#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <dirent.h>
#include <dlfcn.h>
#include "list.h"
#include "mapcalc.h"

typedef char *(*func_t)(void);

static int register_function (char *fname, void *func, char *proto);
void init_plug (void);

static int
register_function (char *fname, void *func, char *proto)
{
  STYP type;
  SYMBOL *sym;

  sym = getsym (fname);
  if (sym)
    symtab = (SYMBOL *)listdel ((LIST *)symtab, (LIST *)sym, freesym);

  /*
   * This is quite incomplete
   */

  switch (proto[0])
  {
    case 'd':
      type = st_nfunc;
      break;
    case 'm':
      type = st_mfunc;
      break;
    case 'p':
      type = st_pfunc;
      break;
    default:
      return 0;
  }

  sym = putsym (fname);
  sym->v.p = func;
  sym->type = sym->itype = sym->rettype = type;
  sym->proto = strdup (proto + 2);		/* skip "m=" */

  return 1;
}

void
init_plug (void)
{
  SYMBOL *sym;
  char path[4096], pathname[4096], *ptr, *fname, *proto;
  struct dirent *ent;
  void *handle, *func;
  func_t fh, ph;
  DIR *dir;

  /*
   * Search algorithm:
   * 1. Find "pluginpath" in symbol table. If not found...
   * 2. Find "$GISBASE/plugins". If not defined
   * 3. Use "./plugins"
   */

  sym = getsym ("pluginpath");
  if (sym && sym->v.p)
    strcpy (path, sym->v.p);
  else
  {
    ptr = getenv ("GISBASE");
    if (ptr)
      strcpy (path, ptr);
    else
      strcpy (path, getcwd (path, 4096));
    if (path[strlen (path) - 1] != '/')
      strcat (path, "/");
    strcat (path, "plugins");
  }

  dir = opendir (path);
  if (!dir)
    return;

  while ((ent = readdir (dir)) != NULL)
  {
    if (!strcmp (ent->d_name, ".") || !strcmp (ent->d_name, ".."))
      continue;
    strcpy (pathname, path);
    strcat (pathname, "/");
    strcat (pathname, ent->d_name);
    if (access (pathname, R_OK | X_OK))
      continue;
    handle = dlopen (pathname, RTLD_LAZY);
    if (!handle)
      continue;
    fh = dlsym (handle, "fname");
    if (dlerror ())
    {
      dlclose (handle);
      continue;
    }
    fname = (*fh)();
    if (!fname)
    {
      dlclose (handle);
      continue;
    }
    ph = dlsym (handle, "proto");
    if (dlerror ())
    {
      dlclose (handle);
      continue;
    }
    proto = (*ph)();
    if (!proto)
    {
      dlclose (handle);
      continue;
    }
    func = dlsym (handle, fname);
    if (!func)
    {
      dlclose (handle);
      continue;
    }
    if (!register_function (fname, func, proto))
      dlclose (handle);
  }
  closedir (dir);
}