/*
 * "git fetch"
 */
#include "cache.h"
#include "config.h"
#include "refs.h"
#include "commit.h"
#include "builtin.h"
#include "string-list.h"
#include "remote.h"
#include "transport.h"
#include "run-command.h"
#include "parse-options.h"
#include "sigchain.h"
#include "submodule-config.h"
#include "submodule.h"
#include "connected.h"
#include "argv-array.h"
#include "utf8.h"

static const char * const builtin_fetch_usage[] = {
        N_("git fetch [<options>] [<repository> [<refspec>...]]"),
        N_("git fetch [<options>] <group>"),
        N_("git fetch --multiple [<options>] [(<repository> | <group>)...]"),
        N_("git fetch --all [<options>]"),
        NULL
};

enum {
        TAGS_UNSET = 0,
        TAGS_DEFAULT = 1,
        TAGS_SET = 2
};

static int fetch_prune_config = -1; /* unspecified */
static int prune = -1; /* unspecified */
#define PRUNE_BY_DEFAULT 0 /* do we prune by default? */

static int all, append, dry_run, force, keep, multiple, update_head_ok, verbosity, deepen_relative;
static int progress = -1;
static int tags = TAGS_DEFAULT, unshallow, update_shallow, deepen;
static int max_children = -1;
static enum transport_family family;
static const char *depth;
static const char *deepen_since;
static const char *upload_pack;
static struct string_list deepen_not = STRING_LIST_INIT_NODUP;
static struct strbuf default_rla = STRBUF_INIT;
static struct transport *gtransport;
static struct transport *gsecondary;
static const char *submodule_prefix = "";
static int recurse_submodules = RECURSE_SUBMODULES_DEFAULT;
static int recurse_submodules_default = RECURSE_SUBMODULES_ON_DEMAND;
static int shown_url = 0;
static int refmap_alloc, refmap_nr;
static const char **refmap_array;

static int git_fetch_config(const char *k, const char *v, void *cb)
{
        if (!strcmp(k, "fetch.prune")) {
                fetch_prune_config = git_config_bool(k, v);
                return 0;
        }

        if (!strcmp(k, "submodule.recurse")) {
                int r = git_config_bool(k, v) ?
                        RECURSE_SUBMODULES_ON : RECURSE_SUBMODULES_OFF;
                recurse_submodules = r;
        }

        return git_default_config(k, v, cb);
}

static int parse_refmap_arg(const struct option *opt, const char *arg, int unset)
{
        ALLOC_GROW(refmap_array, refmap_nr + 1, refmap_alloc);

        /*
         * "git fetch --refmap='' origin foo"
         * can be used to tell the command not to store anywhere
         */
        if (*arg)
                refmap_array[refmap_nr++] = arg;
        return 0;
}

static struct option builtin_fetch_options[] = {
        OPT__VERBOSITY(&verbosity),
        OPT_BOOL(0, "all", &all,
                 N_("fetch from all remotes")),
        OPT_BOOL('a', "append", &append,
                 N_("append to .git/FETCH_HEAD instead of overwriting")),
        OPT_STRING(0, "upload-pack", &upload_pack, N_("path"),
                   N_("path to upload pack on remote end")),
        OPT__FORCE(&force, N_("force overwrite of local branch")),
        OPT_BOOL('m', "multiple", &multiple,
                 N_("fetch from multiple remotes")),
        OPT_SET_INT('t', "tags", &tags,
                    N_("fetch all tags and associated objects"), TAGS_SET),
        OPT_SET_INT('n', NULL, &tags,
                    N_("do not fetch all tags (--no-tags)"), TAGS_UNSET),
        OPT_INTEGER('j', "jobs", &max_children,
                    N_("number of submodules fetched in parallel")),
        OPT_BOOL('p', "prune", &prune,
                 N_("prune remote-tracking branches no longer on remote")),
        { OPTION_CALLBACK, 0, "recurse-submodules", &recurse_submodules, N_("on-demand"),
                    N_("control recursive fetching of submodules"),
                    PARSE_OPT_OPTARG, option_fetch_parse_recurse_submodules },
        OPT_BOOL(0, "dry-run", &dry_run,
                 N_("dry run")),
        OPT_BOOL('k', "keep", &keep, N_("keep downloaded pack")),
        OPT_BOOL('u', "update-head-ok", &update_head_ok,
                    N_("allow updating of HEAD ref")),
        OPT_BOOL(0, "progress", &progress, N_("force progress reporting")),
        OPT_STRING(0, "depth", &depth, N_("depth"),
                   N_("deepen history of shallow clone")),
        OPT_STRING(0, "shallow-since", &deepen_since, N_("time"),
                   N_("deepen history of shallow repository based on time")),
        OPT_STRING_LIST(0, "shallow-exclude", &deepen_not, N_("revision"),
                        N_("deepen history of shallow clone, excluding rev")),
        OPT_INTEGER(0, "deepen", &deepen_relative,
                    N_("deepen history of shallow clone")),
        { OPTION_SET_INT, 0, "unshallow", &unshallow, NULL,
                   N_("convert to a complete repository"),
                   PARSE_OPT_NONEG | PARSE_OPT_NOARG, NULL, 1 },
        { OPTION_STRING, 0, "submodule-prefix", &submodule_prefix, N_("dir"),
                   N_("prepend this to submodule path output"), PARSE_OPT_HIDDEN },
        { OPTION_CALLBACK, 0, "recurse-submodules-default",
                   &recurse_submodules_default, N_("on-demand"),
                   N_("default for recursive fetching of submodules "
                      "(lower priority than config files)"),
                   PARSE_OPT_HIDDEN, option_fetch_parse_recurse_submodules },
        OPT_BOOL(0, "update-shallow", &update_shallow,
                 N_("accept refs that update .git/shallow")),
        { OPTION_CALLBACK, 0, "refmap", NULL, N_("refmap"),
          N_("specify fetch refmap"), PARSE_OPT_NONEG, parse_refmap_arg },
        OPT_SET_INT('4', "ipv4", &family, N_("use IPv4 addresses only"),
                        TRANSPORT_FAMILY_IPV4),
        OPT_SET_INT('6', "ipv6", &family, N_("use IPv6 addresses only"),
                        TRANSPORT_FAMILY_IPV6),
        OPT_END()
};

static void unlock_pack(void)
{
        if (gtransport)
                transport_unlock_pack(gtransport);
        if (gsecondary)
                transport_unlock_pack(gsecondary);
}

static void unlock_pack_on_signal(int signo)
{
        unlock_pack();
        sigchain_pop(signo);
        raise(signo);
}

static void add_merge_config(struct ref **head,
                           const struct ref *remote_refs,
                           struct branch *branch,
                           struct ref ***tail)
{
        int i;

        for (i = 0; i < branch->merge_nr; i++) {
                struct ref *rm, **old_tail = *tail;
                struct refspec refspec;

                for (rm = *head; rm; rm = rm->next) {
                        if (branch_merge_matches(branch, i, rm->name)) {
                                rm->fetch_head_status = FETCH_HEAD_MERGE;
                                break;
                        }
                }
                if (rm)
                        continue;

                /*
                 * Not fetched to a remote-tracking branch?  We need to fetch
                 * it anyway to allow this branch's "branch.$name.merge"
                 * to be honored by 'git pull', but we do not have to
                 * fail if branch.$name.merge is misconfigured to point
                 * at a nonexisting branch.  If we were indeed called by
                 * 'git pull', it will notice the misconfiguration because
                 * there is no entry in the resulting FETCH_HEAD marked
                 * for merging.
                 */
                memset(&refspec, 0, sizeof(refspec));
                refspec.src = branch->merge[i]->src;
                get_fetch_map(remote_refs, &refspec, tail, 1);
                for (rm = *old_tail; rm; rm = rm->next)
                        rm->fetch_head_status = FETCH_HEAD_MERGE;
        }
}

static int add_existing(const char *refname, const struct object_id *oid,
                        int flag, void *cbdata)
{
        struct string_list *list = (struct string_list *)cbdata;
        struct string_list_item *item = string_list_insert(list, refname);
        struct object_id *old_oid = xmalloc(sizeof(*old_oid));

        oidcpy(old_oid, oid);
        item->util = old_oid;
        return 0;
}

static int will_fetch(struct ref **head, const unsigned char *sha1)
{
        struct ref *rm = *head;
        while (rm) {
                if (!hashcmp(rm->old_oid.hash, sha1))
                        return 1;
                rm = rm->next;
        }
        return 0;
}

static void find_non_local_tags(struct transport *transport,
                        struct ref **head,
                        struct ref ***tail)
{
        struct string_list existing_refs = STRING_LIST_INIT_DUP;
        struct string_list remote_refs = STRING_LIST_INIT_NODUP;
        const struct ref *ref;
        struct string_list_item *item = NULL;

        for_each_ref(add_existing, &existing_refs);
        for (ref = transport_get_remote_refs(transport); ref; ref = ref->next) {
                if (!starts_with(ref->name, "refs/tags/"))
                        continue;

                /*
                 * The peeled ref always follows the matching base
                 * ref, so if we see a peeled ref that we don't want
                 * to fetch then we can mark the ref entry in the list
                 * as one to ignore by setting util to NULL.
                 */
                if (ends_with(ref->name, "^{}")) {
                        if (item &&
                            !has_object_file_with_flags(&ref->old_oid,
                                                        OBJECT_INFO_QUICK) &&
                            !will_fetch(head, ref->old_oid.hash) &&
                            !has_sha1_file_with_flags(item->util,
                                                      OBJECT_INFO_QUICK) &&
                            !will_fetch(head, item->util))
                                item->util = NULL;
                        item = NULL;
                        continue;
                }

                /*
                 * If item is non-NULL here, then we previously saw a
                 * ref not followed by a peeled reference, so we need
                 * to check if it is a lightweight tag that we want to
                 * fetch.
                 */
                if (item &&
                    !has_sha1_file_with_flags(item->util, OBJECT_INFO_QUICK) &&
                    !will_fetch(head, item->util))
                        item->util = NULL;

                item = NULL;

                /* skip duplicates and refs that we already have */
                if (string_list_has_string(&remote_refs, ref->name) ||
                    string_list_has_string(&existing_refs, ref->name))
                        continue;

                item = string_list_insert(&remote_refs, ref->name);
                item->util = (void *)&ref->old_oid;
        }
        string_list_clear(&existing_refs, 1);

        /*
         * We may have a final lightweight tag that needs to be
         * checked to see if it needs fetching.
         */
        if (item &&
            !has_sha1_file_with_flags(item->util, OBJECT_INFO_QUICK) &&
            !will_fetch(head, item->util))
                item->util = NULL;

        /*
         * For all the tags in the remote_refs string list,
         * add them to the list of refs to be fetched
         */
        for_each_string_list_item(item, &remote_refs) {
                /* Unless we have already decided to ignore this item... */
                if (item->util)
                {
                        struct ref *rm = alloc_ref(item->string);
                        rm->peer_ref = alloc_ref(item->string);
                        oidcpy(&rm->old_oid, item->util);
                        **tail = rm;
                        *tail = &rm->next;
                }
        }

        string_list_clear(&remote_refs, 0);
}

static struct ref *get_ref_map(struct transport *transport,
                               struct refspec *refspecs, int refspec_count,
                               int tags, int *autotags)
{
        int i;
        struct ref *rm;
        struct ref *ref_map = NULL;
        struct ref **tail = &ref_map;

        /* opportunistically-updated references: */
        struct ref *orefs = NULL, **oref_tail = &orefs;

        const struct ref *remote_refs = transport_get_remote_refs(transport);

        if (refspec_count) {
                struct refspec *fetch_refspec;
                int fetch_refspec_nr;

                for (i = 0; i < refspec_count; i++) {
                        get_fetch_map(remote_refs, &refspecs[i], &tail, 0);
                        if (refspecs[i].dst && refspecs[i].dst[0])
                                *autotags = 1;
                }
                /* Merge everything on the command line (but not --tags) */
                for (rm = ref_map; rm; rm = rm->next)
                        rm->fetch_head_status = FETCH_HEAD_MERGE;

                /*
                 * For any refs that we happen to be fetching via
                 * command-line arguments, the destination ref might
                 * have been missing or have been different than the
                 * remote-tracking ref that would be derived from the
                 * configured refspec.  In these cases, we want to
                 * take the opportunity to update their configured
                 * remote-tracking reference.  However, we do not want
                 * to mention these entries in FETCH_HEAD at all, as
                 * they would simply be duplicates of existing
                 * entries, so we set them FETCH_HEAD_IGNORE below.
                 *
                 * We compute these entries now, based only on the
                 * refspecs specified on the command line.  But we add
                 * them to the list following the refspecs resulting
                 * from the tags option so that one of the latter,
                 * which has FETCH_HEAD_NOT_FOR_MERGE, is not removed
                 * by ref_remove_duplicates() in favor of one of these
                 * opportunistic entries with FETCH_HEAD_IGNORE.
                 */
                if (refmap_array) {
                        fetch_refspec = parse_fetch_refspec(refmap_nr, refmap_array);
                        fetch_refspec_nr = refmap_nr;
                } else {
                        fetch_refspec = transport->remote->fetch;
                        fetch_refspec_nr = transport->remote->fetch_refspec_nr;
                }

                for (i = 0; i < fetch_refspec_nr; i++)
                        get_fetch_map(ref_map, &fetch_refspec[i], &oref_tail, 1);
        } else if (refmap_array) {
                die("--refmap option is only meaningful with command-line refspec(s).");
        } else {
                /* Use the defaults */
                struct remote *remote = transport->remote;
                struct branch *branch = branch_get(NULL);
                int has_merge = branch_has_merge_config(branch);
                if (remote &&
                    (remote->fetch_refspec_nr ||
                     /* Note: has_merge implies non-NULL branch->remote_name */
                     (has_merge && !strcmp(branch->remote_name, remote->name)))) {
                        for (i = 0; i < remote->fetch_refspec_nr; i++) {
                                get_fetch_map(remote_refs, &remote->fetch[i], &tail, 0);
                                if (remote->fetch[i].dst &&
                                    remote->fetch[i].dst[0])
                                        *autotags = 1;
                                if (!i && !has_merge && ref_map &&
                                    !remote->fetch[0].pattern)
                                        ref_map->fetch_head_status = FETCH_HEAD_MERGE;
                        }
                        /*
                         * if the remote we're fetching from is the same
                         * as given in branch.<name>.remote, we add the
                         * ref given in branch.<name>.merge, too.
                         *
                         * Note: has_merge implies non-NULL branch->remote_name
                         */
                        if (has_merge &&
                            !strcmp(branch->remote_name, remote->name))
                                add_merge_config(&ref_map, remote_refs, branch, &tail);
                } else {
                        ref_map = get_remote_ref(remote_refs, "HEAD");
                        if (!ref_map)
                                die(_("Couldn't find remote ref HEAD"));
                        ref_map->fetch_head_status = FETCH_HEAD_MERGE;
                        tail = &ref_map->next;
                }
        }

        if (tags == TAGS_SET)
                /* also fetch all tags */
                get_fetch_map(remote_refs, tag_refspec, &tail, 0);
        else if (tags == TAGS_DEFAULT && *autotags)
                find_non_local_tags(transport, &ref_map, &tail);

        /* Now append any refs to be updated opportunistically: */
        *tail = orefs;
        for (rm = orefs; rm; rm = rm->next) {
                rm->fetch_head_status = FETCH_HEAD_IGNORE;
                tail = &rm->next;
        }

        return ref_remove_duplicates(ref_map);
}

#define STORE_REF_ERROR_OTHER 1
#define STORE_REF_ERROR_DF_CONFLICT 2

static int s_update_ref(const char *action,
                        struct ref *ref,
                        int check_old)
{
        char *msg;
        char *rla = getenv("GIT_REFLOG_ACTION");
        struct ref_transaction *transaction;
        struct strbuf err = STRBUF_INIT;
        int ret, df_conflict = 0;

        if (dry_run)
                return 0;
        if (!rla)
                rla = default_rla.buf;
        msg = xstrfmt("%s: %s", rla, action);

        transaction = ref_transaction_begin(&err);
        if (!transaction ||
            ref_transaction_update(transaction, ref->name,
                                   ref->new_oid.hash,
                                   check_old ? ref->old_oid.hash : NULL,
                                   0, msg, &err))
                goto fail;

        ret = ref_transaction_commit(transaction, &err);
        if (ret) {
                df_conflict = (ret == TRANSACTION_NAME_CONFLICT);
                goto fail;
        }

        ref_transaction_free(transaction);
        strbuf_release(&err);
        free(msg);
        return 0;
fail:
        ref_transaction_free(transaction);
        error("%s", err.buf);
        strbuf_release(&err);
        free(msg);
        return df_conflict ? STORE_REF_ERROR_DF_CONFLICT
                           : STORE_REF_ERROR_OTHER;
}

static int refcol_width = 10;
static int compact_format;

static void adjust_refcol_width(const struct ref *ref)
{
        int max, rlen, llen, len;

        /* uptodate lines are only shown on high verbosity level */
        if (!verbosity && !oidcmp(&ref->peer_ref->old_oid, &ref->old_oid))
                return;

        max    = term_columns();
        rlen   = utf8_strwidth(prettify_refname(ref->name));

        llen   = utf8_strwidth(prettify_refname(ref->peer_ref->name));

        /*
         * rough estimation to see if the output line is too long and
         * should not be counted (we can't do precise calculation
         * anyway because we don't know if the error explanation part
         * will be printed in update_local_ref)
         */
        if (compact_format) {
                llen = 0;
                max = max * 2 / 3;
        }
        len = 21 /* flag and summary */ + rlen + 4 /* -> */ + llen;
        if (len >= max)
                return;

        /*
         * Not precise calculation for compact mode because '*' can
         * appear on the left hand side of '->' and shrink the column
         * back.
         */
        if (refcol_width < rlen)
                refcol_width = rlen;
}

static void prepare_format_display(struct ref *ref_map)
{
        struct ref *rm;
        const char *format = "full";

        git_config_get_string_const("fetch.output", &format);
        if (!strcasecmp(format, "full"))
                compact_format = 0;
        else if (!strcasecmp(format, "compact"))
                compact_format = 1;
        else
                die(_("configuration fetch.output contains invalid value %s"),
                    format);

        for (rm = ref_map; rm; rm = rm->next) {
                if (rm->status == REF_STATUS_REJECT_SHALLOW ||
                    !rm->peer_ref ||
                    !strcmp(rm->name, "HEAD"))
                        continue;

                adjust_refcol_width(rm);
        }
}

static void print_remote_to_local(struct strbuf *display,
                                  const char *remote, const char *local)
{
        strbuf_addf(display, "%-*s -> %s", refcol_width, remote, local);
}

static int find_and_replace(struct strbuf *haystack,
                            const char *needle,
                            const char *placeholder)
{
        const char *p = strstr(haystack->buf, needle);
        int plen, nlen;

        if (!p)
                return 0;

        if (p > haystack->buf && p[-1] != '/')
                return 0;

        plen = strlen(p);
        nlen = strlen(needle);
        if (plen > nlen && p[nlen] != '/')
                return 0;

        strbuf_splice(haystack, p - haystack->buf, nlen,
                      placeholder, strlen(placeholder));
        return 1;
}

static void print_compact(struct strbuf *display,
                          const char *remote, const char *local)
{
        struct strbuf r = STRBUF_INIT;
        struct strbuf l = STRBUF_INIT;

        if (!strcmp(remote, local)) {
                strbuf_addf(display, "%-*s -> *", refcol_width, remote);
                return;
        }

        strbuf_addstr(&r, remote);
        strbuf_addstr(&l, local);

        if (!find_and_replace(&r, local, "*"))
                find_and_replace(&l, remote, "*");
        print_remote_to_local(display, r.buf, l.buf);

        strbuf_release(&r);
        strbuf_release(&l);
}

static void format_display(struct strbuf *display, char code,
                           const char *summary, const char *error,
                           const char *remote, const char *local,
                           int summary_width)
{
        int width = (summary_width + strlen(summary) - gettext_width(summary));

        strbuf_addf(display, "%c %-*s ", code, width, summary);
        if (!compact_format)
                print_remote_to_local(display, remote, local);
        else
                print_compact(display, remote, local);
        if (error)
                strbuf_addf(display, "  (%s)", error);
}

static int update_local_ref(struct ref *ref,
                            const char *remote,
                            const struct ref *remote_ref,
                            struct strbuf *display,
                            int summary_width)
{
        struct commit *current = NULL, *updated;
        enum object_type type;
        struct branch *current_branch = branch_get(NULL);
        const char *pretty_ref = prettify_refname(ref->name);

        type = sha1_object_info(ref->new_oid.hash, NULL);
        if (type < 0)
                die(_("object %s not found"), oid_to_hex(&ref->new_oid));

        if (!oidcmp(&ref->old_oid, &ref->new_oid)) {
                if (verbosity > 0)
                        format_display(display, '=', _("[up to date]"), NULL,
                                       remote, pretty_ref, summary_width);
                return 0;
        }

        if (current_branch &&
            !strcmp(ref->name, current_branch->name) &&
            !(update_head_ok || is_bare_repository()) &&
            !is_null_oid(&ref->old_oid)) {
                /*
                 * If this is the head, and it's not okay to update
                 * the head, and the old value of the head isn't empty...
                 */
                format_display(display, '!', _("[rejected]"),
                               _("can't fetch in current branch"),
                               remote, pretty_ref, summary_width);
                return 1;
        }

        if (!is_null_oid(&ref->old_oid) &&
            starts_with(ref->name, "refs/tags/")) {
                int r;
                r = s_update_ref("updating tag", ref, 0);
                format_display(display, r ? '!' : 't', _("[tag update]"),
                               r ? _("unable to update local ref") : NULL,
                               remote, pretty_ref, summary_width);
                return r;
        }

        current = lookup_commit_reference_gently(&ref->old_oid, 1);
        updated = lookup_commit_reference_gently(&ref->new_oid, 1);
        if (!current || !updated) {
                const char *msg;
                const char *what;
                int r;
                /*
                 * Nicely describe the new ref we're fetching.
                 * Base this on the remote's ref name, as it's
                 * more likely to follow a standard layout.
                 */
                const char *name = remote_ref ? remote_ref->name : "";
                if (starts_with(name, "refs/tags/")) {
                        msg = "storing tag";
                        what = _("[new tag]");
                } else if (starts_with(name, "refs/heads/")) {
                        msg = "storing head";
                        what = _("[new branch]");
                } else {
                        msg = "storing ref";
                        what = _("[new ref]");
                }

                if ((recurse_submodules != RECURSE_SUBMODULES_OFF) &&
                    (recurse_submodules != RECURSE_SUBMODULES_ON))
                        check_for_new_submodule_commits(&ref->new_oid);
                r = s_update_ref(msg, ref, 0);
                format_display(display, r ? '!' : '*', what,
                               r ? _("unable to update local ref") : NULL,
                               remote, pretty_ref, summary_width);
                return r;
        }

        if (in_merge_bases(current, updated)) {
                struct strbuf quickref = STRBUF_INIT;
                int r;
                strbuf_add_unique_abbrev(&quickref, current->object.oid.hash, DEFAULT_ABBREV);
                strbuf_addstr(&quickref, "..");
                strbuf_add_unique_abbrev(&quickref, ref->new_oid.hash, DEFAULT_ABBREV);
                if ((recurse_submodules != RECURSE_SUBMODULES_OFF) &&
                    (recurse_submodules != RECURSE_SUBMODULES_ON))
                        check_for_new_submodule_commits(&ref->new_oid);
                r = s_update_ref("fast-forward", ref, 1);
                format_display(display, r ? '!' : ' ', quickref.buf,
                               r ? _("unable to update local ref") : NULL,
                               remote, pretty_ref, summary_width);
                strbuf_release(&quickref);
                return r;
        } else if (force || ref->force) {
                struct strbuf quickref = STRBUF_INIT;
                int r;
                strbuf_add_unique_abbrev(&quickref, current->object.oid.hash, DEFAULT_ABBREV);
                strbuf_addstr(&quickref, "...");
                strbuf_add_unique_abbrev(&quickref, ref->new_oid.hash, DEFAULT_ABBREV);
                if ((recurse_submodules != RECURSE_SUBMODULES_OFF) &&
                    (recurse_submodules != RECURSE_SUBMODULES_ON))
                        check_for_new_submodule_commits(&ref->new_oid);
                r = s_update_ref("forced-update", ref, 1);
                format_display(display, r ? '!' : '+', quickref.buf,
                               r ? _("unable to update local ref") : _("forced update"),
                               remote, pretty_ref, summary_width);
                strbuf_release(&quickref);
                return r;
        } else {
                format_display(display, '!', _("[rejected]"), _("non-fast-forward"),
                               remote, pretty_ref, summary_width);
                return 1;
        }
}

static int iterate_ref_map(void *cb_data, unsigned char sha1[20])
{
        struct ref **rm = cb_data;
        struct ref *ref = *rm;

        while (ref && ref->status == REF_STATUS_REJECT_SHALLOW)
                ref = ref->next;
        if (!ref)
                return -1; /* end of the list */
        *rm = ref->next;
        hashcpy(sha1, ref->old_oid.hash);
        return 0;
}

static int store_updated_refs(const char *raw_url, const char *remote_name,
                struct ref *ref_map)
{
        FILE *fp;
        struct commit *commit;
        int url_len, i, rc = 0;
        struct strbuf note = STRBUF_INIT;
        const char *what, *kind;
        struct ref *rm;
        char *url;
        const char *filename = dry_run ? "/dev/null" : git_path_fetch_head();
        int want_status;
        int summary_width = transport_summary_width(ref_map);

        fp = fopen(filename, "a");
        if (!fp)
                return error_errno(_("cannot open %s"), filename);

        if (raw_url)
                url = transport_anonymize_url(raw_url);
        else
                url = xstrdup("foreign");

        rm = ref_map;
        if (check_connected(iterate_ref_map, &rm, NULL)) {
                rc = error(_("%s did not send all necessary objects\n"), url);
                goto abort;
        }

        prepare_format_display(ref_map);

        /*
         * We do a pass for each fetch_head_status type in their enum order, so
         * merged entries are written before not-for-merge. That lets readers
         * use FETCH_HEAD as a refname to refer to the ref to be merged.
         */
        for (want_status = FETCH_HEAD_MERGE;
             want_status <= FETCH_HEAD_IGNORE;
             want_status++) {
                for (rm = ref_map; rm; rm = rm->next) {
                        struct ref *ref = NULL;
                        const char *merge_status_marker = "";

                        if (rm->status == REF_STATUS_REJECT_SHALLOW) {
                                if (want_status == FETCH_HEAD_MERGE)
                                        warning(_("reject %s because shallow roots are not allowed to be updated"),
                                                rm->peer_ref ? rm->peer_ref->name : rm->name);
                                continue;
                        }

                        commit = lookup_commit_reference_gently(&rm->old_oid,
                                                                1);
                        if (!commit)
                                rm->fetch_head_status = FETCH_HEAD_NOT_FOR_MERGE;

                        if (rm->fetch_head_status != want_status)
                                continue;

                        if (rm->peer_ref) {
                                ref = alloc_ref(rm->peer_ref->name);
                                oidcpy(&ref->old_oid, &rm->peer_ref->old_oid);
                                oidcpy(&ref->new_oid, &rm->old_oid);
                                ref->force = rm->peer_ref->force;
                        }


                        if (!strcmp(rm->name, "HEAD")) {
                                kind = "";
                                what = "";
                        }
                        else if (starts_with(rm->name, "refs/heads/")) {
                                kind = "branch";
                                what = rm->name + 11;
                        }
                        else if (starts_with(rm->name, "refs/tags/")) {
                                kind = "tag";
                                what = rm->name + 10;
                        }
                        else if (starts_with(rm->name, "refs/remotes/")) {
                                kind = "remote-tracking branch";
                                what = rm->name + 13;
                        }
                        else {
                                kind = "";
                                what = rm->name;
                        }

                        url_len = strlen(url);
                        for (i = url_len - 1; url[i] == '/' && 0 <= i; i--)
                                ;
                        url_len = i + 1;
                        if (4 < i && !strncmp(".git", url + i - 3, 4))
                                url_len = i - 3;

                        strbuf_reset(&note);
                        if (*what) {
                                if (*kind)
                                        strbuf_addf(&note, "%s ", kind);
                                strbuf_addf(&note, "'%s' of ", what);
                        }
                        switch (rm->fetch_head_status) {
                        case FETCH_HEAD_NOT_FOR_MERGE:
                                merge_status_marker = "not-for-merge";
                                /* fall-through */
                        case FETCH_HEAD_MERGE:
                                fprintf(fp, "%s\t%s\t%s",
                                        oid_to_hex(&rm->old_oid),
                                        merge_status_marker,
                                        note.buf);
                                for (i = 0; i < url_len; ++i)
                                        if ('\n' == url[i])
                                                fputs("\\n", fp);
                                        else
                                                fputc(url[i], fp);
                                fputc('\n', fp);
                                break;
                        default:
                                /* do not write anything to FETCH_HEAD */
                                break;
                        }

                        strbuf_reset(&note);
                        if (ref) {
                                rc |= update_local_ref(ref, what, rm, &note,
                                                       summary_width);
                                free(ref);
                        } else
                                format_display(&note, '*',
                                               *kind ? kind : "branch", NULL,
                                               *what ? what : "HEAD",
                                               "FETCH_HEAD", summary_width);
                        if (note.len) {
                                if (verbosity >= 0 && !shown_url) {
                                        fprintf(stderr, _("From %.*s\n"),
                                                        url_len, url);
                                        shown_url = 1;
                                }
                                if (verbosity >= 0)
                                        fprintf(stderr, " %s\n", note.buf);
                        }
                }
        }

        if (rc & STORE_REF_ERROR_DF_CONFLICT)
                error(_("some local refs could not be updated; try running\n"
                      " 'git remote prune %s' to remove any old, conflicting "
                      "branches"), remote_name);

 abort:
        strbuf_release(&note);
        free(url);
        fclose(fp);
        return rc;
}

/*
 * We would want to bypass the object transfer altogether if
 * everything we are going to fetch already exists and is connected
 * locally.
 */
static int quickfetch(struct ref *ref_map)
{
        struct ref *rm = ref_map;
        struct check_connected_options opt = CHECK_CONNECTED_INIT;

        /*
         * If we are deepening a shallow clone we already have these
         * objects reachable.  Running rev-list here will return with
         * a good (0) exit status and we'll bypass the fetch that we
         * really need to perform.  Claiming failure now will ensure
         * we perform the network exchange to deepen our history.
         */
        if (deepen)
                return -1;
        opt.quiet = 1;
        return check_connected(iterate_ref_map, &rm, &opt);
}

static int fetch_refs(struct transport *transport, struct ref *ref_map)
{
        int ret = quickfetch(ref_map);
        if (ret)
                ret = transport_fetch_refs(transport, ref_map);
        if (!ret)
                ret |= store_updated_refs(transport->url,
                                transport->remote->name,
                                ref_map);
        transport_unlock_pack(transport);
        return ret;
}

static int prune_refs(struct refspec *refs, int ref_count, struct ref *ref_map,
                const char *raw_url)
{
        int url_len, i, result = 0;
        struct ref *ref, *stale_refs = get_stale_heads(refs, ref_count, ref_map);
        char *url;
        int summary_width = transport_summary_width(stale_refs);
        const char *dangling_msg = dry_run
                ? _("   (%s will become dangling)")
                : _("   (%s has become dangling)");

        if (raw_url)
                url = transport_anonymize_url(raw_url);
        else
                url = xstrdup("foreign");

        url_len = strlen(url);
        for (i = url_len - 1; url[i] == '/' && 0 <= i; i--)
                ;

        url_len = i + 1;
        if (4 < i && !strncmp(".git", url + i - 3, 4))
                url_len = i - 3;

        if (!dry_run) {
                struct string_list refnames = STRING_LIST_INIT_NODUP;

                for (ref = stale_refs; ref; ref = ref->next)
                        string_list_append(&refnames, ref->name);

                result = delete_refs("fetch: prune", &refnames, 0);
                string_list_clear(&refnames, 0);
        }

        if (verbosity >= 0) {
                for (ref = stale_refs; ref; ref = ref->next) {
                        struct strbuf sb = STRBUF_INIT;
                        if (!shown_url) {
                                fprintf(stderr, _("From %.*s\n"), url_len, url);
                                shown_url = 1;
                        }
                        format_display(&sb, '-', _("[deleted]"), NULL,
                                       _("(none)"), prettify_refname(ref->name),
                                       summary_width);
                        fprintf(stderr, " %s\n",sb.buf);
                        strbuf_release(&sb);
                        warn_dangling_symref(stderr, dangling_msg, ref->name);
                }
        }

        free(url);
        free_refs(stale_refs);
        return result;
}

static void check_not_current_branch(struct ref *ref_map)
{
        struct branch *current_branch = branch_get(NULL);

        if (is_bare_repository() || !current_branch)
                return;

        for (; ref_map; ref_map = ref_map->next)
                if (ref_map->peer_ref && !strcmp(current_branch->refname,
                                        ref_map->peer_ref->name))
                        die(_("Refusing to fetch into current branch %s "
                            "of non-bare repository"), current_branch->refname);
}

static int truncate_fetch_head(void)
{
        const char *filename = git_path_fetch_head();
        FILE *fp = fopen_for_writing(filename);

        if (!fp)
                return error_errno(_("cannot open %s"), filename);
        fclose(fp);
        return 0;
}

static void set_option(struct transport *transport, const char *name, const char *value)
{
        int r = transport_set_option(transport, name, value);
        if (r < 0)
                die(_("Option \"%s\" value \"%s\" is not valid for %s"),
                    name, value, transport->url);
        if (r > 0)
                warning(_("Option \"%s\" is ignored for %s\n"),
                        name, transport->url);
}

static struct transport *prepare_transport(struct remote *remote, int deepen)
{
        struct transport *transport;
        transport = transport_get(remote, NULL);
        transport_set_verbosity(transport, verbosity, progress);
        transport->family = family;
        if (upload_pack)
                set_option(transport, TRANS_OPT_UPLOADPACK, upload_pack);
        if (keep)
                set_option(transport, TRANS_OPT_KEEP, "yes");
        if (depth)
                set_option(transport, TRANS_OPT_DEPTH, depth);
        if (deepen && deepen_since)
                set_option(transport, TRANS_OPT_DEEPEN_SINCE, deepen_since);
        if (deepen && deepen_not.nr)
                set_option(transport, TRANS_OPT_DEEPEN_NOT,
                           (const char *)&deepen_not);
        if (deepen_relative)
                set_option(transport, TRANS_OPT_DEEPEN_RELATIVE, "yes");
        if (update_shallow)
                set_option(transport, TRANS_OPT_UPDATE_SHALLOW, "yes");
        return transport;
}

static void backfill_tags(struct transport *transport, struct ref *ref_map)
{
        int cannot_reuse;

        /*
         * Once we have set TRANS_OPT_DEEPEN_SINCE, we can't unset it
         * when remote helper is used (setting it to an empty string
         * is not unsetting). We could extend the remote helper
         * protocol for that, but for now, just force a new connection
         * without deepen-since. Similar story for deepen-not.
         */
        cannot_reuse = transport->cannot_reuse ||
                deepen_since || deepen_not.nr;
        if (cannot_reuse) {
                gsecondary = prepare_transport(transport->remote, 0);
                transport = gsecondary;
        }

        transport_set_option(transport, TRANS_OPT_FOLLOWTAGS, NULL);
        transport_set_option(transport, TRANS_OPT_DEPTH, "0");
        transport_set_option(transport, TRANS_OPT_DEEPEN_RELATIVE, NULL);
        fetch_refs(transport, ref_map);

        if (gsecondary) {
                transport_disconnect(gsecondary);
                gsecondary = NULL;
        }
}

static int do_fetch(struct transport *transport,
                    struct refspec *refs, int ref_count)
{
        struct string_list existing_refs = STRING_LIST_INIT_DUP;
        struct ref *ref_map;
        struct ref *rm;
        int autotags = (transport->remote->fetch_tags == 1);
        int retcode = 0;

        for_each_ref(add_existing, &existing_refs);

        if (tags == TAGS_DEFAULT) {
                if (transport->remote->fetch_tags == 2)
                        tags = TAGS_SET;
                if (transport->remote->fetch_tags == -1)
                        tags = TAGS_UNSET;
        }

        if (!transport->get_refs_list || !transport->fetch)
                die(_("Don't know how to fetch from %s"), transport->url);

        /* if not appending, truncate FETCH_HEAD */
        if (!append && !dry_run) {
                retcode = truncate_fetch_head();
                if (retcode)
                        goto cleanup;
        }

        ref_map = get_ref_map(transport, refs, ref_count, tags, &autotags);
        if (!update_head_ok)
                check_not_current_branch(ref_map);

        for (rm = ref_map; rm; rm = rm->next) {
                if (rm->peer_ref) {
                        struct string_list_item *peer_item =
                                string_list_lookup(&existing_refs,
                                                   rm->peer_ref->name);
                        if (peer_item) {
                                struct object_id *old_oid = peer_item->util;
                                oidcpy(&rm->peer_ref->old_oid, old_oid);
                        }
                }
        }

        if (tags == TAGS_DEFAULT && autotags)
                transport_set_option(transport, TRANS_OPT_FOLLOWTAGS, "1");
        if (prune) {
                /*
                 * We only prune based on refspecs specified
                 * explicitly (via command line or configuration); we
                 * don't care whether --tags was specified.
                 */
                if (ref_count) {
                        prune_refs(refs, ref_count, ref_map, transport->url);
                } else {
                        prune_refs(transport->remote->fetch,
                                   transport->remote->fetch_refspec_nr,
                                   ref_map,
                                   transport->url);
                }
        }
        if (fetch_refs(transport, ref_map)) {
                free_refs(ref_map);
                retcode = 1;
                goto cleanup;
        }
        free_refs(ref_map);

        /* if neither --no-tags nor --tags was specified, do automated tag
         * following ... */
        if (tags == TAGS_DEFAULT && autotags) {
                struct ref **tail = &ref_map;
                ref_map = NULL;
                find_non_local_tags(transport, &ref_map, &tail);
                if (ref_map)
                        backfill_tags(transport, ref_map);
                free_refs(ref_map);
        }

 cleanup:
        string_list_clear(&existing_refs, 1);
        return retcode;
}

static int get_one_remote_for_fetch(struct remote *remote, void *priv)
{
        struct string_list *list = priv;
        if (!remote->skip_default_update)
                string_list_append(list, remote->name);
        return 0;
}

struct remote_group_data {
        const char *name;
        struct string_list *list;
};

static int get_remote_group(const char *key, const char *value, void *priv)
{
        struct remote_group_data *g = priv;

        if (skip_prefix(key, "remotes.", &key) && !strcmp(key, g->name)) {
                /* split list by white space */
                while (*value) {
                        size_t wordlen = strcspn(value, " \t\n");

                        if (wordlen >= 1)
                                string_list_append_nodup(g->list,
                                                   xstrndup(value, wordlen));
                        value += wordlen + (value[wordlen] != '\0');
                }
        }

        return 0;
}

static int add_remote_or_group(const char *name, struct string_list *list)
{
        int prev_nr = list->nr;
        struct remote_group_data g;
        g.name = name; g.list = list;

        git_config(get_remote_group, &g);
        if (list->nr == prev_nr) {
                struct remote *remote = remote_get(name);
                if (!remote_is_configured(remote, 0))
                        return 0;
                string_list_append(list, remote->name);
        }
        return 1;
}

static void add_options_to_argv(struct argv_array *argv)
{
        if (dry_run)
                argv_array_push(argv, "--dry-run");
        if (prune != -1)
                argv_array_push(argv, prune ? "--prune" : "--no-prune");
        if (update_head_ok)
                argv_array_push(argv, "--update-head-ok");
        if (force)
                argv_array_push(argv, "--force");
        if (keep)
                argv_array_push(argv, "--keep");
        if (recurse_submodules == RECURSE_SUBMODULES_ON)
                argv_array_push(argv, "--recurse-submodules");
        else if (recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND)
                argv_array_push(argv, "--recurse-submodules=on-demand");
        if (tags == TAGS_SET)
                argv_array_push(argv, "--tags");
        else if (tags == TAGS_UNSET)
                argv_array_push(argv, "--no-tags");
        if (verbosity >= 2)
                argv_array_push(argv, "-v");
        if (verbosity >= 1)
                argv_array_push(argv, "-v");
        else if (verbosity < 0)
                argv_array_push(argv, "-q");

}

static int fetch_multiple(struct string_list *list)
{
        int i, result = 0;
        struct argv_array argv = ARGV_ARRAY_INIT;

        if (!append && !dry_run) {
                int errcode = truncate_fetch_head();
                if (errcode)
                        return errcode;
        }

        argv_array_pushl(&argv, "fetch", "--append", NULL);
        add_options_to_argv(&argv);

        for (i = 0; i < list->nr; i++) {
                const char *name = list->items[i].string;
                argv_array_push(&argv, name);
                if (verbosity >= 0)
                        printf(_("Fetching %s\n"), name);
                if (run_command_v_opt(argv.argv, RUN_GIT_CMD)) {
                        error(_("Could not fetch %s"), name);
                        result = 1;
                }
                argv_array_pop(&argv);
        }

        argv_array_clear(&argv);
        return result;
}

static int fetch_one(struct remote *remote, int argc, const char **argv)
{
        static const char **refs = NULL;
        struct refspec *refspec;
        int ref_nr = 0;
        int exit_code;

        if (!remote)
                die(_("No remote repository specified.  Please, specify either a URL or a\n"
                    "remote name from which new revisions should be fetched."));

        gtransport = prepare_transport(remote, 1);

        if (prune < 0) {
                /* no command line request */
                if (0 <= gtransport->remote->prune)
                        prune = gtransport->remote->prune;
                else if (0 <= fetch_prune_config)
                        prune = fetch_prune_config;
                else
                        prune = PRUNE_BY_DEFAULT;
        }

        if (argc > 0) {
                int j = 0;
                int i;
                refs = xcalloc(st_add(argc, 1), sizeof(const char *));
                for (i = 0; i < argc; i++) {
                        if (!strcmp(argv[i], "tag")) {
                                i++;
                                if (i >= argc)
                                        die(_("You need to specify a tag name."));
                                refs[j++] = xstrfmt("refs/tags/%s:refs/tags/%s",
                                                    argv[i], argv[i]);
                        } else
                                refs[j++] = argv[i];
                }
                refs[j] = NULL;
                ref_nr = j;
        }

        sigchain_push_common(unlock_pack_on_signal);
        atexit(unlock_pack);
        refspec = parse_fetch_refspec(ref_nr, refs);
        exit_code = do_fetch(gtransport, refspec, ref_nr);
        free_refspec(ref_nr, refspec);
        transport_disconnect(gtransport);
        gtransport = NULL;
        return exit_code;
}

int cmd_fetch(int argc, const char **argv, const char *prefix)
{
        int i;
        struct string_list list = STRING_LIST_INIT_DUP;
        struct remote *remote;
        int result = 0;
        struct argv_array argv_gc_auto = ARGV_ARRAY_INIT;

        packet_trace_identity("fetch");

        /* Record the command line for the reflog */
        strbuf_addstr(&default_rla, "fetch");
        for (i = 1; i < argc; i++)
                strbuf_addf(&default_rla, " %s", argv[i]);

        git_config(git_fetch_config, NULL);

        argc = parse_options(argc, argv, prefix,
                             builtin_fetch_options, builtin_fetch_usage, 0);

        if (deepen_relative) {
                if (deepen_relative < 0)
                        die(_("Negative depth in --deepen is not supported"));
                if (depth)
                        die(_("--deepen and --depth are mutually exclusive"));
                depth = xstrfmt("%d", deepen_relative);
        }
        if (unshallow) {
                if (depth)
                        die(_("--depth and --unshallow cannot be used together"));
                else if (!is_repository_shallow())
                        die(_("--unshallow on a complete repository does not make sense"));
                else
                        depth = xstrfmt("%d", INFINITE_DEPTH);
        }

        /* no need to be strict, transport_set_option() will validate it again */
        if (depth && atoi(depth) < 1)
                die(_("depth %s is not a positive number"), depth);
        if (depth || deepen_since || deepen_not.nr)
                deepen = 1;

        if (recurse_submodules != RECURSE_SUBMODULES_OFF) {
                set_config_fetch_recurse_submodules(recurse_submodules_default);
                gitmodules_config();
                git_config(submodule_config, NULL);
        }

        if (all) {
                if (argc == 1)
                        die(_("fetch --all does not take a repository argument"));
                else if (argc > 1)
                        die(_("fetch --all does not make sense with refspecs"));
                (void) for_each_remote(get_one_remote_for_fetch, &list);
                result = fetch_multiple(&list);
        } else if (argc == 0) {
                /* No arguments -- use default remote */
                remote = remote_get(NULL);
                result = fetch_one(remote, argc, argv);
        } else if (multiple) {
                /* All arguments are assumed to be remotes or groups */
                for (i = 0; i < argc; i++)
                        if (!add_remote_or_group(argv[i], &list))
                                die(_("No such remote or remote group: %s"), argv[i]);
                result = fetch_multiple(&list);
        } else {
                /* Single remote or group */
                (void) add_remote_or_group(argv[0], &list);
                if (list.nr > 1) {
                        /* More than one remote */
                        if (argc > 1)
                                die(_("Fetching a group and specifying refspecs does not make sense"));
                        result = fetch_multiple(&list);
                } else {
                        /* Zero or one remotes */
                        remote = remote_get(argv[0]);
                        result = fetch_one(remote, argc-1, argv+1);
                }
        }

        if (!result && (recurse_submodules != RECURSE_SUBMODULES_OFF)) {
                struct argv_array options = ARGV_ARRAY_INIT;

                add_options_to_argv(&options);
                result = fetch_populated_submodules(&options,
                                                    submodule_prefix,
                                                    recurse_submodules,
                                                    verbosity < 0,
                                                    max_children);
                argv_array_clear(&options);
        }

        string_list_clear(&list, 0);

        close_all_packs();

        argv_array_pushl(&argv_gc_auto, "gc", "--auto", NULL);
        if (verbosity < 0)
                argv_array_push(&argv_gc_auto, "--quiet");
        run_command_v_opt(argv_gc_auto.argv, RUN_GIT_CMD);
        argv_array_clear(&argv_gc_auto);

        return result;
}