//-----------------------------------------------------------------------------
// File:     HelloMath1.cpp
// Class:    None
// Parent:   None
// Children: None
// Purpose:  Tests out various mathematical functions and my coding abilities
//-----------------------------------------------------------------------------
// 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)
//-----------------------------------------------------------------------------

//-----------------------------------------------------------------------------
// Prototypes for local functions (functions not called by code in other files)
//-----------------------------------------------------------------------------
bool   GetStringFromKeyboard( char inputString[], unsigned long sizeOfString );
bool   GetStringFromFile(     char inputString[], unsigned long sizeOfString, FILE *fptr );
bool   WriteStringToScreen(   const char outputString[] );
bool   WriteStringToFile(     const char outputString[], FILE *fptr );

const char* ConvertStringToDouble( const char *s, double &returnValue, double defaultValue );

double  ConvertFromRadiansToDegrees( double angleInRadians )  { return angleInRadians * 57.295779513082320876798154814105170332405472466564321549160243861; }
double  ConvertFromDegreesToRadians( double angleInDegrees )  { return angleInDegrees * 0.017453292519943295769236907684886127134428718885417254560971914402; }


//-----------------------------------------------------------------------------
int  main( void )
{
   // Write  " Hello math!"  to the screen and then put a newline
   printf( " Hello math!\n" );

   // Prompt the user to enter an angle in degrees
   printf( " Enter an angle in degrees:\n");
   char stringFromKeyboard[10];
   GetStringFromKeyboard( stringFromKeyboard, 10);
   double angleInDegrees;
   ConvertStringToDouble( stringFromKeyboard, angleInDegrees, 45);

   // Convert the angle to radians
   double angleInRadians = ConvertFromDegreesToRadians(angleInDegrees);

   // Calculate sine, cosine, and tangent of the angle
   double angleSin = sin(angleInRadians);
   double angleCos = cos(angleInRadians);
   double angleTan = tan(angleInRadians);

   // Write angle in deg, angle in rad, sine, cosine, and tangent to screen
   printf( " \n\n Angle in degrees: %g\n", angleInDegrees);
   printf( " \n Angle in radians: %g\n", angleInRadians);
   printf( " \n Sine of angle: %g\n", angleSin);
   printf( " \n Cosine of angle: %g\n", angleCos);
   printf( " \n Tangent of angle: %g\n", angleTan);

   // Exit program
   printf( "\n\n Press  Enter  to terminate the program: " );
   getchar();

   return 0;

}


//-----------------------------------------------------------------------------
bool   GetStringFromKeyboard( char inputString[], unsigned long sizeOfString )
{

	return GetStringFromFile( inputString, sizeOfString, stdin ) ;
}


//------------------------------------------------------------------------------------------
bool   GetStringFromFile(     char inputString[], unsigned long sizeOfString, FILE *fptr )
{
	return fgets( inputString, sizeOfString, fptr ) != NULL;
}


//------------------------------------------------------------------------------------------
bool   WriteStringToScreen(   const char outputString[] )
{
	return( WriteStringToFile( outputString, stdout ) );
}


//------------------------------------------------------------------------------------------
bool   WriteStringToFile(     const char outputString[], FILE *fptr )
{
	return fputs( outputString, fptr ) != EOF;
}


//------------------------------------------------------------------------------------------
const char* ConvertStringToDouble( const char *s, double &returnValue, double defaultValue )
{
	// Default return value, use if string is not a valid number
	returnValue = defaultValue;

	// Check if s is a NULL string or not a number "sldkfn"
	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'
		char characterAfterNumber = pointerToCharacterAfterNumber ? *pointerToCharacterAfterNumber : 'z';
		if( characterAfterNumber == '\0' || isspace(characterAfterNumber) )
		{
			returnValue = x;
			return pointerToCharacterAfterNumber;
		}
	}
	return NULL;
}