#include <iostream>
#include <vector>
#include <string>
#include <map>
#include <algorithm>
#include <fstream>
#include <set>

using namespace std;


vector<string> *getfilenames()
{
    vector<string> *books = new vector<string>(5);
    cout << "Enter filenames for books (Q to quit)" << endl;

    string inp;
    cout << ">> ";
    for (cin >> inp; inp != "Q"; cin >> inp) {
        cout << ">> ";
        books->push_back(string(inp));
    }
    return books;
}

bool invalidchar(char x) {return x < 'a' || x > 'z';}
void normalize(string *st)
{
    transform(st->begin(), st->end(), st->begin(), ::tolower);
    string::iterator end = remove_if(st->begin(), st->end(), invalidchar);
    st->erase(end, st->end());
}

set<string> *readDictionary()
{
    ifstream file;
    set<string> *dict = new set<string>();
    string word;
    file.open("dictionary.txt");
    while (file.good()) {
        file >> word;
        normalize(&word);
        dict->insert(string(word));
    }
    file.close();
    return dict;
}

map<string,int> *readfiles(vector<string> *books)
{
    map<string,int> *frequency = new map<string,int>();

    ifstream file;
    string curword;
    vector<string>::iterator it;
    for(it = books->begin(); it < books->end(); it++) {
        file.open(it->c_str());
        while (file.good()) {
            file >> curword;
            normalize(&curword);
            if (curword.size() != 0)
                (*frequency)[string(curword)] += 1;
        }
        file.close();
    }
    return frequency;
}

int getUserChoice()
{
    int choice;
    do {
        cout << "Please pick an operation" << endl;
        cout << "1: Show number of times a word occurs" << endl;
        cout << "2: Show which words occur more than some number of times" << endl;
        cout << "3: quit and show nonexistant words found in the books" << endl;
        cout << ">> ";
        cin >> choice;
    } while(choice < 1 && choice >3);
    return choice;
}

string *getUserWord()
{
    string *input = new string();
    cout << "Enter a word: ";
    cin >> *input;
    normalize(input);
    return input;
}

void examineSingleWord(map<string, int> *freqs)
{
    string *word = getUserWord();
    int count = (*freqs)[*word];
    cout << "The word \" " << *word << "\" occurs " << count << " times" << endl;
    delete word;
}

int getUserCount()
{
    int input;
    do {
        cout << "Enter a number: ";
        cin >> input;
    } while (input <= 0);
    return input;
}

void showWordsMoreFrequentThan(map<string,int> *freqs)
{
    int count = getUserCount();
    map<string,int>::iterator it;
    for (it = freqs->begin(); it != freqs->end(); it++)
        if ((*it).second >= count)
            cout << (*it).first << ": " << (*it).second << endl;
}

vector<string> *nonExistantWords(set<string> *keys, set<string> *dict)
{
    vector<string> *diff = new vector<string>();
    set_difference(keys->begin(), keys->end(), dict->begin(), dict->end(),inserter(*diff, diff->begin()));
    return diff;
}

void printUnrealWords(vector<string> *fakes)
{
    cout << "The following words were used in the books, but are not real" << endl;
    vector<string>::iterator it;
    for (it = fakes->begin(); it != fakes->end(); it++) {
        cout << *it << endl;
    }
}

set<string> *getKeys(map<string,int> *freqs)
{
    map<string,int>::iterator it;
    set<string> *keys = new set<string>();
    for (it = freqs->begin(); it != freqs->end(); it++) {
        keys->insert((*it).first);
    }
    return keys;
}

int main(int argc, const char *argv[])
{
    set<string> *dict = readDictionary();
    vector<string> *books = getfilenames();
    map<string,int>::iterator it;
    map<string,int> *freqs = readfiles(books);

    int choice;
    do {
        choice = getUserChoice();
        switch (choice) {
            case 1: 
                examineSingleWord(freqs);
                break;
            case 2:
                showWordsMoreFrequentThan(freqs);
                break;
        }
    } while(choice != 3);

    set<string> *keys = getKeys(freqs);
    vector<string> *fakes = nonExistantWords(keys, dict);
    printUnrealWords(fakes);
    cout << "There are " << fakes->size() << " nonreal words" << endl;
    return 0;
}