/*
 * Copyright (C) 2009-2011 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 "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"

static int filter_wants(git_remote *remote)
{
	git_vector list;
	git_headarray refs;
	git_remote_head *head;
	git_transport *t = remote->transport;
	git_repository *repo = remote->repo;
	const git_refspec *spec;
	int error;
	unsigned int i = 0;

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

	error = t->ls(t, &refs);
	if (error < GIT_SUCCESS) {
		error = git__rethrow(error, "Failed to get remote ref list");
		goto cleanup;
	}

	/*
	 * The fetch refspec can be NULL, and what this means is that the
	 * user didn't specify one. This is fine, as it means that we're
	 * not interested in any particular branch but just the remote's
	 * HEAD, which will be stored in FETCH_HEAD after the fetch.
	 */
	spec = git_remote_fetchspec(remote);

	/*
	 * We need to handle HEAD separately, as we always want it, but it
	 * probably won't matcht he refspec.
	 */
	head = refs.heads[0];
	if (refs.len > 0 && !strcmp(head->name, GIT_HEAD_FILE)) {
		if (git_odb_exists(repo->db, &head->oid))
			head->local = 1;
		else
			remote->need_pack = 1;

		i = 1;
		error = git_vector_insert(&list, refs.heads[0]);
		if (error < GIT_SUCCESS)
			goto cleanup;
	}

	for (; i < refs.len; ++i) {
		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 we have the object, mark it so we don't ask for it */
		if (git_odb_exists(repo->db, &head->oid))
			head->local = 1;
		else
			remote->need_pack = 1;

		error = git_vector_insert(&list, head);
		if (error < GIT_SUCCESS)
			goto cleanup;
	}

	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)
{
	int error;
	git_headarray *list = &remote->refs;
	git_transport *t = remote->transport;

	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;
	if (!remote->need_pack)
		return GIT_SUCCESS;

	/*
	 * Now we have everything set up so we can start tell the server
	 * what we want and what we have.
	 */
	error = t->send_wants(t, list);
	if (error < GIT_SUCCESS)
		return git__rethrow(error, "Failed to send want list");

	return t->negotiate_fetch(t, remote->repo, &remote->refs);
}

int git_fetch_download_pack(char **out, git_remote *remote)
{
	if(!remote->need_pack) {
		*out = NULL;
		return GIT_SUCCESS;
	}

	return remote->transport->download_pack(out, remote->transport, remote->repo);
}