/* Assignment 2.cpp
Michael Ainsworth
15737944	
15.05.2004 
Assignment 2.cpp
Computerized Sketchpad
*/ 

//Preprocessor Section
#include <iostream>
#include <stdlib.h>

using namespace std;

const int MAXCOMMANDS = 100;
const int SIZE = 20;	// grid is SIZE * SIZE
const int RIGHT = 0;	// facing right
const int DOWN = 1;		// facing down
const int LEFT = 2;		// facing left
const int UP = 3;		// facing up

//Main Program Section
void ClearFloor(int floor[SIZE][SIZE])
{ // set the floor array to all clear
	for (int x = 0; x < SIZE; x++)
	{
		for (int y = 0; y < SIZE; y++)
		{
			floor[y][x] = 0;
		}
	}
}

void ClearCommands(int commandArray[MAXCOMMANDS][2])
{ // empty the commands array
	for (int i = 0; i < MAXCOMMANDS; i++)
	{
		commandArray[i][0] = 0;
		commandArray[i][1] = 0;
	}
}

void GetCommands(int commandArray[MAXCOMMANDS][2])
{
	int		count = 0;	// count of commands so far received
	char	buff[255];	// temp buffer for storing info in
	int		command;	// command request
	int		distance;	// distance to move if request is of type 5
	int		i;			// temp value
	char	loadfile;	// should we load from file
	bool	bLoadFile;	// are we loading from file
	FILE	*fp = NULL;	// file pointer we are reading from

	cout << "Computerized Sketchpad" << endl;

	
	cout << "Would you like to load your commands from file (y/n) ? ";
	cin >> loadfile;

	if (loadfile == 'y' || loadfile == 'Y')
		bLoadFile = true;
	else
		bLoadFile = false;

	if (!bLoadFile)
	{ // not loading from file so request manual command entry
		cout << endl;
		cout << "Please enter the commands you wish to execute, 1 per line." << endl << endl << "Enter 9 to finish" << endl << endl 
			<< "Command Meanings" << endl 
			<< "1:Pen up" << endl
			<< "2:Pen down" << endl
			<< "3:Turn Right" << endl
			<< "4:Turn Left" << endl
			<< "5,10: Move Forward 10 spaces" << endl 
			<< "6:Print the 20-by-20 array" << endl << endl
			<<  "(in this example)(eg. 5,5 would move the turtle forward 5 spaces)" << endl << endl;
		
	}
 
	else
	{ // load commands from file
		do
		{ // loop until we get a valid file
			cout << endl << "Type name of file with type of file example (test.txt)!" << endl << endl
			<< "Filename?" ;
			cin >> buff;
			fp = fopen(buff, "rt"); // open the file as text
			if (fp == NULL)
			{ // failed to open specified file, let them know
				cout << "Unable to open file '" << buff << "' Please try again" << endl;
			}
		}
		while (fp == NULL);
	}

	do
	{ // loop through until we get a command 9, end of file or reach MAXCOMMANDS
		command = 0;
		distance = 0;
		cout << "Command " << count + 1 << " : ";
		if (bLoadFile)
		{ // load from file so get next line
			if (fgets(buff, 255, fp) == NULL)
			{ // no line read, set buffer to 9 to trigger exit
				strcpy(buff, "9\n");
			}
			cout << buff; // output to screen what command we got from the file
		}
		else
		{ // get command from user
			cin >> buff;
		}
		i = sscanf(buff, "%i, %i", &command, &distance);
		switch (i)
		{ // how many items did we parse from the command
			case 1: // must be a 1,2,3,4,6 or 9 command
				if ((command > 0 && command < 5) || (command == 6) || (command == 9))
				{ // is the commands we know
					commandArray[count][0] = command;
					commandArray[count][1] = 0;
					count++;
				}
				else if (command == 5)
				{ // command 5 with no distance, complain
					cout << "Move command must have a distance component (eg 5,10), please re-enter" << endl;
				}
				else
				{ // invalid command, complain
					cout << "unable to parse line '" << buff << "', please re-enter" << endl;
				}
				break;
			case 2: // must be a 5 command
				if (command == 5)
				{ // it is a 5 command
					commandArray[count][0] = command;
					commandArray[count][1] = distance;
					count++;
				}
				else
				{ // complain
					cout << "unable to parse line '" << buff << "', please re-enter" << endl;
				}
				break;
			default: // unknown, complain
				cout << "unable to parse line '" << buff << "', please re-enter" << endl;
				break;
		}
	}
	while ((command != 9) && (count < MAXCOMMANDS - 1));

	system("pause"); // pause so they can see all commands before processing

	commandArray[MAXCOMMANDS - 1][0] = 9; // just in case set the last entry in array to end command

	if (fp != NULL) // close the file if it is open
		fclose(fp);

	return;
}

// Direction the pen is moving
//            3 (up)
//            ^
//            |
// (left) 2 <-+-> 0 (right)
//            |
//            v
//            1 (down)

int turnRight(int direction)
{
	// right -> down -> left -> up -> right ....
	direction++;

	if (direction > UP) // rotated past up so reset to facing right
		direction = RIGHT;

	return direction;
}

int turnLeft(int direction)
{
	// up -> left -> down -> right -> up ...
	direction--;

	if (direction < RIGHT) // rotated past right so reset to facing up
		direction = UP;

	return direction;
}

void printArray(int floor[SIZE][SIZE])
{ // draw the sketch pad
	for (int y = 0; y < SIZE; y++)
	{
		for (int x = 0; x < SIZE; x++)
		{
			if (floor[y][x] == 0)
				cout << " "; // empty grid spot
			else
				cout << "*"; // active grid spot
		}
		cout << endl;
	}
}

void movePen(bool penDown, int floor[SIZE][SIZE], int direction, int distance, int &x, int &y)
{
	int xmov = 0;
	int ymov = 0;
	int value;

	if (penDown == false)
	{ // pen up so set floor values changed to 0 (unset)
		value = 0;
	}
	else
	{ // pen down so set floor values to 1 (set)
		value = 1;
	}

	switch (direction)
	{ // assuming top,left is 0,0
		case LEFT: // xpos will decrease when moving left
			xmov = -1;
			break;
		case RIGHT: // xpos will increase when moving right
			xmov = 1;
			break;
		case UP: // ypos will descrease if moving up
			ymov = -1;
			break;
		case DOWN: // ypos will increase if moving down
			ymov = 1;
			break;
	}

	// change the set/unset value of the current pen position
	floor[y][x] = value;

	for(int i = 0; i < distance; i++)
	{
		x += xmov; // move our x position
		y += ymov; // move our y position

		if (x < 0)
			x = 0;
		if (x >= SIZE)
			x = SIZE - 1;
		if (y < 0)
			y = 0;
		if (y >= SIZE)
			y = SIZE - 1;

		// set/unset the value of the spot we have moved to.
		floor[y][x] = value;
	}

	return;
}

int main(int argc, char* argv[])
{
	int		floor[SIZE][SIZE] = {0};			// size of the drawing space on screen
	int		command = 0;						// records current command
	int		distance = 0;						// distance to be moved on the screen
	int		direction = 0;						// current direction
	int		count = 0;							// loop counter
	int		x, y;								// x & y pos on sketchpad
	int		commandArray[MAXCOMMANDS][2] = {0};	// array to record a set of commands
	bool	penDown = false;					// pen position
	char	again = 'n';						// program flag


	do
	{
		// initialize variables each time
		command = 0;
		distance = 0;
		direction = 0;
		count = 0;
		x = -1;
		y = -1;
		penDown = false;
		ClearFloor(floor);
		ClearCommands(commandArray);
		system("cls");

		// get the commands
		GetCommands(commandArray);
		system("cls");

		// retrieve first command
		command = commandArray[count][0];

		while ( (command != 9))
		{ // loop through commands until we hit marker
			switch ( command )
			{
				case 1: // penDown
					penDown = false;
					break;
				case 2: // penUp
					penDown = true;
					break;
				case 3: // turn right
					direction = turnRight(direction);
					break;
				case 4: // turn left
					direction = turnLeft(direction);
					break;
				case 5: // move the pen
					distance = commandArray[count][1];
					movePen(penDown, floor, direction, distance, x, y);
					break;
				case 6: // draw the sketch pad
					cout << endl << "The drawing is:" << endl << endl;
					printArray(floor);
					break;
			}
			command = commandArray[++count][0];
		}

		cout << endl << "Do you want to draw again (y/n)? ";
		cin >> again;
	}
	while ( (again == 'y') || (again == 'Y') );

	return 0;
}