#include "linker.h"

int tryLink(string filename, proc_t *proc) {
	//variables
	source_file_t header;
	mapping_t mapping, rom;
	int fd;
	int pos;
	int hasRom=0;
	
	//open the file
	fd=File_open(filename, FILE_OPEN_read);
	if(fd==-1) {
		Platform_setError(LINKER_ERR_NOOPEN);
		return 0;
	}
	pos=0;
	
	//read the header
	if(File_read(fd, pos, &header, HEADER_LENGTH)!=HEADER_LENGTH) {
		Platform_setError(LINKER_ERR_READ);
		File_close(fd);
		return 0;
	}
	pos+=HEADER_LENGTH;
	if(header.magic!=MAGIC||header.version!=SOURCE_VERSION) {
		Platform_setError(LINKER_ERR_COMPAT);
		File_close(fd);
		return 0;
	}
	
	//read the mappings one by one
	for(int i=0; i<header.mappings; i++) {
		//read the base mapping
		if(File_read(fd, pos, &mapping, MAPPING_LENGTH)!=MAPPING_LENGTH) {
			Platform_setError(LINKER_ERR_READ);
			File_close(fd);
			return 0;
		}
		pos+=MAPPING_LENGTH;
		
		//map accordingly
		if(mapping.type==MAPPING_TYPE_ram) {
			//map the RAM in the MMU
			if(!Segments_mapRam(&proc->mmu, mapping.offset, mapping.length, mapping.access)) {
				Platform_setError(LINKER_ERR_MAP_RAM);
				File_close(fd);
				return 0;
			}
		} else if(mapping.type==MAPPING_TYPE_stack) {
			//map the stack
			if(!Segments_mapStack(&proc->mmu, &proc->stack, mapping.offset, mapping.access)) {
				Platform_setError(LINKER_ERR_MAP_STACK);
				File_close(fd);
				return 0;
			}
		} else if(mapping.type==MAPPING_TYPE_vram) {
			//map the stack
			if(!Segments_mapVram(&proc->mmu, mapping.offset)) {
				Platform_setError(LINKER_ERR_MAP_VRAM);
				File_close(fd);
				return 0;
			}
		} else if(mapping.type==MAPPING_TYPE_file||mapping.type==MAPPING_TYPE_file_raw) {
			//read the filename length
			char recursive[16];
			big_endian_int_t len;
			if(File_read(fd, pos, &len, sizeof(big_endian_int_t))!=sizeof(big_endian_int_t)) {
				Platform_setError(LINKER_ERR_READ);
				File_close(fd);
				return 0;
			}
			pos+=sizeof(big_endian_int_t);
			
			//read the filename
			if(File_read(fd, pos, recursive, len.value)!=len.value) {
				Platform_setError(LINKER_ERR_READ);
				File_close(fd);
				return 0;
			}
			pos+=len.value;
			
			if(mapping.type==MAPPING_TYPE_file) {
				//map the file recursively
				if(!tryLink(recursive, proc)) {
					File_close(fd);
					return 0;
				}
			} else {
				//open the file
				int flags=0;
				if(mapping.access&MAPPING_ACCESS_r) flags|=FILE_OPEN_read;
				if(mapping.access&MAPPING_ACCESS_w) flags|=FILE_OPEN_write;
				int mapFd=File_open(recursive, flags);
				if(mapFd==-1) {
					Platform_setError(LINKER_ERR_NOOPEN);
					File_close(fd);
					return 0;
				}
				//map the file directly
				if(!Segments_mapFile(&proc->mmu, fd, mapping.offset, mapping.length, 0, mapping.access)) {
					Platform_setError(LINKER_ERR_MAP_FILE);
					File_close(mapFd);
					File_close(fd);
					return 0;
				}
			}
		} else if(mapping.type==MAPPING_TYPE_rom) {
			//check if we already have a ROM mapping
			if(hasRom) {
				Platform_setError(LINKER_ERR_DUPROM);
				File_close(fd);
				return 0;
			}
			
			//store this for later
			rom=mapping;
			hasRom=1;
		}
	}
	
	//map the ROM if present
	if(hasRom) {
		//open the ROM correctly
		if(rom.access&MAPPING_ACCESS_w) {
			File_close(fd);
			fd=File_open(filename, FILE_OPEN_read|FILE_OPEN_write);
			if(fd==-1) {
				Platform_setError(LINKER_ERR_NOOPEN);
				return 0;
			}
		}
		
		//map the ROM
		if(!Segments_mapFile(&proc->mmu, fd, rom.offset, rom.length, pos, rom.access)) {
			Platform_setError(LINKER_ERR_MAP_ROM);
			File_close(fd);
			return 0;
		}
	} else {
		//close the file
		File_close(fd);
	}
	
	//setup the entry point and return
	proc->registers[0].i=header.entryPoint;
	return 1;
}

int Linker_link(string filename, proc_t *proc) {
	if(!tryLink(filename, proc)) {
		Segments_unmapAll(&proc->mmu);
		return 0;
	}
	return 1;
}