/** @module reflect */
import { ConfigException } from '../errors/ConfigException';

/**
 * Descriptor that points to specific object type by it's name
 * and optional library (or module) where this type is defined.
 * 
 * This class has symmetric implementation across all languages supported
 * by Pip.Services toolkit and used to support dynamic data processing.
 */
export class TypeDescriptor {
	private _name: string;
	private _library: string;
		
	/**
	 * Creates a new instance of the type descriptor and sets its values.
	 * 
	 * @param name 		a name of the object type.
	 * @param library 	a library or module where this object type is implemented.
	 */
	public constructor(name: string, library: string) {
		this._name = name;
		this._library = library;
	}
	
	/**
	 * Get the name of the object type.
	 * 
	 * @returns the name of the object type.
	 */
	public getName(): string { 
        return this._name; 
    }
	
	/**
	 * Gets the name of the library or module where the object type is defined.
	 * 
	 * @returns the name of the library or module.
	 */
	public getLibrary(): string { 
        return this._library; 
    }
	
	/**
	 * Compares this descriptor to a value.
	 * If the value is also a TypeDescriptor it compares their name and library fields.
	 * Otherwise this method returns false.
	 * 
	 * @param value		a value to compare.
	 * @returns true if value is identical TypeDescriptor and false otherwise.
	 */
	public equals(value: any): boolean {
		if (typeof value === "object" && value.constructor.name === "TypeDescriptor") {
			let otherType = <TypeDescriptor>value;
			if (this.getName() == null || otherType.getName() == null)
				return false;
			if (this.getName() != otherType.getName())
				return false;
			if (this.getLibrary() == null || otherType.getLibrary() == null
				|| this.getLibrary() == otherType.getLibrary())
				return true;
		}
		
		return false;
	}
	
	/**
     * Gets a string representation of the object.
     * The result has format name[,library]
     * 
     * @returns a string representation of the object.
	 * 
	 * @see [[fromString]]
	 */
	public toString(): string {
		let builder = '' + this._name;
		if (this._library != null) {
			builder += ',' + this._library;
		}
		return builder.toString();
	}
	
	/**
     * Parses a string to get descriptor fields and returns them as a Descriptor.
	 * The string must have format name[,library]
     * 
     * @param value     a string to parse.
     * @returns         a newly created Descriptor.
	 * @throws a [[ConfigException]] if the descriptor string is of a wrong format.
	 * 
	 * @see [[toString]]
	 */
	public static fromString(value: string): TypeDescriptor {
		if (value == null || value.length == 0) {
			return null;
		}
				
		let tokens = value.split(",");
		if (tokens.length == 1) {
			return new TypeDescriptor(tokens[0].trim(), null);
		} else if (tokens.length == 2) {
			return new TypeDescriptor(tokens[0].trim(), tokens[1].trim());		
		} else {
			throw new ConfigException(
				null, "BAD_DESCRIPTOR", "Type descriptor " + value + " is in wrong format"
			).withDetails("descriptor", value);
		}			
	}

}