<template>
    <div class="p-galleria-thumbnail-wrapper">
        <div class="p-galleria-thumbnail-container">
            <button v-if="showThumbnailNavigators" v-ripple :class="navBackwardClass" @click="navBackward($event)" :disabled="isNavBackwardDisabled()" type="button">
                <span :class="navBackwardIconClass"></span>
            </button>
            <div class="p-galleria-thumbnail-items-container" :style="{ height: isVertical ? contentHeight : '' }">
                <div ref="itemsContainer" class="p-galleria-thumbnail-items" @transitionend="onTransitionEnd" @touchstart="onTouchStart($event)" @touchmove="onTouchMove($event)" @touchend="onTouchEnd($event)">
                    <div
                        v-for="(item, index) of value"
                        :key="`p-galleria-thumbnail-item-${index}`"
                        :class="[
                            'p-galleria-thumbnail-item',
                            {
                                'p-galleria-thumbnail-item-current': activeIndex === index,
                                'p-galleria-thumbnail-item-active': isItemActive(index),
                                'p-galleria-thumbnail-item-start': firstItemAciveIndex() === index,
                                'p-galleria-thumbnail-item-end': lastItemActiveIndex() === index
                            }
                        ]"
                    >
                        <div class="p-galleria-thumbnail-item-content" :tabindex="isItemActive(index) ? 0 : null" @click="onItemClick(index)" @keydown.enter="onItemClick(index)">
                            <component v-if="templates.thumbnail" :is="templates.thumbnail" :item="item" />
                        </div>
                    </div>
                </div>
            </div>
            <button v-if="showThumbnailNavigators" v-ripple :class="navForwardClass" @click="navForward($event)" :disabled="isNavForwardDisabled()" type="button">
                <span :class="navForwardIconClass"></span>
            </button>
        </div>
    </div>
</template>

<script>
import { DomHandler } from 'primevue/utils';
import Ripple from 'primevue/ripple';

export default {
    name: 'GalleriaThumbnails',
    emits: ['stop-slideshow', 'update:activeIndex'],
    props: {
        containerId: {
            type: String,
            default: null
        },
        value: {
            type: Array,
            default: null
        },
        numVisible: {
            type: Number,
            default: 3
        },
        activeIndex: {
            type: Number,
            default: 0
        },
        isVertical: {
            type: Boolean,
            default: false
        },
        slideShowActive: {
            type: Boolean,
            default: false
        },
        circular: {
            type: Boolean,
            default: false
        },
        responsiveOptions: {
            type: Array,
            default: null
        },
        contentHeight: {
            type: String,
            default: '300px'
        },
        showThumbnailNavigators: {
            type: Boolean,
            default: true
        },
        templates: {
            type: null,
            default: null
        }
    },
    startPos: null,
    thumbnailsStyle: null,
    sortedResponsiveOptions: null,
    data() {
        return {
            d_numVisible: this.numVisible,
            d_oldNumVisible: this.numVisible,
            d_activeIndex: this.activeIndex,
            d_oldActiveItemIndex: this.activeIndex,
            totalShiftedItems: 0,
            page: 0
        };
    },
    watch: {
        numVisible(newValue, oldValue) {
            this.d_numVisible = newValue;
            this.d_oldNumVisible = oldValue;
        },
        activeIndex(newValue, oldValue) {
            this.d_activeIndex = newValue;
            this.d_oldActiveItemIndex = oldValue;
        }
    },
    mounted() {
        this.createStyle();
        this.calculatePosition();

        if (this.responsiveOptions) {
            this.bindDocumentListeners();
        }
    },
    updated() {
        let totalShiftedItems = this.totalShiftedItems;

        if (this.d_oldNumVisible !== this.d_numVisible || this.d_oldActiveItemIndex !== this.d_activeIndex) {
            if (this.d_activeIndex <= this.getMedianItemIndex()) {
                totalShiftedItems = 0;
            } else if (this.value.length - this.d_numVisible + this.getMedianItemIndex() < this.d_activeIndex) {
                totalShiftedItems = this.d_numVisible - this.value.length;
            } else if (this.value.length - this.d_numVisible < this.d_activeIndex && this.d_numVisible % 2 === 0) {
                totalShiftedItems = this.d_activeIndex * -1 + this.getMedianItemIndex() + 1;
            } else {
                totalShiftedItems = this.d_activeIndex * -1 + this.getMedianItemIndex();
            }

            if (totalShiftedItems !== this.totalShiftedItems) {
                this.totalShiftedItems = totalShiftedItems;
            }

            this.$refs.itemsContainer.style.transform = this.isVertical ? `translate3d(0, ${totalShiftedItems * (100 / this.d_numVisible)}%, 0)` : `translate3d(${totalShiftedItems * (100 / this.d_numVisible)}%, 0, 0)`;

            if (this.d_oldActiveItemIndex !== this.d_activeIndex) {
                DomHandler.removeClass(this.$refs.itemsContainer, 'p-items-hidden');
                this.$refs.itemsContainer.style.transition = 'transform 500ms ease 0s';
            }

            this.d_oldActiveItemIndex = this.d_activeIndex;
            this.d_oldNumVisible = this.d_numVisible;
        }
    },
    beforeUnmount() {
        if (this.responsiveOptions) {
            this.unbindDocumentListeners();
        }

        if (this.thumbnailsStyle) {
            this.thumbnailsStyle.parentNode.removeChild(this.thumbnailsStyle);
        }
    },
    methods: {
        step(dir) {
            let totalShiftedItems = this.totalShiftedItems + dir;

            if (dir < 0 && -1 * totalShiftedItems + this.d_numVisible > this.value.length - 1) {
                totalShiftedItems = this.d_numVisible - this.value.length;
            } else if (dir > 0 && totalShiftedItems > 0) {
                totalShiftedItems = 0;
            }

            if (this.circular) {
                if (dir < 0 && this.value.length - 1 === this.d_activeIndex) {
                    totalShiftedItems = 0;
                } else if (dir > 0 && this.d_activeIndex === 0) {
                    totalShiftedItems = this.d_numVisible - this.value.length;
                }
            }

            if (this.$refs.itemsContainer) {
                DomHandler.removeClass(this.$refs.itemsContainer, 'p-items-hidden');
                this.$refs.itemsContainer.style.transform = this.isVertical ? `translate3d(0, ${totalShiftedItems * (100 / this.d_numVisible)}%, 0)` : `translate3d(${totalShiftedItems * (100 / this.d_numVisible)}%, 0, 0)`;
                this.$refs.itemsContainer.style.transition = 'transform 500ms ease 0s';
            }

            this.totalShiftedItems = totalShiftedItems;
        },
        stopSlideShow() {
            if (this.slideShowActive && this.stopSlideShow) {
                this.$emit('stop-slideshow');
            }
        },
        getMedianItemIndex() {
            let index = Math.floor(this.d_numVisible / 2);

            return this.d_numVisible % 2 ? index : index - 1;
        },
        navBackward(e) {
            this.stopSlideShow();

            let prevItemIndex = this.d_activeIndex !== 0 ? this.d_activeIndex - 1 : 0;
            let diff = prevItemIndex + this.totalShiftedItems;

            if (this.d_numVisible - diff - 1 > this.getMedianItemIndex() && (-1 * this.totalShiftedItems !== 0 || this.circular)) {
                this.step(1);
            }

            let activeIndex = this.circular && this.d_activeIndex === 0 ? this.value.length - 1 : prevItemIndex;

            this.$emit('update:activeIndex', activeIndex);

            if (e.cancelable) {
                e.preventDefault();
            }
        },
        navForward(e) {
            this.stopSlideShow();

            let nextItemIndex = this.d_activeIndex + 1;

            if (nextItemIndex + this.totalShiftedItems > this.getMedianItemIndex() && (-1 * this.totalShiftedItems < this.getTotalPageNumber() - 1 || this.circular)) {
                this.step(-1);
            }

            let activeIndex = this.circular && this.value.length - 1 === this.d_activeIndex ? 0 : nextItemIndex;

            this.$emit('update:activeIndex', activeIndex);

            if (e.cancelable) {
                e.preventDefault();
            }
        },
        onItemClick(index) {
            this.stopSlideShow();

            let selectedItemIndex = index;

            if (selectedItemIndex !== this.d_activeIndex) {
                const diff = selectedItemIndex + this.totalShiftedItems;
                let dir = 0;

                if (selectedItemIndex < this.d_activeIndex) {
                    dir = this.d_numVisible - diff - 1 - this.getMedianItemIndex();

                    if (dir > 0 && -1 * this.totalShiftedItems !== 0) {
                        this.step(dir);
                    }
                } else {
                    dir = this.getMedianItemIndex() - diff;

                    if (dir < 0 && -1 * this.totalShiftedItems < this.getTotalPageNumber() - 1) {
                        this.step(dir);
                    }
                }

                this.$emit('update:activeIndex', selectedItemIndex);
            }
        },
        onTransitionEnd() {
            if (this.$refs.itemsContainer) {
                DomHandler.addClass(this.$refs.itemsContainer, 'p-items-hidden');
                this.$refs.itemsContainer.style.transition = '';
            }
        },
        onTouchStart(e) {
            let touchobj = e.changedTouches[0];

            this.startPos = {
                x: touchobj.pageX,
                y: touchobj.pageY
            };
        },
        onTouchMove(e) {
            if (e.cancelable) {
                e.preventDefault();
            }
        },
        onTouchEnd(e) {
            let touchobj = e.changedTouches[0];

            if (this.isVertical) {
                this.changePageOnTouch(e, touchobj.pageY - this.startPos.y);
            } else {
                this.changePageOnTouch(e, touchobj.pageX - this.startPos.x);
            }
        },
        changePageOnTouch(e, diff) {
            if (diff < 0) {
                // left
                this.navForward(e);
            } else {
                // right
                this.navBackward(e);
            }
        },
        getTotalPageNumber() {
            return this.value.length > this.d_numVisible ? this.value.length - this.d_numVisible + 1 : 0;
        },
        createStyle() {
            if (!this.thumbnailsStyle) {
                this.thumbnailsStyle = document.createElement('style');
                this.thumbnailsStyle.type = 'text/css';
                document.body.appendChild(this.thumbnailsStyle);
            }

            let innerHTML = `
                #${this.containerId} .p-galleria-thumbnail-item {
                    flex: 1 0 ${100 / this.d_numVisible}%
                }
            `;

            if (this.responsiveOptions) {
                this.sortedResponsiveOptions = [...this.responsiveOptions];
                this.sortedResponsiveOptions.sort((data1, data2) => {
                    const value1 = data1.breakpoint;
                    const value2 = data2.breakpoint;
                    let result = null;

                    if (value1 == null && value2 != null) result = -1;
                    else if (value1 != null && value2 == null) result = 1;
                    else if (value1 == null && value2 == null) result = 0;
                    else if (typeof value1 === 'string' && typeof value2 === 'string') result = value1.localeCompare(value2, undefined, { numeric: true });
                    else result = value1 < value2 ? -1 : value1 > value2 ? 1 : 0;

                    return -1 * result;
                });

                for (let i = 0; i < this.sortedResponsiveOptions.length; i++) {
                    let res = this.sortedResponsiveOptions[i];

                    innerHTML += `
                        @media screen and (max-width: ${res.breakpoint}) {
                            #${this.containerId} .p-galleria-thumbnail-item {
                                flex: 1 0 ${100 / res.numVisible}%
                            }
                        }
                    `;
                }
            }

            this.thumbnailsStyle.innerHTML = innerHTML;
        },
        calculatePosition() {
            if (this.$refs.itemsContainer && this.sortedResponsiveOptions) {
                let windowWidth = window.innerWidth;
                let matchedResponsiveData = {
                    numVisible: this.numVisible
                };

                for (let i = 0; i < this.sortedResponsiveOptions.length; i++) {
                    let res = this.sortedResponsiveOptions[i];

                    if (parseInt(res.breakpoint, 10) >= windowWidth) {
                        matchedResponsiveData = res;
                    }
                }

                if (this.d_numVisible !== matchedResponsiveData.numVisible) {
                    this.d_numVisible = matchedResponsiveData.numVisible;
                }
            }
        },
        bindDocumentListeners() {
            if (!this.documentResizeListener) {
                this.documentResizeListener = () => {
                    this.calculatePosition();
                };

                window.addEventListener('resize', this.documentResizeListener);
            }
        },
        unbindDocumentListeners() {
            if (this.documentResizeListener) {
                window.removeEventListener('resize', this.documentResizeListener);
                this.documentResizeListener = null;
            }
        },
        isNavBackwardDisabled() {
            return (!this.circular && this.d_activeIndex === 0) || this.value.length <= this.d_numVisible;
        },
        isNavForwardDisabled() {
            return (!this.circular && this.d_activeIndex === this.value.length - 1) || this.value.length <= this.d_numVisible;
        },
        firstItemAciveIndex() {
            return this.totalShiftedItems * -1;
        },
        lastItemActiveIndex() {
            return this.firstItemAciveIndex() + this.d_numVisible - 1;
        },
        isItemActive(index) {
            return this.firstItemAciveIndex() <= index && this.lastItemActiveIndex() >= index;
        }
    },
    computed: {
        navBackwardClass() {
            return [
                'p-galleria-thumbnail-prev p-link',
                {
                    'p-disabled': this.isNavBackwardDisabled()
                }
            ];
        },
        navForwardClass() {
            return [
                'p-galleria-thumbnail-next p-link',
                {
                    'p-disabled': this.isNavForwardDisabled()
                }
            ];
        },
        navBackwardIconClass() {
            return [
                'p-galleria-thumbnail-prev-icon pi',
                {
                    'pi-chevron-left': !this.isVertical,
                    'pi-chevron-up': this.isVertical
                }
            ];
        },
        navForwardIconClass() {
            return [
                'p-galleria-thumbnail-next-icon pi',
                {
                    'pi-chevron-right': !this.isVertical,
                    'pi-chevron-down': this.isVertical
                }
            ];
        }
    },
    directives: {
        ripple: Ripple
    }
};
</script>
