using System;

namespace PS4_Q1
{	//
	// Probem Set 4, Question 1
	// Written by Paul Hudak
	// October 7, 2006
	//
	class Class1
	{	//
		// A program to play Tic Tac Toe
		//
		[STAThread]
		static void Main(string[] args)
		{
			// ask user for names of players
			Console.Write("Please type the name of the X player: ");
			string Xname = Console.ReadLine();
			Console.Write("Please type the name of the O player: ");
			string Oname = Console.ReadLine();

			// create new board and player objects
			Board  bd = new Board();
			Player Xp = new Player(Xname, 'X');
			Player Op = new Player(Oname, 'O');

			// initialize variables for loop
			int  cnt    = 1;	// counts how many moves have been made
			bool Xturn  = true; // X moves first
			char winner = '-';	// no winner yet

			// as long as the board still has empty squares,
			// and there is no winner, we keep playing, while
			// alternating moves between player X and player O.
			while (cnt<=9 && winner=='-')
			{
				if (Xturn)
					Xp.Move(bd);	// X moves
				else 
					Op.Move(bd);	// O moves

				bd.Display();		// display board

				// update loop variables
				Xturn  = !Xturn;
				cnt    = cnt+1;
				winner = bd.Winner();
			}

			// declare winner or draw
			string winName;
			if      (winner=='X')
				Console.WriteLine("\nThe winner is {0}.\n", Xp.Name());
            else if (winner=='O')
				Console.WriteLine("\nThe winner is {0}.\n", Op.Name());
			else
				Console.WriteLine("\nThe game ended in a draw.\n");
		}
	}

	class Board
	{	// INSTANCE VARIABLES
		// create one variable for each square
		// top middle bottom; left middle right
		private char tl = '-'; private char tm = '-'; private char tr = '-';
		private char ml = '-'; private char mm = '-'; private char mr = '-';
		private char bl = '-'; private char bm = '-'; private char br = '-';

		// CONSTRUCTORS
		// new board contains all blanks
		public Board()
		{	}
		
		// INSTANCE METHODS
		// display board as 3x3 square of characters
		public void Display()
		{	
			Console.Write("\n{0}{1}{2}\n{3}{4}{5}\n{6}{7}{8}\n",
				tl,tm,tr,ml,mm,mr,bl,bm,br);
		}

		// returns content of given square
		public char GetSquare(int x, int y)
		{	// compute unique index for each square
			int i = 3*x + y;	

			switch (i)
			{	// i identifies the square uniquely
				case 0: return tl;	case 1: return tm;	case 2: return tr;
				case 3: return ml;	case 4: return mm;	case 5: return mr;
				case 6: return bl;	case 7: return bm;	case 8: return br;
				default: return 'Z';  // this should never happen
			}
		}

		// sets a square to given content
		public void SetSquare(char c, int x, int y)
		{	// compute unique index for each square
			int i = 3*x + y;

			switch (i)
			{	// i identifies the square uniquely
				case 0: tl=c; break;	case 1: tm=c; break;	case 2: tr=c; break;
				case 3: ml=c; break;	case 4: mm=c; break;	case 5: mr=c; break;
				case 6: bl=c; break;	case 7: bm=c; break;	case 8: br=c; break;
				default: break;  // this should never happen
			}
		}

		// determine winner, if there is one
		public char Winner()
		{	// most of the work is done in win
			if (win('X'))
				return 'X';
			else if (win('O'))
				return 'O';
			else return '-';
		}

		// private helper functions
		private bool win(char c)
		{	// check all 8 possibilities for a winner
			// (3 horizontal, 3 vertical, and 2 diagonal)
			return ( line(tl,tm,tr,c) || line(ml,mm,mr,c) || line(bl,bm,br,c) ||
				line(tl,ml,bl,c) || line(tm,mm,bm,c) || line(tr,mr,br,c) ||
				line(tl,mm,br,c) || line(tr,mm,bl,c) );
		}

		private bool line(char x, char y, char z, char c)
		{	// return true if we have a line of the same 3 characters
			return ( x==c && y==c && z==c );
		}
        
	}
	
	class Player
	{	// CLASS VARIABLES
		// static class variable shared by all Players
		private static Random randGen = new Random();

		// INSTANCE VARIABLES
		private string name;
		private char role;		// 'X', 'O', or '-'

		// CONSTRUCTORS
		public Player(string nm, char xoro)
		{	// a Player's state is just name and role
			name = nm;
			role = xoro;
		}

		// INSTANCE METHODS
		// return name of player
		public string Name()
		{	// return Player's name
			return name;  
		}

		// make a random move on given board object
		public void Move(Board bd)
		{	
			int x;
			int y;

			// generate a random board position that is not occupied
			do
			{	// need two calls to the random number generator
				x = randGen.Next(3);
				y = randGen.Next(3);
			}
			while (bd.GetSquare(x,y) != '-');

			// modify the board
			bd.SetSquare(role, x, y);
		}
	}
}