//
// Program: WordLadder
//
// Purpose: plays game with user to transform one word into
//	another word, changing only one letter at a time.  
//
// Programmer: Pamela J. Vermeer
//
// Date: 4/20/00
//

#include <iostream>
#include <string>

using namespace std;

const int MAX_CHANGES = 30;

void main() {

	void GetData(string& start, string& finish, int& maxChanges);
	void PlayGame(string start, string finish, int maxChanges);

	string start, finish;
	int maxChanges;

	GetData(start, finish, maxChanges);
	PlayGame(start, finish, maxChanges);

}

// 
// void GetData(string& start, string& finish, int& maxChanges)
//
// Purpose: Reads in game data from user, making sure the data
//  is correct before returning
//
// Parameters: start and finish: strings containing the start and
//  finish words
//		maxChanges: maximum number of changes allowed
//
void GetData(string& start, string& finish, int& maxChanges)
{
	char answer; // whether the data is OK or not
	do {

		// get the data
		cout << "Enter a start string ";
		cin >> start;
		cout << "Enter the finish string ";
		cin >> finish;
		cout << "Enter the maximum number of changes allowed, less than "
			 << MAX_CHANGES << " ";
		cin >> maxChanges;

		// check input
		cout << "Your start word is " << start 
			 << " and your finish word is " << finish << endl;
		cout << "You have " << maxChanges << " maximum changes" << endl;
		cout << "Is this correct?  ";
		cin >> answer;
	} while (answer != 'y' && answer != 'Y');


}

// 
// void PlayGame(string start, string finish, int maxChanges)
//
// Purpose: Plays a round of the game, reports whether the player
//  won or lost, and displays the player's ladder
//
// Parameters: start and finish: strings containing the start and
//  finish words
//		maxChanges: maximum number of changes allowed
//
void PlayGame(string start, string finish, int maxChanges)
{
	void PrintStringArray(string word[], int size);
	int changes = 0;	// number of changes made so far
	string word[MAX_CHANGES]; // words in the ladder
	int position;	// the position within the word to change
	char letter;	// the character to change the position to

	// initialize the word ladder
	word[0] = start;

	while (changes < maxChanges && word[changes] != finish) {
		cout << "Position to change (starting at 0): ";
		cin >>  position;
		cout << "Letter to use: ";
		cin >> letter;

		// copy previous word into next spot in array
		word[changes+1] = word[changes];

		// make last word in array the current word, and change 
		// it's letter in the given position
		changes++;
		word[changes][position] = letter;

		cout << "The word is now " << word[changes] << endl << endl;

	}

	// check whether the game was won or lost
	if (word[changes] == finish)
		cout << "Congratulations! You won the game.  Your ladder is " << endl;
	else
		cout << "Sorry, you did not complete the ladder within " 
			 << maxChanges << " letter changes. " 
			 << "Your ladder is " << endl;

	// Have to add 1 to changes, because we want what is in position
	// word[changes] to print
	PrintStringArray(word, changes+1);

}

//
// void PrintStringArray(string word[], int size)
//
// Purpose: prints an array of strings, one per line, with a tab at 
//  the front of each line
//
// Parameters:
//		word: the array of strings
//		size: the number of positions in the array to pring
//

void PrintStringArray(string word[], int size)
{

	for (int i = 0; i < size; i++)
		cout << "\t" << word[i] << endl;

}