/*
 * diff.c :  routines for doing diffs
 *
 * ====================================================================
 * Copyright (c) 2000-2004 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 <apr.h>
#include <apr_pools.h>
#include <apr_general.h>

#include "svn_pools.h"
#include "svn_error.h"
#include "svn_diff.h"
#include "svn_types.h"

#include "diff.h"


svn_diff_t *
svn_diff__diff(svn_diff__lcs_t *lcs,
               apr_off_t original_start, apr_off_t modified_start,
               svn_boolean_t want_common,
               apr_pool_t *pool)
{
  svn_diff_t *diff;
  svn_diff_t **diff_ref = &diff;

  while (1)
    {
      if (original_start < lcs->position[0]->offset
          || modified_start < lcs->position[1]->offset)
      {
          (*diff_ref) = apr_palloc(pool, sizeof(**diff_ref));

          (*diff_ref)->type = svn_diff__type_diff_modified;
          (*diff_ref)->original_start = original_start - 1;
          (*diff_ref)->original_length = 
            lcs->position[0]->offset - original_start;
          (*diff_ref)->modified_start = modified_start - 1;
          (*diff_ref)->modified_length = 
            lcs->position[1]->offset - modified_start;
          (*diff_ref)->latest_start = 0;
          (*diff_ref)->latest_length = 0;

          diff_ref = &(*diff_ref)->next;
      }

      /* Detect the EOF */
      if (lcs->length == 0)
          break;

      original_start = lcs->position[0]->offset;
      modified_start = lcs->position[1]->offset;

      if (want_common)
        {
          (*diff_ref) = apr_palloc(pool, sizeof(**diff_ref));

          (*diff_ref)->type = svn_diff__type_common;
          (*diff_ref)->original_start = original_start - 1;
          (*diff_ref)->original_length = lcs->length;
          (*diff_ref)->modified_start = modified_start - 1;
          (*diff_ref)->modified_length = lcs->length;
          (*diff_ref)->latest_start = 0;
          (*diff_ref)->latest_length = 0;

          diff_ref = &(*diff_ref)->next;
        }

      original_start += lcs->length;
      modified_start += lcs->length;

      lcs = lcs->next;
    }

  *diff_ref = NULL;

  return diff;
}


svn_error_t *
svn_diff_diff(svn_diff_t **diff,
              void *diff_baton,
              const svn_diff_fns_t *vtable,
              apr_pool_t *pool)
{
  svn_diff__tree_t *tree;
  svn_diff__position_t *position_list[2];
  svn_diff__lcs_t *lcs;
  apr_pool_t *subpool;
  apr_pool_t *treepool;

  *diff = NULL;

  subpool = svn_pool_create(pool);
  treepool = svn_pool_create(pool);

  svn_diff__tree_create(&tree, treepool);

  /* Insert the data into the tree */
  SVN_ERR(svn_diff__get_tokens(&position_list[0],
                               tree,
                               diff_baton, vtable,
                               svn_diff_datasource_original,
                               subpool));

  SVN_ERR(svn_diff__get_tokens(&position_list[1],
                               tree,
                               diff_baton, vtable,
                               svn_diff_datasource_modified,
                               subpool));

  /* The cool part is that we don't need the tokens anymore.
   * Allow the app to clean them up if it wants to.
   */
  if (vtable->token_discard_all != NULL)
    vtable->token_discard_all(diff_baton);

  /* We don't need the nodes in the tree either anymore, nor the tree itself */
  svn_pool_destroy(treepool);

  /* Get the lcs */
  lcs = svn_diff__lcs(position_list[0], position_list[1], subpool);

  /* Produce the diff */
  *diff = svn_diff__diff(lcs, 1, 1, TRUE, pool);

  /* Get rid of all the data we don't have a use for anymore */
  svn_pool_destroy(subpool);

  return SVN_NO_ERROR;
}
