// RoadNetwork.java
/** Road network simulator (or it will become one once it's done)
 *  @author Douglas W. Jones
 *  @version Feb. 15, 2021
 */

import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
import java.util.Collection;

/** Centralized error reporting tools
 *  error reports are output to System.err (standard error, aka stderr)
 */
class Error {

    /** Fatal error
     *  @param msg -- the warning message
     *  this never returns, the application is terminated abnormally
     */
    public static void fatal( String msg ) {
	System.err.println( "Error: " + msg );
	System.exit( 1 ); // report failure to the OS (or to the shell)
    }

    /** Non-fatal warning
     *  @param msg -- the warning message
     */
    public static void warn( String msg ) {
	System.err.println( "Warning: " + msg );
    }
}

class Road {
    Intersection source;      // road from here
    Intersection destination; // road to there
    double travelTime;	// time in seconds

    public Road( Scanner in ) {
	String srcname; // name of source intersection
	String dstname; // name of destination intersection
	float time;     // travel time between intersections

        if (in.hasNext()) {
	    srcname = in.next();
	} else {
	    Error.warn( "road with no source" );
	    srcname = "???";
	}

        if (in.hasNext()) {
	    dstname = in.next();
	} else {
	    Error.warn( "road " + srcname + " with no destination" );
	    dstname = "???";
	}

        if (in.hasNextFloat()) {
	    time = in.nextFloat();
	} else {
	    Error.warn(
		"road " + srcname + " " + dstname + " with no travel time"
	    );
	    time = 99999.9F;
	}

	// BUG:  What about time units?

        if (in.hasNext( ";" )) {
	    in.next( ";" );
	} else {
	    Error.warn(
		"road " + srcname + " " + dstname + " " + time +
		" with no semicolon"
	    );
	}

	if (time <= 0.0F) {
	    Error.warn(
		"road " + srcname + " " + dstname + " " + time +
		" with negative travel time"
	    );
	    time = 99999.9F;
	}

	// look up the intersection called srcname to set source
	// look up the intersection called dstname to set destination
	// set travelTime to time
    }

    // BUG: need to add behavior for roads
}

class Intersection {
    // BUG: is collection the right class?  Should I pick a subclass?
    Collection <Road> incoming; // the roads leading here
    Collection <Road> outgoing; // the roads that come from here

    public Intersection( Scanner in ) {
        // BUG: need detail!
    }

    // BUG: need to add behavior for roads
}

public class RoadNetwork {

    /** build a road network model by scanning an input file
     *  @param in -- the scanner used to read the file
     *  Input file contains keywords road and intersection,
     *  details beyond that are handled by the appropriate classes
     */
    private static void buildModel( Scanner in ) {
	while (in.hasNext()) {
	    String keyword = in.next();
	    if ("intersection".equals( keyword )) {
		new Intersection( in );
	    } else if ("road".equals( keyword )) {
		new Road( in );
	    } else {
	        Error.warn( "not a keyword in the input: " + keyword );
	    }
	}
    } 

    /** main method mostly concerned with command line arguments
     *  @param args -- the command line arguments
     *  Want just one argument, the file name for model description
     */
    public static void main( String[] args ) {
	// arg[0] should be the name of a file describing a road network
	if (args.length < 1) {
	    Error.fatal( "missing command line argument, a file name" );
	}
	if (args.length > 1) {
	    Error.warn( "extra command line argument: " + args[1] );
	}
	try {
	    buildModel( new Scanner( new File( args[0] ) ) );
	    // BUG: simulate the network that was built
 	} catch ( FileNotFoundException e ) {
	    Error.fatal( "could not open file: " + args[0] );
	}
    }
}