/****************************************************************************
 * Copyright 2017 EPAM Systems
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 ***************************************************************************/

var s = require('subscription');

var Set = require('../util/set');
var Vec2 = require('../util/vec2');

var Struct = require('../chem/struct');

var Render = require('../render');
var Action = require('./action');

var closest = require('./closest');

var toolMap = {
	rgroupatom: require('./tool/rgroupatom'),
	select: require('./tool/select'),
	sgroup: require('./tool/sgroup'),
	eraser: require('./tool/eraser'),
	atom: require('./tool/atom'),
	bond: require('./tool/bond'),
	chain: require('./tool/chain'),
	chiralFlag: require('./tool/chiral-flag'),
	template: require('./tool/template'),
	charge: require('./tool/charge'),
	rgroupfragment: require('./tool/rgroupfragment'),
	apoint: require('./tool/apoint'),
	attach: require('./tool/attach'),
	reactionarrow: require('./tool/reactionarrow'),
	reactionplus: require('./tool/reactionplus'),
	reactionmap: require('./tool/reactionmap'),
	reactionunmap: require('./tool/reactionunmap'),
	paste: require('./tool/paste'),
	rotate: require('./tool/rotate')
};

const SCALE = 40;  // const
const HISTORY_SIZE = 32; // put me to options

var structObjects = ['atoms', 'bonds', 'frags', 'sgroups', 'sgroupData', 'rgroups', 'rxnArrows', 'rxnPluses', 'chiralFlags'];

function Editor(clientArea, options) {
	this.render = new Render(clientArea, Object.assign({
		scale: SCALE
	}, options));

	this._selection = null; // eslint-disable-line
	this._tool = null; // eslint-disable-line
	this.historyStack = [];
	this.historyPtr = 0;

	this.event = {
		message: new s.Subscription(),
		elementEdit: new s.PipelineSubscription(),
		bondEdit: new s.PipelineSubscription(),
		rgroupEdit: new s.PipelineSubscription(),
		sgroupEdit: new s.PipelineSubscription(),
		sdataEdit: new s.PipelineSubscription(),
		quickEdit: new s.PipelineSubscription(),
		attachEdit: new s.PipelineSubscription(),
		change: new s.PipelineSubscription(),
		selectionChange: new s.PipelineSubscription()
	};

	domEventSetup(this, clientArea);
}

Editor.prototype.tool = function (name, opts) {
	/* eslint-disable no-underscore-dangle */
	if (arguments.length > 0) {
		if (this._tool && this._tool.cancel)
			this._tool.cancel();
		var tool = toolMap[name](this, opts);
		if (!tool)
			return null;
		this._tool = tool;
	}
	return this._tool;
	/* eslint-enable no-underscore-dangle */
};

Editor.prototype.struct = function (value) {
	if (arguments.length > 0) {
		this.selection(null);
		this.update(Action.fromNewCanvas(this.render.ctab,
		                                 value || new Struct()));
		recoordinate(this, getStructCenter(this.render.ctab));
	}
	return this.render.ctab.molecule;
};

Editor.prototype.options = function (value) {
	if (arguments.length > 0) {
		var struct = this.render.ctab.molecule;
		var zoom = this.render.options.zoom;
		this.render.clientArea.innerHTML = '';
		this.render = new Render(this.render.clientArea, Object.assign({ scale: SCALE }, value));
		this.render.setMolecule(struct); // TODO: reuse this.struct here?
		this.render.setZoom(zoom);
		this.render.update();
	}
	return this.render.options;
};

Editor.prototype.zoom = function (value) {
	if (arguments.length > 0) {
		this.render.setZoom(value);
		recoordinate(this, getStructCenter(this.render.ctab,
		                                   this.selection()));
		this.render.update();
	}
	return this.render.options.zoom;
};

Editor.prototype.selection = function (ci) {
	var restruct = this.render.ctab;
	if (arguments.length > 0) {
		this._selection = null; // eslint-disable-line
		if (ci === 'all') {   // TODO: better way will be this.struct()
			ci = structObjects.reduce(function (res, key) {
				res[key] = restruct[key].ikeys();
				return res;
			}, {});
		}

		if (ci === 'descriptors') {
			restruct = this.render.ctab;
			ci = { sgroupData: restruct['sgroupData'].ikeys() };
		}

		if (ci) {
			var res = {};
			for (var key in ci) {
				if (ci.hasOwnProperty(key) && ci[key].length > 0) // TODO: deep merge
					res[key] = ci[key].slice();
			}
			if (Object.keys(res) !== 0)
				this._selection = res; // eslint-disable-line
		}

		this.render.ctab.setSelection(this._selection); // eslint-disable-line
		this.event.selectionChange.dispatch(this._selection); // eslint-disable-line

		this.render.update();
	}
	return this._selection; // eslint-disable-line
};

Editor.prototype.hover = function (ci) {
	var tool = this._tool; // eslint-disable-line
	if ('ci' in tool && (!ci || tool.ci.map !== ci.map || tool.ci.id !== ci.id)) {
		this.highlight(tool.ci, false);
		delete tool.ci;
	}
	if (ci && this.highlight(ci, true))
		tool.ci = ci;
};

Editor.prototype.highlight = function (ci, visible) {
	if (['atoms', 'bonds', 'rxnArrows', 'rxnPluses', 'chiralFlags', 'frags',
		'rgroups', 'sgroups', 'sgroupData'].indexOf(ci.map) === -1)
		return false;

	var rnd = this.render;
	var item = rnd.ctab[ci.map].get(ci.id);
	if (!item)
		return true; // TODO: fix, attempt to highlight a deleted item
	if ((ci.map === 'sgroups' && item.item.type === 'DAT') || ci.map === 'sgroupData') {
		// set highlight for both the group and the data item
		var item1 = rnd.ctab.sgroups.get(ci.id);
		var item2 = rnd.ctab.sgroupData.get(ci.id);
		if (item1)
			item1.setHighlight(visible, rnd);
		if (item2)
			item2.setHighlight(visible, rnd);
	} else {
		item.setHighlight(visible, rnd);
	}
	return true;
};

Editor.prototype.update = function (action, ignoreHistory) {
	if (action === true) {
		this.render.update(true); // force
	} else {
		if (!ignoreHistory && !action.isDummy()) {
			this.historyStack.splice(this.historyPtr, HISTORY_SIZE + 1, action);
			if (this.historyStack.length > HISTORY_SIZE)
				this.historyStack.shift();
			this.historyPtr = this.historyStack.length;
			this.event.change.dispatch(action); // TODO: stoppable here
		}
		this.render.update();
	}
};

Editor.prototype.historySize = function () {
	return {
		undo: this.historyPtr,
		redo: this.historyStack.length - this.historyPtr
	};
};

Editor.prototype.undo = function () {
	if (this.historyPtr === 0)
		throw new Error('Undo stack is empty');

	if (this.tool() && this.tool().cancel)
		this.tool().cancel();
	this.selection(null);
	this.historyPtr--;
	var action = this.historyStack[this.historyPtr].perform(this.render.ctab);
	this.historyStack[this.historyPtr] = action;
	this.event.change.dispatch(action);
	this.render.update();
};

Editor.prototype.redo = function () {
	if (this.historyPtr === this.historyStack.length)
		throw new Error('Redo stack is empty');

	if (this.tool() && this.tool().cancel)
		this.tool().cancel();
	this.selection(null);
	var action = this.historyStack[this.historyPtr].perform(this.render.ctab);
	this.historyStack[this.historyPtr] = action;
	this.historyPtr++;
	this.event.change.dispatch(action);
	this.render.update();
};

Editor.prototype.on = function (eventName, handler) {
	this.event[eventName].add(handler);
};

function domEventSetup(editor, clientArea) {
	// TODO: addEventListener('resize', ...);
	['click', 'dblclick', 'mousedown', 'mousemove',
	 'mouseup', 'mouseleave'].forEach(eventName => {
		 const subs = editor.event[eventName] = new s.DOMSubscription();
		 clientArea.addEventListener(eventName, subs.dispatch.bind(subs));

		 subs.add(event => {
			 editor.lastEvent = event;
			 if (editor.tool() && eventName in editor.tool())
				 editor.tool()[eventName](event);
			 return true;
		 }, -1);
	});
}

Editor.prototype.findItem = function (event, maps, skip) {
	var pos = global._ui_editor ? new Vec2(this.render.page2obj(event)) : // eslint-disable-line
	    new Vec2(event.pageX, event.pageY).sub(elementOffset(this.render.clientArea));
	var options = this.render.options;

	return closest.item(this.render.ctab, pos, maps, skip, options.scale);
};

Editor.prototype.explicitSelected = function () {
	var selection = this.selection() || {};
	var res = structObjects.reduce(function (res, key) {
		res[key] = selection[key] ? selection[key].slice() : [];
		return res;
	}, {});

	var struct = this.render.ctab.molecule;
	// "auto-select" the atoms for the bonds in selection
	if ('bonds' in res) {
		res.bonds.forEach(function (bid) {
			var bond = struct.bonds.get(bid);
			res.atoms = res.atoms || [];
			if (res.atoms.indexOf(bond.begin) < 0) res.atoms.push(bond.begin);
			if (res.atoms.indexOf(bond.end) < 0) res.atoms.push(bond.end);
		});
	}
	// "auto-select" the bonds with both atoms selected
	if ('atoms' in res && 'bonds' in res) {
		struct.bonds.each(function (bid) {
			if (!('bonds' in res) || res.bonds.indexOf(bid) < 0) {
				var bond = struct.bonds.get(bid);
				if (res.atoms.indexOf(bond.begin) >= 0 && res.atoms.indexOf(bond.end) >= 0) {
					res.bonds = res.bonds || [];
					res.bonds.push(bid);
				}
			}
		});
	}

	return res;
};

Editor.prototype.structSelected = function () {
	var struct = this.render.ctab.molecule;
	var selection = this.explicitSelected();
	var dst = struct.clone(Set.fromList(selection.atoms),
						   Set.fromList(selection.bonds), true);

	// Copy by its own as Struct.clone doesn't support
	// arrows/pluses id sets
	struct.rxnArrows.each(function (id, item) {
		if (selection.rxnArrows.indexOf(id) != -1)
			dst.rxnArrows.add(item.clone());
	});
	struct.rxnPluses.each(function (id, item) {
		if (selection.rxnPluses.indexOf(id) != -1)
			dst.rxnPluses.add(item.clone());
	});
	dst.isChiral = struct.isChiral;

	// TODO: should be reaction only if arrwos? check this logic
	dst.isReaction = struct.isReaction &&
		(dst.rxnArrows.count() || dst.rxnPluses.count());

	return dst;
};

Editor.prototype.alignDescriptors = function () {
	this.selection(null);
	const action = Action.fromDescriptorsAlign(this.render.ctab);
	this.update(action);
	this.render.update(true);
};

function recoordinate(editor, rp/* , vp*/) {
	// rp is a point in scaled coordinates, which will be positioned
	// vp is the point where the reference point should now be (in view coordinates)
	//    or the center if not set
	console.assert(rp, 'Reference point not specified');
	editor.render.setScrollOffset(0, 0);
}

function getStructCenter(restruct, selection) {
	var bb = restruct.getVBoxObj(selection || {});
	return Vec2.lc2(bb.p0, 0.5, bb.p1, 0.5);
}

// TODO: find DOM shorthand
function elementOffset(element) {
	var top = 0,
		left = 0;
	do {
		top += element.offsetTop  || 0;
		left += element.offsetLeft || 0;
		element = element.offsetParent;
	} while (element);
	return new Vec2(left, top);
}

module.exports = Editor;