//FloatParser.cpp

#include "FloatParser.h"
#include <string>
#include <cmath>
#include <cstring>

using namespace std;

//Makros, um Funktionen einfacher parser zu können
#define CASE_1(var) if (!strcmp(SWITCH,var))
#define CASE(var) else if (!strcmp(SWITCH,var))
#define CASE_ELSE else

#define PARSE_BLANKS while (*reading_stream == ' ') ++reading_stream;

//static enumerations and variables
static enum binary_operator { b_plus, b_minus, mal, durch, modulo, hoch, undef, oder, und, gleich, b_nicht, kleiner, groesser, ungleich, kleinergleich, groessergleich};
static enum unary_operator { u_plus, u_minus, u_nicht };
static binary_operator op;
static char* reading_stream;
static bool parse_float_failed = false;

//static funtions
static double parse_expr_1();
static double parse_expr_2();
static double parse_expr_3();
static double parse_expr_4();
static double parse_expr_5();
static double parse_expr_6();
static double parse_expr_7();
static double parse_expr_8();
static inline char* parse_word(char* str);
static inline binary_operator parse_binary_operator();
static inline unary_operator parse_unary_operator();
static double parse_argument();
static double parse_last_argument();

//Public functions:
/******************/
bool parse_float(char* const string, char **endptr, double* result)
{
   parse_float_failed = false;
   reading_stream = string;
   double value = parse_expr_8();
   if ( !parse_float_failed && (
      *reading_stream == ')' || \
      *reading_stream == '}' || \
      *reading_stream == ']' || \
      *reading_stream == ',' || \
      *reading_stream == ';' || \
      *reading_stream == '_' || \
      *reading_stream == '\0' || \
      *reading_stream > 64 && *reading_stream < 91 || \
      *reading_stream > 96 && *reading_stream < 123))
   {
      endptr = &reading_stream;
      *result = value;
      return true;
   }
   else
   {
     *result = 0;
     return false;
   }
}

bool parse_float(char* const string, char** endptr, char delimiter, double* result)
{
   parse_float_failed = false;
   reading_stream = string;
   double value = parse_expr_8();
   if (*reading_stream == delimiter && !parse_float_failed)
   {
      endptr = &reading_stream;
      *result = value;
      return true;
   }
   else
   {
     *result = 0;
     return false;
   }
}

bool parse_vector_float(char* const string, char** endptr, bool last_float, double* result)
{
   parse_float_failed = false;
   reading_stream = string;
   double value = parse_expr_4();
   if (last_float)
   {
      if (*reading_stream == '>')
      {
         endptr = &reading_stream;
         *result = value;
      }
      else
        parse_float_failed = true;
   }
   else
   {
      if (*reading_stream == ',')
      {
         *endptr = reading_stream;
         *result = value;
      }
      else
        parse_float_failed = true;
   }
   if (parse_float_failed)
   {
     *result = 0;
     return false;
   }
   else
     return true;
}

//Private functions:
/******************/
static double parse_argument()
{
   double value = parse_expr_8();
   if (*reading_stream == ',')
   {
      ++reading_stream;
      return value;
   }
   else
   {
     parse_float_failed = true;
     return 0;
   }
}

static double parse_last_argument()
{
   double value = parse_expr_8();
   if (*reading_stream == ')')
   {
      ++reading_stream;
      return value;
   }
   else
   {
     parse_float_failed = true;
     return 0;
   }
}

static double parse_expr_8()
{
   double value = parse_expr_7();
   for(;;)
   {
      switch (op)
      {
         case oder:
            value = parse_expr_7() || value;
            break;
         default: return value;
      }
   };
}


static double parse_expr_7()
{
   double value = parse_expr_6();
   for(;;)
   {
      switch (op)
      {
         case und:
            value = value && parse_expr_6();
            break;
         default: return value;
      }
   };
}

static double parse_expr_6()
{
   double value = parse_expr_5();
   for(;;)
   {
      switch (op)
      {
         case gleich:
            value = (value == parse_expr_5());
            break;
         case ungleich:
            value = (value != parse_expr_5());
            break;
         default:
            return value;
      }
   };
}

static double parse_expr_5()
{
   double value = parse_expr_4();
   for(;;)
   {
      switch (op)
      {
         case kleiner:
            value = (value < parse_expr_4());
            break;
         case kleinergleich:
            value = (value <= parse_expr_4());
            break;
         case groesser:
            value = (value > parse_expr_4());
            break;
         case groessergleich:
            value = (value >= parse_expr_4());
            break;
         default:
            return value;
      }
   };
}

static double parse_expr_4()
{
   double value = parse_expr_3();
   for(;;)
   {
      switch (op)
      {
         case b_plus:
            value += parse_expr_3();
            break;
         case b_minus:
            value -= parse_expr_3();
            break;
         default:
            return value;
      }
   };
}

static double parse_expr_3()
{
   double value = parse_expr_2();
   for(;;)
   {
      switch (op)
      {
         case mal:
            value *= parse_expr_2();
            break;
         case durch:
            value /= parse_expr_2();
            break;
         case modulo:
         {
            double temp = parse_expr_2();
            value = value - floor(value/temp)*temp;
            break;
         }
         default:
            return value;
      }
   };
}

static double parse_expr_2()
{
   double value = parse_expr_1();
   while (*reading_stream != '\0')
   {
      op = parse_binary_operator();
      switch (op)
      {
         case hoch:
            value = pow(value,parse_expr_1());
            break;
         default:
            return value;
      }
   };
   op = undef;
   return value;
}

static double parse_expr_1()
{
   PARSE_BLANKS
   double value;
   
   unary_operator op = parse_unary_operator();
   PARSE_BLANKS

   if (*reading_stream == '\0')
   {
     // end of string
     parse_float_failed = true;
     return 0;
   }
   else if (*reading_stream > 47 && *reading_stream < 59 || *reading_stream == 46)
   {  //Zahl
      value = strtod(reading_stream,&reading_stream);
   }
   else if (*reading_stream > 64 && *reading_stream < 91 || *reading_stream > 96 && *reading_stream < 123 || *reading_stream == 46)
   {  //Variable oder Funktion
      char* word = new char[256];
      parse_word(word);
      PARSE_BLANKS
      if (*reading_stream == '(')
      {
         ++reading_stream;
#define SWITCH word
         CASE_1("sin")
            value = sin(parse_last_argument());
         CASE("asin")
            value = asin(parse_last_argument());
         CASE("sinh")
            value = sinh(parse_last_argument());
         CASE("asinh")
         {
            value = parse_last_argument();
            value = log(sqrt(pow(value, 2) + 1) + value);
         }
         CASE("cos")
            value = cos(parse_last_argument());
         CASE("acos")
            value = acos(parse_last_argument());
         CASE("cosh")
            value = cosh(parse_last_argument());
         CASE("acosh")
         {
            value = parse_last_argument();
            value = log(sqrt(pow(value, 2) - 1) + value);
         }
         CASE("tan")
            value = tan(parse_last_argument());
         CASE("atan")
            value = atan(parse_last_argument());
         CASE("atan2")
            value = atan2(parse_argument(),parse_last_argument());
         CASE("tanh")
            value = tanh(parse_last_argument());
         CASE("atanh")
         {
            value = parse_last_argument();
            value = 0.5*log((value + 1)/(value - 1));
         }
         CASE("int")
            value = floor(parse_last_argument());
         CASE("floor")
            value = floor(parse_last_argument());
         CASE("ceil")
            value = ceil(parse_last_argument());
         CASE("abs")
            value = abs(parse_last_argument());
         CASE("exp")
            value = exp(parse_last_argument());
         CASE("log")
            value = log10(parse_last_argument());
         CASE("ln")
            value = log(parse_last_argument());
         CASE("sign")
         {
            value = parse_last_argument();
            value = (value>0 ? 1 : (value<0 ? -1 : 0));
         }
         CASE("sqrt")
            value = sqrt(parse_last_argument());
         CASE("degrees")
            value = parse_last_argument()*180/3.1415926535897932;
         CASE("radians")
            value = parse_last_argument()*3.1415926535897932/180;
         CASE("mod")
         {
            value = parse_argument();
            double value2 = parse_last_argument();
            value = value - floor(value/value2)*value2;
         }
         CASE("pow")
            value = pow(parse_argument(),parse_last_argument());
         CASE("div")
            value = floor(parse_argument()/parse_last_argument());
         CASE("max")
            value = max(parse_argument(),parse_last_argument());
         CASE("min")
            value = min(parse_argument(),parse_last_argument());
         CASE_ELSE
         {
           parse_float_failed = true;
           return 0;
         }
      }
      else
      {
         //TODO: Variablen-Liste durchsuchen
         //Momentaner Ersatzwert für jede Variable:
         //value = 0;
         parse_float_failed = true;
         return 0;
      }
      delete[] word;
   }
   else if (*reading_stream == 40)
   {  //Audruck in Klammern
      ++reading_stream;
      value = parse_last_argument();
   }
   else
   {
     parse_float_failed = true;
     return 0;
   }
 
   PARSE_BLANKS
   switch (op)
   {
      case u_nicht: return !value;
      case u_plus:  return  value;
      case u_minus: return -value;
      default:
        {
          parse_float_failed = true;
          return 0;
        }
   }
}

static inline char* parse_word(char* str)
{
   char* word = str;
   int counter = 0;
   while (*reading_stream > 47 && *reading_stream < 58 || *reading_stream > 64 && *reading_stream < 91 || *reading_stream > 96 && *reading_stream < 123 || *reading_stream == 46)
   {
      *word++ = *reading_stream++;
      counter++;
      if (counter > 255)
      {
        parse_float_failed = true;
        return '\0';
      }
   };
   *word = '\0';
   return str;
}

static inline binary_operator parse_binary_operator()
{
   binary_operator op;
   switch (*reading_stream)
   {
      case '+': op = b_plus; break;
      case '-': op = b_minus; break;
      case '*': op = mal; break;
      case '/': op = durch; break;
      case '^': op = hoch; break;
      case '%': op = modulo; break;
      case '&': op = und; break;
      case '|': op = oder; break;
      case '=': op = gleich; break;
      case '!': op = b_nicht; break;
      case '<': op = kleiner; break;
      case '>': op = groesser; break;
      default: return undef;
   }
   if (*++reading_stream == '=')
   {
      if (op > 9)
      {
         ++reading_stream;
         return (binary_operator)(op + 3);
      }
      else
      {
         --reading_stream;
         return undef;
      }
   }
   else
      return op;
}

static inline unary_operator parse_unary_operator()
{
   switch (*reading_stream)
   {
      case '!':
         ++reading_stream;
         return u_nicht;
      case '+':
         ++reading_stream;
         return u_plus;
      case '-':
         ++reading_stream;
         return u_minus;
      default :
         return u_plus;
   }
}