/* GNU Mailutils -- a suite of utilities for electronic mail
   Copyright (C) 1999-2025 Free Software Foundation, Inc.

   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 3 of the License, or (at your option) any later version.

   This library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General
   Public License along with this library.  If not, see
   <http://www.gnu.org/licenses/>. */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <stdlib.h>
#include <string.h>
#include <errno.h>
#ifdef HAVE_STRINGS_H
# include <strings.h>
#endif
#include <unistd.h>

#include <mailutils/iterator.h>
#include <mailutils/list.h>
#include <mailutils/monitor.h>
#include <mailutils/errno.h>
#include <mailutils/nls.h>
#include <mailutils/error.h>
#include <mailutils/url.h>
#include <mailutils/util.h>
#include <mailutils/sys/registrar.h>

/* NOTE: We will leak here since the monitor and the registrar will never
   be released. That's ok we can live with this, it's only done once.  */
static mu_list_t registrar_list;
struct mu_monitor registrar_monitor = MU_MONITOR_INITIALIZER;

static mu_record_t mu_default_record;

void
mu_registrar_set_default_record (mu_record_t record)
{
  mu_default_record = record;
}

int
mu_registrar_get_default_record (mu_record_t *prec)
{
  if (mu_default_record)
    {
      if (prec)
	*prec = mu_default_record;
      return 0;
    }
  return MU_ERR_NOENT;
}

int
mu_registrar_set_default_scheme (const char *scheme)
{
  int status;
  mu_record_t rec;
  
  status = mu_registrar_lookup_scheme (scheme, &rec);
  if (status == 0)
    mu_registrar_set_default_record (rec);
  return status;
}

const char *
mu_registrar_get_default_scheme (void)
{
  return mu_default_record ? mu_default_record->scheme : NULL;
}

static int
_registrar_get_list (mu_list_t *plist)
{
  int status = 0;

  if (plist == NULL)
    return MU_ERR_OUT_PTR_NULL;
  mu_monitor_wrlock (&registrar_monitor);
  if (registrar_list == NULL)
    status = mu_list_create (&registrar_list);
  *plist = registrar_list;
  mu_monitor_unlock (&registrar_monitor);
  return status;
}

int
mu_registrar_get_iterator (mu_iterator_t *pitr)
{
  int status = 0;
  if (pitr == NULL)
    return MU_ERR_OUT_PTR_NULL;
  mu_monitor_wrlock (&registrar_monitor);
  if (registrar_list == NULL)
    {
      status = mu_list_create (&registrar_list);
      if (status)
	return status;
    }
  status = mu_list_get_iterator (registrar_list, pitr);
  mu_monitor_unlock (&registrar_monitor);
  return status;
}

int
mu_registrar_lookup_scheme (const char *scheme, mu_record_t *precord)
{
  size_t len;
  mu_iterator_t iterator;
  int status = mu_registrar_get_iterator (&iterator);
  if (status != 0)
    return status;
  status = MU_ERR_NOENT;
  len = strcspn (scheme, ":");
  for (mu_iterator_first (iterator); !mu_iterator_is_done (iterator);
       mu_iterator_next (iterator))
    {
      mu_record_t record;
      mu_iterator_current (iterator, (void **)&record);
      if (strlen (record->scheme) == len
	  && memcmp (record->scheme, scheme, len) == 0)
	{
	  if (precord)
	    *precord = record;
	  status = 0;
	  break;
	}
    }
  mu_iterator_destroy (&iterator);
  return status;
}

int
mu_registrar_lookup_url (mu_url_t url, int flags,
			 mu_record_t *precord, int *pflags)
{
  mu_iterator_t iterator;
  mu_record_t last_record = NULL;
  int last_flags = 0;
  int status;

  status = mu_registrar_get_iterator (&iterator);
  if (status != 0)
    return status;
  status = MU_ERR_NOENT;
  for (mu_iterator_first (iterator); !mu_iterator_is_done (iterator);
       mu_iterator_next (iterator))
    {
      int rc;
      mu_record_t record;
      mu_iterator_current (iterator, (void **)&record);
      if ((rc = mu_record_is_scheme (record, url, flags)))
	{
	  if (rc == flags)
	    {
	      status = 0;
	      last_record = record;
	      last_flags = rc;
	      break;
	    }
	  else if (rc > last_flags)
	    {
	      status = 0;
	      last_record = record;
	      last_flags = rc;
	    }
	}
    }
  mu_iterator_destroy (&iterator);

  if (status
      && !mu_is_proto (mu_url_to_string (url)) /* FIXME: This check is not
						  enough. */
      && mu_default_record
      && (mu_record_is_local (mu_default_record) == 0
	  || access (mu_url_to_string (url), F_OK)))
    {
      /* If the default record is local and the mailbox does not exist,
	 it possibly can be created if requested. */
      status = 0;
      last_record = mu_default_record;
      last_flags = flags & MU_FOLDER_ATTRIBUTE_FILE; /* FIXME? */
    }

  if (status == 0)
    {
      if (precord)
	*precord = last_record;
      if (pflags)
	*pflags = last_flags;
    }
  
  return status;
}

int
mu_registrar_lookup (const char *name, int flags,
		     mu_record_t *precord, int *pflags)
{
  int rc;
  mu_url_t url;
  
  rc = mu_url_create (&url, name);
  if (rc)
    return rc;
  rc = mu_registrar_lookup_url (url, flags, precord, pflags);
  mu_url_destroy (&url);
  return rc;
}

static int
_compare_prio (const void *item, const void *value)
{
  const mu_record_t a = (const mu_record_t) item;
  const mu_record_t b = (const mu_record_t) value;
  if (a->priority > b->priority)
    return 0;
  return -1;
}

int
mu_registrar_record (mu_record_t record)
{
  int status;
  mu_list_t list;
  mu_list_comparator_t comp;
  
  if (!record)
    return 0;
  _registrar_get_list (&list);
  comp = mu_list_set_comparator (list, _compare_prio);
  status = mu_list_insert (list, record, record, 1);
  if (status == MU_ERR_NOENT)
    status = mu_list_append (list, record);
  mu_list_set_comparator (list, comp);
  return status;
}

int
mu_unregistrar_record (mu_record_t record)
{
  mu_list_t list;
  _registrar_get_list (&list);
  mu_list_remove (list, record);
  return 0;
}

int
mu_record_is_scheme (mu_record_t record, mu_url_t url, int flags)
{
  if (record == NULL)
    return 0;

  /* Overload.  */
  if (record->_is_scheme)
    return record->_is_scheme (record, url, flags);

  if (mu_url_is_scheme (url, record->scheme))
    return MU_FOLDER_ATTRIBUTE_ALL;

  return 0;
}

int
mu_record_is_local (mu_record_t record)
{
  return record->flags & MU_RECORD_LOCAL;
}

int
mu_record_get_url (mu_record_t record, int (*(*_purl)) (mu_url_t))
{
  if (record == NULL)
    return EINVAL;
  if (_purl == NULL)
    return MU_ERR_OUT_PTR_NULL;
  /* Overload.  */
  if (record->_get_url)
    return record->_get_url (record, _purl);
  *_purl = record->_url;
  return 0;
}

int
mu_record_get_mailbox (mu_record_t record, int (*(*_pmailbox)) (mu_mailbox_t))
{
  if (record == NULL)
    return EINVAL;
  if (_pmailbox == NULL)
    return MU_ERR_OUT_PTR_NULL;
  /* Overload.  */
  if (record->_get_mailbox)
    return record->_get_mailbox (record, _pmailbox);
  *_pmailbox = record->_mailbox;
  return 0;
}

int
mu_record_get_mailer (mu_record_t record, int (*(*_pmailer)) (mu_mailer_t))
{
  if (record == NULL)
    return EINVAL;
  if (_pmailer == NULL)
    return MU_ERR_OUT_PTR_NULL;
  /* Overload.  */
  if (record->_get_mailer)
    return record->_get_mailer (record, _pmailer);
  *_pmailer = record->_mailer;
  return 0;
}

int
mu_record_get_folder (mu_record_t record, int (*(*_pfolder)) (mu_folder_t))
{
  if (record == NULL)
    return EINVAL;
  if (_pfolder == NULL)
    return MU_ERR_OUT_PTR_NULL;
  /* Overload.  */
  if (record->_get_folder)
    return record->_get_folder (record, _pfolder);
  *_pfolder = record->_folder;
  return 0;
}

int
mu_record_list_p (mu_record_t record, const char *name, int flags)
{
  return record == NULL
          || !record->_list_p
          || record->_list_p (record, name, flags);
}

int
mu_record_check_url (mu_record_t record, mu_url_t url, int *pmask)
{
  int mask;
  int flags;
  int rc;
  
  if (!record || !url)
    return EINVAL;

  rc = mu_url_get_flags (url, &flags);
  if (rc)
    return rc;

  mask = flags & record->url_must_have;
  if (mask != record->url_must_have)
    {
      if (pmask)
	*pmask = record->url_must_have & ~mask;
      return MU_ERR_URL_MISS_PARTS;
    }
  mask = flags & ~(record->url_may_have | record->url_must_have);
  if (mask)
    {
      if (pmask)
	*pmask = mask;
      return MU_ERR_URL_EXTRA_PARTS;
    }
  return 0;
}

/* Test if URL corresponds to a local record.  
   Return:
     0            -  OK, the result is stored in *pres;
     MU_ERR_NOENT -  don't know: there's no matching record;
     EINVAL       -  some of the arguments is not valid;
     other        -  URL lookup failed.
*/
int
mu_registrar_test_local_url (mu_url_t url, int *pres)
{
  int rc;
  mu_record_t rec;

  if (!url || !pres)
    return EINVAL;
  rc = mu_registrar_lookup_url (url, MU_FOLDER_ATTRIBUTE_ALL, &rec, NULL);
  if (rc)
    return rc;
  *pres = mu_record_is_local (rec);
  return 0;
}

struct listable_closure
{
  char const *name;
  int flags;
};

static int
record_listable (void *item, void *data)
{
  mu_record_t record = item;
  struct listable_closure *cls = data;
  return !mu_record_list_p (record, cls->name, cls->flags);
}

int
mu_registrar_list_p (mu_list_t rlist, char const *name, int flags)
{
  struct listable_closure cls = { name, flags };
  if (!rlist)
    rlist = registrar_list;
  return !mu_list_foreach (rlist, record_listable, &cls);
}	

/* Apply flt to each record in the registry and remove those, for which it
   returns non-zero. */
int
mu_registrar_apply_filter (int (*flt) (mu_record_t, void *), void *data)
{
  mu_iterator_t iterator;
  
  int status = mu_registrar_get_iterator (&iterator);
  if (status != 0)
    return status;
  mu_monitor_wrlock (&registrar_monitor);
  for (mu_iterator_first (iterator); !mu_iterator_is_done (iterator);
       mu_iterator_next (iterator))
    {
      mu_record_t record;
      mu_iterator_current (iterator, (void **)&record);
      if (flt (record, data))
	mu_list_remove (registrar_list, record);
    }
  mu_iterator_destroy (&iterator);
  mu_monitor_unlock (&registrar_monitor);
  return 0;
}

struct match_closure
{
  mu_url_t url;
  int flags;
  int err;
};

static int
select_match (void **itmv, size_t itmc, void *call_data)
{
  struct match_closure *mc = call_data;
  int rc = mu_record_is_scheme (itmv[0], mc->url, mc->flags);
  if (rc)
    {
      struct mu_record_match *match = malloc (sizeof (*match));
      if (!match)
	{
	  mc->err = errno;
	  return MU_LIST_MAP_STOP;
	}
      match->record = itmv[0];
      match->flags = rc;
      itmv[0] = match;
      return MU_LIST_MAP_OK;
    }
  return MU_LIST_MAP_SKIP;
}

/* Select records matching pathname NAME with given FLAGS
   (MU_FOLDER_ATTRIBUTE_* bitmask). On success, store each
   match as a pointer to struct mu_record_match in *RET.
*/
int
mu_registrar_match_records (char const *name, int flags, mu_list_t *ret)
{
  int rc;
  struct match_closure mc;
  mu_list_t lst;

  rc = mu_url_create (&mc.url, name);
  if (rc)
    return rc;
  mc.flags = flags;
  mc.err = 0;

  mu_monitor_wrlock (&registrar_monitor);
  rc = mu_list_map (registrar_list, select_match, &mc, 1, &lst);
  mu_monitor_unlock (&registrar_monitor);
  mu_url_destroy (&mc.url);
  if (rc == 0)
    {
      mu_list_set_destroy_item (lst, mu_list_free_item);
      if (mc.err)
	{
	  mu_list_destroy (&lst);
	  rc = mc.err;
	}
    }
  if (rc == 0)
    *ret = lst;
  return rc;
}
