import h from '../Util/DomUtil.js';

class Layer {
	constructor(id, name) {
		this.id = id;
		this.name = name;
		this.subLayers = [];
		this.visible = true;
	}
}

class LayerData {
	constructor() {
		this.layers = [];
		this.idPool = 0;
	}

	_getNewId() {
		const id = this.idPool;
		this.idPool += 1;
		return `layer${id}`;
	}

	_getContainerAndId(idChain) {
		if (idChain.length === 0)
			return [ this.layers, null ];

		let container = this.layers;
		while (idChain.length > 1) {
			const id = idChain.pop();
			console.log(container, id);
			container = container.find(layer => layer.id === id).subLayers;
			console.log(idChain);
		}

		return [ container, idChain[0] ];
	}

	_idToIndex(container, id) {
		return container.findIndex(layer => layer.id === id);
	}

	insertLayer(idChain) {
		const layerId = this._getNewId();
		const newLayer = new Layer(layerId, `Layer ${layerId}`);

		const [ container, id ] = this._getContainerAndId(idChain);
		if (id === null) {
			container.push(newLayer);
			return;
		}

		const index = this._idToIndex(container, id);
		container.splice(index+1, 0, newLayer);
	}

	removeLayer(idChain) {
		const [ container, id ] = this._getContainerAndId(idChain);
		if (id === null) return;

		const index = this._idToIndex(container, id);
		container.splice(index, 1);
	}

	pushLayer(idChain) {
		const [ container, id ] = this._getContainerAndId(idChain);
		if (id === null) return; // nothing to do

		const index = this._idToIndex(container, id);
		const after = container[index+1];
		if (!after) return; // no successor to push to, do nothing
		after.subLayers.push(container[index]);
		container.splice(index, 1);
	}
}


class LayerView {
	constructor(parentId) {
		const parentElement = document.getElementById(parentId);

		const button = (label, f) => {
			const b = h('button', label, { 'style': 'margin: 0 5px' });
			b.onclick = f;
			return b;
		}

		this.layersList = h('ul');

		const root = h('fieldset', { 'class': 'layer-view' }, [
			h('legend', 'Layers'),
			this.layersList,
			button('Move Up', () => this.onMoveUp(this._getIdChain())),
			button('Move Down', () => this.onMoveDown(this._getIdChain())),
			button('Toggle Visible', () => this.onShowHideLayer(this._getIdChain())),
			button('Rename', () => this.onRenameLayer(this._getIdChain())),
			h('br'), h('br'),
			button('Add Layer', () => this.onAddLayer(this._getIdChain())),
			button('Remove Layer', () => this.onRemoveLayer(this._getIdChain())),
			button('Push', () => this.onPushLayer(this._getIdChain())), 
			button('Pop', () => this.onPopLayer(this._getIdChain())),
		]);

		parentElement.appendChild(root);
		
		this.selectedId = null;

		this.onAddLayer = () => {};
		this.onRemoveLayer = () => {};
		this.onPushLayer = () => {};
		this.onPopLayer = () => {};

		this.onMoveUp = () => {};
		this.onMoveDown = () => {};
		this.onShowHideLayer = () => {};
		this.onRenameLayer = () => {};
	}

	_getIdChain() {
		const chain = [];
		let el = this.selected;

		if (el === null || el === undefined) return [];
		while (el !== this.layersList && el !== null) {
			if (el.nodeName.toLowerCase() === 'li')
				chain.push(el.id);
			el = el.parentNode;
		}
		return chain;
	}

	renderLayers(layers, root=this.layersList) {
		let selectedId = '';
		if (this.selected) selectedId = this.selected.id;
		if (root === this.layersList) this.layersList.replaceChildren();
		for (let layer of layers) {
			let classList = '';
			if (layer.visible) classList += 'visible ';
			const el = h(
				'li', 
				layer.name, 
				{
					id: layer.id, 
					'class': classList,
				}
			);

			if (selectedId === layer.id) {
				el.classList.add('selected');
				this.selected = el;
			}
			el.onclick = e => {
				e.stopPropagation();
				if (this.selected) this.selected.classList.remove('selected');
				this.selected = el;
				el.classList.add('selected');
			};
			if (layer.subLayers.length !== 0) {
				const ul = h('ul');
				this.renderLayers(layer.subLayers, ul);
				el.appendChild(ul);
			}
			root.prepend(el);
		}
	}
}


class LayerController {
	constructor(data, view) {
		this.data = data;
		this.view = view;

		const respond = f => ( idChain => { f(idChain); this.updateView(); } );

		this.view.onAddLayer = idChain => { this.data.insertLayer(idChain); this.updateView(); };
		this.view.onPushLayer = idChain => { this.data.pushLayer(idChain); this.updateView(); };
		this.view.onRemoveLayer = idChain => { this.data.removeLayer(idChain); this.updateView(); }
	}

	updateView() {
		this.view.renderLayers(this.data.layers);
	}
}


export { LayerData, LayerView, LayerController };