const TAP_OFFSET = 5;
import { atom } from "@cn-ui/reactive";

type Direction = "" | "vertical" | "horizontal";

function getDirection(x: number, y: number) {
    if (x > y) {
        return "horizontal";
    }
    if (y > x) {
        return "vertical";
    }
    return "";
}

export function useTouch() {
    const startX = atom(0);
    const startY = atom(0);
    const deltaX = atom(0);
    const deltaY = atom(0);
    const offsetX = atom(0);
    const offsetY = atom(0);
    const direction = atom<Direction>("");
    const isTap = atom(true);

    const isVertical = () => direction() === "vertical";
    const isHorizontal = () => direction() === "horizontal";

    const reset = () => {
        deltaX(0);
        deltaY(0);
        offsetX(0);
        offsetY(0);
        direction("");
        isTap(true);
    };

    const start = ((event: TouchEvent) => {
        reset();
        startX(event.touches[0].clientX);
        startY(event.touches[0].clientY);
    }) as EventListener;

    const move = ((event: TouchEvent) => {
        const touch = event.touches[0];
        // safari back will set clientX to negative number
        deltaX((touch.clientX < 0 ? 0 : touch.clientX) - startX());
        deltaY(touch.clientY - startY());
        offsetX(Math.abs(deltaX()));
        offsetY(Math.abs(deltaY()));

        // lock direction when distance is greater than a certain value
        const LOCK_DIRECTION_DISTANCE = 10;
        if (
            !direction() ||
            (offsetX() < LOCK_DIRECTION_DISTANCE && offsetY() < LOCK_DIRECTION_DISTANCE)
        ) {
            direction(getDirection(offsetX(), offsetY()));
        }

        if (isTap() && (offsetX() > TAP_OFFSET || offsetY() > TAP_OFFSET)) {
            isTap(false);
        }
    }) as EventListener;

    return {
        move,
        start,
        reset,
        startX,
        startY,
        deltaX,
        deltaY,
        offsetX,
        offsetY,
        direction,
        isVertical,
        isHorizontal,
        isTap,
    };
}