#include <stdint.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>

FILE *fOut = NULL;

bool testCpp( const char *prog )
{
    FILE *pop = popen("g++ -x c++ - -o /dev/null", "w");
    fwrite( prog, 1, strlen( prog ), pop );
    return pclose(pop) == 0;
}

void detectEndianness()
{
    printf("Detecting endian support...");
    fflush( stdout );
    if( testCpp("#include <endian.h>\n\nint main() { return BYTE_ORDER; }\n") )
    {
        fprintf( fOut, "#include <endian.h>\n\n");
        printf("header file endian.h found, using that.\n");
    }
    else
    {
        uint16_t x=0x0100;
        fprintf( fOut,
            "#define LITTLE_ENDIAN 0\n"
            "#define BIG_ENDIAN 1\n"
            "#define BYTE_ORDER %d\n\n",
            ((uint8_t *)&x)[0]
            );
        printf("no header file found, faking it...\n"
            "\tArchetecture is: %s Endian\n",
            ((uint8_t *)&x)[0]?"Big":"Little"
            );
    }
}

int main( int argc, char *argv[] )
{
    if( argc == 1 )
    {
        fprintf( stderr,
            "Invalid usage: specify a file to generate:\n"
            "    src/autoconfig.h\n"
            "    src/version.h\n"
            "\n"
            );
        return 127;
    }
    if( strcmp( argv[1], "src/autoconfig.h" ) == 0 )
    {
        fOut = fopen( argv[1], "w" );
        fprintf( fOut,
            "#ifndef BU_AUTO_CONFIG_H\n"
            "#define BU_AUTO_CONFIG_H\n\n"
            );

        detectEndianness();

        fprintf( fOut, "#endif\n");
    }
    else if( strcmp( argv[1], "src/version.h" ) == 0 )
    {
        FILE *fVer = fopen("version", "rt");
        char buf[1024];
        buf[fread( buf, 1, 1024, fVer )] = '\0';
        for( int j = 0; buf[j]; j++ )
            if( buf[j] == '\n' )
                buf[j] = '\0';
        fclose( fVer );

        fOut = fopen( argv[1], "w" );
        fprintf( fOut,
            "#ifndef BU_VERSION_H\n"
            "#define BU_VERSION_H\n\n"
            "#define LIBBU_VERSION		0\n"
            "#define LIBBU_REVISION		1\n"
            "#define LIBBU_VERSION_STR	\"%s\"\n"
            "#define LIBBU_API		0\n"
            "#define LIBBU_VC_ID		\"",
			buf
			);
		FILE *psub = popen("svnversion -n", "r");
		fwrite( buf, fread( buf, 1, 1024, psub ), 1, fOut );
		pclose( psub );
		fprintf( fOut, "\"\n\n#endif\n");
    }

    return 0;
}