/* 
 * Example session of using Cassowary.net
 * Author: Jo Vermeulen <jo@lumumba.uhasselt.be>
 *
 * Be sure to link against Cassowary.dll, otherwise
 * this won't work!
 * 
 * When using the Mono commandline compiler, add the 
 * argument -r:Cassowary.dll like this:
 * $ mcs -r:Cassowary.dll CassowaryExample.cs
 * 
 * When using Visual Studio, right click on your 
 * project in the Solution view and choose 
 * 'Add reference'. Then browse to the Cassowary.dll
 * library.
 */

using System;

// we want to use the Cassowary library
using Cassowary;

public class CassowaryExample
{
	public static void Main(string[] args)
	{
		try
		{
			// create the constraint solver
			ClSimplexSolver solver = new ClSimplexSolver();

			// add a few variables: x and y
			ClVariable x = new ClVariable("x");
			ClVariable y = new ClVariable("y");

			// we want x to be greater than or equal to 
			// twice times y 
			// [x >= 2*y]
			solver.AddConstraint(
				new ClLinearInequality(x, Cl.GEQ, Cl.Times(2, y)));

			// we also like x to be equal to 20, but give it a weak strength
			// (meaning stronger constraints will have greater precedence)
			// [x = 20]
			//
			// remember: the default strength is required
			solver.AddConstraint(
				new ClLinearEquation(x, 20, ClStrength.Weak));

			// let's enforce that x and y together are less than or equal to 50
			// [x + y <= 50]
			//
			// unfortunately, we have to wrap a few things in ClLinearExpression 
			// instances for now (will hopefully be improved in a future release)
			solver.AddConstraint(
				new ClLinearInequality(Cl.Plus(x, new ClLinearExpression(y)),
									   Cl.LEQ, new ClLinearExpression(50)));

			// there is no need to explicitly call solver.Solve(): by default
			// the solver auto solves after each AddConstraint() call
			
			// now print out the solution
			Console.WriteLine("x == " + x.Value); // should be x == 20
			Console.WriteLine("y == " + y.Value); // should be y == 10
		} 
		catch (ExClRequiredFailure rf)
		{
			Console.WriteLine("The constraint system could not be solved:");
			Console.WriteLine(rf.StackTrace);
		}
		catch (ExClInternalError ie)
		{
			Console.WriteLine("There was an internal Cassowary error:");
			Console.WriteLine(ie.StackTrace);
		}
		catch (ExClError e)
		{
			Console.WriteLine("Other error -- " + e.GetType() + ":");
			Console.WriteLine(e.StackTrace);
		}
	}
}