/**
 * CALCULATE VECTOR
 * REF: https://github.com/toji/gl-matrix/blob/master/src/vec2.js
 */
export const isF = (f: unknown): f is Function => typeof f === 'function'

const Vec = typeof Float32Array !== 'undefined' ? Float32Array : Array

export const vec2 = (x = 0, y = 0, out = new Vec(2)): Vec2 => {
        out[0] = x
        out[1] = y
        return out as Vec2
}

export type Vec2 = [x: number, y: number]

export const addV = (a: Vec2, b: Vec2, out = vec2()): Vec2 => {
        out[0] = a[0] + b[0]
        out[1] = a[1] + b[1]
        return out
}

export const subV = (a: Vec2, b: Vec2, out = vec2()): Vec2 => {
        out[0] = a[0] - b[0]
        out[1] = a[1] - b[1]
        return out
}

export const cpV = (a: Vec2, out = vec2()): Vec2 => {
        out[0] = a[0]
        out[1] = a[1]
        return out
}

/**
 * SUPPORT
 */
const isBrowser = typeof window !== 'undefined' && !!window.document && !!window.document.createElement

const supportsTouchEvents = () => isBrowser && 'ontouchstart' in window

const isTouchScreen = () => supportsTouchEvents() || (isBrowser && window.navigator.maxTouchPoints > 1)

const supportsPointerEvents = () => isBrowser && 'onpointerdown' in window

const supportsPointerLock = () => isBrowser && 'exitPointerLock' in window.document

const supportsGestureEvents = () => {
        try {
                // @ts-ignore eslint-disable-next-line
                return 'constructor' in GestureEvent
        } catch (e) {
                return false
        }
}

// prettier-ignore
export const SUPPORT: Record<string, boolean> = {                       // Mac
        isBrowser, // true
        get gesture() {
                return (
                        SUPPORT._gesture ??
                        (SUPPORT._gesture = supportsGestureEvents())
                )
        },
        get touch() {
                return (
                        SUPPORT._touch ??
                        (SUPPORT._touch = supportsTouchEvents())
                )
        },
        get touchscreen() {
                return (
                        SUPPORT._touchscreen ??
                        (SUPPORT._touchscreen = isTouchScreen())
                )
        },
        get pointer() {
                return (
                        SUPPORT._pointer ??
                        (SUPPORT._pointer = supportsPointerEvents())
                )
        },
        get pointerLock() {
                return (
                        SUPPORT._pointerLock ??
                        (SUPPORT._pointerLock = supportsPointerLock())
                )
        },
}

/**
 * https://github.com/pmndrs/use-gesture/blob/main/packages/core/src/config/dragConfigResolver.ts
 */
export const getDevice = (lock = false) => {
        const pointerLock = lock && SUPPORT.pointerLock
        if (pointerLock) return 'mouse'
        if (SUPPORT.touch) return 'touch'
        if (SUPPORT.pointer) return 'pointer'
        return 'mouse'
}

export const getClientVec2 = (e: any, device: unknown, out: Vec2): Vec2 => {
        if (device !== 'touch') {
                return vec2(e.clientX, e.clientY, out)
        }
        const [touch] = e.changedTouches
        return vec2(touch.clientX, touch.clientY, out)
}