/* This file contains auxiliary functions to check data type compliance */

bool is_number(string &number)
{
    // -- Checks if a string is a valid real number --
    unsigned int firstchar = 0;
    if (number[0] == '-')
        firstchar = 1;
    if (number[firstchar] == '.')
        return false; // .12 is not a valid decimal in LDPL, 0.12 is.
    if (number[firstchar] == '+')
        return false; // +5 is not a valid decimal in LDPL, 5 is.
    istringstream iss(number);
    double f;
    iss >> f;
    bool isNumber = iss.eof() && !iss.fail();
    // If it is a number, it might be an octal literal (e.g. 025, 067, 003 etc)
    // so we proceed to fix the original number to make it decimal.
    if (isNumber)
    {
        string f_number = "";
        unsigned int i;
        for (i = 1; i < number.length(); ++i)
        {
            if (number[i - 1] != '0')
            {
                // If prev char not 0
                if (number[i - 1] == '-')
                    // if prev char is -, continue check
                    f_number += '-';
                else
                    // if prev char is number, break
                    break;
            }
            else if (number[i] == '.')
                // If prev number is 0
                f_number += '0';
        }
        f_number += number.substr(i - 1);
        number = f_number;
        return true;
    }
    else
        return false;
}

bool is_natural(string number)
{
    // -- Checks if a string is a valid natural number --
    if (!is_number(number))
        return false;
    if (stod(number) <= 0)
        return false;
    for (char l : number)
        if (l == '.')
            return false;
    return true;
}

bool is_label(string &token)
{
    // -- Checks if a string is a valid label --
    for (char letter : token)
        if (letter == '\"')
            return false;
    return true;
}

bool is_math_symbol(string &token)
{
    // -- Checks if a string is a valid math symbol --
    string syms = "+-*/()";
    return token.size() == 1 && syms.find(token[0]) != string::npos;
}

bool is_string(string &token)
{
    // -- Checks if a string is a valid LDPL string --
    if (token.size() < 2 || token[0] != '"' || token[token.size() - 1] != '"')
        return false;
    // Check for unescaped quotes
    for (unsigned int i = 1; i < token.size() - 1; ++i)
    {
        if (token[i] == '\"' && token[i - 1] != '\\')
            return false;
    }
    return true;
}