#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <unistd.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>

#define UPKG_MAGIC 0x9E2A83C1

typedef struct
{
	uint32_t magic;
	uint16_t pkgver, license;
	uint32_t flags, nnames, onames, nexports, oexports, nimports, oimports;
} upkg_header_t;

uint8_t *pkgfile;
upkg_header_t *head;
size_t fpos = 0;

uint8_t readbyte( void )
{
	uint8_t val = pkgfile[fpos];
	fpos++;
	return val;
}

uint16_t readword( void )
{
	uint16_t val = *(uint16_t*)(pkgfile+fpos);
	fpos += 2;
	return val;
}

uint32_t readdword( void )
{
	uint32_t val = *(uint32_t*)(pkgfile+fpos);
	fpos += 4;
	return val;
}

float readfloat( void )
{
	float val = *(float*)(pkgfile+fpos);
	fpos += 4;
	return val;
}

#define READSTRUCT(x,y) {memcpy(&x,pkgfile+fpos,sizeof(y));fpos+=sizeof(y);}

// reads a compact index value
int32_t readindex( void )
{
	uint8_t byte[5] = {0};
	byte[0] = readbyte();
	if ( !byte[0] ) return 0;
	if ( byte[0]&0x40 )
	{
		for ( int i=1; i<5; i++ )
		{
			byte[i] = readbyte();
			if ( !(byte[i]&0x80) ) break;
		}
	}
	int32_t tf = byte[0]&0x3f;
	tf |= (int32_t)(byte[1]&0x7f)<<6;
	tf |= (int32_t)(byte[2]&0x7f)<<13;
	tf |= (int32_t)(byte[3]&0x7f)<<20;
	tf |= (int32_t)(byte[4]&0x7f)<<27;
	if ( byte[0]&0x80 ) tf *= -1;
	return tf;
}

// reads a name table entry
size_t readname( int *olen )
{
	size_t pos = fpos;
	if ( head->pkgver >= 64 )
	{
		int32_t len = readindex();
		pos = fpos;
		if ( olen ) *olen = len;
		if ( len <= 0 ) return pos;
		fpos += len;
	}
	else
	{
		int c, p = 0;
		while ( (c = readbyte()) ) p++;
		if ( olen ) *olen = p;
	}
	fpos += 4;
	return pos;
}

size_t getname( int index, int *olen )
{
	size_t prev = fpos;
	fpos = head->onames;
	size_t npos = 0;
	for ( int i=0; i<=index; i++ )
		npos = readname(olen);
	fpos = prev;
	return npos;
}

// checks if a name exists
int hasname( const char *needle )
{
	if ( !needle ) return 0;
	size_t prev = fpos;
	fpos = head->onames;
	int found = 0;
	int nlen = strlen(needle);
	for ( uint32_t i=0; i<head->nnames; i++ )
	{
		int32_t len = 0;
		if ( head->pkgver >= 64 )
		{
			len = readindex();
			if ( len <= 0 ) continue;
		}
		int c = 0, p = 0, match = 1;
		while ( (c = readbyte()) )
		{
			if ( (p >= nlen) || (needle[p] != c) ) match = 0;
			p++;
			if ( len && (p > len) ) break;
		}
		if ( match )
		{
			found = 1;
			break;
		}
		fpos += 4;
	}
	fpos = prev;
	return found;
}

// read import table entry and return index of its object name
int32_t readimport( void )
{
	readindex();
	readindex();
	if ( head->pkgver >= 55 ) fpos += 4;
	else readindex();
	return readindex();
}

int32_t getimport( int index )
{
	size_t prev = fpos;
	fpos = head->oimports;
	int32_t iname = 0;
	for ( int i=0; i<=index; i++ )
		iname = readimport();
	fpos = prev;
	return iname;
}

// fully read import table entry
void readimport2( int32_t *cpkg, int32_t *cname, int32_t *pkg, int32_t *name )
{
	*cpkg = readindex();
	*cname = readindex();
	if ( head->pkgver >= 55 ) *pkg = readdword();
	else *pkg = 0;
	*name = readindex();
}

void getimport2( int index, int32_t *cpkg, int32_t *cname, int32_t *pkg,
	int32_t *name )
{
	size_t prev = fpos;
	fpos = head->oimports;
	for ( int i=0; i<=index; i++ )
		readimport2(cpkg,cname,pkg,name);
	fpos = prev;
}

// read export table entry
void readexport( int32_t *class, int32_t *ofs, int32_t *siz, int32_t *name )
{
	*class = readindex();
	readindex();
	if ( head->pkgver >= 55 ) fpos += 4;
	*name = readindex();
	fpos += 4;
	*siz = readindex();
	if ( *siz > 0 ) *ofs = readindex();
}

void getexport( int index, int32_t *class, int32_t *ofs, int32_t *siz,
	int32_t *name )
{
	size_t prev = fpos;
	fpos = head->oexports;
	for ( int i=0; i<=index; i++ )
		readexport(class,ofs,siz,name);
	fpos = prev;
}

// fully read export table entry
void readexport2( int32_t *class, int32_t *super, int32_t *pkg, int32_t *name,
	uint32_t *flags, int32_t *siz, int32_t *ofs )
{
	*class = readindex();
	*super = readindex();
	if ( head->pkgver >= 55 ) *pkg = readdword();
	else *pkg = 0;
	*name = readindex();
	*flags = readdword();
	*siz = readindex();
	if ( *siz > 0 ) *ofs = readindex();
}

void getexport2( int index, int32_t *class, int32_t *super, int32_t *pkg,
	int32_t *name, uint32_t *flags, int32_t *siz, int32_t *ofs )
{
	size_t prev = fpos;
	fpos = head->oexports;
	for ( int i=0; i<=index; i++ )
		readexport2(class,super,pkg,name,flags,siz,ofs);
	fpos = prev;
}

int main( int argc, char **argv )
{
	if ( argc < 2 )
	{
		printf("Usage: unrundeleter <map file>\n");
		return 1;
	}
	int fd = open(argv[1],O_RDWR);
	if ( fd == -1 )
	{
		printf("Failed to open file %s: %s\n",argv[1],strerror(errno));
		return 1;
	}
	struct stat st;
	fstat(fd,&st);
	pkgfile = malloc(st.st_size);
	memset(pkgfile,0,st.st_size);
	head = (upkg_header_t*)pkgfile;
	int r = 0;
	do
	{
		r = read(fd,pkgfile+fpos,131072);
		if ( r == -1 )
		{
			close(fd);
			free(pkgfile);
			printf("Read failed for file %s: %s\n",argv[1],
				strerror(errno));
			return 4;
		}
		fpos += r;
	}
	while ( r > 0 );
	fpos = 0;
	if ( head->magic != UPKG_MAGIC )
	{
		printf("File %s is not a valid unreal package!\n",argv[1]);
		free(pkgfile);
		return 2;
	}
	if ( !hasname("bDeleteMe") )
	{
		printf("Package %s does not contain deleted exports\n",argv[1]);
		free(pkgfile);
		return 4;
	}
	// loop through exports and search for bDeleteMe properties
	fpos = head->oexports;
	for ( uint32_t i=0; i<head->nexports; i++ )
	{
		int32_t class, super, pkg, name, flags, siz, ofs;
		readexport2(&class,&super,&pkg,&name,&flags,&siz,&ofs);
		if ( (siz <= 0) || (class >= 0) ) continue;
		// check the class
		class = -class-1;
		if ( (uint32_t)class > head->nimports ) continue;
		// read name
		int32_t l = 0;
		char *ename = (char*)(pkgfile+getname(name,&l));
		printf("checking %.*s\n",l,ename);
		// begin reading data
		size_t prev = fpos;
		fpos = ofs;
		if ( head->pkgver < 45 ) fpos += 4;
		if ( head->pkgver < 55 ) fpos += 16;
		if ( head->pkgver <= 44 ) fpos -= 6;	// ???
		if ( head->pkgver == 45 ) fpos -= 2;	// ???
		if ( head->pkgver == 41 ) fpos += 2;	// ???
		if ( head->pkgver <= 35 ) fpos += 8;	// ???
		// process stack
		if ( flags&0x2000000 )
		{
			int32_t node = readindex();
			readindex();
			readdword();
			readdword();
			readdword();
			if ( node != 0 ) readindex();
		}
		// process properties
		int32_t prop = readindex();
		if ( (uint32_t)prop >= head->nnames )
		{
			printf("Unknown property %d, skipping\n",prop);
			fpos = prev;
			continue;
		}
		char *pname = (char*)(pkgfile+getname(prop,&l));
retry:
		if ( strncasecmp(pname,"None",l) )
		{
			size_t ptr = fpos;
			uint8_t info = readbyte();
			int array = info&0x80;
			int type = info&0xf;
			int psiz = (info>>4)&0x7;
			int32_t tl = 0;
			char *sname;
			if ( type == 10 )
			{
				int32_t sn;
				sn = readindex();
				sname = (char*)(pkgfile+getname(sn,&tl));
			}
			switch ( psiz )
			{
			case 0:
				psiz = 1;
				break;
			case 1:
				psiz = 2;
				break;
			case 2:
				psiz = 4;
				break;
			case 3:
				psiz = 12;
				break;
			case 4:
				psiz = 16;
				break;
			case 5:
				psiz = readbyte();
				break;
			case 6:
				psiz = readword();
				break;
			case 7:
				psiz = readdword();
				break;
			}
			//printf(" prop %.*s (%u, %u, %u, %u)\n",l,pname,array,type,(info>>4)&7,psiz);
			//if ( tl ) printf("  struct: %.*s\n",tl,sname);
			if ( array && (type != 3) )
			{
				int idx = readindex();
				//printf("  index: %d\n",idx);
			}
			fpos += psiz;
			// set bDeleteMe to false
			if ( !strncasecmp(pname,"bDeleteMe",l) && array )
			{
				printf(" toggled bDeleteMe\n");
				lseek(fd,ptr,SEEK_SET);
				info &= ~0x80;
				write(fd,&info,1);
			}
			prop = readindex();
			pname = (char*)(pkgfile+getname(prop,&l));
			goto retry;
		}
		fpos = prev;
	}
	free(pkgfile);
	close(fd);
	return 0;
}