// A utility class that we use in FormModel to set up a convention for the default labels for each form input field.
var StringUtils = {
	
	/* 
	Assumes that the argument is a camel-case string.
	It places spaces between each word and capitalize the first letter. So, a string like "camelCase" becomes "Camel Case".
	*/
	humanize: function(string) {
		return this.capitalize(this.convertCamelToSpaces(string));
	},
	
	capitalize: function(string) {
		return string.charAt(0).toUpperCase() + string.slice(1);
	},
	
	convertCamelToSpaces: function(string) {
		return string.replace(/([A-Z])/g, function(match) {
			return ' ' + match;
		});
	}
}


// A class that provides all the functionality required to generate a form from a database record.
var FormModel = Class.extend({
	
	/*
	Class constructor:
	collection: The MongoDB collection the record will be saved to.
	data: The record data if generating a form for an already-existing record. This argument is optional. 
	*/
	init: function(collection, data) {
		this.collection = collection;
		
		/*
		blankSchema is an object that each extending class must provide. 
		It contains all the fields to be saved to the database and their default values.
		*/
		this.schema = this.blankSchema;		
		
		// jsonform options that would override the defaults
		this.formOptions = {};
		
		this.load(data)
	},
	
	// If data has been provided in the constructor, load it into the current class
	load: function(data) {
		if (data) {
			this._id = data._id;
		
			for (field in this.schema) {
				if (data[field]) this.schema[field] = data[field];
			}
		}		
	},
	
	// Generate a jsonform schema for this object based on the form options given and conventions
	formSchema: function() {
		var formSchema = {};
		
		// Each field stored in the database is represented by a form input
		for (var field in this.schema) {
			
			formSchema[field] = {			
				// If type is already given in formOptions, use that, otherwise guess the input type by inspecting the field type
				type: this.option(field, 'type') || this.schema[field].constructor.name.toLowerCase(),
				
				// If the label text is already specified in formOptions, use that, otherwise use a humanized version of the field name (see StringUtils)
				title: this.option(field, 'title') || StringUtils.humanize(field),
				
				// Use the field name as an ID; jsonform will add a prefix to avoid name conflicts
				id: field,
				
				// Display the data in the input
				default: this.schema[field]
			}				

			// If an 'enum' option is provided in formOptions, turn the input into a select by adding the enum options to the jsonform schema
			if(this.option(field, 'enum')) formSchema[field]['enum'] = this.option(field, 'enum');
		}
		
		return formSchema;
	},	
	
	option: function(field, optionName) {
		if (this.formOptions[field]) return this.formOptions[field][optionName];
		return null;
	},
	
	// Overwrite the default label for a field by adding a 'title' entry to its form options
	overwriteTitle: function(field, title) {
		if (this.formOptions[field]) this.formOptions[field]['title'] = title;
		else this.formOptions[field] = { 'title': title };
	},
	
	// Overwrite the default type for a field by adding a 'type' entry to its form options
	overwriteType: function(field, type) {
		if (this.formOptions[field]) this.formOptions[field]['type'] = type;
		else this.formOptions[field] = { 'type': type }; 
	},
	
	// Make the input type of a string field be a select by editing formOptions appropriately
	makeSelect: function(field, options) {
		if (this.formOptions[field]) this.formOptions[field]['enum'] = options;
		else this.formOptions[field] = { 'enum': options };		
	},

	// If the record was originally loaded from the database, update it. Otherwise, create a new record with the appropriate data.
	save: function(createHandler, updateHandler) {
		if (this._id) {
			this.collection.update(this._id, {$set: this.schema}, updateHandler);
	    } else {
	       this._id = this.collection.insert(this.schema, createHandler);   
	    }		
	}
});