/* Last edited on 2024-12-25 10:13:37 by stolfi */ 

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

#include <merge-paths_doc.h>

int main(int argc, char **argv);
int dir_is_local(char *h, char *a);
int cmp_dirs(char *h, char *a, char *b);

int fprintf(FILE *, const char *, ...);
int _flsbuf(unsigned char, FILE*);
int fclose(FILE *);
int fflush(FILE *);

int main(int argc, char *argv[])
{
  char *a; char *b; int which, ndirs;
  
  if (argc != 4)
    { fflush(stdout);
      fprintf(stderr, "argc = %d\n", argc);
      fprintf(stderr, "usage: merge-paths <home> <path1> <path2>\n");
      exit(1);
    }
    
  a = argv[2]; 
  b = argv[3];
  ndirs = 0;
  
  while ((*a != '\0') || (*b != '\0'))
    { if ((*a) == ':') a++;
      else if ((*b) == ':') b++;
      else
        { /* Insert ':' if needed: */
          if ( ndirs != 0 ) { putchar(':'); }
          ndirs++;
          
          /* Decide which directory should come first: */
          if ((*a) == '\0') 
            { which = 1;  }
          else if ((*b) == '\0')
            { which = 0; }
          else
            { which = cmp_dirs(argv[1], a, b); }
            
          /* Output and skip selected directory: */
          if ( which == 0 )
            { while (((*a) != '\0') && ((*a) != ':')) { putchar(*a); a++; } }
          else 
            { while (((*b) != '\0') && ((*b) != ':')) { putchar(*b); b++; } }
        }
    }
  putchar('\n');
  fclose(stdout);
  return (0);
}

int cmp_dirs(char *h, char *a, char *b)
/* Returns 0 if directory "*a" should precede "*b" in the path, else 1.
   Assumes that directories that begin with "." or "h" must come first,
   else "a" must come first. */
{
  int a_local = dir_is_local(h, a);
  int b_local = dir_is_local(h, b);
  if ( a_local ) 
    { return (0); }
  else if ( b_local ) 
    { return (1); }
  else
    { return (0); }
}

int dir_is_local(char *h, char *a)
/* Returns TRUE iff "*a" begins with ".", "~", or "*h" */
{
  if (((*a) == '\0') || ((*a) == ':'))
    { fflush(stdout);
      fprintf(stderr, "merge-paths: internal error\n"); 
      exit(1); 
    }
  else if (((*a) == '.') || ((*a) == '~'))
    { return (1); }
  else
    { while ((*h) != '\0')
        { if ((*a) != (*h)) return (0); else { a++; h++; } }
      return (1);
    }
}