//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
// File:     HelloMath2.cpp
// Class:    None
// Parent:   None
// Children: None
// Purpose:  Takes an angle and precision from the user.  Writes to a file the
//           angle in degrees, sine, cosine, and tangent of that angle, going from 
//           0 to the angle given by the user, to the precision specified by the user.
//-----------------------------------------------------------------------------
// The following are standard C/C++ header files.
// If a filename is enclosed inside < >  it means the header file is in the Include directory.
// If a filename is enclosed inside " "  it means the header file is in the current directory.
#include <ctype.h>      // Character Types
#include <math.h>       // Mathematical Constants
#include <stdarg.h>     // Variable Argument Lists
#include <stdio.h>      // Standard Input/Output Functions
#include <stdlib.h>     // Utility Functions
#include <string.h>     // String Operations
#include <signal.h>     // Signals (Contol-C + Unix System Calls)
#include <setjmp.h>     // Nonlocal Goto (For Control-C)
#include <time.h>       // Time and Date information
#include <assert.h>     // Verify Program Assertion
#include <errno.h>      // Error Codes (Used in Unix system())
#include <float.h>      // Floating Point Constants
#include <limits.h>     // Implementation Constants
#include <stddef.h>     // Standard Definitions
#include <exception>    // Exception handling (e.g., try, catch throw)
//-----------------------------------------------------------------------------

bool  GetStringFromFile( char inputString[], const unsigned long maxSizeOfString, FILE *fptr ){ return fgets(inputString, maxSizeOfString, fptr) == NULL;}
bool  GetStringFromKeyboard( char inputString[], const unsigned long maxSizeOfString ){ return GetStringFromFile( inputString, maxSizeOfString, stdin );}
bool  WriteStringToFile( const char outputString[], FILE *fptr ) { return fprintf( fptr, outputString) != NULL; }
bool  WriteStringToScreen( const char outputString[] ){return WriteStringToFile(outputString, stdout);}
const char*  ConvertStringToDouble( const char *s, double &returnValue, double defaultValue );
double  ConvertFromRadiansToDegrees( double angleInRadians ){return angleInRadians*57.2957795; /*1 radian is approx 57.3 degrees*/}
double  ConvertFromDegreesToRadians( double angleInDegrees ){return angleInDegrees/57.2957795;/*1 radian is approximately 57.3 degrees*/}
FILE*  FileOpenWithMessageIfCannotOpen( const char *filename, const char *attribute );
bool  WriteDoubleToFileWithEExponentInSpecifiedPrecision( double x, int precision, FILE *fptr );
const char*  ConvertStringToLong( const char *s, long &returnValue, long defaultValue );

//-----------------------------------------------------------------------------
int main()
{
   //get the angle from the user and convert to a long
   WriteStringToScreen("Enter an integer between 180 and 720 representing an angle in degrees:");
   char stringInDegrees[15];
   GetStringFromKeyboard( stringInDegrees, 15 );   

   long angleInDegrees; 
   if( ConvertStringToLong(stringInDegrees, angleInDegrees, 360) == false )
	  WriteStringToScreen("\nYour angle was not valid.  360 degrees will be used instead.");
   else if(angleInDegrees<180 || angleInDegrees>720)
   {
      WriteStringToScreen("\nYour angle was not valid.  360 degrees will be used instead.");
      angleInDegrees=360;
   }
   
   //get the precision from the user and convert to a long
   WriteStringToScreen("\nEnter the precision for writing numbers as an integer from 1 to 17:");
   char precisionString[15];
   GetStringFromKeyboard(precisionString, 15);

   long precisionNumber;

   if( ConvertStringToLong( precisionString, precisionNumber, 5 ) == false )
	   WriteStringToScreen("\nYour precision was not valid.  5 will be used instead.");
   else if( precisionNumber<1 || precisionNumber>17 )
   {
      WriteStringToScreen("\nYour precision was not valid.  5 will be used instead.");
      precisionNumber=5;
   }
   

   double angleInRadians;
  
   //print to a file the values of the angle in degrees and the sine, cosine, and tangent of the angle.
   if( FILE *fileToWrite = FileOpenWithMessageIfCannotOpen("HelloMath2.txt","w") )
   {
      for( int i=0;  i <= angleInDegrees;  i++ )
      {
         angleInRadians=ConvertFromDegreesToRadians(i);
         WriteDoubleToFileWithEExponentInSpecifiedPrecision( i, precisionNumber, fileToWrite );
	      WriteDoubleToFileWithEExponentInSpecifiedPrecision( sin(angleInRadians), precisionNumber, fileToWrite);
	      WriteDoubleToFileWithEExponentInSpecifiedPrecision( cos(angleInRadians), precisionNumber, fileToWrite);
	      WriteDoubleToFileWithEExponentInSpecifiedPrecision( tan(angleInRadians), precisionNumber, fileToWrite);
	      fprintf(fileToWrite,"\n");
      }
	   fclose(fileToWrite);
   }
   

   // Keep the screen displayed until the user presses the Enter key
   WriteStringToScreen( "\n\n Press  Enter  to terminate the program: " );
   int key = getchar();

   return 0;
}





//-----------------------------------------------------------------------------
const char* ConvertStringToDouble( const char *s, double &returnValue, double defaultValue )
{
   // Default return value (in case the string is not a valid number)
   returnValue = defaultValue;
   // Check if s is a NULL string or "&^%$#" or "abc" or "123huh"
   if( s )
   {
      // Use the standard math function strtod to parse the number
      char *pointerToCharacterAfterNumber = NULL;
      double x = strtod( s, &pointerToCharacterAfterNumber );
      // Ensure the character after the number is a space or ’\0’, not ’a’ or ’z’ or ...
      char characterAfterNumber = pointerToCharacterAfterNumber ? *pointerToCharacterAfterNumber : 'z';
      if( characterAfterNumber == '\0' || isspace(characterAfterNumber) )
      {
         returnValue = x;
         return pointerToCharacterAfterNumber;
      }
   }
   return NULL;
}


//-----------------------------------------------------------------------------
FILE* FileOpenWithMessageIfCannotOpen( const char *filename, const char *attribute )
{
   FILE *openedFile = fopen(filename,attribute);
   if( !openedFile ) printf("Error opening file.");
   return openedFile;
}

//-----------------------------------------------------------------------------
bool WriteDoubleToFileWithEExponentInSpecifiedPrecision( double x, int precision, FILE *fptr )
{
   int fieldWidth=precision+8;
	// Create the format specifier and print the number
   char format[20];
   sprintf( format, " %%- %d.%dE", fieldWidth, precision );
   return fprintf( fptr, format, x ) > 0;
}

//-----------------------------------------------------------------------------
const char* ConvertStringToLong( const char *s, long &returnValue, long defaultValue )
{
   // Default return value (in case the string is not a valid number)
   returnValue = defaultValue;
   // Check if s is a NULL string or "&^%$#" or "abc" or "123huh"
   if( s )
   {
      // Use the standard math function strtod to parse the number
      char *pointerToCharacterAfterNumber = NULL;
      long x = strtol( s, &pointerToCharacterAfterNumber, 10 );
      // Ensure the character after the number is a space or ’\0’, not ’a’ or ’z’ or ...
      char characterAfterNumber = pointerToCharacterAfterNumber ? *pointerToCharacterAfterNumber : 'z';
      if( characterAfterNumber == '\0' || isspace(characterAfterNumber) )
      {
         returnValue = x;
         return pointerToCharacterAfterNumber;
      }
   }
   return NULL;
}