import {
    event as d3_event,
    select as d3_select
} from 'd3-selection';

import marked from 'marked';
import { t } from '../util/locale';
import { svgIcon } from '../svg';
import { icon } from 'intro/helper';


// This currently only works with the 'restrictions' field
var fieldHelpKeys = {
    restrictions: [
        ['inspecting',[
            'title',
            'about',
            'from',
            'allow',
            'restrict',
            'only'
        ]],
        ['modifying',[
            'title',
            'about',
            'indicators',
            'allow',
            'restrict',
            'only'
        ]],
        ['tips',[
            'title',
            'tip1',
            'tip2',
            'tip3',
            'tip4',
            'tip5'
        ]]
    ]
};

var fieldHelpHeadings = {
    'help.field.restrictions.inspecting.title': 3,
    'help.field.restrictions.modifying.title': 3,
    'help.field.restrictions.tips.title': 3
};

var replacements = {
    fromShadow: icon('#turn-shadow', 'pre-text shadow from'),
    allowShadow: icon('#turn-shadow', 'pre-text shadow allow'),
    restrictShadow: icon('#turn-shadow', 'pre-text shadow restrict'),
    onlyShadow: icon('#turn-shadow', 'pre-text shadow only'),
    allowTurn: icon('#turn-yes', 'pre-text turn'),
    restrictTurn: icon('#turn-no', 'pre-text turn'),
    onlyTurn: icon('#turn-only', 'pre-text turn')
};


export function uiFieldHelp(context, fieldName) {
    var fieldHelp = {};
    var _inspector = d3_select(null);
    var _wrap = d3_select(null);
    var _body = d3_select(null);

    // For each section, squash all the texts into a single markdown document
    var docs = fieldHelpKeys[fieldName].map(function(key) {
        var helpkey = 'help.field.' + fieldName + '.' + key[0];
        var text = key[1].reduce(function(all, part) {
            var subkey = helpkey + '.' + part;
            var depth = fieldHelpHeadings[subkey];                     // is this subkey a heading?
            var hhh = depth ? Array(depth + 1).join('#') + ' ' : '';   // if so, prepend with some ##'s
            return all + hhh + t(subkey, replacements) + '\n\n';
        }, '');

        return {
            key: helpkey,
            title: t(helpkey + '.title'),
            html: marked(text.trim())
        };
    });


    function show() {
        updatePosition();

        _body
            .classed('hide', false)
            .style('opacity', '0')
            .transition()
            .duration(200)
            .style('opacity', '1');
    }


    function hide() {
        _body
            .classed('hide', true)
            .transition()
            .duration(200)
            .style('opacity', '0')
            .on('end', function () {
                _body.classed('hide', true);
            });
    }


    function clickHelp(d, i) {
        var content = _body.selectAll('.field-help-content')
            .html(d.html);

        // add an image for some help sections
        var img;
        switch (d.key) {
            case 'help.field.restrictions.inspecting':
            img = 'tr_inspect.gif';
            break;
            case 'help.field.restrictions.modifying':
            img = 'tr_modify.gif';
            break;
        }

        if (img) {
            content
                .append('img')
                .attr('class', 'field-help-image')
                .attr('src', context.imagePath(img));
        }
    }


    fieldHelp.button = function(selection) {
        if (_body.empty()) return;

        var button = selection.selectAll('.field-help-button')
            .data([0]);

        // enter/update
        button.enter()
            .append('button')
            .attr('class', 'field-help-button')
            .attr('tabindex', -1)
            .call(svgIcon('#icon-help'))
            .merge(button)
            .on('click', function () {
                d3_event.stopPropagation();
                d3_event.preventDefault();
                if (_body.classed('hide')) {
                    show();
                } else {
                    hide();
                }
            });
    };


    function updatePosition() {
        var wrap = _wrap.node();
        var inspector = _inspector.node();
        var wRect = wrap.getBoundingClientRect();
        var iRect = inspector.getBoundingClientRect();

        _body
            .style('left', wRect.left + 'px')
            .style('width', wRect.width - 10 + 'px')
            .style('top', wRect.top + inspector.scrollTop - iRect.top + 5 + 'px');
    }


    fieldHelp.body = function(selection) {
        // this control expects the field to have a preset-input-wrap div
        _wrap = selection.selectAll('.preset-input-wrap');
        if (_wrap.empty()) return;

        _inspector = d3_select('#sidebar .entity-editor-pane .inspector-body');
        if (_inspector.empty()) return;

        _body = _inspector.selectAll('.field-help-body')
            .data([0]);

        var enter = _body.enter()
            .append('div')
            .attr('class', 'field-help-body hide');   // initially hidden
            // .style('height', '0px');

        var titleEnter = enter
            .append('div')
            .attr('class', 'field-help-title cf');

        titleEnter
            .append('h2')
            .attr('class', 'fl')
            .text(t('help.field.' + fieldName + '.title'));

        titleEnter
            .append('button')
            .attr('class', 'fr close')
            .on('click', function() {
                d3_event.stopPropagation();
                d3_event.preventDefault();
                hide();
            })
            .call(svgIcon('#icon-close'));

        var navEnter = enter
            .append('ul')
            .attr('class', 'field-help-nav');

        var titles = docs.map(function(d) { return d.title; });
        navEnter.selectAll('.field-help-nav-item')
            .data(titles)
            .enter()
            .append('li')
            .attr('class', 'field-help-nav-item')
            .append('a')
            .attr('class', 'next')
            .text(function(d) { return d; })
            .on('click', function(d, i) {
                d3_event.stopPropagation();
                d3_event.preventDefault();
                clickHelp(docs[i], i);
            });

        enter
            .append('div')
            .attr('class', 'field-help-content');

        _body = _body
            .merge(enter);

        clickHelp(docs[0], 0);
    };


    return fieldHelp;
}