import { ref, onMounted } from "vue";

/**
 * 绘制图形验证码
 * @param width - 图形宽度
 * @param height - 图形高度
 */
export const useImageVerify = (width = 120, height = 40) => {
    const domRef = ref<HTMLCanvasElement>();
    const imgCode = ref("");

    function setImgCode(code: string) {
        imgCode.value = code;
    }

    function getImgCode() {
        if (!domRef.value) return;
        imgCode.value = draw(domRef.value, width, height);
    }

    onMounted(() => {
        getImgCode();
    });

    return {
        domRef,
        imgCode,
        setImgCode,
        getImgCode,
    };
};

function randomNum(min: number, max: number) {
    const num = Math.floor(Math.random() * (max - min) + min);
    return num;
}

function randomColor(min: number, max: number) {
    const r = randomNum(min, max);
    const g = randomNum(min, max);
    const b = randomNum(min, max);
    return `rgb(${r},${g},${b})`;
}

function draw(dom: HTMLCanvasElement, width: number, height: number) {
    let imgCode = "";

    const NUMBER_STRING = "0123456789";

    const ctx = dom.getContext("2d");
    if (!ctx) return imgCode;

    ctx.fillStyle = randomColor(180, 230);
    ctx.fillRect(0, 0, width, height);
    for (let i = 0; i < 4; i += 1) {
        const text = NUMBER_STRING[randomNum(0, NUMBER_STRING.length)];
        imgCode += text;
        const fontSize = randomNum(18, 41);
        const deg = randomNum(-30, 30);
        ctx.font = `${fontSize}px Simhei`;
        ctx.textBaseline = "top";
        ctx.fillStyle = randomColor(80, 150);
        ctx.save();
        ctx.translate(30 * i + 15, 15);
        ctx.rotate((deg * Math.PI) / 180);
        ctx.fillText(text, -15 + 5, -15);
        ctx.restore();
    }
    for (let i = 0; i < 5; i += 1) {
        ctx.beginPath();
        ctx.moveTo(randomNum(0, width), randomNum(0, height));
        ctx.lineTo(randomNum(0, width), randomNum(0, height));
        ctx.strokeStyle = randomColor(180, 230);
        ctx.closePath();
        ctx.stroke();
    }
    for (let i = 0; i < 41; i += 1) {
        ctx.beginPath();
        ctx.arc(randomNum(0, width), randomNum(0, height), 1, 0, 2 * Math.PI);
        ctx.closePath();
        ctx.fillStyle = randomColor(150, 200);
        ctx.fill();
    }
    return imgCode;
}