/*
 * usage:  ppmview <imagefile>
 *
 * displays on the screen a PGM or PPM image (raw mode only).
 */

#include <windows.h>
#include <stdlib.h>
#include <stdio.h>
#include <malloc.h>

#define USE_ISPRINTF		LPSTR ___isprintfbuf=(char*)_alloca(1024)
#define __                  (sprintf(___isprintfbuf,
#define _                   ),___isprintfbuf)

typedef struct _imageinfo
{
	int width;
	int height;
	BITMAPINFOHEADER* bmihBitmap;
	unsigned char* data;
	HWND hWnd;
} imageinfo;

int windowcount = 0;

long WINAPI WndProc( HWND hWnd, WORD message, WORD wParam, LONG lParam );
imageinfo* LoadPPM( LPSTR filename );

int WINAPI WinMain( HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpszCmdParam,
			int nCmdShow )
{
	USE_ISPRINTF;
	static char		szAppName[] = "PPMView";
	HWND			hWnd;
	MSG				msg;
	WNDCLASSEX		wndclass;
	char*			token;

	if ( !hPrevInstance )
	{
		wndclass.cbSize = sizeof( WNDCLASSEX );
		wndclass.style = CS_HREDRAW | CS_VREDRAW;
		wndclass.lpfnWndProc = (WNDPROC)WndProc;
		wndclass.cbClsExtra = 0;
		wndclass.cbWndExtra = 0;
		wndclass.hInstance = hInstance;
		wndclass.hIcon = LoadIcon( NULL, IDI_APPLICATION );
		wndclass.hCursor = LoadCursor( NULL, IDC_ARROW );
		wndclass.hbrBackground = (HBRUSH) GetStockObject( WHITE_BRUSH );
		wndclass.lpszMenuName = NULL;
		wndclass.lpszClassName = szAppName;
		wndclass.hIconSm = NULL;

		int j = RegisterClassEx( &wndclass );
		int k = GetLastError();
	}

	for( token = strtok( lpszCmdParam, " " ); token; token = strtok( NULL, " " ) )
	{
		imageinfo* currimage;

		if ( *token == 0 )
			continue;

		currimage = LoadPPM( token );
		if ( currimage == NULL )
			continue;
	
		hWnd = CreateWindowEx( 0,
			szAppName, 
			__ "%s (%d x %d)", token, currimage->width, currimage->height _,
			WS_OVERLAPPED | WS_SYSMENU,
			CW_USEDEFAULT, 
			CW_USEDEFAULT, 
			currimage->width + 2 * GetSystemMetrics( SM_CXFIXEDFRAME ),
			currimage->height + 2 * GetSystemMetrics( SM_CYFIXEDFRAME ) + GetSystemMetrics( SM_CYCAPTION ), 
			NULL, 
			NULL, 
			hInstance, 
			NULL );
		int i = GetLastError();
		currimage->hWnd = hWnd;
		SetWindowLong( hWnd, GWL_USERDATA, (LONG)currimage );

		ShowWindow( hWnd, nCmdShow );
		UpdateWindow( hWnd );

		++windowcount;
	}

	if ( windowcount == 0 )
		return 1;

	while( GetMessage( &msg, NULL, 0, 0 ) )
	{
		TranslateMessage( &msg );
		DispatchMessage( &msg );
	}

	return msg.wParam;
}

long WINAPI WndProc( HWND hWnd, WORD message, WORD wParam, LONG lParam )
{
	HDC hdc;
	PAINTSTRUCT ps;
	imageinfo* currimage;

	switch( message )
	{
	case WM_PAINT:
		if ( GetUpdateRect( hWnd, NULL, false ) == 0 )
			return 0;

		currimage = (imageinfo*)GetWindowLong( hWnd, GWL_USERDATA );

		hdc = BeginPaint( hWnd, &ps );

		if ( ps.rcPaint.right > currimage->width )
		{
			FillRect( hdc, &(ps.rcPaint), ( struct HBRUSH__ * ) GetStockObject( GRAY_BRUSH ) );
		}

		SetDIBitsToDevice( hdc, 0, 0, currimage->width, currimage->height, 
			0, 0, 0, currimage->height, currimage->data,
			(BITMAPINFO*)(currimage->bmihBitmap), DIB_RGB_COLORS );

		EndPaint( hWnd, &ps );
		return 0;

	case WM_DESTROY:
		currimage = (imageinfo*)GetWindowLong( hWnd, GWL_USERDATA );
		free( currimage->bmihBitmap );
		--windowcount;
		
		if ( windowcount == 0 )
			PostQuitMessage( 0 );

		return 0;
	}

	return DefWindowProc( hWnd, message, wParam, lParam );
}

imageinfo* LoadPPM( LPSTR filename )
{
	USE_ISPRINTF;
	FILE* f;
	int i, j;
	char buffer[80];
	int phase = 0;
	int type;
	int maxval;
	imageinfo* currimage = NULL;

	f = fopen( filename, "rb" );
	if ( f == NULL )
		return NULL;

	currimage = (imageinfo*)malloc( sizeof(imageinfo) );

	while(phase < 4)
	{
		fgets( buffer, 80, f );
		if ( buffer[0] == '#' ) continue;

		switch( phase )
		{
		case 0:	j = sscanf( buffer, "P%d %d %d %d\n", &type, &(currimage->width), &(currimage->height), &maxval ); break;
		case 1:	j = sscanf( buffer, "%d %d %d\n", &(currimage->width), &(currimage->height), &maxval ); break;
		case 2:	j = sscanf( buffer, "%d %d\n", &(currimage->height), &maxval ); break;
		case 3:	j = sscanf( buffer, "%d\n", &maxval ); break;
		case 4: j = 0; break;
		}

		phase += j;
	}

	OutputDebugString( __ "type is %d; picture is %d x %d; maxval is %d\n", type, currimage->width, currimage->height, maxval _ );

	BITMAPINFOHEADER* bmihBitmap = NULL;
	unsigned char* data;
	int height = currimage->height;
	int width = currimage->width;
	int rowwidth = (width*3) + (((width*3)%4) ? (4-((width*3)%4)) : 0);

	switch ( type )
	{
	case 5:
		bmihBitmap = (BITMAPINFOHEADER*)malloc( sizeof(BITMAPINFOHEADER) + rowwidth*height );
		data = ((unsigned char *)bmihBitmap) + sizeof(BITMAPINFOHEADER);
		for ( i = 0; i < height; ++i )
		{
			fread( data + (height-1-i)*rowwidth, 1, width, f );
		}
		for ( i = 0; i < height; ++i )
		{
			for ( j = width-1; j >= 0; --j )
			{
				(data+i*rowwidth)[j*3+2] = (data+i*rowwidth)[j];
				(data+i*rowwidth)[j*3+1] = (data+i*rowwidth)[j];
				(data+i*rowwidth)[j*3] = (data+i*rowwidth)[j];
			}	
		}
		break;

	case 6:
		bmihBitmap = (BITMAPINFOHEADER*)malloc( sizeof(BITMAPINFOHEADER) + rowwidth*height );
		data = ((unsigned char *)bmihBitmap) + sizeof(BITMAPINFOHEADER);
		for ( i = 0; i < height; ++i )
			fread( data + (height-1-i)*rowwidth, 1, width * 3, f );
		for ( i = 0; i < height; ++i )
			for ( j = 0; j < width; ++j )
			{
				int k = (data+i*rowwidth)[j*3];
				(data+i*rowwidth)[j*3] = (data+i*rowwidth)[j*3+2];
				(data+i*rowwidth)[j*3+2] = k;
			}

		break;

	default:
		return NULL;

	}

	if ( bmihBitmap )
	{
		bmihBitmap->biSize = sizeof( BITMAPINFOHEADER );
		bmihBitmap->biWidth = width;
		bmihBitmap->biHeight = height;
		bmihBitmap->biPlanes = 1;
		bmihBitmap->biBitCount = 24;
		bmihBitmap->biCompression = 0;
		bmihBitmap->biSizeImage = 0;
		bmihBitmap->biXPelsPerMeter = 0;
		bmihBitmap->biYPelsPerMeter = 0;
		bmihBitmap->biClrUsed = 0;
		bmihBitmap->biClrImportant = 0;
	}

	currimage->data = data;
	currimage->bmihBitmap = bmihBitmap;

	fclose( f );

	return currimage;
}