/**
 * Lambdas 
 */
var accessNumber = e => {
    if (e.childElementCount == 0) return 0;
    if (e.children[0].childElementCount == 0) return 0;
    return e.children[0].children[0];
}

var getAncestorByAttribute = (elem,attr,val) => {
    while (elem.getAttribute(attr) != val || elem == null) elem = elem.parentElement;
    return elem;
}

var getDescendantByAttribute = (elem,attr,val) => {
    if (elem == null || elem.getAttribute(attr) == val) return elem;
    return Array.from(elem.children).reduce( (a,b) => {
        let x = getDescendantByAttribute(a,attr,val);
        let y = getDescendantByAttribute(b,attr,val);
        return x == null ? y : x;
    }, null);
}

/**
 * Armado de formulario 
 */
function removeTab(button){
    let tabs = document.getElementById('tabs')
    tabs.removeChild(
        getAncestorByAttribute(button,'name','Tab')
    )
    if (tabs.childElementCount == 0){
        document.getElementById("ContinuarText").style.display = 'none';
        document.getElementById("ContinuarButton").style.display = 'none';
    }
}

function addField(b,n){
    let newfield = document.createElement("div");
    newfield.setAttribute("name","Field");
    newfield.innerHTML = document.getElementById("fieldTemplate").innerHTML;
    accessNumber(newfield).setAttribute("value",n);
    // swap
    let container = b.parentElement;
    container.appendChild(newfield);
    container.appendChild(b);
}

function addTab(t,n){
    document.getElementById("ContinuarText").style.display = 'block';
    document.getElementById("ContinuarButton").style.display = 'block';
    let newtab = document.createElement("div");
    newtab.setAttribute("name","Tab");
    newtab.innerHTML = document.getElementById("tabTemplate").innerHTML;
    accessNumber(newtab).setAttribute("value",n);
    t.appendChild(newtab);
}

/**
 * Lectura de información y formateado
 */
function processField(field){
    let data = field.children[0];
    return {
        'Title' : data.children[1].value,
        'Input' : data.children[2].selectedOptions[0].value,
        'Required' : data.children[3].checked,
    };
}

function processTab(tab){
    let dict = [];
    let container = getDescendantByAttribute(tab,"name","Field");
    if (container == null) return dict;
    container = container.parentElement;
    for(let i = 0; i < container.children.length; i++){
        if (container.children[i].getAttribute("name") == "Field") {
            dict.push(processField(container.children[i]));
        }
    }
    return dict;
}

function generate(tabs){
    let dict = [];
    for (let i = 0; i < tabs.children.length; i++) {
        let c = tabs.children[i];
        if (c.getAttribute("name") == "Tab") {
            dict.push({
                "Title" : getDescendantByAttribute(c,"class","TabTitle").value,
                "Fields" : processTab(c),
            });
        }
    }
    console.log(JSON.stringify(dict));
    return dict;
}

function sortChildren(container,number){
    let fixinput = a => number(a).nodeName == "INPUT" && number(a).type == "number" ? parseInt(number(a).value) : Infinity;

    Array.from(container.children).sort(
        (a,b) => fixinput(a) < fixinput(b) ? -1 : fixinput(a) > fixinput(b) ? 1 : 0
    ).forEach(
        c => container.appendChild(c)
    )
}

function maxChild(container,number){
    let fixinput = a => number(a).nodeName == "INPUT" && number(a).type == "number" ? parseInt(number(a).value) : 0;

    if (container.childElementCount == 0) return 0;
    let max = Array.from(container.children).reduce(
        (a,b) => fixinput(a) > fixinput(b) ? a : b
    );
    return fixinput(max);
}

function validate(obj){
    const internal = "Hubo un error en la generación del formulario";
    
    if (typeof obj != "object") return triggerError(internal,"not object");
    
    for (let t_it = 0; t_it < obj.length; t_it++) {
        let tab = obj[t_it];
    
        if ("Title" in tab && "Fields" in tab){

            if (typeof tab.Title != "string") return triggerError(internal,"wrong type in tab title");
            if (typeof tab.Fields != "object") return triggerError(internal,"wrong type in tab fields");
            if (tab.Title == "") return triggerError("La tab " + (t_it + 1) + " necesita un título","empty tab title");
            if (tab.Fields.length == 0) return triggerError("La tab " + (t_it + 1) + " requiere campos","empty tab fields");
            
            for (let f_it = 0; f_it < tab.Fields.length; f_it++) {
                let field = tab.Fields[f_it];

                if ("Title" in field && "Input" in field && "Required" in field) {
                    
                    if (typeof field.Title != "string") return triggerError(internal,"wrong type in field title");
                    if (typeof field.Input != "string") return triggerError(internal,"wrong type in field input");
                    if (typeof field.Required != "boolean") return triggerError(internal,"wrong type in field required");
                    if (field.Title == "") return triggerError("El campo " + (f_it + 1) + " del tab " + (t_it + 1) + " necesita un título","empty field title");
                    if (field.Input == "") return triggerError("El campo " + (f_it + 1) + " del tab " + (t_it + 1) + " necesita un input","empty field input");
                    
                } else { return triggerError(internal,"field lacks property") }
            }

        } else { return triggerError(internal,"tab lacks property") }
    }
}

function triggerError(type,log){
    let out = "triggerError => \nerror_message = " + type;
    if (log) out += "\nlog_message = " + log;
    console.log(out);
    document.getElementById("ErrorMessage").innerText = type;
}