#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;
}

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

        if (resolve_ref(ref.buf, sha1, 1, NULL)) {
                if (!force && track == BRANCH_TRACK_OVERRIDE)
                        dont_change_ref = 1;
                else if (!force)
                        die("A branch named '%s' already exists.", name);
                else if (!is_bare_repository() && head && !strcmp(head, name))
                        die("Cannot force update the current branch.");
                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(name, 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"));
}