import { useCallback, useEffect, useRef } from "react";

const primaryLineColor = "rgb(203,213,245)";
const subLineColor = "rgb(226,231,232)";

export default function GridLayer(props: {
	width: number;
	height: number;
	leftPadding: number;
	rightPadding: number;
	topPadding: number;
	bottomPadding: number;
	columns: number;
	rows: number;
	colCellNum: number;
	rowCellNum: number;
	visibility: 'hidden' | 'visible'; 
}) {
	const xStartPx = props.leftPadding;
	const xEndPx = props.width - props.rightPadding;
	const xStepPx = (props.width - props.leftPadding - props.rightPadding) / props.columns;
	const xUnitPx = xStepPx / props.colCellNum;
	const yStartPx = props.topPadding;
	const yEndPx = props.height - props.bottomPadding;
	const yStepPx = (props.height - props.topPadding - props.bottomPadding) / props.rows;
	const yUnitPx = yStepPx / props.rowCellNum;

	const canvasRef = useRef<HTMLCanvasElement | null>(null);
	const drawGrid = useCallback(
		(ctx: CanvasRenderingContext2D) => {
			ctx.resetTransform();
			ctx.clearRect(0, 0, props.width, props.height);

			ctx.beginPath();
			ctx.strokeStyle = subLineColor;
			for (let i = 1; i < props.columns * props.colCellNum; ++i) {
				if (i % props.colCellNum === 0) continue;
				ctx.moveTo(xStartPx + xUnitPx * i, yStartPx);
				ctx.lineTo(xStartPx + xUnitPx * i, yEndPx);
			}
			for (let j = 1; j < props.rows * props.rowCellNum; ++j) {
				if (j % props.rowCellNum === 0) continue;
				ctx.moveTo(xStartPx, yStartPx + yUnitPx * j);
				ctx.lineTo(xEndPx, yStartPx + yUnitPx * j);
			}
			ctx.stroke()

			ctx.beginPath();
			ctx.strokeStyle = primaryLineColor;
			for (let i = 0; i <= props.columns; ++i) {
				ctx.moveTo(xStartPx + xStepPx * i, yStartPx);
				ctx.lineTo(xStartPx + xStepPx * i, yEndPx);
			}
			for (let j = 0; j <= props.rows; ++j) {
				ctx.moveTo(xStartPx, yStartPx + yStepPx * j);
				ctx.lineTo(xEndPx, yStartPx + yStepPx * j);
			}
			ctx.stroke()


			ctx.beginPath();
			ctx.strokeStyle = "#999";
			// 偏移原点
			const xOffset = (xEndPx - xStartPx) / 2;
			const yOffset = yStepPx * 2;
			const yMax = yEndPx - yStartPx - yOffset;
			ctx.translate(xStartPx + xOffset, yStartPx + yOffset);
			// 绘制原点交叉线
			ctx.moveTo(-xOffset, 0);
			ctx.lineTo(xOffset, 0);
			ctx.moveTo(0, -yOffset);
			ctx.lineTo(0, yMax);
			ctx.stroke()

			// 绘制x轴y轴 单位数值
			ctx.beginPath();
			ctx.fillStyle = "#333333";
			ctx.textAlign = "center";
			ctx.font = "normal 14px system";
			for (let index = -4; index < 5; index++) {
				ctx.fillText((index * 10).toString(), xStepPx * index, yMax + 20);
			}
			for (let index = -1; index < 5; index++) {
				ctx.fillText((index * 10).toString(), -xOffset - (index > 0 ? 18 : 14), yStepPx * index + 4);
			}
		},
		[props.colCellNum, props.columns, props.height, props.rowCellNum, props.rows, props.width, xEndPx, xStartPx, xStepPx, xUnitPx, yEndPx, yStartPx, yStepPx, yUnitPx]
	);

	useEffect(() => {
		// 获取canvas的2D绘图上下文
		const canvas = canvasRef.current;
		if (!canvas) return;

		const context = canvas.getContext("2d");
		if (!context) return;
		// 使用context对象进行绘图
		drawGrid(context);
	}, [drawGrid]);

	return (
		<div style={{visibility: props.visibility}}>
			<canvas ref={canvasRef} width={props.width} height={props.height}></canvas>
		</div>
	);
}