/*
 * "git fetch"
 */
#include "cache.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"

static const char * const builtin_fetch_usage[] = {
        "git fetch [options] [<repository> <refspec>...]",
        NULL
};

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

static int append, force, keep, update_head_ok, verbosity;
static int tags = TAGS_DEFAULT;
static const char *depth;
static const char *upload_pack;
static struct strbuf default_rla = STRBUF_INIT;
static struct transport *transport;

static struct option builtin_fetch_options[] = {
        OPT__VERBOSITY(&verbosity),
        OPT_BOOLEAN('a', "append", &append,
                    "append to .git/FETCH_HEAD instead of overwriting"),
        OPT_STRING(0, "upload-pack", &upload_pack, "PATH",
                   "path to upload pack on remote end"),
        OPT_BOOLEAN('f', "force", &force,
                    "force overwrite of local branch"),
        OPT_SET_INT('t', "tags", &tags,
                    "fetch all tags and associated objects", TAGS_SET),
        OPT_SET_INT('n', NULL, &tags,
                    "do not fetch all tags (--no-tags)", TAGS_UNSET),
        OPT_BOOLEAN('k', "keep", &keep, "keep downloaded pack"),
        OPT_BOOLEAN('u', "update-head-ok", &update_head_ok,
                    "allow updating of HEAD ref"),
        OPT_STRING(0, "depth", &depth, "DEPTH",
                   "deepen history of shallow clone"),
        OPT_END()
};

static void unlock_pack(void)
{
        if (transport)
                transport_unlock_pack(transport);
}

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->merge = 1;
                                break;
                        }
                }
                if (rm)
                        continue;

                /*
                 * Not fetched to a 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.
                 */
                refspec.src = branch->merge[i]->src;
                refspec.dst = NULL;
                refspec.pattern = 0;
                refspec.force = 0;
                get_fetch_map(remote_refs, &refspec, tail, 1);
                for (rm = *old_tail; rm; rm = rm->next)
                        rm->merge = 1;
        }
}

static void find_non_local_tags(struct transport *transport,
                        struct ref **head,
                        struct ref ***tail);

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

        const struct ref *remote_refs = transport_get_remote_refs(transport);

        if (ref_count || tags == TAGS_SET) {
                for (i = 0; i < ref_count; i++) {
                        get_fetch_map(remote_refs, &refs[i], &tail, 0);
                        if (refs[i].dst && refs[i].dst[0])
                                *autotags = 1;
                }
                /* Merge everything on the command line, but not --tags */
                for (rm = ref_map; rm; rm = rm->next)
                        rm->merge = 1;
                if (tags == TAGS_SET)
                        get_fetch_map(remote_refs, tag_refspec, &tail, 0);
        } 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 || has_merge)) {
                        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->merge = 1;
                        }
                        /*
                         * 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.
                         */
                        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->merge = 1;
                        tail = &ref_map->next;
                }
        }
        if (tags == TAGS_DEFAULT && *autotags)
                find_non_local_tags(transport, &ref_map, &tail);
        ref_remove_duplicates(ref_map);

        return 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[1024];
        char *rla = getenv("GIT_REFLOG_ACTION");
        static struct ref_lock *lock;

        if (!rla)
                rla = default_rla.buf;
        snprintf(msg, sizeof(msg), "%s: %s", rla, action);
        lock = lock_any_ref_for_update(ref->name,
                                       check_old ? ref->old_sha1 : NULL, 0);
        if (!lock)
                return errno == ENOTDIR ? STORE_REF_ERROR_DF_CONFLICT :
                                          STORE_REF_ERROR_OTHER;
        if (write_ref_sha1(lock, ref->new_sha1, msg) < 0)
                return errno == ENOTDIR ? STORE_REF_ERROR_DF_CONFLICT :
                                          STORE_REF_ERROR_OTHER;
        return 0;
}

#define SUMMARY_WIDTH (2 * DEFAULT_ABBREV + 3)
#define REFCOL_WIDTH  10

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

        *display = 0;
        type = sha1_object_info(ref->new_sha1, NULL);
        if (type < 0)
                die("object %s not found", sha1_to_hex(ref->new_sha1));

        if (!hashcmp(ref->old_sha1, ref->new_sha1)) {
                if (verbosity > 0)
                        sprintf(display, "= %-*s %-*s -> %s", SUMMARY_WIDTH,
                                "[up to date]", REFCOL_WIDTH, remote,
                                pretty_ref);
                return 0;
        }

        if (current_branch &&
            !strcmp(ref->name, current_branch->name) &&
            !(update_head_ok || is_bare_repository()) &&
            !is_null_sha1(ref->old_sha1)) {
                /*
                 * If this is the head, and it's not okay to update
                 * the head, and the old value of the head isn't empty...
                 */
                sprintf(display, "! %-*s %-*s -> %s  (can't fetch in current branch)",
                        SUMMARY_WIDTH, "[rejected]", REFCOL_WIDTH, remote,
                        pretty_ref);
                return 1;
        }

        if (!is_null_sha1(ref->old_sha1) &&
            !prefixcmp(ref->name, "refs/tags/")) {
                int r;
                r = s_update_ref("updating tag", ref, 0);
                sprintf(display, "%c %-*s %-*s -> %s%s", r ? '!' : '-',
                        SUMMARY_WIDTH, "[tag update]", REFCOL_WIDTH, remote,
                        pretty_ref, r ? "  (unable to update local ref)" : "");
                return r;
        }

        current = lookup_commit_reference_gently(ref->old_sha1, 1);
        updated = lookup_commit_reference_gently(ref->new_sha1, 1);
        if (!current || !updated) {
                const char *msg;
                const char *what;
                int r;
                if (!strncmp(ref->name, "refs/tags/", 10)) {
                        msg = "storing tag";
                        what = "[new tag]";
                }
                else {
                        msg = "storing head";
                        what = "[new branch]";
                }

                r = s_update_ref(msg, ref, 0);
                sprintf(display, "%c %-*s %-*s -> %s%s", r ? '!' : '*',
                        SUMMARY_WIDTH, what, REFCOL_WIDTH, remote, pretty_ref,
                        r ? "  (unable to update local ref)" : "");
                return r;
        }

        if (in_merge_bases(current, &updated, 1)) {
                char quickref[83];
                int r;
                strcpy(quickref, find_unique_abbrev(current->object.sha1, DEFAULT_ABBREV));
                strcat(quickref, "..");
                strcat(quickref, find_unique_abbrev(ref->new_sha1, DEFAULT_ABBREV));
                r = s_update_ref("fast forward", ref, 1);
                sprintf(display, "%c %-*s %-*s -> %s%s", r ? '!' : ' ',
                        SUMMARY_WIDTH, quickref, REFCOL_WIDTH, remote,
                        pretty_ref, r ? "  (unable to update local ref)" : "");
                return r;
        } else if (force || ref->force) {
                char quickref[84];
                int r;
                strcpy(quickref, find_unique_abbrev(current->object.sha1, DEFAULT_ABBREV));
                strcat(quickref, "...");
                strcat(quickref, find_unique_abbrev(ref->new_sha1, DEFAULT_ABBREV));
                r = s_update_ref("forced-update", ref, 1);
                sprintf(display, "%c %-*s %-*s -> %s  (%s)", r ? '!' : '+',
                        SUMMARY_WIDTH, quickref, REFCOL_WIDTH, remote,
                        pretty_ref,
                        r ? "unable to update local ref" : "forced update");
                return r;
        } else {
                sprintf(display, "! %-*s %-*s -> %s  (non fast forward)",
                        SUMMARY_WIDTH, "[rejected]", REFCOL_WIDTH, remote,
                        pretty_ref);
                return 1;
        }
}

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, note_len, shown_url = 0, rc = 0;
        char note[1024];
        const char *what, *kind;
        struct ref *rm;
        char *url, *filename = git_path("FETCH_HEAD");

        fp = fopen(filename, "a");
        if (!fp)
                return error("cannot open %s: %s\n", filename, strerror(errno));

        if (raw_url)
                url = transport_anonymize_url(raw_url);
        else
                url = xstrdup("foreign");
        for (rm = ref_map; rm; rm = rm->next) {
                struct ref *ref = NULL;

                if (rm->peer_ref) {
                        ref = xcalloc(1, sizeof(*ref) + strlen(rm->peer_ref->name) + 1);
                        strcpy(ref->name, rm->peer_ref->name);
                        hashcpy(ref->old_sha1, rm->peer_ref->old_sha1);
                        hashcpy(ref->new_sha1, rm->old_sha1);
                        ref->force = rm->peer_ref->force;
                }

                commit = lookup_commit_reference_gently(rm->old_sha1, 1);
                if (!commit)
                        rm->merge = 0;

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

                note_len = 0;
                if (*what) {
                        if (*kind)
                                note_len += sprintf(note + note_len, "%s ",
                                                    kind);
                        note_len += sprintf(note + note_len, "'%s' of ", what);
                }
                note[note_len] = '\0';
                fprintf(fp, "%s\t%s\t%s",
                        sha1_to_hex(commit ? commit->object.sha1 :
                                    rm->old_sha1),
                        rm->merge ? "" : "not-for-merge",
                        note);
                for (i = 0; i < url_len; ++i)
                        if ('\n' == url[i])
                                fputs("\\n", fp);
                        else
                                fputc(url[i], fp);
                fputc('\n', fp);

                if (ref)
                        rc |= update_local_ref(ref, what, note);
                else
                        sprintf(note, "* %-*s %-*s -> FETCH_HEAD",
                                SUMMARY_WIDTH, *kind ? kind : "branch",
                                 REFCOL_WIDTH, *what ? what : "HEAD");
                if (*note) {
                        if (verbosity >= 0 && !shown_url) {
                                fprintf(stderr, "From %.*s\n",
                                                url_len, url);
                                shown_url = 1;
                        }
                        if (verbosity >= 0)
                                fprintf(stderr, " %s\n", note);
                }
        }
        free(url);
        fclose(fp);
        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);
        return rc;
}

/*
 * We would want to bypass the object transfer altogether if
 * everything we are going to fetch already exists and is connected
 * locally.
 *
 * The refs we are going to fetch are in ref_map.  If running
 *
 *  $ git rev-list --objects --stdin --not --all
 *
 * (feeding all the refs in ref_map on its standard input)
 * does not error out, that means everything reachable from the
 * refs we are going to fetch exists and is connected to some of
 * our existing refs.
 */
static int quickfetch(struct ref *ref_map)
{
        struct child_process revlist;
        struct ref *ref;
        int err;
        const char *argv[] = {"rev-list",
                "--quiet", "--objects", "--stdin", "--not", "--all", NULL};

        /*
         * 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 (depth)
                return -1;

        if (!ref_map)
                return 0;

        memset(&revlist, 0, sizeof(revlist));
        revlist.argv = argv;
        revlist.git_cmd = 1;
        revlist.no_stdout = 1;
        revlist.no_stderr = 1;
        revlist.in = -1;

        err = start_command(&revlist);
        if (err) {
                error("could not run rev-list");
                return err;
        }

        /*
         * If rev-list --stdin encounters an unknown commit, it terminates,
         * which will cause SIGPIPE in the write loop below.
         */
        sigchain_push(SIGPIPE, SIG_IGN);

        for (ref = ref_map; ref; ref = ref->next) {
                if (write_in_full(revlist.in, sha1_to_hex(ref->old_sha1), 40) < 0 ||
                    write_str_in_full(revlist.in, "\n") < 0) {
                        if (errno != EPIPE && errno != EINVAL)
                                error("failed write to rev-list: %s", strerror(errno));
                        err = -1;
                        break;
                }
        }

        if (close(revlist.in)) {
                error("failed to close rev-list's stdin: %s", strerror(errno));
                err = -1;
        }

        sigchain_pop(SIGPIPE);

        return finish_command(&revlist) || err;
}

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 add_existing(const char *refname, const unsigned char *sha1,
                        int flag, void *cbdata)
{
        struct string_list *list = (struct string_list *)cbdata;
        string_list_insert(refname, list);
        return 0;
}

static int will_fetch(struct ref **head, const unsigned char *sha1)
{
        struct ref *rm = *head;
        while (rm) {
                if (!hashcmp(rm->old_sha1, sha1))
                        return 1;
                rm = rm->next;
        }
        return 0;
}

struct tag_data {
        struct ref **head;
        struct ref ***tail;
};

static int add_to_tail(struct string_list_item *item, void *cb_data)
{
        struct tag_data *data = (struct tag_data *)cb_data;
        struct ref *rm = NULL;

        /* We have already decided to ignore this item */
        if (!item->util)
                return 0;

        rm = alloc_ref(item->string);
        rm->peer_ref = alloc_ref(item->string);
        hashcpy(rm->old_sha1, item->util);

        **data->tail = rm;
        *data->tail = &rm->next;

        return 0;
}

static void find_non_local_tags(struct transport *transport,
                        struct ref **head,
                        struct ref ***tail)
{
        struct string_list existing_refs = { NULL, 0, 0, 0 };
        struct string_list remote_refs = { NULL, 0, 0, 0 };
        struct tag_data data = {head, tail};
        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 (prefixcmp(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 (!strcmp(ref->name + strlen(ref->name) - 3, "^{}")) {
                        if (item && !has_sha1_file(ref->old_sha1) &&
                            !will_fetch(head, ref->old_sha1) &&
                            !has_sha1_file(item->util) &&
                            !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(item->util) &&
                    !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(ref->name, &remote_refs);
                item->util = (void *)ref->old_sha1;
        }
        string_list_clear(&existing_refs, 0);

        /*
         * We may have a final lightweight tag that needs to be
         * checked to see if it needs fetching.
         */
        if (item && !has_sha1_file(item->util) &&
            !will_fetch(head, item->util))
                item->util = NULL;

        /*
         * For all the tags in the remote_refs string list, call
         * add_to_tail to add them to the list of refs to be fetched
         */
        for_each_string_list(add_to_tail, &remote_refs, &data);

        string_list_clear(&remote_refs, 0);
}

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 do_fetch(struct transport *transport,
                    struct refspec *refs, int ref_count)
{
        struct ref *ref_map;
        struct ref *rm;
        int autotags = (transport->remote->fetch_tags == 1);
        if (transport->remote->fetch_tags == 2 && tags != TAGS_UNSET)
                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) {
                char *filename = git_path("FETCH_HEAD");
                FILE *fp = fopen(filename, "w");
                if (!fp)
                        return error("cannot open %s: %s\n", filename, strerror(errno));
                fclose(fp);
        }

        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)
                        read_ref(rm->peer_ref->name, rm->peer_ref->old_sha1);
        }

        if (tags == TAGS_DEFAULT && autotags)
                transport_set_option(transport, TRANS_OPT_FOLLOWTAGS, "1");
        if (fetch_refs(transport, ref_map)) {
                free_refs(ref_map);
                return 1;
        }
        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) {
                        transport_set_option(transport, TRANS_OPT_FOLLOWTAGS, NULL);
                        transport_set_option(transport, TRANS_OPT_DEPTH, "0");
                        fetch_refs(transport, ref_map);
                }
                free_refs(ref_map);
        }

        return 0;
}

static void set_option(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);
}

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

        /* 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]);

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

        if (argc == 0)
                remote = remote_get(NULL);
        else
                remote = remote_get(argv[0]);

        if (!remote)
                die("Where do you want to fetch from today?");

        transport = transport_get(remote, NULL);
        if (verbosity >= 2)
                transport->verbose = 1;
        if (verbosity < 0)
                transport->verbose = -1;
        if (upload_pack)
                set_option(TRANS_OPT_UPLOADPACK, upload_pack);
        if (keep)
                set_option(TRANS_OPT_KEEP, "yes");
        if (depth)
                set_option(TRANS_OPT_DEPTH, depth);

        if (argc > 1) {
                int j = 0;
                refs = xcalloc(argc + 1, sizeof(const char *));
                for (i = 1; i < argc; i++) {
                        if (!strcmp(argv[i], "tag")) {
                                char *ref;
                                i++;
                                if (i >= argc)
                                        die("You need to specify a tag name.");
                                ref = xmalloc(strlen(argv[i]) * 2 + 22);
                                strcpy(ref, "refs/tags/");
                                strcat(ref, argv[i]);
                                strcat(ref, ":refs/tags/");
                                strcat(ref, argv[i]);
                                refs[j++] = ref;
                        } else
                                refs[j++] = argv[i];
                }
                refs[j] = NULL;
                ref_nr = j;
        }

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