import React, { useState, useRef, useEffect, useReducer } from 'react'
import { initialState, reducer } from '../../reducers/assembly-items'
import './styles/assembly-items.css'

export const AssemblyItems = ({ registerEvent }) => {
    const [assemblyItems, dispatch] = useReducer(reducer, initialState)
    const [selectedItem, setSelectedItem] = useState(0)
    const refs = useRef({})
    const asmItemsRef = useRef(null)

    useEffect(()=>{
        registerEvent && registerEvent('codeManagerChanged', (code, address, index) => {
            dispatch({ type: 'FETCH_OPCODES_SUCCESS', payload: { code, address, index } })
        })
    }, [])

    useEffect(() => {
        if (selectedItem !== assemblyItems.index) {
            indexChanged(assemblyItems.index)
        }
    }, [assemblyItems.index])

    const indexChanged = (index: number) => {
        if (index < 0) return
        let currentItem = refs.current[selectedItem] ? refs.current[selectedItem] : null

        if (currentItem) {
            currentItem.removeAttribute('selected')
            currentItem.removeAttribute('style')
            if (currentItem.firstChild) {
                currentItem.firstChild.removeAttribute('style')
            }
            const codeView = asmItemsRef.current
    
            currentItem = codeView.children[index]
            currentItem.style.setProperty('border-color', 'var(--primary)')
            currentItem.style.setProperty('border-style', 'solid')
            currentItem.setAttribute('selected', 'selected')
            codeView.scrollTop = currentItem.offsetTop - parseInt(codeView.offsetTop)
            setSelectedItem(index)
        }
    }

    return (
        <div className="border rounded px-1 mt-1 bg-light">
            <div className='dropdownpanel'>
                <div className='dropdowncontent'>
                    <div className="pl-2 my-1 small instructions" id='asmitems' ref={asmItemsRef}>
                        {
                            assemblyItems.display.map((item, i) => {
                                return <div className="px-1" key={i} ref={ref => refs.current[i] = ref}><span>{item}</span></div>
                            })
                        }
                    </div>
                </div>
            </div>
        </div>
    )
}

export default AssemblyItems