<template>
	<div class="scroll">
		<Expand
			v-if="expanded"
			:expanded="expanded"
			class="expand-light"
			@expand="(state) => $emit('expand', state)"
		/>

		<Expand
			v-if="expanded"
			:expanded="expanded"
			class="expand-dark"
			@expand="(state) => $emit('expand', state)"
		/>

		<div class="scrollable">
			<div
				v-show="enabled && !expanded"
				class="scroll-button scroll-left noselect"
				:class="{ 'scroll-start': scrollAtStart }"
				@click="scroll('left')"
			><Icon icon="arrow-left3" /></div>

			<div
				ref="content"
				class="scroll-content"
			>
				<slot :loaded="loaded" />
			</div>

			<div
				v-show="enabled && !expanded"
				class="scroll-button scroll-right noselect"
				:class="{ 'scroll-end': scrollAtEnd }"
				@click="scroll('right')"
			><Icon icon="arrow-right3" /></div>
		</div>

		<Expand
			v-if="expanded || (expandable && scrollable)"
			:expanded="expanded"
			class="expand-light"
			@expand="(state) => $emit('expand', state)"
		/>

		<Expand
			v-if="expanded || (expandable && scrollable)"
			:expanded="expanded"
			class="expand-dark"
			@expand="(state) => $emit('expand', state)"
		/>
	</div>
</template>

<script>
import Expand from '../expand/expand.vue';

function updateScroll() {
	this.scrollable = this.$refs.content.scrollWidth > this.$refs.content.clientWidth;
	this.scrollAtStart = this.$refs.content.scrollLeft === 0;
	this.scrollAtEnd = this.$refs.content.scrollWidth - this.$refs.content.clientWidth === this.$refs.content.scrollLeft;
}

function scroll(direction) {
	if (direction === 'right') {
		this.$refs.content.scrollLeft = this.$refs.content.scrollLeft + this.$refs.content.clientWidth - 100;
	}

	if (direction === 'left') {
		this.$refs.content.scrollLeft = this.$refs.content.scrollLeft - this.$refs.content.clientWidth + 100;
	}
}

function loaded(_event) {
	// typically triggered by slotted component when an image loads, affecting scrollWidth
	this.updateScroll();
}

function mounted() {
	this.$refs.content.addEventListener('scroll', () => this.updateScroll());
	window.addEventListener('resize', this.updateScroll);

	this.updateScroll();
}

function beforeUnmount() {
	this.$refs.content.removeEventListener('scroll', this.updateScroll);

	window.removeEventListener('resize', this.updateScroll);
}

function updated() {
	this.updateScroll();
}

export default {
	components: {
		Expand,
	},
	props: {
		enabled: {
			type: Boolean,
			default: true,
		},
		expandable: {
			type: Boolean,
			default: true,
		},
		expanded: {
			type: Boolean,
			default: false,
		},
	},
	data() {
		return {
			scrollable: true,
			scrollAtStart: true,
			scrollAtEnd: false,
		};
	},
	mounted,
	updated,
	beforeUnmount,
	methods: {
		scroll,
		loaded,
		updateScroll,
	},
};
</script>

<style lang="scss" scoped>
@import 'breakpoints';

.scroll.expanded {
	padding: 0;

	.scroll {
		display: none;
	}
}

.scrollable {
	position: relative;
}

.scroll-content {
	overflow-x: scroll;
	scroll-behavior: smooth;
	scrollbar-width: none;

    &::-webkit-scrollbar {
        display: none;
    }
}

.scroll-button {
	height: 100%;
	display: flex;
	align-items: center;
	box-sizing: border-box;
	position: absolute;
	top: 0;
	bottom: 0;
	z-index: 10;

	&.scroll-start,
	&.scroll-end {
		/* use over v-show so button stays visible while still hovered */
		display: none;
	}

	&.scroll-start {
		left: 0;
	}

	&.scroll-end {
		right: 0;
	}

	.icon {
		width: 1.5rem;
		height: 1.5rem;
		fill: var(--lighten);
	}

	&.scroll-start .icon,
	&.scroll-end .icon {
		fill: var(--lighten-weak);
	}

	&:hover:not(.scroll-start):not(.scroll-end) .icon {
		fill: var(--lighten-strong);
	}

	&:hover {
		display: flex;
		cursor: pointer;
	}
}

.scroll-left {
	left: 0;
	padding: 1rem 2rem 1rem .5rem;
}

.scroll-right {
	right: 0;
	padding: 1rem .5rem 1rem 2rem;
}

.scroll .expand-light {
	display: none;
}

.scroll-light {
	.expand-light {
		display: block;
	}

	.expand-dark {
		display: none;
	}
}

.scroll-dark .expand-light {
	display: none;
}

@media(max-width: $breakpoint-micro) {
	/* buttons block swiping motion */
	.scroll-button {
		display: none;
	}
}
</style>
