/* Brainfuck Utility Debugger by Uranium-239 C */

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

/*
+++++++++[>+++++++++<-]++++[>++++<-]>[->+>+>+>+<<<<]>>>>[-
|                                                         |
|                     Uranium 239                         |
|                                                         |
<<<<+>>>>]<[<]>>+++++++++++++>+++>>++++[-<++++++>]<[<]>[.>]
*/

int RewindPosition(FILE* read){
     char a;
     while(ftell(read)>0){
           fseek(read,-2,SEEK_CUR);
           a = fgetc(read);
           if(a==']'){
              if(!RewindPosition(read)){
                  return 0;
              }
           }else if(a=='[') return 1;
     }
     return 0;
}

int ForwardPosition(FILE* read){
     char a;
     while(!feof(read)){
           if((a=fgetc(read))==']'){
              return 1;
           }else if(a=='['){
              if(!ForwardPosition(read)){
                 return 0;
              }
           }
     }
     return 0;
}

int main(int argc,char *argv[]){
    char file_buf[500];
    if(!argv[1]){
       printf("File: ");
       fgets(file_buf,sizeof(file_buf),stdin);
       if(strlen(file_buf)>0) file_buf[strlen(file_buf)-1]=0;
    }else strncpy(file_buf,argv[1],sizeof(file_buf)-1);
    
    FILE* read = fopen(file_buf,"rb");
    unsigned short loops = 0;
    if(read==NULL){
        puts("Could not open handle to file");
        getchar();
        return 0;
    }
    char *ptr,byte,*mem,*min,*max;
    if(!(mem=(char*)malloc(30000))){
        puts("Error allocating memory");
        getchar();
        return 0;
    }
    
    memset(mem,0,30000);
    ptr = mem;
    min = ptr;
    max = ptr + 30000 - 1;
    
    while((byte=fgetc(read))!=EOF){
          switch(byte){
                 case '<':
                      if(min<ptr)--ptr;
                      else{
                         puts("\n-- Pointer Error : Invalid left shift\n");
                         fclose(read);
                         free(mem);
                         getchar();
                         return 0;
                      }
                      break;
                 case '>':
                      if(max>ptr)++ptr;
                      else{
                         puts("\n-- Pointer Error : Invalid righ shift\n");
                         fclose(read);
                         free(mem);
                         getchar();
                         return 0;
                      }
                      break;
                 case '+':
                      ++*ptr;
                      break;
                 case '[':
                      loops++;
                      if(!*ptr){
                         if(!ForwardPosition(read)){
                             puts("--Loop Error-- \"Expected ]\"");
                             fclose(read);
                             free(mem);
                             getchar();
                             return 0;
                         }
                      }
                      break;
                 case '-':
                      --*ptr;
                      break;
                 case '.':
                      putchar(*ptr);
                      break;
                 case ',':
                      *ptr = getchar();
                      break;
                 case ']':
                      if(!loops){
                         puts("--Loop Error-- \"Expected [ before ]\"");
                         fclose(read);
                         free(mem);
                         getchar();
                         return 0;
                      }
                      if(*ptr){
                         if(!RewindPosition(read)){
                             puts("--Loop Error-- \"Expected [ \"");
                             fclose(read);
                             free(mem);
                             getchar();
                             return 0;
                         }
                      }
                      break;
          }
    }
    free(mem);
    fclose(read);
    puts("\n\n-Executing Note- Program execution complete\n");
    getchar();
    
    return 0;
}