const PassiveListener = { passive: true };

// Get an element by id or an Element object
function getelem(id) {
    return (id instanceof Element) ? id : document.getElementById(id);
}

// Find a child with a specific tag
function chi(me,tag) { return me.getElementsByTagName(tag)[0]; }

// Find a sibling element with a specific tag
function sib(me,tag) { return chi(me.parentElement, tag); }

// Read a key=value text file and return it as a Promise of a Map
function fetchconfig(url) {
    return fetch(url, {redirect: "follow"})
	.then(res => {
	    if (!res.ok) {
		throw new Error("HTTP error "+response.status);
	    } else {
		return res.text();
	    }
	})
	.then(text => {
	    var map = new Map();
	    for (const c of text.split(/[\r\n]+/)) {
		var m = c.match(/^\s*([\;\/]?)((?:"[^"]*"|[^"])*?)\s*=(.*)$/);
		if (m && m[1] == "") {
		    var k = m[2].replaceAll(/(^"|"$|(")")/g, "$2");
		    map.set(k, m[3]);
		}
	    }
	    return map;
	});
}

// Parse a string for a valid boolean truth value
function cfgbool(str) {
    return str && !str.match(/^(0*|[fnd].*|of.*)$/i);
}

// Initialize a form from a map. Checkboxes take a cfgbool string;
// if in the HTML their value is set to a false cfgbool string then
// the checkbox is inverted logic.
function initform(form,map) {
    var button = null;
    var clearers = new Set;
    form = getelem(form);

    for (var e of form.elements) {
	if (e.classList.contains('noinit')) {
	    continue;
	} else if (e instanceof HTMLInputElement ||
		   e instanceof HTMLSelectElement) {
	    const val = map.get(e.name);
	    if (val == null)
		continue;
	    if (e.type == 'checkbox') {
		e.checked = cfgbool(val) == cfgbool(e.value);
	    } else if (e.type == 'radio') {
		e.checked = (val == e.name);
	    } else {
		e.value = val;
	    }
	} else if (e instanceof HTMLButtonElement &&
		   e.type == 'submit') {
	    button = e;
	}
    }
    if (button) {
	button.disabled = false; // All loaded, enable the submit button
    }
}

// Load form initialization data
function loadform(form, url) {
    fetchconfig(url)
	.then(map => { initform(form, map) })
	.catch(() => {});
}

// Replace the contents of selected HTML elements based on a map with
// selectors.
function fillin(map,html = false,top = document)
{
    for (const [key,val] of map) {
	try {
	    const m = key.match(/(.*?)(?:\;([\w.-]*)(\??))?$/);
	    for (var e of top.querySelectorAll(m[1])) {
		try {
		    if (!html) e.textContents = val;
		    else if (!m[2]) e.innerHTML = val;
		    else if (!m[3]) e.setAttribute(m[2],val);
		    else if (!cfgbool(val)) e.removeAttribute(m[2]);
		    else e.setAttribute(m[2],'');
		} catch(e) { };
	    }
	} catch(e) { };
    }
}

// Load status or HTML data
function load(url,html = false)
{
    fetchconfig(url)
	.then(map => fillin(map,html))
	.catch(() => {});
}

// POST upload of data from within a form, with progress and response text
function upload(form,data) {
    var xhr = new XMLHttpRequest();

    var progress = chi(form,'progress');
    if (progress) {
	progress.value = 0;
	xhr.upload.addEventListener('progress', (e) => {
	    if (!e.lengthComputable)
		return;
	    progress.max   = e.total * 1.05;
	    progress.value = e.loaded;
	}, PassiveListener);
    }

    var result = chi(form,'output');
    if (result)
	result.classList.remove('result');

    xhr.addEventListener('readystatechange', (e) => {
	if (xhr.readyState != XMLHttpRequest.DONE)
	    return;
	const ok = xhr.status >= 200 && xhr.status < 400;
	if (progress)
	    progress.value = ok ? progress.max : 0;
	if (result) {
	    var msg = xhr.responseText.trimEnd();
	    if (!msg)
		msg = xhr.status + ' ' + xhr.statusText;
	    result.textContent = msg;
	    result.classList.toggle('ok', ok);
	    result.classList.toggle('err', !ok);
	    result.classList.add('result');
	}
	const rf = parseInt(xhr.getResponseHeader('Refresh'));
	if (rf && ok)
	    setTimeout(() => window.location.reload(), rf * 1000);
    }, PassiveListener);

    xhr.open(form.method, form.action);
    xhr.responseType = 'text';
    xhr.send(data);
    return xhr;
}

// Upload a data file blob
function uploadfile() {
    event.preventDefault();
    const form = event.target.form || event.target;
    var files = form.elements['file'];
    return (files.files.length == 1)
	? upload(form,files.files[0]) : files.click();
}

// key=value formatting of form data; including inverted checkboxes
function textformdata(form) {
    var data = '';
    for (var e of form.elements) {
	var val = e.value;
	if (val == undefined || !e.name || e instanceof HTMLButtonElement) {
	    continue;
	} else if (e instanceof HTMLInputElement) {
	    if (e.type == 'checkbox')
		val = e.checked == cfgbool(val) ? '1' : '0';
	    else if (e.type == 'radio' && !e.checked)
		continue;
	}
	data += e.name + '=' + val + "\r\n";
    }
    return data;
}

// POST form contents upload with response text
function uploadform() {
    event.preventDefault();
    const form = event.target.form || event.target;
    return upload(form,textformdata(form));
}

// Flip the status of an INPUT element between text and password
function showpwd(me = event.target) {
    const now_visible = me.classList.toggle('hide');
    const new_type = now_visible ? 'text' : 'password';
    me.classList.toggle('show',!now_visible);
    sib(me,'input').setAttribute('type', new_type);
}

// Insert translations as needed
var translations = null;
var delay_translate = false;
function translate(top = document) {
    delay_translate = (!translations || document.readyState != 'complete');
    if (!delay_translate)
	fillin(translations, true, top);
}
document.addEventListener('load', (e) => translate(), PassiveListener);

fetchconfig('/sys/lang')
    .then((map) => {
	translations = map;
	if (delay_translate)
	    translate();
    })
    .catch(() => {});

// Hack to include an HTML files. Sadly, does not support
// including files with <script> tags.
function inc(url) {
    var me = document.currentScript;
    fetch(url, {redirect: "follow"})
	.then((response) => response.text())
	.then((text) => {
	    const p = me.parentElement;
	    me.outerHTML = text;
	    translate(p);
	});
}