/*
 * Copyright (C) 2009-2012 the libgit2 contributors
 *
 * This file is part of libgit2, distributed under the GNU GPL v2 with
 * a Linking Exception. For full terms see the included COPYING file.
 */

#include "repository.h"
#include "revwalk.h"
#include "buffer.h"
#include "merge.h"
#include "refs.h"
#include "git2/repository.h"
#include "git2/merge.h"
#include "git2/reset.h"
#include "commit_list.h"

int git_merge__cleanup(git_repository *repo)
{
	int error = 0;
	git_buf merge_head_path = GIT_BUF_INIT,
		merge_mode_path = GIT_BUF_INIT,
		merge_msg_path = GIT_BUF_INIT;

	assert(repo);

	if (git_buf_joinpath(&merge_head_path, repo->path_repository, GIT_MERGE_HEAD_FILE) < 0 ||
		git_buf_joinpath(&merge_mode_path, repo->path_repository, GIT_MERGE_MODE_FILE) < 0 ||
		git_buf_joinpath(&merge_mode_path, repo->path_repository, GIT_MERGE_MODE_FILE) < 0)
		return -1;

	if (git_path_isfile(merge_head_path.ptr)) {
		if ((error = p_unlink(merge_head_path.ptr)) < 0)
			goto cleanup;
	}

	if (git_path_isfile(merge_mode_path.ptr))
		(void)p_unlink(merge_mode_path.ptr);

	if (git_path_isfile(merge_msg_path.ptr))
		(void)p_unlink(merge_msg_path.ptr);

cleanup:
	git_buf_free(&merge_msg_path);
	git_buf_free(&merge_mode_path);
	git_buf_free(&merge_head_path);

	return error;
}

int git_merge_base_many(git_oid *out, git_repository *repo, const git_oid input_array[], size_t length)
{
	git_revwalk *walk;
	git_vector list;
	git_commit_list *result = NULL;
	int error = -1;
	unsigned int i;
	git_commit_list_node *commit;

	assert(out && repo && input_array);

	if (length < 2) {
		giterr_set(GITERR_INVALID, "At least two commits are required to find an ancestor. Provided 'length' was %u.", length);
		return -1;
	}

	if (git_vector_init(&list, length - 1, NULL) < 0)
		return -1;

	if (git_revwalk_new(&walk, repo) < 0)
		goto cleanup;

	for (i = 1; i < length; i++) {
		commit = git_revwalk__commit_lookup(walk, &input_array[i]);
		if (commit == NULL)
			goto cleanup;

		git_vector_insert(&list, commit);
	}

	commit = git_revwalk__commit_lookup(walk, &input_array[0]);
	if (commit == NULL)
		goto cleanup;

	if (git_merge__bases_many(&result, walk, commit, &list) < 0)
		goto cleanup;

	if (!result) {
		error = GIT_ENOTFOUND;
		goto cleanup;
	}

	git_oid_cpy(out, &result->item->oid);

	error = 0;

cleanup:
	git_commit_list_free(&result);
	git_revwalk_free(walk);
	git_vector_free(&list);
	return error;
}

int git_merge_base(git_oid *out, git_repository *repo, const git_oid *one, const git_oid *two)
{
	git_revwalk *walk;
	git_vector list;
	git_commit_list *result = NULL;
	git_commit_list_node *commit;
	void *contents[1];

	if (git_revwalk_new(&walk, repo) < 0)
		return -1;

	commit = git_revwalk__commit_lookup(walk, two);
	if (commit == NULL)
		goto on_error;

	/* This is just one value, so we can do it on the stack */
	memset(&list, 0x0, sizeof(git_vector));
	contents[0] = commit;
	list.length = 1;
	list.contents = contents;

	commit = git_revwalk__commit_lookup(walk, one);
	if (commit == NULL)
		goto on_error;

	if (git_merge__bases_many(&result, walk, commit, &list) < 0)
		goto on_error;

	if (!result) {
		git_revwalk_free(walk);
		giterr_clear();
		return GIT_ENOTFOUND;
	}

	git_oid_cpy(out, &result->item->oid);
	git_commit_list_free(&result);
	git_revwalk_free(walk);

	return 0;

on_error:
	git_revwalk_free(walk);
	return -1;
}

static int interesting(git_pqueue *list)
{
	unsigned int i;
	/* element 0 isn't used - we need to start at 1 */
	for (i = 1; i < list->size; i++) {
		git_commit_list_node *commit = list->d[i];
		if ((commit->flags & STALE) == 0)
			return 1;
	}

	return 0;
}

int git_merge__bases_many(git_commit_list **out, git_revwalk *walk, git_commit_list_node *one, git_vector *twos)
{
	int error;
	unsigned int i;
	git_commit_list_node *two;
	git_commit_list *result = NULL, *tmp = NULL;
	git_pqueue list;

	/* if the commit is repeated, we have a our merge base already */
	git_vector_foreach(twos, i, two) {
		if (one == two)
			return git_commit_list_insert(one, out) ? 0 : -1;
	}

	if (git_pqueue_init(&list, twos->length * 2, git_commit_list_time_cmp) < 0)
		return -1;

	if (git_commit_list_parse(walk, one) < 0)
	    return -1;

	one->flags |= PARENT1;
	if (git_pqueue_insert(&list, one) < 0)
		return -1;

	git_vector_foreach(twos, i, two) {
		git_commit_list_parse(walk, two);
		two->flags |= PARENT2;
		if (git_pqueue_insert(&list, two) < 0)
			return -1;
	}

	/* as long as there are non-STALE commits */
	while (interesting(&list)) {
		git_commit_list_node *commit;
		int flags;

		commit = git_pqueue_pop(&list);

		flags = commit->flags & (PARENT1 | PARENT2 | STALE);
		if (flags == (PARENT1 | PARENT2)) {
			if (!(commit->flags & RESULT)) {
				commit->flags |= RESULT;
				if (git_commit_list_insert(commit, &result) == NULL)
					return -1;
			}
			/* we mark the parents of a merge stale */
			flags |= STALE;
		}

		for (i = 0; i < commit->out_degree; i++) {
			git_commit_list_node *p = commit->parents[i];
			if ((p->flags & flags) == flags)
				continue;

			if ((error = git_commit_list_parse(walk, p)) < 0)
				return error;

			p->flags |= flags;
			if (git_pqueue_insert(&list, p) < 0)
				return -1;
		}
	}

	git_pqueue_free(&list);

	/* filter out any stale commits in the results */
	tmp = result;
	result = NULL;

	while (tmp) {
		struct git_commit_list *next = tmp->next;
		if (!(tmp->item->flags & STALE))
			if (git_commit_list_insert_by_date(tmp->item, &result) == NULL)
				return -1;

		git__free(tmp);
		tmp = next;
	}

	*out = result;
	return 0;
}
