SW 2022-05-20

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title lang="PT">Algoritmo do nº do Bilhete de Identidade / PT Citizen ID card algorithm</title>
    <script src="bi.js"></script>
</head>
<body>
    <form id="idForm">
        <fieldset>
        <legend>Dados do BI</legend>
        <label for="idBI">Um nº de BI: </label>
        <!-- aqui pretendo impedir a escrita de letras, só aceitar digitos -->
        <input type="text" id="idBI"><br>
        <label for="idDC">Digito de controlo: </label>
        <!-- aqui pretendo impedir a escrita de letras, só aceitar digitos -->
        <!-- só com HTML, não temos solução para essa restrição -->
        <!-- a restrição terá q ser programada com captura de keyboard-related events em JS -->
        <input type="text" id="idDC" size="4">
        </fieldset>
        <input type="submit" value="submeter dados">
    </form>
    <hr>
    <section id="idSectionFeedback"></section>
</body>
</html>

***
//bi.js
window.onload = boot

const ID_FORM="idForm",
    ID_BI = "idBI",
    ID_DC = "idDC",
    ID_SECTION_FEEDBACK = "idSectionFeedback"

var oForm, oBI, oDC, oSectionFeedback

function id(pId){return document.getElementById(pId)}

function boot(){
    oForm = id(ID_FORM)
    oBI = id(ID_BI)
    oDC = id(ID_DC)
    oSectionFeedback = id(ID_SECTION_FEEDBACK)

    oBI.onkeydown = oDC.onkeydown = actionOnlyDigits
    oBI.oninput = oDC.oninput = actionShowSomaDoBI

    oForm.onsubmit = actionAcceptOrNot
}//boot

//event handler
function actionAcceptOrNot(){
    var dcCorrect = digitoControlo(oBI.value)
    var bAccept = Number(oDC.value)===dcCorrect
    if (bAccept){
        oSectionFeedback.innerHTML = "<mark>OK, não me enganas.</mark>"
    }
    else{
        oSectionFeedback.innerHTML = "<mark>Presta atenção ao digito de controlo.</mark>"
    }

    return false
}//actionAcceptOrNot

function actionShowSomaDoBI(e){
    var theEvent = e?e:window.event
    var theTarget = theEvent.target ? theEvent.target : theEvent.srcElement

    var theSum = somaDoBI (oBI.value)
    var theDC = digitoControlo(oBI.value)
    var anterior = oSectionFeedback.innerHTML
    oSectionFeedback.innerHTML = "<br>Soma do BI = "+theSum
    oSectionFeedback.innerHTML += "<br>DC = "+theDC
    //oSectionFeedback.innerHTML += anterior

    return false
}//actionShowSomaDoBI

function somaDoBI(pBI){
    var bi = pBI+""

    for(
        var peso=2, pos=bi.length-1, soma=0;
        pos>=0;
        peso+=1, pos-=1
    ){
        var digito = Number(bi[pos])
        var parcela = digito * peso
        soma+=parcela
    }
    return soma
}//somaDoBI

function actionOnlyDigits(e){
    var theEvent = e ? e : window.event
    //theTarget é o objeto em q o evento aconteceu
    var theTarget = theEvent.target ?
        theEvent.target : theEvent.srcElement

    var iCode = theEvent.which ?
        theEvent.which : theEvent.keyCode

    //observar os códigos
    //oSectionFeedback.innerHTML = iCode
    var code0 = "0".charCodeAt(0)
    var code9 = "9".charCodeAt(0)
    var bAcceptableCode = iCode>=code0 && iCode<=code9
    var bCodeLeft = iCode===37
    var bCodeRight = iCode===39
    var bCodeDelete = iCode===8
    var bAlwaysAcceptable = bCodeLeft || bCodeRight || bCodeDelete

    var bLetTheEventKeepGoing =
        (bAcceptableCode || bAlwaysAcceptable)?
            true : false

    switch(theTarget.id){
        case ID_BI:
            return bLetTheEventKeepGoing
            break
        case ID_DC:
            if (bAlwaysAcceptable)
                return true
            else
                return bLetTheEventKeepGoing && (oDC.value.length<1)
            break
    }
    return bLetTheEventKeepGoing
}//actionOnlyDigits

function digitoControlo(pBI){
    var soma = somaDoBI(pBI)

    for (var dc=0; dc<=10; dc+=1){
        var novaSoma = soma + dc
        var bM11 = novaSoma % 11 === 0
        if (bM11) return dc
    }
}//digitoControlo