#include "git-compat-util.h"

#include "diff.h"

#include "commit.h"

#include "hash.h"

#include "hex.h"

#include "patch-ids.h"

static int patch_id_defined(struct commit *commit)

{

  /* must be 0 or 1 parents */

  return !commit->parents || !commit->parents->next;

}

int commit_patch_id(struct commit *commit, struct diff_options *options,

        struct object_id *oid, int diff_header_only)

{

  if (!patch_id_defined(commit))

    return -1;

  if (commit->parents)

    diff_tree_oid(&commit->parents->item->object.oid,

            &commit->object.oid, "", options);

  else

    diff_root_tree_oid(&commit->object.oid, "", options);

  diffcore_std(options);

  return diff_flush_patch_id(options, oid, diff_header_only);

}

/*

 * When we cannot load the full patch-id for both commits for whatever

 * reason, the function returns -1 (i.e. return error(...)). Despite

 * the "neq" in the name of this function, the caller only cares about

 * the return value being zero (a and b are equivalent) or non-zero (a

 * and b are different), and returning non-zero would keep both in the

 * result, even if they actually were equivalent, in order to err on

 * the side of safety.  The actual value being negative does not have

 * any significance; only that it is non-zero matters.

 */

static int patch_id_neq(const void *cmpfn_data,

      const struct hashmap_entry *eptr,

      const struct hashmap_entry *entry_or_key,

      const void *keydata UNUSED)

{

  /*

   * We drop the 'const' modifier here intentionally.

   *

   * Even though eptr and entry_or_key are const, we want to

   * lazily compute their .patch_id members; see b3dfeebb (rebase:

   * avoid computing unnecessary patch IDs, 2016-07-29). So we cast

   * the constness away with container_of().

   */

  struct diff_options *opt = (void *)cmpfn_data;

  struct patch_id *a, *b;

  a = container_of(eptr, struct patch_id, ent);

  b = container_of(entry_or_key, struct patch_id, ent);

  if (is_null_oid(&a->patch_id) &&

      commit_patch_id(a->commit, opt, &a->patch_id, 0))

    return error("Could not get patch ID for %s",

      oid_to_hex(&a->commit->object.oid));

  if (is_null_oid(&b->patch_id) &&

      commit_patch_id(b->commit, opt, &b->patch_id, 0))

    return error("Could not get patch ID for %s",

      oid_to_hex(&b->commit->object.oid));

  return !oideq(&a->patch_id, &b->patch_id);

}

int init_patch_ids(struct repository *r, struct patch_ids *ids)

{

  memset(ids, 0, sizeof(*ids));

  repo_diff_setup(r, &ids->diffopts);

  ids->diffopts.detect_rename = 0;

  ids->diffopts.flags.recursive = 1;

  diff_setup_done(&ids->diffopts);

  hashmap_init(&ids->patches, patch_id_neq, &ids->diffopts, 256);

  return 0;

}

int free_patch_ids(struct patch_ids *ids)

{

  hashmap_clear_and_free(&ids->patches, struct patch_id, ent);

  return 0;

}

static int init_patch_id_entry(struct patch_id *patch,

             struct commit *commit,

             struct patch_ids *ids)

{

  struct object_id header_only_patch_id;

  patch->commit = commit;

  if (commit_patch_id(commit, &ids->diffopts, &header_only_patch_id, 1))

    return -1;

  hashmap_entry_init(&patch->ent, oidhash(&header_only_patch_id));

  return 0;

}

struct patch_id *patch_id_iter_first(struct commit *commit,

             struct patch_ids *ids)

{

  struct patch_id patch;

  if (!patch_id_defined(commit))

    return NULL;

  memset(&patch, 0, sizeof(patch));

  if (init_patch_id_entry(&patch, commit, ids))

    return NULL;

  return hashmap_get_entry(&ids->patches, &patch, ent, NULL);

}

struct patch_id *patch_id_iter_next(struct patch_id *cur,

            struct patch_ids *ids)

{

  return hashmap_get_next_entry(&ids->patches, cur, ent);

}

int has_commit_patch_id(struct commit *commit,

      struct patch_ids *ids)

{

  return !!patch_id_iter_first(commit, ids);

}

struct patch_id *add_commit_patch_id(struct commit *commit,

             struct patch_ids *ids)

{

  struct patch_id *key;

  if (!patch_id_defined(commit))

    return NULL;

  CALLOC_ARRAY(key, 1);

  if (init_patch_id_entry(key, commit, ids)) {

    free(key);

    return NULL;

  }

  hashmap_add(&ids->patches, &key->ent);

  return key;

}