var Lot = require('./lot');
var LotIface = require('./lot-iface');
var Spec = require('./spec');
var Value = require('./value');

module.exports = new Class({
	Extends: Lot
	,Tag: 'vn-lot-query'
	,Properties: {
		fields: { 
			type: Array
			,set: function(x) {
				this._fields = x;
				this._onSourceChange();
			}
			,get: function() {
				return this._fields;
			}
		},
		source: { 
			type: LotIface
			,set: function(x) {
				this.link({_source: x}, {change: this._onSourceChange});
				this._onSourceChange();
			}
			,get: function() {
				return this._source;
			}
		}
	}

	,initialize: function(props) {
		Object.assign(this, {
			_fields: null,
			_source: null,
			_lockSource: false,
			_specs: {}
		});
		Lot.prototype.initialize.call(this, props);
	}

	,appendChild: function(child) {
		if (!(child instanceof Spec))
			throw new Error('VnLotQuery: Child must be a Vn.Spec instance');

		this._specs[child.name] = child;
		this._onSourceChange();
	}

	,_onSourceChange: function() {
		if (this._lockSource)
			return;

		var params = this._source ? this._source.params : {};
		var myParams = {};

		for (var key in this._specs)
			myParams[key] = Value.simpleClone(params[key]);

		this.assign(myParams);
	}

	,assign: function(params) {
		params = this.transformParams(params);
		var diff = Value.partialDiff(this._params, params);
		this._assign(diff);
	}

	,setAll: function(params) {
		params = this.transformParams(params);
		var diff = Value.diff(this._params, params);
		this._assign(diff);
	}

	,_assign: function(diff) {
		if (diff) {
			Object.assign(this._params, diff);

			if (this.source) {
				this._lockSource = true;
				this.source.assign(diff);
				this._lockSource = false;
			}

			this._paramsChanged(diff);
			this.changed(diff);
		}
	}

	,transformParams: function(params) {
		var newParams = {};

		for (var key in this._specs) {
			var spec = this._specs[key];
			if (params[key])
				newParams[key] = cast(params[key], spec.type);
		}

		return Object.assign(params, newParams);
	}
});

function cast(value, type) {
	switch (type) {
		case Boolean:
			return (/^(true|1)$/i).test(value);
		case Number:
			return 0 + new Number(value);
		case Date:
			var date = new Date(value);
			date.setHours(0, 0, 0, 0);
			return date;
		case String:
			return value;
		default:
		if (type instanceof Object)
			return JSON.parse(value);
		else
			return value;
	}
}