#include <iostream>
#include <string>
using namespace std;

#include "board.h"
#include "prompt.h"
#include "hmap.h"

class Game
{
  public:

    Game();
    void display();     // show the current game board
    void play();        // play a game, start to finish
    
  private:

    Board myBoard;
    int   myCount;      // bookkeeping statistics
    
    int bestMove(Board::Player p, int& move);
    int getHumanMove();
    
    bool scoreIsBetter(int score, int best, Board::Player p) const;
    Board::Player opposite(Board::Player p)                  const;
    int           bestScore(Board::Player p)                 const;

    HMap<int> myMap;
    
    static int COMPUTER_WIN;    // a big number
    static int DRAW;            // a middle number
    static int HUMAN_WIN;       // a low number
};

int Game::COMPUTER_WIN   = 10;
int Game::DRAW           = 0;
int Game::HUMAN_WIN      = -10;

Game::Game()
    : myCount(0),
      myMap(10001)
{
    
}

void Game::display()
// post: game board displayed    
{
    cout << "current board -----" << endl;
    myBoard.print();
    cout << endl << "-----" << endl;
}

Board::Player Game::opposite(Board::Player p) const
// post: return opposite of p, i.e., X for O and O for X    
{
    if (p == Board::X) {
	return Board::O;
    }
    return Board::X;
}

int Game::bestScore(Board::Player p) const
// post: return the best possible score for player p    
{
    if (p == Board::X) {
	return COMPUTER_WIN;
    }
    return HUMAN_WIN;
}

bool Game::scoreIsBetter(int score, int best, Board::Player p) const
// post: return true if score is better than best for p
//       return false otherwise    
{
    if (p == Board::X) {
	if (score > best) return true;
    }
    else {
	if (score < best) return true;
    }
    return false;
}


int Game::getHumanMove()
// post: move entered by human player is returned   
{
    int move;
    while (true) {
	move = PromptlnRange("enter square: ",0,myBoard.size()-1);
	if (myBoard.isClear(move)) {
	    return move;
	}
	cout << "illegal move" << endl;
    }
}

int Game::bestMove(Board::Player p, int & move)
// post: return best score for player p, this
//       is the HIGHEST score for X/Computer and LOWEST score for O/Human
//       move is set to the move that achieves this score        
{
    if (myBoard.isFull()) {        // game is a draw
	myCount++;
	return Game::DRAW;
    }

    if (myBoard.isWin(p)) {        // win for p ?
	myCount++;
	return bestScore(p);
    }

    int k;
    int best = bestScore(opposite(p));   // assume opponent does well
    int score;
    int dontCareMove;
    for(k=0; k < myBoard.size(); k++) {
	
	if (myBoard.isClear(k)) {        // can we move here?
	    
	    myBoard.place(k,p);


	    string boardString = myBoard.tostring();
	    if (myMap.contains(boardString)) {
		score =  myMap.get(boardString);
	    }
	    else {
		score = bestMove(opposite(p),dontCareMove);
		myMap.insert(boardString,score);
	    }

	    myBoard.unplace(k);
	    
	    if (scoreIsBetter(score, best,p)) {
		best = score;
		move = k;
	    }
	}
    }
    return best;
}

void Game::play()
// post: game is played    
{
    int move;
    int score;

    // loop until game over: draw or someone wins

    Board::Player player = Board::X;
    
    while (true) {
	
	// determine computer move
	
	myCount = 0;
	score = bestMove(player, move);
	myBoard.place(move, player);
	display();
	cout << "# boards looked at " << myCount << endl;
	cout << "size of map = " << myMap.size() << endl;

	if (myBoard.isWin(player) || myBoard.isFull()) {
	    break;
	}
	// determine human move

	player = opposite(player);
	move = getHumanMove();
	myBoard.place(move, player);
	display();
	if (myBoard.isWin(player) || myBoard.isFull()) {
	    break;
	}

	player = opposite(player);
    }
}

int main()
{
    Game g;
    g.play();
    return 0;
    
}