// MP1.java
// Author:  Douglas W. Jones
// the official solution

import java.io.FileInputStream;
import java.io.FileNotFoundException;

/** Error reporting package
 *  Provide a standard prefix and behavior for error reporting
 *  @author Douglas W. Jones
 *  @version 2019-02-07 
 */
class Errors {
    /** Prefix string for error messages
     */
    private static String prefix = "??: ";

    /** Set prefix on error reports, should be done before any error reports
     *  @arg p the prefix on any error messages
     */
    public static void setPrefix( String p ) {
   	prefix = p;
    }

    /** Report nonfatal errors, output a message and return
     *  @arg m the message to output
     */
    public static void warn( String m ) {
	System.err.println( prefix + ": " + m );
    }

    /** Report fatal errors, output a message and terminate the program
     *  @arg m the message to output
     */
    public static void fatal( String m ) {
	warn( m );		// could duplicate code from warn instead
	System.exit( 1 );
    }
}

/** Main program for MP1
 *  All this version does is take a command line-parameter and report
 *    if it can open it.
 *  @author Douglas W. Jones
 *  @version 2019-02-07
 */
public class MP1 {

    /** Main program
     */ 
    public static void main( String[] args ) {
	Errors.setPrefix( "MP1" );
	if (args.length < 1) {
	    Errors.fatal( "Missing argument" );
	}
	if (args.length > 1) {
	    Errors.warn( "Too many arguments " + args[1] );
	    // it's unnecessary to iterate through all the extra args
	}
	try {
	    FileInputStream f = new FileInputStream( args[0] );
	    System.out.println( "Opened " + args[0] );
	} catch (FileNotFoundException e) {
	    Errors.fatal( "Can't open " + args[0] );
	}
    }
}