/* - BEGIN OF FILE  - */
/* - include statements - */
#include <iostream>
#include <cstdlib>
#include <fstream>
#include <cctype>
#include <string>
using namespace std;
/* - - - - - - - - - - - */

/* - global variables - */
const int DICT_SIZE = 250000;
const int ALPHABET_SIZE = 26;
const int FAILED = -1;
const int ZERO = 0;
const int ONE = 1;
/* - - - - - - - - - - - */

/* - function prototypes - */
int readDict(string readin[]);
int menu();
int checkString(string m);
int checkInput(string m);
string toLowerCase(string n);
int binarySearch(string list[], int size, string target);
void searchFull(string list[], string target, int size);
bool match(string target, string w);
/* - - - - - - - - - - - - */

int main () {
    /* - variable initialisation - */
    string target;
    string input;
    string dictionary[DICT_SIZE];
    int size;
    int find;
    /* - - - - - - - - - - - - - */

    size = readDict(dictionary);
    if (size == FAILED) {
       cout << "Read Failed: Check location for dict.txt" << endl;
       system("pause");
       return EXIT_FAILURE;
    }
    
    /* - enable looped menu - */       
    while(true) {
             switch(menu()) {
                            case 1:  
                                 cout << "Enter word" << endl;
                                 cin >> input;
                                 if (checkString(input) == FAILED) {
                                                         cout << "Inappropriate Entry" << endl;
                                 }
                                 else {
                                      target = toLowerCase(input);  
                                      find = binarySearch(dictionary,size,target);
                                      if (find == FAILED) {
                                           cout << target << " is not in dictionary" << endl;
                                               }
                                      else {
                                           cout << target << " is in dictionary" << endl;
                                           }                                                                   
                                      }
                                 break;
                            case 2: 
                                 cout << "Enter word pattern with ? for missing letters " << endl;
                                 cin >> input;                                 
                                 if (checkString(input) == FAILED) {
                                                         cout << "Inappropriate Entry" << endl;
                                 }
                                 else {
                                      target = toLowerCase(input);
                                      searchFull(dictionary, target, size);                    
                                 }
                                 break;
                            case 3: 
                                 system("pause");
                                 return EXIT_SUCCESS;
                            default: 
                                     cout << "Invalid Choice" << endl;
                            }
    }
    /* - - - - - - - - - - */
}    

/* - functions - */
int readDict(string readin[]) {
//precondition - none
//postcondition - reads dict.txt into an array 
    int loop = ZERO;
    string line; 
    ifstream myfile ("dict.txt"); 
    if (myfile.is_open()) 
    {
        while (! myfile.eof() ) 
        {
            getline (myfile,line); 
            readin[loop] = line;
            loop++;
        }
        myfile.close(); 
        return loop;
    }
    else {
         return FAILED;
    }
}

int menu() {
//precondition - none
//postcondition - users entry point
     // using a cstring so can to atoi to find menu option
     // as well as using isdigit function 
     string choice;
     cout << "\tCrossword Helper " << endl << endl;
     cout << " 1 : Check if word is in dictionary " << endl;
     cout << " 2 : Find words in dictionary which match pattern " << endl;
     cout << " 3 : Quit " << endl;
     cin >> choice;
     cin.clear();
     if (checkInput(choice) != ZERO) {
        return FAILED;
     }
     return atoi(choice.c_str());

}

int checkString(string m) {
//precondition - none
//postcondition - checks to see whether string m contains any incorrect chars
    for (int i = ZERO; i < m.length(); i++) { 
        if (isalpha(m.at(i))) {
        }
        else if (m.at(i) != '?') {
             return FAILED;
        }
    }
    return ZERO;
}

int checkInput(string m) {
//precondition - none
//postcondition - checks to see whether string m contains any incorrect chars
    for (int i = ZERO; i < m.length(); i++) { 
        if (isdigit(m.at(i))) {
        }
        else {
             return FAILED;
        }
    }
    return ZERO;
}

string toLowerCase(string n) {
//precondition - none
//postcondition - switches string n into lower case
       for (int i = ZERO; i < n.length(); i++) {
           if (isupper(n.at(i))) {
                                 n.at(i) = tolower(n.at(i));
           }
       }
       return n;
}

// the following segment of code has been modified from 
// http://www.paked.net/subject_pages/computer_science/prog1.htm
int binarySearch(string list[], int size, string target) {
//precondition - dictionary array, size of dictionary array and target string
//postcondition - returns integer based on whether or not string is found in array list[]
    int left, right, midpt;

    left = ZERO;
    right = size - 1;
    int key;
    while (left <= right) {
          midpt = (int) ((left + right) / 2);
          key = list[midpt].compare(target);
          if (key == ZERO) {
             return midpt;
          }
          else if (key < ZERO) {
               left = midpt + ONE;
          }
          else {
               right = midpt - ONE;
          }        
    }         
    return FAILED;
}
// end of code segment modified from
// http://www.paked.net/subject_pages/computer_science/prog1.htm

// the following segment of code has been modified from 
// http://www.fredosaurus.com/notes-cpp/examples/crosswordhelper/crosswordhelper.html
void searchFull(string list[], string target, int size) {
//precondition - dictionary array, size of dictionary array and target string
//postcondition - sends each term to the match function and if it matches prints it
        for (int i = ZERO; i < size; i++) {
            if (match(target, list[i])) {
                cout << list[i] << endl;
            }
        }
}

bool match(string target, string findMatch) {
//precondition - none
//postcondition - looks for matches between strings with ? as a wildcard
    if (findMatch.size() != target.size()) {
                           return false;
                           }
    for (int i = ZERO; i < target.size(); i++) { 
        if (target[i] != '?') {
            if (target[i] != findMatch[i]) {
                return false;
            }
        }
    }
    return true;   
}

// end of code segment modified from 
// http://www.fredosaurus.com/notes-cpp/examples/crosswordhelper/crosswordhelper.html                                 
    
                  
/* - - - - - - - */
/* - END OF FILE - */