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

int searchOptab(char opcode[10]) {
    FILE *optab;
    char op[10];
    int value;
    optab = fopen("optab.txt", "r");
    if (optab == NULL) {
        printf("Error in opening optab file.");
        exit(1);
    }
    while (fscanf(optab, "%s%d", op, &value) != EOF) {
        if (strcmp(op, opcode) == 0) {
            fclose(optab);
            return value;
        }
    }
    fclose(optab);
    return -1;
}

int searchSymtab(char label[10]) {
    FILE *symtab;
    char sym[10];
    int value;
    symtab = fopen("symtab.txt", "r");
    if (symtab == NULL) {
        printf("Error in opening symtab file.");
        exit(1);
    }
    while (fscanf(symtab, "%s%d", sym, &value) != EOF) {
        if (strcmp(sym, label) == 0) {
            fclose(symtab);
            return value;
        }
    }
    fclose(symtab);
    return -1;
}

int main() {
    FILE *intermediate, *output, *header, *text, *end;
    char label[10], opcode[10], operand[10], obcode[10], obcodeTe[100] = "", obcodeCopy[10] = "";
    int LOCCTR, symaddr, opaddr, i, sa, leng, lenObCode = 0, flag = 0, flag2 = 0, opc;

    intermediate = fopen("intermediate.txt", "r");
    output = fopen("output.txt", "w");
    header = fopen("header.txt", "w");
    text = fopen("text.txt", "w");
    end = fopen("end.txt", "w");

    if (intermediate == NULL || output == NULL || header == NULL || text == NULL || end == NULL) {
        printf("Error in opening file.");
        return 1;
    }

    fscanf(intermediate,"%s%s%s",label,opcode,operand);      
    if(strcmp(opcode,"START")==0){
        fprintf(header,"H^00%s^00%s",label,operand);
        fprintf(text,"T^00%s",operand);
        fprintf(end,"E^00%s",operand);
        fprintf(output,"\t%s\t%s\t%s\n",label,opcode,operand);
        sa=atoi(operand);
    }
    while (strcmp(opcode,"END")!=0){
        fscanf(intermediate,"%d%s%s%s",&LOCCTR,label,opcode,operand);
        if(strcmp(label,"**")==0){
            opaddr=searchOptab(opcode);
            if(opaddr!=-1){
                symaddr=searchSymtab(operand);
                if(symaddr!=-1){
                    sprintf(obcode,"%02d%d",opaddr,symaddr);
                    lenObCode+=3;
                } 
                strcat(obcodeTe,"^");
                strcat(obcodeTe,obcode);
            }
        }
        else if(strcmp(opcode,"BYTE")==0){
            if(flag==0){            
                fprintf(text,"^%02d%s",lenObCode,obcodeTe);
                strcpy(obcodeTe,"");
                lenObCode=0;
                flag=1;
                flag2=1;
            }
            for(i=strlen(operand);i<(6+3);i++){
                strcat(obcodeCopy,"0");
            }
            for(i=2;i<strlen(operand)-1;i++){
                strncat(obcodeCopy,&operand[i],1);
            }
            lenObCode+=3;
            sprintf(obcode,"%s",obcodeCopy);
            strcat(obcodeTe,"^");
            strcat(obcodeTe,obcode);
        }
        else if(strcmp(opcode,"WORD")==0){
            //strcpy(obcode,"");
            if(flag==0){           
                fprintf(text,"^%02d%s",lenObCode,obcodeTe);
                strcpy(obcodeTe,"");
                lenObCode=0;
                flag=1;
                flag2=1;
            }
            for(i=strlen(operand);i<6;i++){
                strcat(obcode,"0");
            }
            strcat(obcode,operand);
            lenObCode+=3;
            strcat(obcodeTe,"^");
            strcat(obcodeTe,obcode);
        }
        else{
            strcpy(obcode,"");
        }
        fprintf(output,"%d\t%s\t\t%s\t\t%s\t\t%s\n",LOCCTR,label,opcode,operand,obcode);
        if(strcmp(obcode,"")!=0){             
            if(flag2==1 && (strcmp(obcodeTe,"")!=0)){      
                fprintf(text,"\nT^%06d",LOCCTR);
                flag2=0;
            }
            if(lenObCode>17){                             
                fprintf(text,"^%02d%s",lenObCode,obcodeTe);
                strcpy(obcodeTe,"");
                lenObCode=0;
                flag2=1;
            }
        }
    }
    if(lenObCode>0){             
        fprintf(text,"^%02d%s",lenObCode,obcodeTe);
    }
    leng=LOCCTR-sa;

    fclose(intermediate);
    fclose(output);
    fclose(header);
    fclose(text);
    fclose(end);
    printf("Output generated successfully");
    return 0;
}