/*
 * deadprops.c: mod_dav_svn dead property provider functions for Subversion
 *
 * ====================================================================
 * Copyright (c) 2000-2002 CollabNet.  All rights reserved.
 *
 * This software is licensed as described in the file COPYING, which
 * you should have received as part of this distribution.  The terms
 * are also available at http://subversion.tigris.org/license-1.html.
 * If newer versions of this license are posted there, you may use a
 * newer version instead, at your option.
 *
 * This software consists of voluntary contributions made by many
 * individuals.  For exact contribution history, see the revision
 * history and logs, available at http://subversion.tigris.org/.
 * ====================================================================
 */


#include <httpd.h>
#include <mod_dav.h>

#include <apr_hash.h>

#include "dav_svn.h"
#include "svn_xml.h"


struct dav_db {
  const dav_resource *resource;
  apr_pool_t *p;

  /* the resource's properties that we are sequencing over */
  apr_hash_t *props;
  apr_hash_index_t *hi;

  /* used for constructing repos-local names for properties */
  svn_stringbuf_t *work;
};

struct dav_deadprop_rollback {
  dav_prop_name name;
  svn_string_t value;
};


/* retrieve the "right" string to use as a repos path */
static const char *get_repos_path (struct dav_resource_private *info)
{
  return info->node_id_str ? info->node_id_str : info->repos_path;
}


/* construct the repos-local name for the given DAV property name */
static void get_repos_propname(dav_db *db, const dav_prop_name *name,
                               char **repos_propname)
{
  if (strcmp(name->ns, SVN_PROP_PREFIX) == 0)
    {
      /* recombine the namespace ("svn:") and the name. */
      svn_stringbuf_set(db->work, SVN_PROP_PREFIX);
      svn_stringbuf_appendcstr(db->work, name->name);
      *repos_propname = db->work->data;
    }
  else if (strcmp(name->ns, SVN_PROP_CUSTOM_PREFIX) == 0)
    {
      /* the name of a custom prop is just the name -- no ns URI */
      *repos_propname = (char *)name->name;
    }
  else
    {
      *repos_propname = NULL;
    }
}

static dav_error *get_value(dav_db *db, const dav_prop_name *name,
                            svn_string_t **pvalue)
{
  char *propname;
  svn_error_t *serr;

  /* get the repos-local name */
  get_repos_propname(db, name, &propname);

  /* ### disallow arbitrary, non-SVN properties. this effectively shuts
     ### off arbitrary DeltaV clients for now. */
  if (propname == NULL)
    {
      /* we know these are not present. */
      *pvalue = NULL;
      return NULL;
    }

  /* ### if db->props exists, then try in there first */

  /* Working Baseline, Baseline, or (Working) Version resource */
  if (db->resource->baselined)
    if (db->resource->type == DAV_RESOURCE_TYPE_WORKING)
      serr = svn_fs_txn_prop(pvalue, db->resource->info->root.txn,
                             propname, db->p);
    else
      serr = svn_fs_revision_prop(pvalue, db->resource->info->repos->fs,
                                  db->resource->info->root.rev,
                                  propname, db->p);
  else
    serr = svn_fs_node_prop(pvalue, db->resource->info->root.root,
                            get_repos_path(db->resource->info),
                            propname, db->p);
  if (serr != NULL)
    return dav_svn_convert_err(serr, HTTP_INTERNAL_SERVER_ERROR,
                               "could not fetch a property");

  return NULL;
}

static dav_error *save_value(dav_db *db, const dav_prop_name *name,
                             const svn_string_t *value)
{
  char *propname;
  svn_error_t *serr;

  /* get the repos-local name */
  get_repos_propname(db, name, &propname);

  /* ### disallow arbitrary, non-SVN properties. this effectively shuts
     ### off arbitrary DeltaV clients for now. */
  if (propname == NULL)
    return dav_new_error(db->p, HTTP_CONFLICT, 0,
                         "Properties may only be defined in the "
                         SVN_PROP_PREFIX " and " SVN_PROP_CUSTOM_PREFIX
                         " namespaces.");

  /* Working Baseline or Working (Version) Resource */
  if (db->resource->baselined)
    serr = svn_fs_change_txn_prop(db->resource->info->root.txn,
                                  propname, value, db->resource->pool);
  else
    serr = svn_fs_change_node_prop(db->resource->info->root.root,
                                   get_repos_path(db->resource->info),
                                   propname, value, db->resource->pool);
  if (serr != NULL)
    return dav_svn_convert_err(serr, HTTP_INTERNAL_SERVER_ERROR,
                               "could not change a property");

  /* a change to the props was made; make sure our cached copy is gone */
  db->props = NULL;

  return NULL;
}

static dav_error *dav_svn_db_open(apr_pool_t *p, const dav_resource *resource,
                                  int ro, dav_db **pdb)
{
  dav_db *db;

  /* Some resource types do not have deadprop databases. Specifically:
     REGULAR, VERSION, and WORKING resources have them. (SVN does not
     have WORKSPACE resources, and isn't covered here) */
  if (resource->type == DAV_RESOURCE_TYPE_HISTORY
      || resource->type == DAV_RESOURCE_TYPE_ACTIVITY
      || resource->type == DAV_RESOURCE_TYPE_PRIVATE)
    {
      *pdb = NULL;
      return NULL;
    }

  /* If the DB is being opened R/W, and this isn't a working resource, then
     we have a problem! */
  if (!ro && resource->type != DAV_RESOURCE_TYPE_WORKING)
    {
      return dav_new_error(p, HTTP_CONFLICT, 0,
                           "Properties may only be changed on working "
                           "resources.");
    }

  db = apr_pcalloc(p, sizeof(*db));

  db->resource = resource;
  db->p = p;

  /* ### temp hack */
  db->work = svn_stringbuf_ncreate("", 0, p);

  /* ### use RO and node's mutable status to look for an error? */

  *pdb = db;

  return NULL;
}

static void dav_svn_db_close(dav_db *db)
{
  /* nothing to do */
}

static dav_error *dav_svn_db_define_namespaces(dav_db *db, dav_xmlns_info *xi)
{
  dav_xmlns_add(xi, "S", SVN_PROP_PREFIX);
  dav_xmlns_add(xi, "C", SVN_PROP_CUSTOM_PREFIX);

  /* ### we don't have any other possible namespaces right now. */

  return NULL;
}

static dav_error *dav_svn_db_output_value(dav_db *db, 
                                          const dav_prop_name *name,
                                          dav_xmlns_info *xi,
                                          apr_text_header *phdr, int *found)
{
  svn_string_t *propval;
  svn_stringbuf_t *xmlsafe = NULL;
  const char *prefix;
  const char *s;
  dav_error *err;

  if ((err = get_value(db, name, &propval)) != NULL)
    return err;

  /* return whether the prop was found, then punt or handle it. */
  *found = propval != NULL;
  if (propval == NULL)
    return NULL;

  /* XML-escape our properties before sending them across the wire. */
  svn_xml_escape_string(&xmlsafe, propval, db->p);

  if (strcmp(name->ns, SVN_PROP_CUSTOM_PREFIX) == 0)
    prefix = "C:";
  else
    prefix = "S:";

  if (xmlsafe->len == 0)
    {
      /* empty value. add an empty elem. */
      s = apr_psprintf(db->p, "<%s%s/>" DEBUG_CR, prefix, name->name);
      apr_text_append(db->p, phdr, s);
    }
  else
    {
      /* add <prefix:name>value</prefix:name> */

      s = apr_psprintf(db->p, "<%s%s>", prefix, name->name);
      apr_text_append(db->p, phdr, s);

      /* the value is in our pool which means it has the right lifetime. */
      /* ### at least, per the current mod_dav architecture/API */
      /* ### oops. apr_text is not binary-safe */
      apr_text_append(db->p, phdr, xmlsafe->data);
      
      s = apr_psprintf(db->p, "</%s%s>" DEBUG_CR, prefix, name->name);
      apr_text_append(db->p, phdr, s);
    }

  return NULL;
}

static dav_error *dav_svn_db_map_namespaces(
    dav_db *db,
    const apr_array_header_t *namespaces,
    dav_namespace_map **mapping)
{
  /* we don't need a namespace mapping right now. nothing to do */

  return NULL;
}

static dav_error *dav_svn_db_store(dav_db *db, const dav_prop_name *name,
                                   const apr_xml_elem *elem,
                                   dav_namespace_map *mapping)
{
  svn_string_t propval;

  /* ### oops. apr_xml is busted: it doesn't allow for binary data at the
     ### moment. thankfully, we aren't using binary props yet. */

  /* SVN sends property values as a big blob of bytes. Thus, there should be
     no child elements of the property-name element. That also means that
     the entire contents of the blob is located in elem->first_cdata. The
     dav_xml_get_cdata() will figure it all out for us, but (normally) it
     should be awfully fast and not need to copy any data. */

  propval.data = dav_xml_get_cdata(elem, db->p, 0 /* strip_white */);
  propval.len = strlen(propval.data);

  return save_value(db, name, &propval);
}

static dav_error *dav_svn_db_remove(dav_db *db, const dav_prop_name *name)
{
  svn_error_t *serr;
  char *propname;

  /* get the repos-local name */
  get_repos_propname(db, name, &propname);

  /* ### non-svn props aren't in our repos, so punt for now */
  if (propname == NULL)
    return NULL;

  /* Working Baseline or Working (Version) Resource */
  if (db->resource->baselined)
    serr = svn_fs_change_txn_prop(db->resource->info->root.txn,
                                  propname, NULL, db->resource->pool);
  else
    serr = svn_fs_change_node_prop(db->resource->info->root.root,
                                   get_repos_path(db->resource->info),
                                   propname, NULL, db->resource->pool);
  if (serr != NULL)
    return dav_svn_convert_err(serr, HTTP_INTERNAL_SERVER_ERROR,
                               "could not remove a property");

  /* a change to the props was made; make sure our cached copy is gone */
  db->props = NULL;

  return NULL;
}

static int dav_svn_db_exists(dav_db *db, const dav_prop_name *name)
{
  char *propname;
  svn_string_t *propval;
  svn_error_t *serr;

  /* get the repos-local name */
  get_repos_propname(db, name, &propname);

  /* ### non-svn props aren't in our repos */
  if (propname == NULL)
    return 0;

  /* Working Baseline, Baseline, or (Working) Version resource */
  if (db->resource->baselined)
    if (db->resource->type == DAV_RESOURCE_TYPE_WORKING)
      serr = svn_fs_txn_prop(&propval, db->resource->info->root.txn,
                             propname, db->p);
    else
      serr = svn_fs_revision_prop(&propval, db->resource->info->repos->fs,
                                  db->resource->info->root.rev,
                                  propname, db->p);
  else
    serr = svn_fs_node_prop(&propval, db->resource->info->root.root,
                            get_repos_path(db->resource->info),
                            propname, db->p);

  /* ### try and dispose of the value? */

  return serr == NULL && propval != NULL;
}

static void get_name(dav_db *db, dav_prop_name *pname)
{
  if (db->hi == NULL)
    {
      pname->ns = pname->name = NULL;
    }
  else
    {
      const void *name;

      apr_hash_this(db->hi, &name, NULL, NULL);

#define PREFIX_LEN (sizeof(SVN_PROP_PREFIX) - 1)
      if (strncmp(name, SVN_PROP_PREFIX, PREFIX_LEN) == 0)
        {
          pname->ns = SVN_PROP_PREFIX;
          pname->name = (const char *)name + 4;
        }
      else
        {
          pname->ns = SVN_PROP_CUSTOM_PREFIX;
          pname->name = name;
        }
    }
}

static dav_error *dav_svn_db_first_name(dav_db *db, dav_prop_name *pname)
{
  /* if we don't have a copy of the properties, then get one */
  if (db->props == NULL)
    {
      svn_error_t *serr;

      /* Working Baseline, Baseline, or (Working) Version resource */
      if (db->resource->baselined)
        if (db->resource->type == DAV_RESOURCE_TYPE_WORKING)
          serr = svn_fs_txn_proplist(&db->props, db->resource->info->root.txn,
                                     db->p);
        else
          serr = svn_fs_revision_proplist(&db->props,
                                          db->resource->info->repos->fs,
                                          db->resource->info->root.rev, db->p);
      else
        serr = svn_fs_node_proplist(&db->props, db->resource->info->root.root,
                                    get_repos_path(db->resource->info), db->p);
      if (serr != NULL)
        return dav_svn_convert_err(serr, HTTP_INTERNAL_SERVER_ERROR,
                                   "could not begin sequencing through "
                                   "properties");
    }

  /* begin the iteration over the hash */
  db->hi = apr_hash_first(db->p, db->props);

  /* fetch the first key */
  get_name(db, pname);

  return NULL;
}

static dav_error *dav_svn_db_next_name(dav_db *db, dav_prop_name *pname)
{
  /* skip to the next hash entry */
  if (db->hi != NULL)
    db->hi = apr_hash_next(db->hi);

  /* fetch the key */
  get_name(db, pname);

  return NULL;
}

static dav_error *dav_svn_db_get_rollback(dav_db *db, const dav_prop_name *name,
                                          dav_deadprop_rollback **prollback)
{
  dav_error *err;
  dav_deadprop_rollback *ddp;
  svn_string_t *propval;

  if ((err = get_value(db, name, &propval)) != NULL)
    return err;

  ddp = apr_palloc(db->p, sizeof(*ddp));
  ddp->name = *name;
  ddp->value.data = propval ? propval->data : NULL;
  ddp->value.len = propval ? propval->len : 0;

  *prollback = ddp;
  return NULL;
}

static dav_error *dav_svn_db_apply_rollback(dav_db *db,
                                            dav_deadprop_rollback *rollback)
{
  if (rollback->value.data == NULL)
    {
      return dav_svn_db_remove(db, &rollback->name);
    }
  
  return save_value(db, &rollback->name, &rollback->value);
}


const dav_hooks_propdb dav_svn_hooks_propdb = {
  dav_svn_db_open,
  dav_svn_db_close,
  dav_svn_db_define_namespaces,
  dav_svn_db_output_value,
  dav_svn_db_map_namespaces,
  dav_svn_db_store,
  dav_svn_db_remove,
  dav_svn_db_exists,
  dav_svn_db_first_name,
  dav_svn_db_next_name,
  dav_svn_db_get_rollback,
  dav_svn_db_apply_rollback,
};


/* 
 * local variables:
 * eval: (load-file "../../tools/dev/svn-dev.el")
 * end:
 */