
            </BaseDialog>
        );
    }
}