'use strict';

import React from 'react';
import createReactClass from 'create-react-class';
import PropTypes from 'prop-types';
import ObserveModelMixin from '../ObserveModelMixin';
import defined from 'terriajs-cesium/Source/Core/defined';

import HelpScreenWindow from './HelpScreenWindow.jsx';
import ObscureOverlay from './ObscureOverlay.jsx';

const HelpOverlay = createReactClass({
    displayName: 'HelpOverlay',
    mixins: [ObserveModelMixin],

    propTypes: {
        helpViewState: PropTypes.object.isRequired,
        viewState: PropTypes.object.isRequired
    },

    getInitialState() {
        return {
            screens: undefined,
            index: undefined,
            currentRectangle: undefined,
            previousRectangle: undefined
        };
    },

    cancel() {
        if (defined(this.setIntervalId)) {
            clearInterval(this.setIntervalId);
        }
        this.setState({
            screens: undefined,
            index: undefined,
            currentRectangle: undefined,
            previousRectangle: undefined
        });
        this.props.helpViewState.currentScreen = undefined;
    },

    help(screens, i) {
        if (i === 0) {
            // If this is the first help screen in a sequence, locate the highlighted element and track the rectangle
            // to make sure the overlay and help screen move with the element.
            const that = this;
            this.setIntervalId = setInterval(function() {
                if (!defined(that.state.screens)) {
                    return;
                }
                if (that.props.helpViewState.cancel) {
                    // Has been cancelled from somewhere else. Abort!
                    that.cancel();
                }
                const i = that.state.index;
                const currentScreen = that.state && that.state.screens && that.state.screens[i];
                if (currentScreen && typeof currentScreen.preDisplayHook === 'function') {
                    currentScreen.preDisplayHook(that.props.viewState);
                }
                updateCurrentRectangle(that, currentScreen);

                if (!that.props.helpViewState.advance && defined(that.state) && defined(that.state.previousRectangle) && that.state.previousRectangle === that.state.currentRectangle) {
                    return;
                }

                if (defined(that.state) && defined(that.state.currentRectangle)) {
                    currentScreen.rectangle = that.state.currentRectangle;
                    currentScreen.currentScreenNumber = i+1;
                    currentScreen.totalNumberOfScreens = that.state.screens.length;
                    currentScreen.onNext = function() {
                        if (typeof currentScreen.postDisplayHook === 'function') {
                            currentScreen.postDisplayHook(that.props.viewState);
                        }
                        if ((i+1) >= that.state.screens.length) {
                            that.cancel();
                        } else {
                            that.help(that.state.screens, i+1);
                        }
                    };
                    that.props.helpViewState.currentScreen = currentScreen;
                    // Processed current rectangle, set as previous.
                    that.setState({previousRectangle: that.state.currentRectangle});
                }

                if (that.props.helpViewState.advance) {
                    // Has been manually advanced from somewhere else. Next screen!
                    that.props.helpViewState.advance = false;
                    currentScreen.onNext();
                }
            }, 10);
        }
        this.props.helpViewState.cancel = false;
        this.setState({
            screens: screens,
            index: i,
            currentRectangle: undefined,
            previousRectangle: undefined
        });
    },

    executeSequence() {
        if (defined(this.props.helpViewState.currentSequence)) {
            if (defined(this.setIntervalId)) {
                clearInterval(this.setIntervalId);
            }
            this.help(this.props.helpViewState.currentSequence.screens, 0);
            // To prevent executeSequence from triggering again before we start a new sequence.
            this.props.helpViewState.currentSequence = undefined;
        }
    },

    componentDidMount() {
        this.executeSequence();
    },

    componentDidUpdate() {
        this.executeSequence();
    },

    render() {
        return (
            <div aria-hidden={ !this.props.helpViewState.currentSequence }>
                <ObscureOverlay helpViewState={this.props.helpViewState}/>
                <HelpScreenWindow helpViewState={this.props.helpViewState}/>
            </div>
        );
    },
});

/**
* Reset currentRectangle to the bounding rectangle of the highlighted element.
* @private
*/
function updateCurrentRectangle(component, currentScreen) {
    if (!defined(currentScreen)) {
        return;
    }
    const highlightedElement = document.getElementsByClassName(currentScreen.highlightedComponentId);
    if (defined(highlightedElement[0])) {
        const screenRect = highlightedElement[0].getBoundingClientRect();
        component.setState({currentRectangle: screenRect});
    }
}

export default HelpOverlay;