<template>
<svg :viewBox="`0 0 ${ viewBoxX } ${ viewBoxY }`" style="overflow:visible">
	<defs>
		<linearGradient :id="gradientId" x1="0" x2="0" y1="1" y2="0">
			<stop offset="0%" :stop-color="color" stop-opacity="0"></stop>
			<stop offset="100%" :stop-color="color" stop-opacity="0.65"></stop>
		</linearGradient>
	</defs>
	<polygon
		:points="polygonPoints"
		:style="`stroke: none; fill: url(#${ gradientId });`"
	/>
	<polyline
		:points="polylinePoints"
		fill="none"
		:stroke="color"
		stroke-width="2"
	/>
	<circle
		:cx="headX"
		:cy="headY"
		r="3"
		:fill="color"
	/>
</svg>
</template>

<script lang="ts" setup>
import { watch } from 'vue';
import { v4 as uuid } from 'uuid';
import tinycolor from 'tinycolor2';
import { useInterval } from '@/scripts/use-interval';

const props = defineProps<{
	src: number[];
}>();

const viewBoxX = 50;
const viewBoxY = 50;
const gradientId = uuid();
let polylinePoints = $ref('');
let polygonPoints = $ref('');
let headX = $ref<number | null>(null);
let headY = $ref<number | null>(null);
const accent = tinycolor(getComputedStyle(document.documentElement).getPropertyValue('--accent'));
const color = accent.toRgbString();

function draw(): void {
	const stats = props.src.slice().reverse();
	const peak = Math.max.apply(null, stats) || 1;

	const _polylinePoints = stats.map((n, i) => [
		i * (viewBoxX / (stats.length - 1)),
		(1 - (n / peak)) * viewBoxY,
	]);

	polylinePoints = _polylinePoints.map(xy => `${xy[0]},${xy[1]}`).join(' ');

	polygonPoints = `0,${ viewBoxY } ${ polylinePoints } ${ viewBoxX },${ viewBoxY }`;

	headX = _polylinePoints[_polylinePoints.length - 1][0];
	headY = _polylinePoints[_polylinePoints.length - 1][1];
}

watch(() => props.src, draw, { immediate: true });

// Vueが何故かWatchを発動させない場合があるので
useInterval(draw, 1000, {
	immediate: false,
	afterMounted: true,
});
</script>
