#include<iostream>
#include <sstream>
using namespace std;


//Order of operations: parenthases functions, mult/devide, add/subtract
//negative numbers wont really work I geuss.
//----Whenever there is a "(-" or "[start]-" replace '-' with "0-"
//Prototypes
string replacesubstr(string modifyString, const string replaceString, const unsigned short start, const unsigned short length);
string math(string mathstring);
string floattostring(const float in);
float stringtofloat(const string in);
float solve(string operationString);

//Main
int main()
{
    string solvestring;
    cout << "Welcome to calculator! Type -help for commands." << endl;
    while(solvestring != "-exit")
    {
    cin >> solvestring;
    if(solvestring == "-help")
    cout << "-exit -- Exit the program\n-save -- Start saveing output in a text file.\n-stopsave -- Stop saving output\n-changesave -- Change the output file is saved too \n-functions -- List avilible functions\n";
    else
    if(solvestring == "-exit")
    return 0;
    else
    if(solvestring == "-save")
    cout << "Not Yet Implanted\n";
    else
    if(solvestring == "-stopsave")
    cout << "Not Yet Implanted\n";
    else
    if(solvestring == "-functions")
    cout << "sin, cos, tan, asin, acos, and atan, sqrt\n";
    else
    if(solvestring == "-changesave")
    cout << "Not Yet Implanted\n";
    else
    if(solvestring[0] == '-')
    cout << "Command not reconized\n";
    else
    if(/*Valid Math Entry*/true)
    cout << solve(solvestring) << endl;
    else
    cout << "Syntax error\n";
    }
}

//Uses string sream to convert a float to a string
string floattostring(const float in)
{
       stringstream ss (stringstream::in | stringstream::out);
       ss << in; 
    return ss.str();
}

//Convert a string to a float using atof with a C style string
float stringtofloat(const string in)
{
    return atof(in.c_str());
}

//Returns an equation fully solved 
float solve(string operationString)
{ 
   unsigned short pernthases = 0;
   for(unsigned short i = 0; operationString[i] != 0; i++)
   if(operationString[i] == '(')
   pernthases++;
   unsigned short start, end, foundPernth;
   //For Each pernthases, set the start of the perenthesis in start, and end in end, then operat on it and replace the substring.
   while(pernthases > 0)
   {
       //Find rightmost '('
       start = 0;
       foundPernth = 0;
       while(foundPernth != pernthases)
       {
            start++;
            if(operationString[start] == '(')
            foundPernth++;
       }
       //Find First closeing ')'
       for(end = start;  operationString[end] != ')'; end++);
       //Solve Inside the Perenthisis
       operationString = replacesubstr(operationString, math(operationString.substr(start+1, end-start)), start, end-start+1);
       pernthases--;
    }
    //Compleat
    return stringtofloat(math(operationString));
}

//Replace a substring in a string with another string
string replacesubstr(string modifyString, const string replaceString, const unsigned short start, const unsigned short length)
{
       //Mofify modifystring so that substring between start and length is replaced with replace string
    return modifyString.substr(0, start) + replaceString + modifyString.substr(length+start+1, modifyString.length()-(length+start+1)); 
}

//Compleates a simple equation (No perantheses)
string math(string mathstring)
{
       
       unsigned short operatorChar, LeftNumber, RightNumber, functions = 0, multaple = 0, power = 0, addition = 0;
       
       for(unsigned short i = 0; mathstring[i] != 0; i++) //Count Each operation
       {
           if(mathstring[i] == '*' || mathstring[i] == '/')  
             multaple++;
           if(mathstring[i] == '+' || mathstring[i] == '-')  
             addition++;
           if(mathstring[i] == '^')  
             power++;
           if(mathstring[i+1] != 0 && mathstring[i+2] != 0 && mathstring[i+3] != 0)
           if(   mathstring[i] == 's' && mathstring[i+1] == 'i' && mathstring[i+2] == 'n' ||
                 mathstring[i] == 'c' && mathstring[i+1] == 'o' && mathstring[i+2] == 's' ||
                 mathstring[i] == 't' && mathstring[i+1] == 'a' && mathstring[i+2] == 'n' ||
                 mathstring[i] == 'a' && mathstring[i+1] == 's' && mathstring[i+2] == 'i' && mathstring[i+3] == 'n' ||
                 mathstring[i] == 'a' && mathstring[i+1] == 'c' && mathstring[i+2] == 'o' && mathstring[i+3] == 's' ||
                 mathstring[i] == 's' && mathstring[i+1] == 'q' && mathstring[i+2] == 'r' && mathstring[i+3] == 't' ||
                 mathstring[i] == 'a' && mathstring[i+1] == 't' && mathstring[i+2] == 'a' && mathstring[i+3] == 'n')  
             functions++;
         }  
             //sin, cos, tan, asin, acos, and atan, sqrt
             
             //for each function
             
             //Power '^'
             while(multaple > 0)
             {
                 for(operatorChar = 0; mathstring[operatorChar] != '*' &&  mathstring[operatorChar] != '/'; operatorChar++);
                 for(LeftNumber = operatorChar-1; LeftNumber != 0 && isdigit(mathstring[LeftNumber]) || mathstring[LeftNumber] == '.'; LeftNumber--);
                 for(RightNumber = operatorChar+1; RightNumber != mathstring.length()-1 && isdigit(mathstring[RightNumber]) || mathstring[RightNumber] == '.'; RightNumber++);
                 if(mathstring[operatorChar] == '*')
                    mathstring = replacesubstr(mathstring, floattostring(stringtofloat(mathstring.substr(LeftNumber,operatorChar-LeftNumber)) * stringtofloat(mathstring.substr(operatorChar+1,operatorChar-RightNumber))), LeftNumber, RightNumber);
                else
                    mathstring = replacesubstr(mathstring, floattostring(stringtofloat(mathstring.substr(LeftNumber,operatorChar-LeftNumber)) / stringtofloat(mathstring.substr(operatorChar+1,operatorChar-RightNumber))), LeftNumber, RightNumber);
                 multaple--;
             }
               while(addition>0)
             {
                 for(operatorChar = 0; mathstring[operatorChar] != '+' &&  mathstring[operatorChar] != '-'; operatorChar++);
                 for(LeftNumber = operatorChar-1; LeftNumber != 0 && isdigit(mathstring[LeftNumber]) || mathstring[LeftNumber] == '.'; LeftNumber--);
                 for(RightNumber = operatorChar+1; RightNumber != mathstring.length()-1 && isdigit(mathstring[RightNumber]) || mathstring[RightNumber] == '.'; RightNumber++);
                 if(mathstring[operatorChar] == '+')
                    mathstring = replacesubstr(mathstring, floattostring(stringtofloat(mathstring.substr(LeftNumber,operatorChar-LeftNumber)) + stringtofloat(mathstring.substr(operatorChar+1,operatorChar-RightNumber))), LeftNumber, RightNumber);
                else
                    mathstring = replacesubstr(mathstring, floattostring(stringtofloat(mathstring.substr(LeftNumber,operatorChar-LeftNumber)) - stringtofloat(mathstring.substr(operatorChar+1,operatorChar-RightNumber))), LeftNumber, RightNumber);
                 addition--;
             }
       return mathstring;
}