/*--------------------------------------------------------------------------------------

    Student's Name:                 Braedon Gernyi

    Student's email address:        bmg295@uowmail.edu.au

    Lab group:                      CL/03

    Purpose of this assignment:     To gain an understanding of modular program
                                    design, pointers, dynamic one and two dimensional
                                    arrays and binary files.

--------------------------------------------------------------------------------------*/


#include <stdio.h>
#include <stdlib.h>
#include <strings.h>
#include <string.h>
#include <math.h>

/* Data type defintions */
#pragma pack( push , 1 )
typedef struct
{
    unsigned char b;
    unsigned char g;
    unsigned char r;
} Pixel;
#pragma pop


#pragma pack( push , 1 )
typedef struct
{
    unsigned short fileMarker1; /* File extension number */
    unsigned int bfSize;
    unsigned short unused1;
    unsigned short unused2;
    unsigned int imageDataOffset; /* Offset to the start of image data */
} FileHeader;
#pragma pop


#pragma pack( push , 1 )
typedef struct
{
    unsigned int biSize;
    int width; /* Width of the image */
    int height; /* Height of the image */
    unsigned short planes;
    unsigned short bitPix;
    unsigned int biCompression;
    unsigned int biSizeImage;
    int biXPelsPerMeter;
    int biYPelsPerMeter;
    unsigned int biClrUsed;
    unsigned int biClrImportant;
} InfoHeader;
#pragma pop


/* Function prototypes */
unsigned char** array2duc( int width, int length ); /* 2 dimensional unsigned char array allocation */
void free2duc( unsigned char** array, int width, int height ); /* 2 dimensional unsigned char array free */
Pixel *pixlinealloc( int length );


/* Start of main function */
int main ( int argc, char *argv[] )
{
    if( argc != 2 ) /* Checks for argument amount (TOTAL INPUTS MUST EQUAL 1) */
    {
        printf("Invalid number of parameters.\n Program terminated");
        return 1;
    }

    char extstr[4]; /* CHECK IF THIS IS VALID ARRAY SIZE BECAUSE VARIABLE */
    /* Copying argument into string */
/*  printf( "File name = %s\n", argv[1] ); */  /* STUB */

/*  printf("size of name = %d\n" , strlen(argv[1])); */ /* STUB */

    int fileext = strlen(argv[1]), i, j = 0; /* Integers used in for loop for getting file extension */
    for ( i = (fileext - 3) ; i < fileext ; i++ )
    {
        extstr[j] = argv[1][i];
        j += 1;
    }

    extstr[3] = 0; /* Setting last char in string to null to specify terminator */

    if ( strcmp( "bmp" , extstr ) != 0 ) /* Checking file input text for bmp file extension */
    {
        printf( "Invalid file extension.\n Program terminated" );
        return 1;
    }

/*  printf( "file ext read = %s \n" , extstr ); */ /* STUB */

    FILE *image; /* Image variable decleration */
    image = fopen( argv[1] , "rb" ); /* Opening image for data reading */
    if ( image == NULL ) /* Terminates program if image reading is un s u c c essful */
    {
        printf( "Unable to read image.\n Program terminated" );
        return 1;
    }

    FileHeader fheader; /* Since read is successful, FileHeader type variable is declared */

    fread(&fheader, sizeof(FileHeader),1,image); /* Reading data into fheader */

    if (fheader.fileMarker1 != 0x4D42) /* Checking for REAL bitmap extension */ /* THIS MIGHT NEED TO BE CHANGED SO SUIT SPECIFICATIONS */
    {
        printf( "Invalid file extension.\n Program terminated" );
        fclose(image);
        return -1;
    }

    InfoHeader iheader;

    fread(&iheader, sizeof(InfoHeader),1,image); /* Reading in information header into iheader for image height and width */

    printf( "\nRead Successful!!\n\nimage width = %d, image height = %d \nImage offset = %d\n" , iheader.width , iheader.height , fheader.imageDataOffset ); /* STUB */

    fseek( image , fheader.imageDataOffset , SEEK_SET ); /* Moving fread back to the data offset */

/*  Pixel test;
    fread( &test , sizeof(Pixel) , 1 , image ); */

/*  printf( "Image test read; Red = %d, Green = %d, Blue = %d" , test.r , test.g , test.b );*/ /* STUB */

/*  printf( "size of Pixel = %d" , sizeof(Pixel) );*/ /* STUB: Checking size of pixel structure (3 bytes) */

    Pixel *lineBuffer = pixlinealloc( iheader.width );
    unsigned char **frameBuffer = array2duc( iheader.width , iheader.height );

    if ( ( lineBuffer == NULL ) || ( frameBuffer == NULL ) )
    {
        printf( "Memory allocation error. \n" );
        fclose ( image );
        return -1;
    }

    int buffCheck, buffMark = 0;

    for ( j = 0 ; j < iheader.height ; j++ )
    {

        for ( i = 0 ; i < iheader.width ; i++ )
        {
            buffCheck = fread( &lineBuffer[i] , sizeof(Pixel) , 1 , image );

            if ( buffCheck < 1 )
            {
                printf( "Error reading image.\n" );
                buffMark = 1;
                break;
            }
        }

        if ( buffMark == 1 )
        {
            break;
        }

        for ( i = 0 ; i < iheader.width ; i++ )
        {
            frameBuffer[i][j] = ( ( lineBuffer[i].b + lineBuffer[i].g + lineBuffer[i].r ) / 3 ) + 0.5;
        }
    }

/*  printf( "LineBuffer @ 5 = %d, %d, %d \n" , lineBuffer[100].b , lineBuffer[100].g , lineBuffer[100].r ); */ /* STUB */

    if ( buffMark == 0 )
    {

        printf("*** Results of the statistical analysis *** \n");

        int sum = 0, min = frameBuffer[0][0], max = frameBuffer[0][0];

        for ( i = 0 ; i < iheader.width ; i++ )
        {
            for ( j = 0 ; j < iheader.height ; j++ )
            {
                sum += frameBuffer[i][j];

                if ( min > frameBuffer[i][j] )
                {
                    min = frameBuffer[i][j];
                }

                if ( max < frameBuffer[i][j] )
                {
                    max = frameBuffer[i][j];
                }
            }
        }

        int n = iheader.height * iheader.width , mean = ( sum / n ) + 0.5;
        printf( "Mean: %d\nMin Intensity: %d\nMax Intensity: %d\n" , mean , min , max );

        float stddevsumm = 0 , stddev;

        if ( n - 1 != 0 )
        {
            for ( i = 0 ; i < iheader.width ; i++ )
            {
                for ( j = 0 ; j < iheader.height ; j++ )
                {
                    stddevsumm += ( frameBuffer[i][j] - mean ) * ( frameBuffer[i][j] - mean );
                }
            }

            stddev = sqrt( stddevsumm / ( n - 1 ) );
            printf( "Standard deviation: %.1f\n" , stddev );
        }
        else
        {
            printf( "Standard deviation: N/A");
        }
    }


    free2duc( frameBuffer , iheader.width , iheader.height );
    free( lineBuffer );
    fclose(image);

    return 0;

    /* LEFT TO DO: Check for memory leakage, add comments */
}

unsigned char** array2duc( int width, int height )
{
    int i;
    unsigned char** array;

    array = calloc( width , sizeof(unsigned char*));

    if ( array == NULL )
    {
        return NULL;
    }

    for ( i = 0 ; i < width ; i++ )
    {
        array[i] = calloc( height , sizeof( unsigned char));
        if ( array[i] == NULL )
        {
            return NULL;
        }
    }

    return array;
}


void free2duc( unsigned char** array, int width, int height )
{
    int i;

    for ( i = 0 ; i < width ; i++ )
    {
        free( array[i] );
    }
    free( array );
}

Pixel *pixlinealloc( int length )
{
    Pixel *array;

    array = (Pixel*)calloc( length, sizeof(Pixel));
    return array;
}