var $ = require('jquery');
var Marionette = require('marionette');
var Paginator = require('backgrid.paginator');

module.exports = Paginator.extend({
    template : 'Shared/Grid/PagerTemplate',

    events : {
        'click .pager-btn'      : 'changePage',
        'click .x-page-number'  : '_showPageJumper',
        'change .x-page-select' : '_jumpToPage',
        'blur .x-page-select'   : 'render'
    },

    windowSize : 1,

    fastForwardHandleLabels : {
        first : 'icon-fast-backward',
        prev  : 'icon-backward',
        next  : 'icon-forward',
        last  : 'icon-fast-forward'
    },

    changePage : function(e) {
        e.preventDefault();

        var target = this.$(e.target);

        if (target.closest('li').hasClass('disabled')) {
            return;
        }

        target.closest('li i').addClass('icon-spinner icon-spin');

        var label = target.attr('data-action');
        var ffLabels = this.fastForwardHandleLabels;

        var collection = this.collection;

        if (ffLabels) {
            switch (label) {
                case 'first':
                    collection.getFirstPage();
                    return;
                case 'prev':
                    if (collection.hasPrevious()) {
                        collection.getPreviousPage();
                    }
                    return;
                case 'next':
                    if (collection.hasNext()) {
                        collection.getNextPage();
                    }
                    return;
                case 'last':
                    collection.getLastPage();
                    return;
            }
        }

        var state = collection.state;
        var pageIndex = target.text();
        collection.getPage(state.firstPage === 0 ? pageIndex - 1 : pageIndex);
    },

    makeHandles : function() {
        var handles = [];

        var collection = this.collection;
        var state = collection.state;

        // convert all indices to 0-based here
        var firstPage = state.firstPage;
        var lastPage = +state.lastPage;
        lastPage = Math.max(0, firstPage ? lastPage - 1 : lastPage);
        var currentPage = Math.max(state.currentPage, state.firstPage);
        currentPage = firstPage ? currentPage - 1 : currentPage;
        var windowStart = Math.floor(currentPage / this.windowSize) * this.windowSize;
        var windowEnd = Math.min(lastPage + 1, windowStart + this.windowSize);

        if (collection.mode !== 'infinite') {
            for (var i = windowStart; i < windowEnd; i++) {
                handles.push({
                    label      : i + 1,
                    title      : 'No. ' + (i + 1),
                    className  : currentPage === i ? 'active' : undefined,
                    pageNumber : i + 1,
                    lastPage   : lastPage + 1
                });
            }
        }

        var ffLabels = this.fastForwardHandleLabels;
        if (ffLabels) {
            if (ffLabels.prev) {
                handles.unshift({
                    label     : ffLabels.prev,
                    className : collection.hasPrevious() ? void 0 : 'disabled',
                    action    : 'prev'
                });
            }

            if (ffLabels.first) {
                handles.unshift({
                    label     : ffLabels.first,
                    className : collection.hasPrevious() ? void 0 : 'disabled',
                    action    : 'first'
                });
            }

            if (ffLabels.next) {
                handles.push({
                    label     : ffLabels.next,
                    className : collection.hasNext() ? void 0 : 'disabled',
                    action    : 'next'
                });
            }

            if (ffLabels.last) {
                handles.push({
                    label     : ffLabels.last,
                    className : collection.hasNext() ? void 0 : 'disabled',
                    action    : 'last'
                });
            }
        }

        return handles;
    },

    render : function() {
        this.$el.empty();

        var templateFunction = Marionette.TemplateCache.get(this.template);

        this.$el.html(templateFunction({
            handles : this.makeHandles(),
            state   : this.collection.state
        }));

        this.delegateEvents();

        return this;
    },

    _showPageJumper : function(e) {
        if ($(e.target).is('select')) {
            return;
        }

        var templateFunction = Marionette.TemplateCache.get('Shared/Grid/JumpToPageTemplate');
        var state = this.collection.state;
        var currentPage = Math.max(state.currentPage, state.firstPage);
        currentPage = state.firstPage ? currentPage - 1 : currentPage;

        var pages = [];

        for (var i = 0; i < this.collection.state.lastPage; i++) {
            if (i === currentPage) {
                pages.push({
                    page    : i + 1,
                    current : true
                });
            } else {
                pages.push({ page : i + 1 });
            }
        }

        this.$el.find('.x-page-number').html(templateFunction({ pages : pages }));
    },

    _jumpToPage : function() {
        var target = this.$el.find('.x-page-select');

        //Remove event handlers so the blur event is not triggered
        this.undelegateEvents();

        var selectedPage = parseInt(target.val(), 10);

        this.$el.find('.x-page-number').html('<i class="icon-spinner icon-spin"></i>');
        this.collection.getPage(selectedPage);
    }
});