/*
Copyright 2017 New Vector 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 React from 'react';
import sdk from '../../../index';
import {_t} from '../../../languageHandler';
import PropTypes from 'prop-types';
import dis from '../../../dispatcher';
import MatrixClientPeg from '../../../MatrixClientPeg';
import {wantsDateSeparator} from '../../../DateUtils';
import {MatrixEvent} from 'matrix-js-sdk';
import {makeEventPermalink, makeUserPermalink} from "../../../matrix-to";
import SettingsStore from "../../../settings/SettingsStore";

// This component does no cycle detection, simply because the only way to make such a cycle would be to
// craft event_id's, using a homeserver that generates predictable event IDs; even then the impact would
// be low as each event being loaded (after the first) is triggered by an explicit user action.
export default class ReplyThread extends React.Component {
    static propTypes = {
        // the latest event in this chain of replies
        parentEv: PropTypes.instanceOf(MatrixEvent),
        // called when the preview's contents has loaded
        onWidgetLoad: PropTypes.func.isRequired,
    };

    constructor(props, context) {
        super(props, context);

        this.state = {
            // The loaded events to be rendered as linear-replies
            events: [],

            // The latest loaded event which has not yet been shown
            loadedEv: null,
            // Whether the component is still loading more events
            loading: true,

            // Whether as error was encountered fetching a replied to event.
            err: false,
        };

        this.onQuoteClick = this.onQuoteClick.bind(this);
    }

    componentWillMount() {
        this.unmounted = false;
        this.room = MatrixClientPeg.get().getRoom(this.props.parentEv.getRoomId());
        this.initialize();
    }

    componentWillUnmount() {
        this.unmounted = true;
    }

    async initialize() {
        const {parentEv} = this.props;
        const inReplyTo = ReplyThread.getInReplyTo(parentEv);
        if (!inReplyTo) {
            this.setState({err: true});
            return;
        }

        const ev = await ReplyThread.getEvent(this.room, inReplyTo['event_id']);
        if (this.unmounted) return;

        if (ev) {
            this.setState({
                events: [ev],
            }, this.loadNextEvent);
        } else {
            this.setState({err: true});
        }
    }

    async loadNextEvent() {
        if (this.unmounted) return;
        const ev = this.state.events[0];
        const inReplyTo = ReplyThread.getInReplyTo(ev);

        if (!inReplyTo) {
            this.setState({
                loading: false,
            }, this.props.onWidgetLoad);
            return;
        }

        const loadedEv = await ReplyThread.getEvent(this.room, inReplyTo['event_id']);
        if (this.unmounted) return;

        if (loadedEv) {
            this.setState({loadedEv}, this.props.onWidgetLoad);
        } else {
            this.setState({err: true}, this.props.onWidgetLoad);
        }
    }

    static async getEvent(room, eventId) {
        const event = room.findEventById(eventId);
        if (event) return event;

        try {
            await MatrixClientPeg.get().getEventTimeline(room.getUnfilteredTimelineSet(), eventId);
        } catch (e) {
            return null;
        }
        return room.findEventById(eventId);
    }

    onQuoteClick() {
        const events = [this.state.loadedEv].concat(this.state.events);

        this.setState({
            loadedEv: null,
            events,
        }, this.loadNextEvent);

        dis.dispatch({action: 'focus_composer'});
    }

    static getInReplyTo(ev) {
        if (!ev || ev.isRedacted()) return;

        const mRelatesTo = ev.getWireContent()['m.relates_to'];
        if (mRelatesTo && mRelatesTo['m.in_reply_to']) {
            const mInReplyTo = mRelatesTo['m.in_reply_to'];
            if (mInReplyTo['event_id']) return mInReplyTo;
        }
    }

    // Part of Replies fallback support
    static stripPlainReply(body) {
        const lines = body.split('\n');
        while (lines.length && lines[0].startsWith('> ')) lines.shift();
        return lines.join('\n');
    }

    // Part of Replies fallback support
    static stripHTMLReply(html) {
        return html.replace(/^<blockquote data-mx-reply>[\s\S]+?<\/blockquote>/, '');
    }

    // Part of Replies fallback support
    static getNestedReplyText(ev) {
        if (!ev) return null;

        let {body, formatted_body: html} = ev.getContent();
        if (this.getInReplyTo(ev)) {
            if (body) body = this.stripPlainReply(body);
            if (html) html = this.stripHTMLReply(html);
        }

        html = `<blockquote data-mx-reply><a href="${makeEventPermalink(ev.getRoomId(), ev.getId())}">In reply to</a> `
            + `<a href="${makeUserPermalink(ev.getSender())}">${ev.getSender()}</a><br>${html || body}</blockquote>`;
        const lines = body.trim().split('\n');
        if (lines.length > 0) {
            lines[0] = `<${ev.getSender()}> ${lines[0]}`;
            body = lines.map((line) => `> ${line}`).join('\n') + '\n\n';
        }

        return {body, html};
    }

    static getReplyEvContent(ev) {
        if (!ev) return {};
        return {
            'm.relates_to': {
                'm.in_reply_to': {
                    'event_id': ev.getId(),
                },
            },
        };
    }

    static getQuote(parentEv, onWidgetLoad) {
        if (!SettingsStore.isFeatureEnabled("feature_rich_quoting") || !ReplyThread.getInReplyTo(parentEv)) {
            return <div />;
        }
        return <ReplyThread parentEv={parentEv} onWidgetLoad={onWidgetLoad} />;
    }

    render() {
        let header = null;

        if (this.state.err) {
            header = <blockquote className="mx_ReplyThread mx_ReplyThread_error">
                {
                    _t('Unable to load event that was replied to, ' +
                        'it either does not exist or you do not have permission to view it.')
                }
            </blockquote>;
        } else if (this.state.loadedEv) {
            const ev = this.state.loadedEv;
            const Pill = sdk.getComponent('elements.Pill');
            const room = MatrixClientPeg.get().getRoom(ev.getRoomId());
            header = <blockquote className="mx_ReplyThread">
                {
                    _t('<a>In reply to</a> <pill>', {}, {
                        'a': (sub) => <a onClick={this.onQuoteClick} className="mx_ReplyThread_show">{ sub }</a>,
                        'pill': <Pill type={Pill.TYPE_USER_MENTION} room={room}
                                      url={makeUserPermalink(ev.getSender())} shouldShowPillAvatar={true} />,
                    })
                }
            </blockquote>;
        } else if (this.state.loading) {
            const Spinner = sdk.getComponent("elements.Spinner");
            header = <Spinner w={16} h={16} />;
        }

        const EventTile = sdk.getComponent('views.rooms.EventTile');
        const DateSeparator = sdk.getComponent('messages.DateSeparator');
        const evTiles = this.state.events.map((ev) => {
            let dateSep = null;

            if (wantsDateSeparator(this.props.parentEv.getDate(), ev.getDate())) {
                dateSep = <a href={this.props.url}><DateSeparator ts={ev.getTs()} /></a>;
            }

            return <blockquote className="mx_ReplyThread" key={ev.getId()}>
                { dateSep }
                <EventTile mxEvent={ev}
                           tileShape="reply"
                           onWidgetLoad={this.props.onWidgetLoad}
                           isTwelveHour={SettingsStore.getValue("showTwelveHourTimestamps")} />
            </blockquote>;
        });

        return <div>
            <div>{ header }</div>
            <div>{ evTiles }</div>
        </div>;
    }
}