import React, {useRef, useEffect, useState} from 'react'
import SliderImage from './SliderImage'

export default ({images = [], imgWidth=377, className, onChange, onClick, ref, siblingOnly, current:propCurrent=0, ...props}) => {
    const containerRef          = useRef()
    const autoscroll            = useRef(false)
    const afterAutoscroll       = useRef(false)
    const inTouch               = useRef(false)
    const timeout               = useRef(false)
    const afterTimeout          = useRef(false)

    const imgs                  = useRef([])
    const currentRef            = useRef(propCurrent)
    const diffRef               = useRef(0)

    const getCurrentImages = (current) => { 
        return [
                   images[(current + images.length -1) % images.length], 
                   images[current], 
                   images[(current + 1) % images.length] 
               ]
    }


    let currentImages = getCurrentImages(currentRef.current)


    useEffect(() => {
        if (containerRef.current)
            containerRef.current.scrollTo({left: imgWidth, behavior: 'auto'})
    }, [containerRef.current])



    const onTouchEnd = () => {
        if (!containerRef.current)
            setTimeout(onTouchEnd, 20)
        // console.log('TOUCH END', inTouch.current, autoscroll.current, afterAutoscroll.current, 
        //                          containerRef.current.scrollLeft, containerRef.current.scrollWidth)
        if (inTouch.current){
            if (timeout.current) clearInterval(timeout.current)

            timeout.current = setTimeout(onTouchEnd, 200)
            return;
        }

        const {scrollLeft, scrollWidth} = containerRef.current;
        const viewPortWidth             = containerRef.current.getBoundingClientRect().width

        console.log(scrollLeft, scrollWidth)

        autoscroll.current = true
        if (scrollLeft < imgWidth/2) {
            console.log('left')
            containerRef.current.scrollTo({left: 0, behavior: 'smooth'})
            diffRef.current = -1
            onScroll()
        }
        else if (scrollLeft >= scrollWidth - viewPortWidth*1.5) {
            console.log('right', (scrollLeft - imgWidth * 2))
            const toRight = imgWidth * 2
            diffRef.current = +1
            containerRef.current.scrollTo({left: toRight, behavior: 'smooth'})
            onScroll()
        }
        else {
            console.log('center', containerRef.current.scrollWidth)
            diffRef.current = 0
            const toCurrent = imgWidth
            if (toCurrent === scrollLeft){
                autoscroll.current = false
            }
            else {
                containerRef.current.scrollTo({left: toCurrent, behavior: 'smooth'})
            }
        }
    }

    const onScroll = () => {
        if (autoscroll.current){
            if (afterTimeout.current) 
                clearInterval(afterTimeout.current)

            afterTimeout.current = setTimeout(() => {
                const {scrollLeft, scrollWidth} = containerRef.current;
                const {current}                 = currentRef
                console.log('AFTER', scrollLeft, scrollWidth)
                const newCurrent = ((currentRef.current + diffRef.current +images.length) % images.length)
                let currentImages = getCurrentImages(newCurrent)
                console.log('move from', diffRef.current, current, newCurrent, currentImages)
                if (newCurrent !== current){
                    imgs.current[0].src   = currentImages[0]
                    imgs.current[1].src   = currentImages[1]
                    imgs.current[2].src   = currentImages[2]
                    containerRef.current.scrollTo({left: imgWidth, behavior: 'auto'})
                    onChange(newCurrent)

                    //afterAutoscroll.current = true
                }

                currentRef.current    = newCurrent
                autoscroll.current    = false
                diffRef.current       = 0


                console.log(diffRef.current, newCurrent)
            }, 200)
            return;
        }

        if (timeout.current) clearInterval(timeout.current)

        timeout.current = setTimeout(onTouchEnd, 200)
        //e.preventDefault();
    }

    //useEffect(scrollToCurrent, [current])

    const isTouchDevice = () => (navigator.maxTouchPoints || 'ontouchstart' in document.documentElement);

    const onImgClick = (e, i) => {
        const touchDevice = isTouchDevice()
        if (touchDevice && typeof onClick === 'function'){
            onClick(i)
        }
        else {
            const viewPortWidth             = containerRef.current.getBoundingClientRect().width
            const clickX                    = e.clientX -e.target.getBoundingClientRect().x 
            const {scrollLeft}              = containerRef.current;
            if (clickX > viewPortWidth * 0.75) {
                containerRef.current.scrollTo({left: scrollLeft + imgWidth*0.8, behavior: 'auto'})
                onTouchEnd()
            }
            else if (clickX < viewPortWidth * 0.25) {
                containerRef.current.scrollTo({left: scrollLeft - imgWidth*0.8, behavior: 'auto'})
                onTouchEnd()
            }
            else if (typeof onClick === 'function'){
                onClick(i)
            }
        }
    }

    const imgStyle = {
        maxWidth: imgWidth + 'px',
        minWidth: imgWidth + 'px',
        width:    imgWidth + 'px',
        boxSizing: 'border-box'
    }


    return (
        <div className={className} 
             style={{cssText: `overflow: auto; overflow-y: hidden; -ms-overflow-style: none; scrollbar-width: none; overscroll-behavior-x: none;`}}
             onScroll={onScroll} //TODO: do it only on desktop, on touch devices use onTouchEnd
             ref={containerRef} 
            {...isTouchDevice() ? {
                onTouchStart(){
                    inTouch.current = true
                    autoscroll.current = false
                },
                onTouchEnd(){
                    inTouch.current = false
                }
            }: {}}
            >
            <div style={{minWidth: imgWidth*3 + 'px'}}>
                <img src={currentImages[0]}
                     style={imgStyle}
                     key={`image_${(currentRef.current -1 +images.length) % images.length}`} 
                     alt={`image ${(currentRef.current -1 +images.length) % images.length}`} 
                     ref={img => imgs.current[0] = img}
                     />
                <img src={currentImages[1]}
                     style={imgStyle}
                     key={`image_${currentRef.current}`} 
                     alt={`image ${currentRef.current}`}
                     ref={img => imgs.current[1] = img}
                     onClick={e => onImgClick(e, currentRef.current)}
                    />
                <img src={currentImages[2]}
                     style={imgStyle}
                     key={`image_${(currentRef.current +1 +images.length) % images.length}`} 
                     alt={`image ${(currentRef.current +1 +images.length) % images.length}`} 
                     ref={img => imgs.current[2] = img}
                     />
            </div>
        </div>
    )
}