import { Y_BUFFER_INDEX } from '@/lib/constants/dom-buffer';
import { getEndIndex, getStartIndex, getViewCount } from '@/lib/calculate/row';
import { Store } from '@/lib/store';

export class ScrollOperator {
    private readonly store: Store;
    private scrollYTicking: boolean;

    constructor(store: Store) {
        this.store = store;
        this.scrollYTicking = false;
    }

    public scrollY = (scrollTop: number) => {
        if (!this.scrollYTicking) {
            requestAnimationFrame(() => {
                // 静止右键菜单
                this.silentEnvironment();
                const { startIndex, endIndex, ignore } = this.calculateYStartAndEnd(scrollTop);
                if (!ignore) {
                    this.changeScrollY(startIndex, endIndex);
                }
                this.scrollYTicking = false;
            });
            this.scrollYTicking = true;
        }
    };

    public scrollX(scrollLeft: number, offsetWidth: number) {
        this.silentEnvironment();
        const { startXLeft, endXLeft } = this.calculateXStartAndEnd(scrollLeft, offsetWidth);
        this.changeScrollX(startXLeft, endXLeft);
    }

    // private async batchScrollY(times: number, step: number, startIndex: number, endIndex: number) {
    //     let startIndexCount = startIndex;
    //     let endIndexCount = endIndex;
    //     for (let i = 0; i < times; i++) {
    //         startIndexCount = startIndexCount + step;
    //         endIndexCount = endIndexCount + step;
    //         console.log(`[test]${startIndexCount}-${endIndexCount}`);
    //         this.changeScrollY(startIndexCount, endIndexCount);
    //         await nextTick();
    //     }
    // }

    private silentEnvironment() {
        // 如果右键菜单是激活态，需要关闭
        // TODO 抽象 rightMenu 的 Operator
        if (this.store.state.rightMenu.active) {
            this.store.mutation.inactiveRightMenu();
        }
    }

    private calculateYStartAndEnd(scrollTop: number) {
        const viewCount = getViewCount(
            this.store.state.config.bodyViewHeight,
            this.store.state.config.rowHeight,
        );
        const startIndex = getStartIndex(scrollTop, this.store.state.config.rowHeight);
        const endIndex = getEndIndex(startIndex, viewCount);
        // 上滑动边界
        const startBoundary = this.getLastYStartIndex() + Y_BUFFER_INDEX / 2;
        const endBoundary = this.getLastYEndIndex() - Y_BUFFER_INDEX / 2;
        // 已经越过边界
        if (startIndex < startBoundary || endIndex > endBoundary) {
            const resultStart = startIndex - Y_BUFFER_INDEX <= 0 ? 0 : startIndex - Y_BUFFER_INDEX;
            const resultEnd = endIndex + Y_BUFFER_INDEX;
            return { startIndex: resultStart, endIndex: resultEnd };
        }
        return { ignore: true };
    }

    private getLastYStartIndex() {
        return this.store.state.virtualScroll.y.startIndex;
    }

    private getLastYEndIndex() {
        return this.store.state.virtualScroll.y.endIndex;
    }

    private calculateXStartAndEnd(scrollLeft: number, offsetWidth: number) {
        const startXLeft = scrollLeft;
        const endXLeft = scrollLeft + offsetWidth;
        return {
            startXLeft,
            endXLeft,
        };
    }

    private changeScrollY(startIndex: number, endIndex: number) {
        this.store.mutation.changeVirtualScroll(startIndex, endIndex);
    }

    private changeScrollX(startXLeft: number, endXLeft: number) {
        this.store.mutation.changeVirtualScrollX(startXLeft, endXLeft);
    }
}