using namespace std;

//Function Definition
void initializeStructure(istream& input, HashMap<string, Vector<string>> &structure);
string makeRandomString(string const &symbol, HashMap<string, Vector<string>> const &structure);
string modifyResult(string &result, string &element, HashMap<string, Vector<string>> const &structure);


/**
 * Generates grammar for a given symbol a certain number of times given
 * a BNF input file.
 *
 * This will be called by grammarmain.cpp.
 *
 * @param input - Input stream of BNF file.
 * @param symbol - Symbol to generate
 * @param times - Number of times grammar is generated
 * @return Vector of strings of size times with random generations of symbol
 */

Vector<string> grammarGenerate(istream& input, string symbol, int times) {
    HashMap<string, Vector<string>> structure;
    initializeStructure(input, structure);
    Vector<string> randomStrings;
    for (int i = 0; i < times; i++) {
        string randomString = makeRandomString(symbol, structure);
        randomStrings.add(randomString);
    }
    return randomStrings;           // This is only here so it will compile
}

void initializeStructure(istream& input, HashMap<string, Vector<string>> &structure) {
    while(!input.eof()) {
        string line;
        getline(input, line);
        string nonTerminal;
        nonTerminal = line.substr(0, line.find("::="));;
        if(structure.containsKey(nonTerminal) || nonTerminal == "") {
            throw("Exception!");
        }
        Vector<string> rules = stringSplit(line.substr(line.find("::=") + 3, line.size()), "|");
        structure.put(nonTerminal, rules);
    }
}

string makeRandomString(string const &symbol, HashMap<string, Vector<string>> const &structure) {
    string result;
    if (!structure.containsKey(symbol)) {
        return symbol;
    }
    Vector<string> rules = structure.get(symbol);
    int randomE = randomInteger(0, rules.size() - 1);
    string element = rules.get(randomE);

    if(stringContains(element, " ")) {
        Vector<string> eleSplit = stringSplit(element," ");
        for (int i = 0; i < (int) eleSplit.size(); i++) {
            result = modifyResult(result, eleSplit[i], structure);
        }
    } else {
        result = modifyResult(result, element, structure);
    }
    return result;
}

string modifyResult(string &result, string &element, HashMap<string, Vector<string>> const &structure) {
    if (structure.containsKey(element)) {
        result += makeRandomString(element, structure);
    } else {
        result += element + " ";
    }
    return result;
}