<template>
    <view class="van-circle">
        <canvas class="van-circle__canvas" :type="type" :style="'width: ' + utils.addUnit(size) + ';height:' + utils.addUnit(size)" id="van-circle" canvas-id="van-circle"></canvas>
        <view v-if="!text" class="van-circle__text">
            <slot></slot>
        </view>
        <cover-view v-else class="van-circle__text">{{ text }}</cover-view>
    </view>
</template>
<script module="utils" lang="wxs" src="@/node_modules/@vant/weapp/dist/wxs/utils.wxs"></script>
<script>
import { VantComponent } from '../common/component';
import { isObj } from '../common/utils';
import { BLUE, WHITE } from '../common/color';
import { adaptor } from './canvas';
function format(rate) {
    return Math.min(Math.max(rate, 0), 100);
}
const PERIMETER = 2 * Math.PI;
const BEGIN_ANGLE = -Math.PI / 2;
const STEP = 1;
export default {
    data() {
        return {
            hoverColor: BLUE
        };
    },
    props: {
        text: String,
        lineCap: {
            type: String,
            default: 'round'
        },
        value: {
            type: Number,
            default: 0
        },
        speed: {
            type: Number,
            default: 50
        },
        size: {
            type: Number,
            default: 100
        },
        fill: String,
        layerColor: {
            type: String,
            default: WHITE
        },
        color: {
            type: [String, Object],
            default: BLUE
        },
        type: {
            type: String,
            default: ''
        },
        strokeWidth: {
            type: Number,
            default: 4
        },
        clockwise: {
            type: Boolean,
            default: true
        }
    },
    methods: {
        getContext() {
            const { type, size } = this;
            if (type === '') {
                const ctx = uni.createCanvasContext('van-circle', this);
                return Promise.resolve(ctx);
            }
            const dpr = uni.getSystemInfoSync().pixelRatio;
            return new Promise((resolve) => {
                uni.createSelectorQuery()
                    .in(this)
                    .select('#van-circle')
                    .node()
                    .exec((res) => {
                        const canvas = res[0].node;
                        const ctx = canvas.getContext(type);
                        if (!this.inited) {
                            this.inited = true;
                            canvas.width = size * dpr;
                            canvas.height = size * dpr;
                            ctx.scale(dpr, dpr);
                        }
                        resolve(adaptor(ctx));
                    });
            });
        },
        setHoverColor() {
            const { color, size } = this;
            if (isObj(color)) {
                return this.getContext().then((context) => {
                    const LinearColor = context.createLinearGradient(size, 0, 0, 0);
                    Object.keys(color)
                        .sort((a, b) => parseFloat(a) - parseFloat(b))
                        .map((key) => LinearColor.addColorStop(parseFloat(key) / 100, color[key]));
                    this.hoverColor = LinearColor;
                });
            }
            this.hoverColor = color;
            return Promise.resolve();
        },
        presetCanvas(context, strokeStyle, beginAngle, endAngle, fill) {
            const { strokeWidth, lineCap, clockwise, size } = this;
            const position = size / 2;
            const radius = position - strokeWidth / 2;
            context.setStrokeStyle(strokeStyle);
            context.setLineWidth(strokeWidth);
            context.setLineCap(lineCap);
            context.beginPath();
            context.arc(position, position, radius, beginAngle, endAngle, !clockwise);
            context.stroke();
            if (fill) {
                context.setFillStyle(fill);
                context.fill();
            }
        },
        renderLayerCircle(context) {
            const { layerColor, fill } = this;
            this.presetCanvas(context, layerColor, 0, PERIMETER, fill);
        },
        renderHoverCircle(context, formatValue) {
            const { clockwise } = this;
            // 结束角度
            const progress = PERIMETER * (formatValue / 100);
            const endAngle = clockwise ? BEGIN_ANGLE + progress : 3 * Math.PI - (BEGIN_ANGLE + progress);
            this.presetCanvas(context, this.hoverColor, BEGIN_ANGLE, endAngle);
        },
        drawCircle(currentValue) {
            const { size } = this;
            this.getContext().then((context) => {
                context.clearRect(0, 0, size, size);
                this.renderLayerCircle(context);
                const formatValue = format(currentValue);
                if (formatValue !== 0) {
                    this.renderHoverCircle(context, formatValue);
                }
                context.draw();
            });
        },
        reRender() {
            // tofector 动画暂时没有想到好的解决方案
            const { value, speed } = this;
            if (speed <= 0 || speed > 1000) {
                this.drawCircle(value);
                return;
            }
            this.clearInterval();
            this.currentValue = this.currentValue || 0;
            this.interval = setInterval(() => {
                if (this.currentValue !== value) {
                    if (this.currentValue < value) {
                        this.currentValue += STEP;
                    } else {
                        this.currentValue -= STEP;
                    }
                    this.drawCircle(this.currentValue);
                } else {
                    this.clearInterval();
                }
            }, 1000 / speed);
        },
        clearInterval() {
            if (this.interval) {
                clearInterval(this.interval);
                this.interval = null;
            }
        }
    },
    mounted() {
        this.currentValue = this.value;
        this.setHoverColor().then(() => {
            this.drawCircle(this.currentValue);
        });
    },
    destroyed() {
        this.clearInterval();
    },
    watch: {
        value: {
            handler: function () {
                // tofector 动画暂时没有想到好的解决方案
                const { value, speed } = this;
                if (speed <= 0 || speed > 1000) {
                    this.drawCircle(value);
                    return;
                }
                this.clearInterval();
                this.currentValue = this.currentValue || 0;
                this.interval = setInterval(() => {
                    if (this.currentValue !== value) {
                        if (this.currentValue < value) {
                            this.currentValue += STEP;
                        } else {
                            this.currentValue -= STEP;
                        }
                        this.drawCircle(this.currentValue);
                    } else {
                        this.clearInterval();
                    }
                }, 1000 / speed);
            },

            immediate: true
        },

        size: {
            handler: function () {
                this.drawCircle(this.currentValue);
            },

            immediate: true
        },

        color: {
            handler: function () {
                this.setHoverColor().then(() => {
                    this.drawCircle(this.currentValue);
                });
            },

            immediate: true
        }
    }
};
</script>
<style>
@import './index.css';
</style>
