/** @module reflect */
/** @hidden */ 
let _ = require('lodash');

import { PropertyReflector } from './PropertyReflector';
import { IntegerConverter } from '../convert/IntegerConverter';

/**
 * Helper class to perform property introspection and dynamic writing.
 * 
 * In contrast to [[PropertyReflector]] which only introspects regular objects,
 * this ObjectWriter is also able to handle maps and arrays.
 * For maps properties are key-pairs identified by string keys,
 * For arrays properties are elements identified by integer index.
 * 
 * This class has symmetric implementation across all languages supported
 * by Pip.Services toolkit and used to support dynamic data processing.
 * 
 * Because all languages have different casing and case sensitivity rules,
 * this ObjectWriter treats all property names as case insensitive.
 *
 * @see [[PropertyReflector]]
 * 
 * ### Example ###
 * 
 *     let myObj = new MyObject();
 *     
 *     ObjectWriter.setProperty(myObj, "myProperty", 123);
 *     
 *     let myMap = { key1: 123, key2: "ABC" };
 *     ObjectWriter.setProperty(myMap, "key1", "XYZ");
 *     
 *     let myArray = [1, 2, 3]
 *     ObjectWriter.setProperty(myArray, "0", 123);
 */
export class ObjectWriter {
	/**
	 * Sets value of object property specified by its name.
	 * 
     * The object can be a user defined object, map or array.
     * The property name correspondently must be object property,
     * map key or array index.
	 * 
	 * If the property does not exist or introspection fails
	 * this method doesn't do anything and doesn't any throw errors.
	 * 
	 * @param obj 	an object to write property to.
	 * @param name 	a name of the property to set.
	 * @param value a new value for the property to set.
	 */ 
	public static setProperty(obj: any, name: string, value: any): void {
		if (obj == null)
			throw new Error("Object cannot be null");
		if (name == null)
			throw new Error("Property name cannot be null");

        if (_.isObject(obj) && !_.isDate(obj)) {
            PropertyReflector.setProperty(obj, name, value);
        } else if (_.isArray(obj)) {
            let index = IntegerConverter.toNullableInteger(name);
            if (index >= 0) {
                while (index < obj.length - 1)
                    obj.push(null);
                obj[index] = value;
            }
		}
	}

	/**
	 * Sets values of some (all) object properties.
	 * 
     * The object can be a user defined object, map or array.
     * Property values correspondently are object properties,
     * map key-pairs or array elements with their indexes.
	 * 
	 * If some properties do not exist or introspection fails
	 * they are just silently skipped and no errors thrown.
	 * 
	 * @param obj 		 an object to write properties to.
	 * @param values 	a map, containing property names and their values.
	 * 
	 * @see [[setProperty]]
	 */
	public static setProperties(obj: any, values: any): void {
		if (values == null) return;
		
		for (let key in values) {
            let value = values[key];
			ObjectWriter.setProperty(obj, key, value);
		}
	}
}