class InterfaceElement {
	constructor({fragment}) {
		if (fragment === undefined) {
			this.fragment = new DocumentFragment();
		} else {
			this.fragment = fragment;
		}
	}

	#hidden = false;
	get hidden() {
		return this.#hidden;
	}
	set hidden(x) {
		this.#hidden = x;

		this.handle.hidden = this.hidden;
		if (this.labelTag !== undefined) {
			this.labelTag.hidden = this.hidden;
		}

		if (this.hidden === true) this.clearAlerts();
	}

}

function dataTypeSupports(params, validTypes) {
	if (params.dataType === undefined) {
		params.dataType = validTypes[0];
	}
	if (!validTypes.includes(params.dataType)) {
		throw `Element can not support '${params.dataType}' data type`;
	}
}

class Form extends InterfaceElement {
	constructor({tag, par=document.body, label}) {
		super({});

		if (tag === undefined) {
			this.handle = document.createElement("div");
		} else {
			this.handle = tag;
		}

		if (label !== undefined) {
			let labelTag = document.createElement("h2");
			labelTag.appendChild(document.createTextNode(label));
			this.fragment.appendChild(labelTag);
		}
		this.fragment.appendChild(this.handle);

		this.elements = [];

		this.clearAlerts = this.clearAlerts.bind(this);

		let advancedToggle = this.createCheckBox({label: "Advanced settings"});
		advancedToggle.handle.addEventListener('change', function() {
			this.advanced = advancedToggle.value;
		}.bind(this));

		par.appendChild(this.fragment);
	}

	#advanced = false;
	get advanced() {
		return this.#advanced;
	}
	set advanced(x) {
		this.#advanced = x;
		for (const element of this.elements) {
			if (element.advanced === true) {
				if (this.advanced === true) {
					element.hidden = false;
				} else {
					element.hidden = true;
				}
			}
		}
	}

	clearAlerts() {
		for (const element of this.elements) {
			element.clearAlerts();
		}
	}

	appendElement(elem) {
		this.handle.append(elem.fragment);
		this.elements.push(elem);
		if (elem.advanced) {
			elem.hidden = !this.advanced;
		}
		return elem;
	}

	createTextBox(params) {
		params.tag = document.createElement("input");
		dataTypeSupports(params, ["plaintext", "b64", "json-b64"]);
		return this.appendElement(new FormElement(params));
	}

	createMediumTextBox(params) {
		params.tag = document.createElement("textarea");
		params.tag.classList.add("mediumbox")
		dataTypeSupports(params, ["plaintext", "b64", "json-b64"]);
		return this.appendElement(new FormElement(params));
	}

	createPasswordInput(params) {
		params.tag = document.createElement("input");
		params.tag.setAttribute("type", "password");
		dataTypeSupports(params, ["plaintext"]);
		return this.appendElement(new FormElement(params));
	}

	createTextArea(params) {
		params.tag = document.createElement("textarea");
		dataTypeSupports(params, ["plaintext", "b64", "json-b64"]);
		return this.appendElement(new FormElement(params));
	}

	createButton(params) {
		params.fragment = new DocumentFragment();
		params.tag = document.createElement("button");
		params.labelTag = document.createTextNode(params.label);
		params.tag.appendChild(params.labelTag);
		params.fragment.appendChild(params.tag);
		dataTypeSupports(params, ["none"]);
		return this.appendElement(new FormElement(params));
	}

	createCheckBox(params) {
		params.fragment = new DocumentFragment();
		params.tag = document.createElement("input");
		params.tag.setAttribute("type", "checkbox");
		params.labelTag = document.createElement("label");
		params.labelTag.appendChild(document.createTextNode(params.label));
		let li = document.createElement("li");
		li.classList.add("checkbox-container");
		params.fragment.appendChild(li);
		li.appendChild(params.tag);
		li.appendChild(params.labelTag);
		dataTypeSupports(params, ["bool"]);
		return this.appendElement(new FormElement(params));
	}

	createOutput(params) {
		params.tag = document.createElement("textarea");
		params.tag.setAttribute("readonly", true);
		dataTypeSupports(params, ["plaintext", "b64", "json-b64"]);
		return this.appendElement(new FormElement(params));
	}
}

function b64ToBuf (b64) {
	let ascii = atob(b64);
	let buf = new ArrayBuffer(ascii.length);
	let bytes = new Uint8Array(buf);
	for (var i = 0; i < ascii.length; i++) {
		bytes[i] = ascii.charCodeAt(i);
	}
	return buf;
}

function bufToB64 (buf) {
	let bytes = new Uint8Array(buf);
	let ascii = '';
	for (var i = 0; i < bytes.byteLength; i++) {
		ascii += String.fromCharCode(bytes[i]);
	}
	return btoa(ascii);
}

class FormElement extends InterfaceElement {
	#enabled = true;
	get enabled() {
		return this.#enabled;
	}
	set enabled(x) {
		this.#enabled = x;
		this.handle.disabled = !this.#enabled;
	}

	constructor({tag, labelTag, label="", fragment, dataType, advanced=false, enabled=true}) {
		super({fragment});

		this.labelText = label;
		if (labelTag === undefined) {
			this.labelTag = document.createElement("label");
			this.labelTag.appendChild(document.createTextNode(this.labelText));
			this.fragment.appendChild(this.labelTag);
			this.fragment.appendChild(tag);
		} else {
			this.labelTag = labelTag;
		}


		this.clearAlerts = this.clearAlerts.bind(this);

		this.handle = tag;
		this.dataType = dataType;
		this.enabled = enabled;
		this.advanced = advanced;

		if (this.advanced === true) this.hidden = true;
	}

	get value() {
		this.clearAlerts();
		switch (this.dataType) {
			case "plaintext":
				return this.handle.value;
			case "b64":
				try {
					return b64ToBuf(this.handle.value);
				} catch (e) {
					this.alertBox("alert-error", "Invalid base64 value.");
					return;
				}
			case "json-b64":
				let jsonString;
				try {
					jsonString = atob(this.handle.value);
				} catch (e) {
					this.alertBox("alert-error", "Invalid base64 value.");
					return;
				}
				try {
					return JSON.parse(jsonString);
				} catch (e) {
					this.alertBox("alert-error", "Invalid JSON encoding.");
					return;
				}
			case "bool":
				return this.handle.checked;
			case "none":
				return undefined;
		}
	}
	set value(x) {
		switch (this.dataType) {
			case "plaintext":
				this.handle.value = x;
				break;
			case "b64":
				this.handle.value = bufToB64(x);
				break;
			case "json-b64":
				this.handle.value = btoa(JSON.stringify(x));
				break;
			case "bool":
				this.handle.checked = x;
				break;
		}
	}

	alerts = [];
	alertBox(type, message, title) {
		// type is alert-error or alert-info
		
		if (this.handle === undefined) {
			throw `can not add alert: still undefined`;
		}

		if (this.hidden === true) {
			throw `can not add alert: hidden`;
		}

		if (title === undefined) {
			switch (type) {
				case "alert-info":
					title = "Info: ";
					break;
				case "alert-error":
					title = "Error: ";
					break;
				default:
					title = "";
					break;
			}
		}

		let box = document.createElement("div");
		box.classList.add(type);
		box.classList.add("alert");
		box.appendChild(document.createTextNode(message));

		if (title !== "") {
			let titleTag = document.createElement("strong");
			titleTag.appendChild(document.createTextNode(title));
			box.prepend(titleTag);
		}

		this.handle.after(box);
		this.alerts.push(box);
	}
	clearAlerts() {
		for (const box of this.alerts) {
			box.remove();
		}
		this.alerts = [];
	}
}