/*
 * This file is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License, version 2,
 * as published by the Free Software Foundation.
 *
 * In addition to the permissions in the GNU General Public License,
 * the authors give you unlimited permission to link the compiled
 * version of this file into combinations with other programs,
 * and to distribute those combinations without any restriction
 * coming from the use of this file.  (The General Public License
 * restrictions do apply in other respects; for example, they cover
 * modification of the file, and distribution when not linked into
 * a combined executable.)
 *
 * This file is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; see the file COPYING.  If not, write to
 * the Free Software Foundation, 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 */

#include "git2/remote.h"
#include "git2/oid.h"
#include "git2/refs.h"
#include "git2/revwalk.h"

#include "common.h"
#include "transport.h"
#include "remote.h"
#include "refspec.h"
#include "fetch.h"

/*
 * Don't forget that this depends on the enum being correctly set
 */
static int whn_cmp(const void *a, const void *b)
{
	git_remote_head *heada = (git_remote_head *) a;
	git_remote_head *headb = (git_remote_head *) b;

	return headb->type - heada->type;
}

int filter_wants(git_remote *remote)
{
	git_vector list;
	git_headarray refs;
	git_transport *t = remote->transport;
	git_repository *repo = remote->repo;
	const git_refspec *spec;
	int error;
	unsigned int i;

	error = git_vector_init(&list, 16, whn_cmp);
	if (error < GIT_SUCCESS)
		return error;

	error = git_transport_ls(t, &refs);
	if (error < GIT_SUCCESS) {
		error = git__rethrow(error, "Failed to list local refs");
		goto cleanup;
	}

	spec = git_remote_fetchspec(remote);
	if (spec == NULL) {
		error = git__throw(GIT_ERROR, "The remote has to fetchspec");
		goto cleanup;
	}

	for (i = 0; i < refs.len; ++i) {
		char local[1024];
		git_reference *ref;
		git_remote_head *head = refs.heads[i];

		/* If it doesn't match the refpec, we don't want it */
		error = git_refspec_src_match(spec, head->name);
		if (error == GIT_ENOMATCH)
			continue;
		if (error < GIT_SUCCESS) {
			error = git__rethrow(error, "Error matching remote ref name");
			goto cleanup;
		}

		/* If the local ref is the same, we don't want it either */
		error = git_refspec_transform(local, sizeof(local), spec, head->name);
		if (error < GIT_SUCCESS) {
			error = git__rethrow(error, "Error transforming ref name");
			goto cleanup;
		}

		error = git_reference_lookup(&ref, repo, local);
		/* If we don't have it locally, it's new, so we want it */
		if (error < GIT_SUCCESS && error != GIT_ENOTFOUND) {
			error = git__rethrow(error, "Error looking up local ref");
			goto cleanup;
		}

		if (ref != NULL) {
			if (!git_oid_cmp(&head->oid, git_reference_oid(ref)))
				continue;

			head->local = 1;
			git_oid_cpy(&head->loid, git_reference_oid(ref));
		}

		/*
		 * Now we know we want to have that ref, so add it as a "want"
		 * to the list, storing the local oid for that branch so we
		 * don't have to look for it again.
		 */
		head->type = GIT_WHN_WANT;
		error = git_vector_insert(&list, head);
		if (error < GIT_SUCCESS)
			goto cleanup;
	}

	git_vector_sort(&list);
	remote->refs.len = list.length;
	remote->refs.heads = (git_remote_head **) list.contents;

	return GIT_SUCCESS;

cleanup:
	git_vector_free(&list);
	return error;
}

/*
 * In this first version, we push all our refs in and start sending
 * them out. When we get an ACK we hide that commit and continue
 * traversing until we're done
 */
int git_fetch_negotiate(git_remote *remote)
{
	git_revwalk *walk;
	int error;
	unsigned int i;
	git_reference *ref;
	git_strarray refs;
	git_headarray *list = &remote->refs;
	git_repository *repo = remote->repo;
	git_oid oid;

	error = filter_wants(remote);
	if (error < GIT_SUCCESS)
		return git__rethrow(error, "Failed to filter the reference list for wants");

	/* Don't try to negotiate when we don't want anything */
	if (list->len == 0)
		return GIT_SUCCESS;

	/*
	 * Now we have everything set up so we can start tell the server
	 * what we want and what we have.
	 */
	git_transport_send_wants(remote->transport, list);

	error = git_reference_listall(&refs, repo, GIT_REF_LISTALL);
	if (error < GIT_ERROR)
		return git__rethrow(error, "Failed to list all references");

	error = git_revwalk_new(&walk, repo);
	if (error < GIT_ERROR) {
		error = git__rethrow(error, "Failed to list all references");
		goto cleanup;
	}

	for (i = 0; i < refs.count; ++i) {
		error = git_reference_lookup(&ref, repo, refs.strings[i]);
		if (error < GIT_ERROR) {
			error = git__rethrow(error, "Failed to lookup %s", refs.strings[i]);
			goto cleanup;
		}

		error = git_revwalk_push(walk, git_reference_oid(ref));
		if (error < GIT_ERROR) {
			error = git__rethrow(error, "Failed to push %s", refs.strings[i]);
			goto cleanup;
		}
	}
	git_strarray_free(&refs);

	while ((error = git_revwalk_next(&oid, walk)) == GIT_SUCCESS) {
		git_transport_send_have(remote->transport, &oid);
	}
	if (error == GIT_EREVWALKOVER)
		error = GIT_SUCCESS;

	/* TODO: git_pkt_send_flush(fd), or git_transport_flush() */
	git_transport_send_flush(remote->transport);
	git_transport_send_done(remote->transport);

cleanup:
	git_revwalk_free(walk);
	return error;
}

int git_fetch_download_pack(git_remote *remote)
{
	return git_transport_download_pack(remote->transport, remote->repo);
}