import {module} from '../module';
import './style.scss';

export default class DropDown {
    constructor($element, $filter, $timeout) {
        this.$element = $element;
        this.$filter = $filter;
        this.$timeout = $timeout;

        this.parent = this.parent || $element[0].parentNode;
        this._search = null;
        this.itemsFiltered = [];
        this._activeOption = -1;
        this._focusingFilter = false;
    }
    get show() {
        return this._show;
    }

    set show(value) {
        let oldValue = this.show;
        this._show = value;
        if (value && !this._focusingFilter && oldValue !== value && this.filter) {
            let inputFilterSearch = this.$element[0].querySelector('input');
            this._focusingFilter = true;
            this.$timeout(() => {
                inputFilterSearch.focus();
                this._focusingFilter = false;
            }, 250);
        }
    }

    get search() {
        return this._search;
    }

    set search(value) {
        let val = (value === undefined || value === '') ? null : value;
        this._search = val;

        if (this.filterAction)
            this.onFilterRest();
        else
            this.filterItems();
    }

    get activeOption() {
        return this._activeOption;
    }

    set activeOption(value) {
        if (value < 0) {
            value = 0;
        } else if (value >= this.items.length) {
            value = this.showLoadMore ? this.items.length : this.items.length - 1;
        }
        this.$timeout(() => {
            this._activeOption = value;
            // AutoLoad items with "scroll" (1st version):
            if (value && value >= this.items.length - 3 && !this.removeLoadMore) {
                this.loadItems();
            }
        });
    }

    filterItems() {
        this.itemsFiltered = this.search ? this.$filter('filter')(this.items, this.search) : this.items;
    }

    onFilterRest() {
        if (this.filterAction) {
            this.filterAction({search: this.search});
        }
    }

    $onChanges(changesObj) {
        if (changesObj.show && changesObj.top && changesObj.top.currentValue) {
            this.$element.css('top', changesObj.top.currentValue + 'px');
        }
        if (changesObj.show && changesObj.itemWidth && changesObj.itemWidth.currentValue) {
            this.$element.css('width', changesObj.itemWidth.currentValue + 'px');
        }
        if (changesObj.items) {
            this.filterItems();
        }
    }

    clearSearch() {
        this.search = null;
    }

    selectOption() {
        if (this.activeOption >= 0 && this.activeOption < this.items.length && this.items[this.activeOption]) {
            this.selected = this.items[this.activeOption];
            this.show = false;
            this.clearSearch();
        } else if (this.showLoadMore && this.activeOption === this.items.length) {
            this.loadMore();
        }
    }

    onKeydown(event) {
        if (this.show) {
            switch (event.keyCode) {
            case 13: // Enter
                this.$timeout(() => {
                    this.selectOption();
                });
                event.preventDefault();
                break;
            case 27: // Escape
                this.clearSearch();
                break;
            case 38: // Arrow up
                this.activeOption--;
                this.$timeout(() => {
                    this.setScrollPosition();
                }, 100);
                break;
            case 40: // Arrow down
                this.activeOption++;
                this.$timeout(() => {
                    this.setScrollPosition();
                }, 100);
                break;
            default:
                return;
            }
        }
    }

    setScrollPosition() {
        let dropdown = this.$element[0].querySelector('ul.dropdown');
        let child = dropdown ? dropdown.childNodes[this.activeOption] : null;
        if (child && typeof child.scrollIntoView === 'function') {
            child.scrollIntoView();
        }
    }

    selectItem(item) {
        this.selected = item;
        if (this.multiple) {
            item.checked = !item.checked;
            this.show = true;
        } else {
            this.show = false;
        }
    }

    loadItems() {
        if (this.showLoadMore && this.loadMore) {
            this.loadMore();
        }
        this.show = true;
    }

    $onInit() {
        if (this.parent)
            this.parent.addEventListener('keydown', e => this.onKeydown(e));
    }
    $onDestroy() {
        if (this.parent)
            this.parent.removeEventListener('keydown', e => this.onKeydown(e));
    }
}

DropDown.$inject = ['$element', '$filter', '$timeout'];

module.component('vnDropDown', {
    template: require('./drop-down.html'),
    controller: DropDown,
    bindings: {
        items: '<',
        show: '<',
        filter: '@?',
        selected: '=',
        search: '=?',
        loadMore: '&?',
        removeLoadMore: '<?',
        filterAction: '&?',
        showLoadMore: '<?',
        top: '<?',
        itemWidth: '<?',
        parent: '<?',
        multiple: '<?'
    },
    transclude: {
        vnItem: '?vnItem'
    }
});