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

#include "reloc.h"

FILE *fdObj, *fdLbl, *fdHol, *fdBin;



void findLabelAddress(char *label, char *buf);

int openWriteDestFiles(char fileName[])
{
	char *fnObj = malloc(strlen(fileName)+4+1);
	char *fnLbl = malloc(strlen(fileName)+4+1);
	char *fnHol = malloc(strlen(fileName)+4+1);
	
	strcpy(fnObj, fileName);
	strcpy(fnLbl, fileName);
	strcpy(fnHol, fileName);

	strcat(fnObj, EXT_CODE);
	strcat(fnLbl, EXT_LABELS);
	strcat(fnHol, EXT_HOLES);

	fdObj = fopen(fnObj, "w");
	fdLbl = fopen(fnLbl, "w");
	fdHol = fopen(fnHol, "w");

	return (fdObj!=NULL) && (fdLbl!=NULL) && (fdHol!=NULL);
}

int writeCode(int opcode, int op1, int op2, int op3)
{
	char ins[4];
	int currAddr;

	ins[0]=opcode & 0xFF;
	ins[1]=op1 & 0xFF;
	ins[2]=op2 & 0xFF;
	ins[3]=op3 & 0xFF; // TODO : est-ce bien propre ? Little ou big endian ?

	currAddr = (int) ftell(fdObj);
	fwrite(ins, sizeof(char), 4, fdObj);

	return currAddr;
}

void writeLabel(char *label)
{
	fprintf(fdLbl, "0x%02x\t%s\n", (int)ftell(fdObj), label);
}

void writeHole(int holeAddr, char *label)
{
	fprintf(fdHol, "0x%02x\t%s\n", holeAddr, label);
}

void closeDestFiles()
{
	fclose(fdObj); fclose(fdLbl); fclose(fdHol);
}

/*
int ftellCode(){
	return ftell(fdObj);
}*/

void linker(char fileName[], int baseAddress) // Génère le .bin a partir des .obj, .lbl, .hol
{
	char *fnObj = malloc(strlen(fileName)+4+1);
	char *fnLbl = malloc(strlen(fileName)+4+1);
	char *fnHol = malloc(strlen(fileName)+4+1);
	char *fnBin = malloc(strlen(fileName)+4+1);
	
	strcpy(fnObj, fileName);
	strcpy(fnLbl, fileName);
	strcpy(fnHol, fileName);
	strcpy(fnBin, fileName);

	strcat(fnObj, EXT_CODE);
	strcat(fnLbl, EXT_LABELS);
	strcat(fnHol, EXT_HOLES);
	strcat(fnBin, EXT_EXEC);

	fdObj = fopen(fnObj, "r");
	fdLbl = fopen(fnLbl, "r");
	fdHol = fopen(fnHol, "r");
	fdBin = fopen(fnBin, "w");

	int holeAddr=0, i;
	char label[MAX_LABEL_LEN];
	char buf;

	while ( fscanf(fdHol, "0x%02x\t%s\n", &holeAddr, label) == 2 )
	{
		int targetAddr = ftell(fdObj);

		for(i=0; i<holeAddr-targetAddr; i++)
		{
			fread(&buf, 1, 1, fdObj);
			fwrite(&buf, 1, 1, fdBin);
		}
		fread(&buf, 1, 1, fdObj); // Saute le trou dans le fichier d'entrée
		
		findLabelAddress(label, &buf);

		fwrite(&buf, 1, 1, fdBin); // Bouche le trou dans le fichier de sortie
		
	}
	
	while (fread(&buf, 1, 1, fdObj)) // Ecrit la fin du fichier
	{
		fwrite(&buf, 1, 1, fdBin);
	}

	fclose(fdObj);
	fclose(fdLbl);
	fclose(fdHol);
	fclose(fdBin);
}

void findLabelAddress(char *label, char *buf) {

	int relAddr, found=0;
	char currLabel[MAX_LABEL_LEN];

	fseek(fdLbl, 0, SEEK_SET);
	
	while ( !found && fscanf(fdLbl, "0x%02x\t%s\n", &relAddr, currLabel) == 2 )
	{
		found = ( strcmp(currLabel, label) == 0 );
		*buf = (char) (relAddr & 0xFF);
	}

	if (!found)
	{
		fprintf(stderr, "linker: ERROR : '%s' not found in .lbl file\n", label);
	}
}