/*

 * Copyright (C) the libgit2 contributors. All rights reserved.

 *

 * 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 "common.h"

#include "commit.h"

#include "odb.h"

#include "pool.h"

#include "revwalk.h"

#include "git2/revparse.h"

#include "merge.h"

#include "vector.h"

git_commit_list_node *git_revwalk__commit_lookup(

	git_revwalk *walk, const git_oid *oid)

{

	git_commit_list_node *commit;

	khiter_t pos;

	int ret;

	/* lookup and reserve space if not already present */

	pos = git_oidmap_lookup_index(walk->commits, oid);

	if (git_oidmap_valid_index(walk->commits, pos))

		return git_oidmap_value_at(walk->commits, pos);

	commit = git_commit_list_alloc_node(walk);

	if (commit == NULL)

		return NULL;

	git_oid_cpy(&commit->oid, oid);

	pos = git_oidmap_put(walk->commits, &commit->oid, &ret;;

	assert(ret != 0);

	git_oidmap_set_value_at(walk->commits, pos, commit);

	return commit;

}

static int push_commit(git_revwalk *walk, const git_oid *oid, int uninteresting, int from_glob)

{

	git_oid commit_id;

	int error;

	git_object *obj, *oobj;

	git_commit_list_node *commit;

	git_commit_list *list;

	if ((error = git_object_lookup(&oobj, walk->repo, oid, GIT_OBJ_ANY)) < 0)

		return error;

	error = git_object_peel(&obj, oobj, GIT_OBJ_COMMIT);

	git_object_free(oobj);

	if (error == GIT_ENOTFOUND || error == GIT_EINVALIDSPEC || error == GIT_EPEEL) {

		/* If this comes from e.g. push_glob("tags"), ignore this */

		if (from_glob)

			return 0;

		giterr_set(GITERR_INVALID, "object is not a committish");

		return -1;

	}

	if (error < 0)

		return error;

	git_oid_cpy(&commit_id, git_object_id(obj));

	git_object_free(obj);

	commit = git_revwalk__commit_lookup(walk, &commit_id);

	if (commit == NULL)

		return -1; /* error already reported by failed lookup */

	/* A previous hide already told us we don't want this commit  */

	if (commit->uninteresting)

		return 0;

	if (uninteresting)

		walk->did_hide = 1;

	else

		walk->did_push = 1;

	commit->uninteresting = uninteresting;

	list = walk->user_input;

	if (git_commit_list_insert(commit, &list) == NULL) {

		giterr_set_oom();

		return -1;

	}

	walk->user_input = list;

	return 0;

}

int git_revwalk_push(git_revwalk *walk, const git_oid *oid)

{

	assert(walk && oid);

	return push_commit(walk, oid, 0, false);

}

int git_revwalk_hide(git_revwalk *walk, const git_oid *oid)

{

	assert(walk && oid);

	return push_commit(walk, oid, 1, false);

}

static int push_ref(git_revwalk *walk, const char *refname, int hide, int from_glob)

{

	git_oid oid;

	if (git_reference_name_to_id(&oid, walk->repo, refname) < 0)

		return -1;

	return push_commit(walk, &oid, hide, from_glob);

}

static int push_glob(git_revwalk *walk, const char *glob, int hide)

{

	int error = 0;

	git_buf buf = GIT_BUF_INIT;

	git_reference *ref;

	git_reference_iterator *iter;

	size_t wildcard;

	assert(walk && glob);

	/* refs/ is implied if not given in the glob */

	if (git__prefixcmp(glob, GIT_REFS_DIR) != 0)

		git_buf_joinpath(&buf, GIT_REFS_DIR, glob);

	else

		git_buf_puts(&buf, glob);

	GITERR_CHECK_ALLOC_BUF(&buf;;

	/* If no '?', '*' or '[' exist, we append '/ *' to the glob */

	wildcard = strcspn(glob, "?*[");

	if (!glob[wildcard])

		git_buf_put(&buf, "/*", 2);

	if ((error = git_reference_iterator_glob_new(&iter, walk->repo, buf.ptr)) < 0)

		goto out;

	while ((error = git_reference_next(&ref, iter)) == 0) {

		error = push_ref(walk, git_reference_name(ref), hide, true);

		git_reference_free(ref);

		if (error < 0)

			break;

	}

	git_reference_iterator_free(iter);

	if (error == GIT_ITEROVER)

		error = 0;

out:

	git_buf_free(&buf;;

	return error;

}

int git_revwalk_push_glob(git_revwalk *walk, const char *glob)

{

	assert(walk && glob);

	return push_glob(walk, glob, 0);

}

int git_revwalk_hide_glob(git_revwalk *walk, const char *glob)

{

	assert(walk && glob);

	return push_glob(walk, glob, 1);

}

int git_revwalk_push_head(git_revwalk *walk)

{

	assert(walk);

	return push_ref(walk, GIT_HEAD_FILE, 0, false);

}

int git_revwalk_hide_head(git_revwalk *walk)

{

	assert(walk);

	return push_ref(walk, GIT_HEAD_FILE, 1, false);

}

int git_revwalk_push_ref(git_revwalk *walk, const char *refname)

{

	assert(walk && refname);

	return push_ref(walk, refname, 0, false);

}

int git_revwalk_push_range(git_revwalk *walk, const char *range)

{

	git_revspec revspec;

	int error = 0;

	if ((error = git_revparse(&revspec, walk->repo, range)))

		return error;

	if (revspec.flags & GIT_REVPARSE_MERGE_BASE) {

		/* TODO: support "<commit>...<commit>" */

		giterr_set(GITERR_INVALID, "symmetric differences not implemented in revwalk");

		return GIT_EINVALIDSPEC;

	}

	if ((error = push_commit(walk, git_object_id(revspec.from), 1, false)))

		goto out;

	error = push_commit(walk, git_object_id(revspec.to), 0, false);

out:

	git_object_free(revspec.from);

	git_object_free(revspec.to);

	return error;

}

int git_revwalk_hide_ref(git_revwalk *walk, const char *refname)

{

	assert(walk && refname);

	return push_ref(walk, refname, 1, false);

}

static int revwalk_enqueue_timesort(git_revwalk *walk, git_commit_list_node *commit)

{

	return git_pqueue_insert(&walk->iterator_time, commit);

}

static int revwalk_enqueue_unsorted(git_revwalk *walk, git_commit_list_node *commit)

{

	return git_commit_list_insert(commit, &walk->iterator_rand) ? 0 : -1;

}

static int revwalk_next_timesort(git_commit_list_node **object_out, git_revwalk *walk)

{

	git_commit_list_node *next;

	while ((next = git_pqueue_pop(&walk->iterator_time)) != NULL) {

		/* Some commits might become uninteresting after being added to the list */

		if (!next->uninteresting) {

			*object_out = next;

			return 0;

		}

	}

	giterr_clear();

	return GIT_ITEROVER;

}

static int revwalk_next_unsorted(git_commit_list_node **object_out, git_revwalk *walk)

{

	git_commit_list_node *next;

	while ((next = git_commit_list_pop(&walk->iterator_rand)) != NULL) {

		/* Some commits might become uninteresting after being added to the list */

		if (!next->uninteresting) {

			*object_out = next;

			return 0;

		}

	}

	giterr_clear();

	return GIT_ITEROVER;

}

static int revwalk_next_toposort(git_commit_list_node **object_out, git_revwalk *walk)

{

	git_commit_list_node *next;

	while ((next = git_commit_list_pop(&walk->iterator_topo)) != NULL) {

		/* Some commits might become uninteresting after being added to the list */

		if (!next->uninteresting) {

			*object_out = next;

			return 0;

		}

	}

	giterr_clear();

	return GIT_ITEROVER;

}

static int revwalk_next_reverse(git_commit_list_node **object_out, git_revwalk *walk)

{

	*object_out = git_commit_list_pop(&walk->iterator_reverse);

	return *object_out ? 0 : GIT_ITEROVER;

}

static void mark_parents_uninteresting(git_commit_list_node *commit)

{

	unsigned short i;

	git_commit_list *parents = NULL;

	for (i = 0; i < commit->out_degree; i++)

		git_commit_list_insert(commit->parents[i], &parents);

	while (parents) {

		commit = git_commit_list_pop(&parents);

		while (commit) {

			if (commit->uninteresting)

				break;

			commit->uninteresting = 1;

			/*

			 * If we've reached this commit some other way

			 * already, we need to mark its parents uninteresting

			 * as well.

			 */

			if (!commit->parents)

				break;

			for (i = 0; i < commit->out_degree; i++)

				git_commit_list_insert(commit->parents[i], &parents);

			commit = commit->parents[0];

		}

	}

}

static int add_parents_to_list(git_revwalk *walk, git_commit_list_node *commit, git_commit_list **list)

{

	unsigned short i;

	int error;

	if (commit->added)

		return 0;

	commit->added = 1;

	/*

	 * Go full on in the uninteresting case as we want to include

	 * as many of these as we can.

	 *

	 * Usually we haven't parsed the parent of a parent, but if we

	 * have it we reached it via other means so we want to mark

	 * its parents recursively too.

	 */

	if (commit->uninteresting) {

		for (i = 0; i < commit->out_degree; i++) {

			git_commit_list_node *p = commit->parents[i];

			p->uninteresting = 1;

			/* git does it gently here, but we don't like missing objects */

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

				return error;

			if (p->parents)

				mark_parents_uninteresting(p);

			p->seen = 1;

			git_commit_list_insert_by_date(p, list);

		}

		return 0;

	}

	/*

	 * Now on to what we do if the commit is indeed

	 * interesting. Here we do want things like first-parent take

	 * effect as this is what we'll be showing.

	 */

	for (i = 0; i < commit->out_degree; i++) {

		git_commit_list_node *p = commit->parents[i];

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

			return error;

		if (walk->hide_cb && walk->hide_cb(&p->oid, walk->hide_cb_payload))

			continue;

		if (!p->seen) {

			p->seen = 1;

			git_commit_list_insert_by_date(p, list);

		}

		if (walk->first_parent)

			break;

	}

	return 0;

}

static int everybody_uninteresting(git_commit_list *orig)

{

	git_commit_list *list = orig;

	while (list) {

		git_commit_list_node *commit = list->item;

		list = list->next;

		if (!commit->uninteresting)

			return 0;

	}

	return 1;

}

/* How many unintersting commits we want to look at after we run out of interesting ones */

#define SLOP 5

static int still_interesting(git_commit_list *list, int64_t time, int slop)

{

	/* The empty list is pretty boring */

	if (!list)

		return 0;

	/*

	 * If the destination list has commits with an earlier date

	 * than our source we want to continue looking.

	 */

	if (time <= list->item->time)

		return SLOP;

	/* If we find interesting commits, we reset the slop count */

	if (!everybody_uninteresting(list))

		return SLOP;

	/* Everything's uninteresting, reduce the count */

	return slop - 1;

}

static int limit_list(git_commit_list **out, git_revwalk *walk, git_commit_list *commits)

{

	int error, slop = SLOP;

	int64_t time = ~0ll;

	git_commit_list *list = commits;

	git_commit_list *newlist = NULL;

	git_commit_list **p = &newlist;

	while (list) {

		git_commit_list_node *commit = git_commit_list_pop(&list);

		if ((error = add_parents_to_list(walk, commit, &list)) < 0)

			return error;

		if (commit->uninteresting) {

			mark_parents_uninteresting(commit);

			slop = still_interesting(list, time, slop);

			if (slop)

				continue;

			break;

		}

		if (!commit->uninteresting && walk->hide_cb && walk->hide_cb(&commit->oid, walk->hide_cb_payload))

				continue;

		time = commit->time;

		p = &git_commit_list_insert(commit, p)->next;

	}

	git_commit_list_free(&list);

	*out = newlist;

	return 0;

}

static int sort_in_topological_order(git_commit_list **out, git_revwalk *walk, git_commit_list *list)

{

	git_commit_list *ll = NULL, *newlist, **pptr;

	git_commit_list_node *next;

	git_pqueue queue;

	git_vector_cmp queue_cmp = NULL;

	unsigned short i;

	int error;

	if (walk->sorting & GIT_SORT_TIME)

		queue_cmp = git_commit_list_time_cmp;

	if ((error = git_pqueue_init(&queue, 0, 8, queue_cmp)))

		return error;

	/*

	 * Start by resetting the in-degree to 1 for the commits in

	 * our list. We want to go through this list again, so we

	 * store it in the commit list as we extract it from the lower

	 * machinery.

	 */

	for (ll = list; ll; ll = ll->next) {

		ll->item->in_degree = 1;

	}

	/*

	 * Count up how many children each commit has. We limit

	 * ourselves to those commits in the original list (in-degree

	 * of 1) avoiding setting it for any parent that was hidden.

	 */

	for(ll = list; ll; ll = ll->next) {

		for (i = 0; i < ll->item->out_degree; ++i) {

			git_commit_list_node *parent = ll->item->parents[i];

			if (parent->in_degree)

				parent->in_degree++;

		}

	}

	/*

	 * Now we find the tips i.e. those not reachable from any other node

	 * i.e. those which still have an in-degree of 1.

	 */

	for(ll = list; ll; ll = ll->next) {

		if (ll->item->in_degree == 1) {

			if ((error = git_pqueue_insert(&queue, ll->item)))

				goto cleanup;

		}

	}

	/*

	 * We need to output the tips in the order that they came out of the

	 * traversal, so if we're not doing time-sorting, we need to reverse the

	 * pqueue in order to get them to come out as we inserted them.

	 */

	if ((walk->sorting & GIT_SORT_TIME) == 0)

		git_pqueue_reverse(&queue);

	pptr = &newlist;

	newlist = NULL;

	while ((next = git_pqueue_pop(&queue)) != NULL) {

		for (i = 0; i < next->out_degree; ++i) {

			git_commit_list_node *parent = next->parents[i];

			if (parent->in_degree == 0)

				continue;

			if (--parent->in_degree == 1) {

				if ((error = git_pqueue_insert(&queue, parent)))

					goto cleanup;

			}

		}

		/* All the children of 'item' have been emitted (since we got to it via the priority queue) */

		next->in_degree = 0;

		pptr = &git_commit_list_insert(next, pptr)->next;

	}

	*out = newlist;

	error = 0;

cleanup:

	git_pqueue_free(&queue);

	return error;

}

static int prepare_walk(git_revwalk *walk)

{

	int error;

	git_commit_list *list, *commits = NULL;

	git_commit_list_node *next;

	/* If there were no pushes, we know that the walk is already over */

	if (!walk->did_push) {

		giterr_clear();

		return GIT_ITEROVER;

	}

	for (list = walk->user_input; list; list = list->next) {

		git_commit_list_node *commit = list->item;

		if ((error = git_commit_list_parse(walk, commit)) < 0)

			return error;

		if (commit->uninteresting)

			mark_parents_uninteresting(commit);

		if (!commit->seen) {

			commit->seen = 1;

			git_commit_list_insert(commit, &commits);

		}

	}

	if ((error = limit_list(&commits, walk, commits)) < 0)

		return error;

	if (walk->sorting & GIT_SORT_TOPOLOGICAL) {

		error = sort_in_topological_order(&walk->iterator_topo, walk, commits);

		git_commit_list_free(&commits);

		if (error < 0)

			return error;

		walk->get_next = &revwalk_next_toposort;

	} else if (walk->sorting & GIT_SORT_TIME) {

		for (list = commits; list && !error; list = list->next)

			error = walk->enqueue(walk, list->item);

		git_commit_list_free(&commits);

		if (error < 0)

			return error;

	} else {

		walk->iterator_rand = commits;

		walk->get_next = revwalk_next_unsorted;

	}

	if (walk->sorting & GIT_SORT_REVERSE) {

		while ((error = walk->get_next(&next, walk)) == 0)

			if (git_commit_list_insert(next, &walk->iterator_reverse) == NULL)

				return -1;

		if (error != GIT_ITEROVER)

			return error;

		walk->get_next = &revwalk_next_reverse;

	}

	walk->walking = 1;

	return 0;

}

int git_revwalk_new(git_revwalk **revwalk_out, git_repository *repo)

{

	git_revwalk *walk = git__calloc(1, sizeof(git_revwalk));

	GITERR_CHECK_ALLOC(walk);

	walk->commits = git_oidmap_alloc();

	GITERR_CHECK_ALLOC(walk->commits);

	if (git_pqueue_init(&walk->iterator_time, 0, 8, git_commit_list_time_cmp) < 0)

		return -1;

	git_pool_init(&walk->commit_pool, COMMIT_ALLOC);

	walk->get_next = &revwalk_next_unsorted;

	walk->enqueue = &revwalk_enqueue_unsorted;

	walk->repo = repo;

	if (git_repository_odb(&walk->odb, repo) < 0) {

		git_revwalk_free(walk);

		return -1;

	}

	*revwalk_out = walk;

	return 0;

}

void git_revwalk_free(git_revwalk *walk)

{

	if (walk == NULL)

		return;

	git_revwalk_reset(walk);

	git_odb_free(walk->odb);

	git_oidmap_free(walk->commits);

	git_pool_clear(&walk->commit_pool);

	git_pqueue_free(&walk->iterator_time);

	git__free(walk);

}

git_repository *git_revwalk_repository(git_revwalk *walk)

{

	assert(walk);

	return walk->repo;

}

void git_revwalk_sorting(git_revwalk *walk, unsigned int sort_mode)

{

	assert(walk);

	if (walk->walking)

		git_revwalk_reset(walk);

	walk->sorting = sort_mode;

	if (walk->sorting & GIT_SORT_TIME) {

		walk->get_next = &revwalk_next_timesort;

		walk->enqueue = &revwalk_enqueue_timesort;

	} else {

		walk->get_next = &revwalk_next_unsorted;

		walk->enqueue = &revwalk_enqueue_unsorted;

	}

}

void git_revwalk_simplify_first_parent(git_revwalk *walk)

{

	walk->first_parent = 1;

}

int git_revwalk_next(git_oid *oid, git_revwalk *walk)

{

	int error;

	git_commit_list_node *next;

	assert(walk && oid);

	if (!walk->walking) {

		if ((error = prepare_walk(walk)) < 0)

			return error;

	}

	error = walk->get_next(&next, walk);

	if (error == GIT_ITEROVER) {

		git_revwalk_reset(walk);

		giterr_clear();

		return GIT_ITEROVER;

	}

	if (!error)

		git_oid_cpy(oid, &next->oid);

	return error;

}

void git_revwalk_reset(git_revwalk *walk)

{

	git_commit_list_node *commit;

	assert(walk);

	git_oidmap_foreach_value(walk->commits, commit, {

		commit->seen = 0;

		commit->in_degree = 0;

		commit->topo_delay = 0;

		commit->uninteresting = 0;

		commit->added = 0;

		commit->flags = 0;

		});

	git_pqueue_clear(&walk->iterator_time);

	git_commit_list_free(&walk->iterator_topo);

	git_commit_list_free(&walk->iterator_rand);

	git_commit_list_free(&walk->iterator_reverse);

	git_commit_list_free(&walk->user_input);

	walk->first_parent = 0;

	walk->walking = 0;

	walk->did_push = walk->did_hide = 0;

}

int git_revwalk_add_hide_cb(

	git_revwalk *walk,

	git_revwalk_hide_cb hide_cb,

	void *payload)

{

	assert(walk);

	if (walk->walking)

		git_revwalk_reset(walk);

	if (walk->hide_cb) {

		/* There is already a callback added */

		giterr_set(GITERR_INVALID, "there is already a callback added to hide commits in revwalk");

		return -1;

	}

	walk->hide_cb = hide_cb;

	walk->hide_cb_payload = payload;

	return 0;

}