import {useState, useEffect} from 'react';

export function useToggle(initVal){
    const [val, setVal] = useState(initVal);
    return [val, () => setVal(!val)];
}

function useTransformState(initVal, transform, callback, validate){
    const [val, setVal] = useState(initVal);
    function set(v0){
	let v = transform(v0);
	if(!validate || validate(v, v0)){
	    setVal(v);
	    !callback || callback(v);
	}
    }
    return [val, set];
}

export function useDefaultState(initVal, transform, callback, validate){
    let def = (v) => (typeof v === 'undefined') ? initVal : v;
    let newTransform = transform ? (v) => transform(def(v)) : def;
    return useTransformState(initVal, newTransform, callback, validate);
}

// if v has a target.value, like an onChange event object, it extracts the value, otherwise passes v unchanged
function checkInput(v){
    return (v && v.target && typeof v.target.value !== 'undefined')
	 ? v.target.value : v;
}

export function useInput(initVal, transform: any = false, callback: any = false, validate: any = false){
    let newTransform = transform ? (v) => transform(checkInput(v)) : checkInput;
    return useDefaultState(initVal, newTransform, callback, validate);
}

export function useNumberInput(initVal, callback: any = false, validate: any = false){
    return useInput(initVal, (e) => {
	switch(typeof e){
	    case 'string':
		return e.length?parseInt(e):0;
	    case 'number':
		return e;
	    default:
		return 0;
	}
	return
    }, callback, validate);
}

export function useSubmit(submitFn){
    const [submitting, setSubmitting] = useState(false);

    useEffect(() => {
	if(submitting){
	    submitFn();
	    setSubmitting(false);
	}
    });

    return (e) => {
	e.preventDefault();
	setSubmitting(true);
    }
}

//callbackFns can be a single callback or an array of them
export function useSubmitPromise(promiseFn, callbackFns){
    if(!Array.isArray(callbackFns)){
	callbackFns = [callbackFns];
    }

    const [submitting, setSubmitting] = useState(false);

    useEffect(() => {
	if(submitting){

	    let promise = promiseFn();

	    for(let i=0; i<callbackFns.length; i++)
	    {
		promise = promise.then(callbackFns[i]);
	    }
	    
	    promise
		.catch(err => {
		    alert(err);
		})
		.finally(() => {
		    setSubmitting(false);		    
		});
	}
    });

    return (e) => {
	e.preventDefault();
	setSubmitting(true);
    }

}