#include "cache.h"
#include "branch.h"
#include "refs.h"
#include "remote.h"
#include "commit.h"

struct tracking {
	struct refspec spec;
	char *src;
	const char *remote;
	int matches;
};

static int find_tracked_branch(struct remote *remote, void *priv)
{
	struct tracking *tracking = priv;

	if (!remote_find_tracking(remote, &tracking->spec)) {
		if (++tracking->matches == 1) {
			tracking->src = tracking->spec.src;
			tracking->remote = remote->name;
		} else {
			free(tracking->spec.src);
			if (tracking->src) {
				free(tracking->src);
				tracking->src = NULL;
			}
		}
		tracking->spec.src = NULL;
	}

	return 0;
}

static int should_setup_rebase(const char *origin)
{
	switch (autorebase) {
	case AUTOREBASE_NEVER:
		return 0;
	case AUTOREBASE_LOCAL:
		return origin == NULL;
	case AUTOREBASE_REMOTE:
		return origin != NULL;
	case AUTOREBASE_ALWAYS:
		return 1;
	}
	return 0;
}

void install_branch_config(int flag, const char *local, const char *origin, const char *remote)
{
	const char *shortname = remote + 11;
	int remote_is_branch = !prefixcmp(remote, "refs/heads/");
	struct strbuf key = STRBUF_INIT;
	int rebasing = should_setup_rebase(origin);

	if (remote_is_branch
	    && !strcmp(local, shortname)
	    && !origin) {
		warning("Not setting branch %s as its own upstream.",
			local);
		return;
	}

	strbuf_addf(&key, "branch.%s.remote", local);
	git_config_set(key.buf, origin ? origin : ".");

	strbuf_reset(&key);
	strbuf_addf(&key, "branch.%s.merge", local);
	git_config_set(key.buf, remote);

	if (rebasing) {
		strbuf_reset(&key);
		strbuf_addf(&key, "branch.%s.rebase", local);
		git_config_set(key.buf, "true");
	}

	if (flag & BRANCH_CONFIG_VERBOSE) {
		strbuf_reset(&key);

		strbuf_addstr(&key, origin ? "remote" : "local");

		/* Are we tracking a proper "branch"? */
		if (remote_is_branch) {
			strbuf_addf(&key, " branch %s", shortname);
			if (origin)
				strbuf_addf(&key, " from %s", origin);
		}
		else
			strbuf_addf(&key, " ref %s", remote);
		printf("Branch %s set up to track %s%s.\n",
		       local, key.buf,
		       rebasing ? " by rebasing" : "");
	}
	strbuf_release(&key);
}

/*
 * This is called when new_ref is branched off of orig_ref, and tries
 * to infer the settings for branch.<new_ref>.{remote,merge} from the
 * config.
 */
static int setup_tracking(const char *new_ref, const char *orig_ref,
                          enum branch_track track)
{
	struct tracking tracking;

	if (strlen(new_ref) > 1024 - 7 - 7 - 1)
		return error("Tracking not set up: name too long: %s",
				new_ref);

	memset(&tracking, 0, sizeof(tracking));
	tracking.spec.dst = (char *)orig_ref;
	if (for_each_remote(find_tracked_branch, &tracking))
		return 1;

	if (!tracking.matches)
		switch (track) {
		case BRANCH_TRACK_ALWAYS:
		case BRANCH_TRACK_EXPLICIT:
		case BRANCH_TRACK_OVERRIDE:
			break;
		default:
			return 1;
		}

	if (tracking.matches > 1)
		return error("Not tracking: ambiguous information for ref %s",
				orig_ref);

	install_branch_config(BRANCH_CONFIG_VERBOSE, new_ref, tracking.remote,
			      tracking.src ? tracking.src : orig_ref);

	free(tracking.src);
	return 0;
}

int validate_new_branchname(const char *name, struct strbuf *ref, int force)
{
	const char *head;
	unsigned char sha1[20];

	if (strbuf_check_branch_ref(ref, name))
		die("'%s' is not a valid branch name.", name);

	if (!ref_exists(ref->buf))
		return 0;
	else if (!force)
		die("A branch named '%s' already exists.", ref->buf + strlen("refs/heads/"));

	head = resolve_ref("HEAD", sha1, 0, NULL);
	if (!is_bare_repository() && head && !strcmp(head, ref->buf))
		die("Cannot force update the current branch.");

	return 1;
}

void create_branch(const char *head,
		   const char *name, const char *start_name,
		   int force, int reflog, enum branch_track track)
{
	struct ref_lock *lock = NULL;
	struct commit *commit;
	unsigned char sha1[20];
	char *real_ref, msg[PATH_MAX + 20];
	struct strbuf ref = STRBUF_INIT;
	int forcing = 0;
	int dont_change_ref = 0;
	int explicit_tracking = 0;

	if (track == BRANCH_TRACK_EXPLICIT || track == BRANCH_TRACK_OVERRIDE)
		explicit_tracking = 1;

	if (validate_new_branchname(name, &ref, force || track == BRANCH_TRACK_OVERRIDE)) {
		if (!force)
			dont_change_ref = 1;
		else
			forcing = 1;
	}

	real_ref = NULL;
	if (get_sha1(start_name, sha1))
		die("Not a valid object name: '%s'.", start_name);

	switch (dwim_ref(start_name, strlen(start_name), sha1, &real_ref)) {
	case 0:
		/* Not branching from any existing branch */
		if (explicit_tracking)
			die("Cannot setup tracking information; starting point is not a branch.");
		break;
	case 1:
		/* Unique completion -- good, only if it is a real branch */
		if (prefixcmp(real_ref, "refs/heads/") &&
		    prefixcmp(real_ref, "refs/remotes/")) {
			if (explicit_tracking)
				die("Cannot setup tracking information; starting point is not a branch.");
			else
				real_ref = NULL;
		}
		break;
	default:
		die("Ambiguous object name: '%s'.", start_name);
		break;
	}

	if ((commit = lookup_commit_reference(sha1)) == NULL)
		die("Not a valid branch point: '%s'.", start_name);
	hashcpy(sha1, commit->object.sha1);

	if (!dont_change_ref) {
		lock = lock_any_ref_for_update(ref.buf, NULL, 0);
		if (!lock)
			die_errno("Failed to lock ref for update");
	}

	if (reflog)
		log_all_ref_updates = 1;

	if (forcing)
		snprintf(msg, sizeof msg, "branch: Reset to %s",
			 start_name);
	else if (!dont_change_ref)
		snprintf(msg, sizeof msg, "branch: Created from %s",
			 start_name);

	if (real_ref && track)
		setup_tracking(ref.buf+11, real_ref, track);

	if (!dont_change_ref)
		if (write_ref_sha1(lock, sha1, msg) < 0)
			die_errno("Failed to write ref");

	strbuf_release(&ref);
	free(real_ref);
}

void remove_branch_state(void)
{
	unlink(git_path("CHERRY_PICK_HEAD"));
	unlink(git_path("MERGE_HEAD"));
	unlink(git_path("MERGE_RR"));
	unlink(git_path("MERGE_MSG"));
	unlink(git_path("MERGE_MODE"));
	unlink(git_path("SQUASH_MSG"));
}