/*
Copyright 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.
*/

const React = require('react');
const ReactDOM = require('react-dom');
const ReactTestUtils = require('react-addons-test-utils');
const expect = require('expect');
import Promise from 'bluebird';
const sinon = require('sinon');

const jssdk = require('matrix-js-sdk');
const EventTimeline = jssdk.EventTimeline;

const sdk = require('matrix-react-sdk');
const TimelinePanel = sdk.getComponent('structures.TimelinePanel');
const peg = require('../../../src/MatrixClientPeg');

const test_utils = require('test-utils');

const ROOM_ID = '!room:localhost';
const USER_ID = '@me:localhost';

// wrap TimelinePanel with a component which provides the MatrixClient in the context.
const WrappedTimelinePanel = React.createClass({
    childContextTypes: {
        matrixClient: React.PropTypes.object,
    },

    getChildContext: function() {
        return {
            matrixClient: peg.get(),
        };
    },

    render: function() {
        return <TimelinePanel ref="panel" {...this.props} />;
    },
});


describe('TimelinePanel', function() {
    let sandbox;
    let timelineSet;
    let room;
    let client;
    let timeline;
    let parentDiv;

    // make a dummy message. eventNum is put in the message text to help
    // identification during debugging, and also in the timestamp so that we
    // don't get lots of events with the same timestamp.
    function mkMessage(eventNum, opts) {
        return test_utils.mkMessage(
            {
                event: true, room: ROOM_ID, user: USER_ID,
                ts: Date.now() + eventNum,
                msg: "Event " + eventNum,
                ...opts,
            });
    }

    function scryEventTiles(panel) {
        return ReactTestUtils.scryRenderedComponentsWithType(
            panel, sdk.getComponent('rooms.EventTile'));
    }

    beforeEach(function() {
        test_utils.beforeEach(this);
        sandbox = test_utils.stubClient(sandbox);

        room = sinon.createStubInstance(jssdk.Room);
        room.roomId = ROOM_ID;

        timelineSet = sinon.createStubInstance(jssdk.EventTimelineSet);
        timelineSet.getPendingEvents.returns([]);
        timelineSet.room = room;

        timeline = new jssdk.EventTimeline(timelineSet);

        timelineSet.getLiveTimeline.returns(timeline);

        client = peg.get();
        client.credentials = {userId: USER_ID};

        // create a div of a useful size to put our panel in, and attach it to
        // the document so that we can interact with it properly.
        parentDiv = document.createElement('div');
        parentDiv.style.width = '800px';

        // This has to be slightly carefully chosen. We expect to have to do
        // exactly one pagination to fill it.
        parentDiv.style.height = '500px';

        parentDiv.style.overflow = 'hidden';
        document.body.appendChild(parentDiv);
    });

    afterEach(function() {
        if (parentDiv) {
            ReactDOM.unmountComponentAtNode(parentDiv);
            parentDiv.remove();
            parentDiv = null;
        }
        sandbox.restore();
    });

    it('should load new events even if you are scrolled up', function(done) {
        // this is https://github.com/vector-im/vector-web/issues/1367

        // enough events to allow us to scroll back
        const N_EVENTS = 30;
        for (let i = 0; i < N_EVENTS; i++) {
            timeline.addEvent(mkMessage(i));
        }

        let scrollDefer;
        const onScroll = (e) => {
            console.log(`TimelinePanel called onScroll: ${e.target.scrollTop}`);
            if (scrollDefer) {
                scrollDefer.resolve();
            }
        };
        const rendered = ReactDOM.render(
                <WrappedTimelinePanel timelineSet={timelineSet} onScroll={onScroll} />,
                parentDiv,
        );
        const panel = rendered.refs.panel;
        const scrollingDiv = ReactTestUtils.findRenderedDOMComponentWithClass(
            panel, "gm-scroll-view");

        // helper function which will return a promise which resolves when the
        // panel isn't paginating
        var awaitPaginationCompletion = function() {
            if(!panel.state.forwardPaginating) {return Promise.resolve();} else {return Promise.delay(0).then(awaitPaginationCompletion);}
        };

        // helper function which will return a promise which resolves when
        // the TimelinePanel fires a scroll event
        const awaitScroll = function() {
            scrollDefer = Promise.defer();
            return scrollDefer.promise;
        };

        // let the first round of pagination finish off
        Promise.delay(5).then(() => {
            expect(panel.state.canBackPaginate).toBe(false);
            expect(scryEventTiles(panel).length).toEqual(N_EVENTS);

            // scroll up
            console.log("setting scrollTop = 0");
            scrollingDiv.scrollTop = 0;

            // wait for the scroll event to land
        }).then(awaitScroll).then(() => {
            expect(scrollingDiv.scrollTop).toEqual(0);

            // there should be no pagination going on now
            expect(panel.state.backPaginating).toBe(false);
            expect(panel.state.forwardPaginating).toBe(false);
            expect(panel.state.canBackPaginate).toBe(false);
            expect(panel.state.canForwardPaginate).toBe(false);
            expect(panel.isAtEndOfLiveTimeline()).toBe(false);
            expect(scrollingDiv.scrollTop).toEqual(0);

            console.log("adding event");

            // a new event!
            const ev = mkMessage(N_EVENTS+1);
            timeline.addEvent(ev);
            panel.onRoomTimeline(ev, room, false, false, {
                liveEvent: true,
                timeline: timeline,
            });

            // that won't make much difference, because we don't paginate
            // unless we're at the bottom of the timeline, but a scroll event
            // should be enough to set off a pagination.
            expect(scryEventTiles(panel).length).toEqual(N_EVENTS);

            scrollingDiv.scrollTop = 10;

            return awaitScroll();
        }).then(awaitPaginationCompletion).then(() => {
            expect(scryEventTiles(panel).length).toEqual(N_EVENTS+1);
        }).done(done, done);
    });

    it('should not paginate forever if there are no events', function(done) {
        // start with a handful of events in the timeline, as would happen when
        // joining a room
        const d = Date.now();
        for (let i = 0; i < 3; i++) {
            timeline.addEvent(mkMessage(i));
        }
        timeline.setPaginationToken('tok', EventTimeline.BACKWARDS);

        // back-pagination returns a promise for true, but adds no events
        client.paginateEventTimeline = sinon.spy((tl, opts) => {
            console.log("paginate:", opts);
            expect(opts.backwards).toBe(true);
            return Promise.resolve(true);
        });

        const rendered = ReactDOM.render(
            <WrappedTimelinePanel timelineSet={timelineSet} />,
            parentDiv,
        );
        const panel = rendered.refs.panel;

        const messagePanel = ReactTestUtils.findRenderedComponentWithType(
            panel, sdk.getComponent('structures.MessagePanel'));

        expect(messagePanel.props.backPaginating).toBe(true);

        // let the first round of pagination finish off
        setTimeout(() => {
            // at this point, the timeline window should have tried to paginate
            // 5 times, and we should have given up paginating
            expect(client.paginateEventTimeline.callCount).toEqual(5);
            expect(messagePanel.props.backPaginating).toBe(false);
            expect(messagePanel.props.suppressFirstDateSeparator).toBe(false);

            // now, if we update the events, there shouldn't be any
            // more requests.
            client.paginateEventTimeline.reset();
            panel.forceUpdate();
            expect(messagePanel.props.backPaginating).toBe(false);
            setTimeout(() => {
                expect(client.paginateEventTimeline.callCount).toEqual(0);
                done();
            }, 0);
        }, 10);
    });

    it("should let you scroll down to the bottom after you've scrolled up", function(done) {
        const N_EVENTS = 120; // the number of events to simulate being added to the timeline

        // sadly, loading all those events takes a while
        this.timeout(N_EVENTS * 50);

        // client.getRoom is called a /lot/ in this test, so replace
        // sinon's spy with a fast noop.
        client.getRoom = function(id) { return null; };

        // fill the timeline with lots of events
        for (let i = 0; i < N_EVENTS; i++) {
            timeline.addEvent(mkMessage(i));
        }
        console.log("added events to timeline");

        let scrollDefer;
        const rendered = ReactDOM.render(
            <WrappedTimelinePanel timelineSet={timelineSet} onScroll={() => {scrollDefer.resolve();}} />,
            parentDiv,
        );
        console.log("TimelinePanel rendered");
        const panel = rendered.refs.panel;
        const messagePanel = ReactTestUtils.findRenderedComponentWithType(
            panel, sdk.getComponent('structures.MessagePanel'));
        const scrollingDiv = ReactTestUtils.findRenderedDOMComponentWithClass(
            panel, "gm-scroll-view");

        // helper function which will return a promise which resolves when
        // the TimelinePanel fires a scroll event
        const awaitScroll = function() {
            scrollDefer = Promise.defer();

            return scrollDefer.promise.then(() => {
                console.log("got scroll event; scrollTop now " +
                            scrollingDiv.scrollTop);
            });
        };

        function setScrollTop(scrollTop) {
            const before = scrollingDiv.scrollTop;
            scrollingDiv.scrollTop = scrollTop;
            console.log("setScrollTop: before update: " + before +
                        "; assigned: " + scrollTop +
                        "; after update: " + scrollingDiv.scrollTop);
        }

        function backPaginate() {
            console.log("back paginating...");
            setScrollTop(0);
            return awaitScroll().then(() => {
                const eventTiles = scryEventTiles(panel);
                const firstEvent = eventTiles[0].props.mxEvent;

                console.log("TimelinePanel contains " + eventTiles.length +
                            " events; first is " +
                            firstEvent.getContent().body);

                if(scrollingDiv.scrollTop > 0) {
                    // need to go further
                    return backPaginate();
                }
                console.log("paginated to start.");
            });
        }

        function scrollDown() {
            // Scroll the bottom of the viewport to the bottom of the panel
            setScrollTop(scrollingDiv.scrollHeight - scrollingDiv.clientHeight);
            console.log("scrolling down... " + scrollingDiv.scrollTop);
            return awaitScroll().delay(0).then(() => {
                const eventTiles = scryEventTiles(panel);
                const events = timeline.getEvents();

                const lastEventInPanel = eventTiles[eventTiles.length - 1].props.mxEvent;
                const lastEventInTimeline = events[events.length - 1];

                // Scroll until the last event in the panel = the last event in the timeline
                if(lastEventInPanel.getId() !== lastEventInTimeline.getId()) {
                    // need to go further
                    return scrollDown();
                }
                console.log("paginated to end.");
            });
        }

        // let the first round of pagination finish off
        awaitScroll().then(() => {
            // we should now have loaded the first few events
            expect(messagePanel.props.backPaginating).toBe(false);
            expect(messagePanel.props.suppressFirstDateSeparator).toBe(true);

            // back-paginate until we hit the start
            return backPaginate();
        }).then(() => {
            // hopefully, we got to the start of the timeline
            expect(messagePanel.props.backPaginating).toBe(false);

            expect(messagePanel.props.suppressFirstDateSeparator).toBe(false);
            const events = scryEventTiles(panel);
            expect(events[0].props.mxEvent).toBe(timeline.getEvents()[0]);

            // At this point, we make no assumption that unpagination has happened. This doesn't
            // mean that we shouldn't be able to scroll all the way down to the bottom to see the
            // most recent event in the timeline.

            // scroll all the way to the bottom
            return scrollDown();
        }).then(() => {
            expect(messagePanel.props.backPaginating).toBe(false);
            expect(messagePanel.props.forwardPaginating).toBe(false);

            const events = scryEventTiles(panel);

            // Expect to be able to see the most recent event
            const lastEventInPanel = events[events.length - 1].props.mxEvent;
            const lastEventInTimeline = timeline.getEvents()[timeline.getEvents().length - 1];
            expect(lastEventInPanel.getContent()).toBe(lastEventInTimeline.getContent());

            console.log("done");
        }).done(done, done);
    });
});