#include "cache.h"
#include "refs.h"
#include "pkt-line.h"
#include "sideband.h"
#include "tag.h"
#include "object.h"
#include "commit.h"
#include "exec_cmd.h"
#include "diff.h"
#include "revision.h"
#include "list-objects.h"
#include "run-command.h"

static const char upload_pack_usage[] = "git-upload-pack [--strict] [--timeout=nn] <dir>";

/* bits #0..7 in revision.h, #8..10 in commit.c */
#define THEY_HAVE       (1u << 11)
#define OUR_REF         (1u << 12)
#define WANTED          (1u << 13)
#define COMMON_KNOWN    (1u << 14)
#define REACHABLE       (1u << 15)

#define SHALLOW         (1u << 16)
#define NOT_SHALLOW     (1u << 17)
#define CLIENT_SHALLOW  (1u << 18)

static unsigned long oldest_have;

static int multi_ack, nr_our_refs;
static int use_thin_pack, use_ofs_delta, no_progress;
static struct object_array have_obj;
static struct object_array want_obj;
static unsigned int timeout;
/* 0 for no sideband,
 * otherwise maximum packet size (up to 65520 bytes).
 */
static int use_sideband;

static void reset_timeout(void)
{
        alarm(timeout);
}

static int strip(char *line, int len)
{
        if (len && line[len-1] == '\n')
                line[--len] = 0;
        return len;
}

static ssize_t send_client_data(int fd, const char *data, ssize_t sz)
{
        if (use_sideband)
                return send_sideband(1, fd, data, sz, use_sideband);
        if (fd == 3)
                /* emergency quit */
                fd = 2;
        if (fd == 2) {
                /* XXX: are we happy to lose stuff here? */
                xwrite(fd, data, sz);
                return sz;
        }
        return safe_write(fd, data, sz);
}

static FILE *pack_pipe = NULL;
static void show_commit(struct commit *commit)
{
        if (commit->object.flags & BOUNDARY)
                fputc('-', pack_pipe);
        if (fputs(sha1_to_hex(commit->object.sha1), pack_pipe) < 0)
                die("broken output pipe");
        fputc('\n', pack_pipe);
        fflush(pack_pipe);
        free(commit->buffer);
        commit->buffer = NULL;
}

static void show_object(struct object_array_entry *p)
{
        /* An object with name "foo\n0000000..." can be used to
         * confuse downstream git-pack-objects very badly.
         */
        const char *ep = strchr(p->name, '\n');
        if (ep) {
                fprintf(pack_pipe, "%s %.*s\n", sha1_to_hex(p->item->sha1),
                       (int) (ep - p->name),
                       p->name);
        }
        else
                fprintf(pack_pipe, "%s %s\n",
                                sha1_to_hex(p->item->sha1), p->name);
}

static void show_edge(struct commit *commit)
{
        fprintf(pack_pipe, "-%s\n", sha1_to_hex(commit->object.sha1));
}

static int do_rev_list(int fd, void *create_full_pack)
{
        int i;
        struct rev_info revs;

        pack_pipe = fdopen(fd, "w");
        if (create_full_pack)
                use_thin_pack = 0; /* no point doing it */
        init_revisions(&revs, NULL);
        revs.tag_objects = 1;
        revs.tree_objects = 1;
        revs.blob_objects = 1;
        if (use_thin_pack)
                revs.edge_hint = 1;

        if (create_full_pack) {
                const char *args[] = {"rev-list", "--all", NULL};
                setup_revisions(2, args, &revs, NULL);
        } else {
                for (i = 0; i < want_obj.nr; i++) {
                        struct object *o = want_obj.objects[i].item;
                        /* why??? */
                        o->flags &= ~UNINTERESTING;
                        add_pending_object(&revs, o, NULL);
                }
                for (i = 0; i < have_obj.nr; i++) {
                        struct object *o = have_obj.objects[i].item;
                        o->flags |= UNINTERESTING;
                        add_pending_object(&revs, o, NULL);
                }
                setup_revisions(0, NULL, &revs, NULL);
        }
        if (prepare_revision_walk(&revs))
                die("revision walk setup failed");
        mark_edges_uninteresting(revs.commits, &revs, show_edge);
        traverse_commit_list(&revs, show_commit, show_object);
        return 0;
}

static void create_pack_file(void)
{
        struct async rev_list;
        struct child_process pack_objects;
        int create_full_pack = (nr_our_refs == want_obj.nr && !have_obj.nr);
        char data[8193], progress[128];
        char abort_msg[] = "aborting due to possible repository "
                "corruption on the remote side.";
        int buffered = -1;
        ssize_t sz;
        const char *argv[10];
        int arg = 0;

        rev_list.proc = do_rev_list;
        /* .data is just a boolean: any non-NULL value will do */
        rev_list.data = create_full_pack ? &rev_list : NULL;
        if (start_async(&rev_list))
                die("git-upload-pack: unable to fork git-rev-list");

        argv[arg++] = "pack-objects";
        argv[arg++] = "--stdout";
        if (!no_progress)
                argv[arg++] = "--progress";
        if (use_ofs_delta)
                argv[arg++] = "--delta-base-offset";
        argv[arg++] = NULL;

        memset(&pack_objects, 0, sizeof(pack_objects));
        pack_objects.in = rev_list.out; /* start_command closes it */
        pack_objects.out = -1;
        pack_objects.err = -1;
        pack_objects.git_cmd = 1;
        pack_objects.argv = argv;

        if (start_command(&pack_objects))
                die("git-upload-pack: unable to fork git-pack-objects");

        /* We read from pack_objects.err to capture stderr output for
         * progress bar, and pack_objects.out to capture the pack data.
         */

        while (1) {
                struct pollfd pfd[2];
                int pe, pu, pollsize;

                reset_timeout();

                pollsize = 0;
                pe = pu = -1;

                if (0 <= pack_objects.out) {
                        pfd[pollsize].fd = pack_objects.out;
                        pfd[pollsize].events = POLLIN;
                        pu = pollsize;
                        pollsize++;
                }
                if (0 <= pack_objects.err) {
                        pfd[pollsize].fd = pack_objects.err;
                        pfd[pollsize].events = POLLIN;
                        pe = pollsize;
                        pollsize++;
                }

                if (!pollsize)
                        break;

                if (poll(pfd, pollsize, -1) < 0) {
                        if (errno != EINTR) {
                                error("poll failed, resuming: %s",
                                      strerror(errno));
                                sleep(1);
                        }
                        continue;
                }
                if (0 <= pu && (pfd[pu].revents & (POLLIN|POLLHUP))) {
                        /* Data ready; we keep the last byte to ourselves
                         * in case we detect broken rev-list, so that we
                         * can leave the stream corrupted.  This is
                         * unfortunate -- unpack-objects would happily
                         * accept a valid packdata with trailing garbage,
                         * so appending garbage after we pass all the
                         * pack data is not good enough to signal
                         * breakage to downstream.
                         */
                        char *cp = data;
                        ssize_t outsz = 0;
                        if (0 <= buffered) {
                                *cp++ = buffered;
                                outsz++;
                        }
                        sz = xread(pack_objects.out, cp,
                                  sizeof(data) - outsz);
                        if (0 < sz)
                                        ;
                        else if (sz == 0) {
                                close(pack_objects.out);
                                pack_objects.out = -1;
                        }
                        else
                                goto fail;
                        sz += outsz;
                        if (1 < sz) {
                                buffered = data[sz-1] & 0xFF;
                                sz--;
                        }
                        else
                                buffered = -1;
                        sz = send_client_data(1, data, sz);
                        if (sz < 0)
                                goto fail;
                }
                if (0 <= pe && (pfd[pe].revents & (POLLIN|POLLHUP))) {
                        /* Status ready; we ship that in the side-band
                         * or dump to the standard error.
                         */
                        sz = xread(pack_objects.err, progress,
                                  sizeof(progress));
                        if (0 < sz)
                                send_client_data(2, progress, sz);
                        else if (sz == 0) {
                                close(pack_objects.err);
                                pack_objects.err = -1;
                        }
                        else
                                goto fail;
                }
        }

        if (finish_command(&pack_objects)) {
                error("git-upload-pack: git-pack-objects died with error.");
                goto fail;
        }
        if (finish_async(&rev_list))
                goto fail;      /* error was already reported */

        /* flush the data */
        if (0 <= buffered) {
                data[0] = buffered;
                sz = send_client_data(1, data, 1);
                if (sz < 0)
                        goto fail;
                fprintf(stderr, "flushed.\n");
        }
        if (use_sideband)
                packet_flush(1);
        return;

 fail:
        send_client_data(3, abort_msg, sizeof(abort_msg));
        die("git-upload-pack: %s", abort_msg);
}

static int got_sha1(char *hex, unsigned char *sha1)
{
        struct object *o;
        int we_knew_they_have = 0;

        if (get_sha1_hex(hex, sha1))
                die("git-upload-pack: expected SHA1 object, got '%s'", hex);
        if (!has_sha1_file(sha1))
                return -1;

        o = lookup_object(sha1);
        if (!(o && o->parsed))
                o = parse_object(sha1);
        if (!o)
                die("oops (%s)", sha1_to_hex(sha1));
        if (o->type == OBJ_COMMIT) {
                struct commit_list *parents;
                struct commit *commit = (struct commit *)o;
                if (o->flags & THEY_HAVE)
                        we_knew_they_have = 1;
                else
                        o->flags |= THEY_HAVE;
                if (!oldest_have || (commit->date < oldest_have))
                        oldest_have = commit->date;
                for (parents = commit->parents;
                     parents;
                     parents = parents->next)
                        parents->item->object.flags |= THEY_HAVE;
        }
        if (!we_knew_they_have) {
                add_object_array(o, NULL, &have_obj);
                return 1;
        }
        return 0;
}

static int reachable(struct commit *want)
{
        struct commit_list *work = NULL;

        insert_by_date(want, &work);
        while (work) {
                struct commit_list *list = work->next;
                struct commit *commit = work->item;
                free(work);
                work = list;

                if (commit->object.flags & THEY_HAVE) {
                        want->object.flags |= COMMON_KNOWN;
                        break;
                }
                if (!commit->object.parsed)
                        parse_object(commit->object.sha1);
                if (commit->object.flags & REACHABLE)
                        continue;
                commit->object.flags |= REACHABLE;
                if (commit->date < oldest_have)
                        continue;
                for (list = commit->parents; list; list = list->next) {
                        struct commit *parent = list->item;
                        if (!(parent->object.flags & REACHABLE))
                                insert_by_date(parent, &work);
                }
        }
        want->object.flags |= REACHABLE;
        clear_commit_marks(want, REACHABLE);
        free_commit_list(work);
        return (want->object.flags & COMMON_KNOWN);
}

static int ok_to_give_up(void)
{
        int i;

        if (!have_obj.nr)
                return 0;

        for (i = 0; i < want_obj.nr; i++) {
                struct object *want = want_obj.objects[i].item;

                if (want->flags & COMMON_KNOWN)
                        continue;
                want = deref_tag(want, "a want line", 0);
                if (!want || want->type != OBJ_COMMIT) {
                        /* no way to tell if this is reachable by
                         * looking at the ancestry chain alone, so
                         * leave a note to ourselves not to worry about
                         * this object anymore.
                         */
                        want_obj.objects[i].item->flags |= COMMON_KNOWN;
                        continue;
                }
                if (!reachable((struct commit *)want))
                        return 0;
        }
        return 1;
}

static int get_common_commits(void)
{
        static char line[1000];
        unsigned char sha1[20];
        char hex[41], last_hex[41];
        int len;

        track_object_refs = 0;
        save_commit_buffer = 0;

        for(;;) {
                len = packet_read_line(0, line, sizeof(line));
                reset_timeout();

                if (!len) {
                        if (have_obj.nr == 0 || multi_ack)
                                packet_write(1, "NAK\n");
                        continue;
                }
                len = strip(line, len);
                if (!prefixcmp(line, "have ")) {
                        switch (got_sha1(line+5, sha1)) {
                        case -1: /* they have what we do not */
                                if (multi_ack && ok_to_give_up())
                                        packet_write(1, "ACK %s continue\n",
                                                     sha1_to_hex(sha1));
                                break;
                        default:
                                memcpy(hex, sha1_to_hex(sha1), 41);
                                if (multi_ack) {
                                        const char *msg = "ACK %s continue\n";
                                        packet_write(1, msg, hex);
                                        memcpy(last_hex, hex, 41);
                                }
                                else if (have_obj.nr == 1)
                                        packet_write(1, "ACK %s\n", hex);
                                break;
                        }
                        continue;
                }
                if (!strcmp(line, "done")) {
                        if (have_obj.nr > 0) {
                                if (multi_ack)
                                        packet_write(1, "ACK %s\n", last_hex);
                                return 0;
                        }
                        packet_write(1, "NAK\n");
                        return -1;
                }
                die("git-upload-pack: expected SHA1 list, got '%s'", line);
        }
}

static void receive_needs(void)
{
        struct object_array shallows = {0, 0, NULL};
        static char line[1000];
        int len, depth = 0;

        for (;;) {
                struct object *o;
                unsigned char sha1_buf[20];
                len = packet_read_line(0, line, sizeof(line));
                reset_timeout();
                if (!len)
                        break;

                if (!prefixcmp(line, "shallow ")) {
                        unsigned char sha1[20];
                        struct object *object;
                        use_thin_pack = 0;
                        if (get_sha1(line + 8, sha1))
                                die("invalid shallow line: %s", line);
                        object = parse_object(sha1);
                        if (!object)
                                die("did not find object for %s", line);
                        object->flags |= CLIENT_SHALLOW;
                        add_object_array(object, NULL, &shallows);
                        continue;
                }
                if (!prefixcmp(line, "deepen ")) {
                        char *end;
                        use_thin_pack = 0;
                        depth = strtol(line + 7, &end, 0);
                        if (end == line + 7 || depth <= 0)
                                die("Invalid deepen: %s", line);
                        continue;
                }
                if (prefixcmp(line, "want ") ||
                    get_sha1_hex(line+5, sha1_buf))
                        die("git-upload-pack: protocol error, "
                            "expected to get sha, not '%s'", line);
                if (strstr(line+45, "multi_ack"))
                        multi_ack = 1;
                if (strstr(line+45, "thin-pack"))
                        use_thin_pack = 1;
                if (strstr(line+45, "ofs-delta"))
                        use_ofs_delta = 1;
                if (strstr(line+45, "side-band-64k"))
                        use_sideband = LARGE_PACKET_MAX;
                else if (strstr(line+45, "side-band"))
                        use_sideband = DEFAULT_PACKET_MAX;
                if (strstr(line+45, "no-progress"))
                        no_progress = 1;

                /* We have sent all our refs already, and the other end
                 * should have chosen out of them; otherwise they are
                 * asking for nonsense.
                 *
                 * Hmph.  We may later want to allow "want" line that
                 * asks for something like "master~10" (symbolic)...
                 * would it make sense?  I don't know.
                 */
                o = lookup_object(sha1_buf);
                if (!o || !(o->flags & OUR_REF))
                        die("git-upload-pack: not our ref %s", line+5);
                if (!(o->flags & WANTED)) {
                        o->flags |= WANTED;
                        add_object_array(o, NULL, &want_obj);
                }
        }
        if (depth == 0 && shallows.nr == 0)
                return;
        if (depth > 0) {
                struct commit_list *result, *backup;
                int i;
                backup = result = get_shallow_commits(&want_obj, depth,
                        SHALLOW, NOT_SHALLOW);
                while (result) {
                        struct object *object = &result->item->object;
                        if (!(object->flags & (CLIENT_SHALLOW|NOT_SHALLOW))) {
                                packet_write(1, "shallow %s",
                                                sha1_to_hex(object->sha1));
                                register_shallow(object->sha1);
                        }
                        result = result->next;
                }
                free_commit_list(backup);
                for (i = 0; i < shallows.nr; i++) {
                        struct object *object = shallows.objects[i].item;
                        if (object->flags & NOT_SHALLOW) {
                                struct commit_list *parents;
                                packet_write(1, "unshallow %s",
                                        sha1_to_hex(object->sha1));
                                object->flags &= ~CLIENT_SHALLOW;
                                /* make sure the real parents are parsed */
                                unregister_shallow(object->sha1);
                                object->parsed = 0;
                                parse_commit((struct commit *)object);
                                parents = ((struct commit *)object)->parents;
                                while (parents) {
                                        add_object_array(&parents->item->object,
                                                        NULL, &want_obj);
                                        parents = parents->next;
                                }
                        }
                        /* make sure commit traversal conforms to client */
                        register_shallow(object->sha1);
                }
                packet_flush(1);
        } else
                if (shallows.nr > 0) {
                        int i;
                        for (i = 0; i < shallows.nr; i++)
                                register_shallow(shallows.objects[i].item->sha1);
                }
        free(shallows.objects);
}

static int send_ref(const char *refname, const unsigned char *sha1, int flag, void *cb_data)
{
        static const char *capabilities = "multi_ack thin-pack side-band"
                " side-band-64k ofs-delta shallow no-progress";
        struct object *o = parse_object(sha1);

        if (!o)
                die("git-upload-pack: cannot find object %s:", sha1_to_hex(sha1));

        if (capabilities)
                packet_write(1, "%s %s%c%s\n", sha1_to_hex(sha1), refname,
                        0, capabilities);
        else
                packet_write(1, "%s %s\n", sha1_to_hex(sha1), refname);
        capabilities = NULL;
        if (!(o->flags & OUR_REF)) {
                o->flags |= OUR_REF;
                nr_our_refs++;
        }
        if (o->type == OBJ_TAG) {
                o = deref_tag(o, refname, 0);
                if (o)
                        packet_write(1, "%s %s^{}\n", sha1_to_hex(o->sha1), refname);
        }
        return 0;
}

static void upload_pack(void)
{
        reset_timeout();
        head_ref(send_ref, NULL);
        for_each_ref(send_ref, NULL);
        packet_flush(1);
        receive_needs();
        if (want_obj.nr) {
                get_common_commits();
                create_pack_file();
        }
}

int main(int argc, char **argv)
{
        char *dir;
        int i;
        int strict = 0;

        for (i = 1; i < argc; i++) {
                char *arg = argv[i];

                if (arg[0] != '-')
                        break;
                if (!strcmp(arg, "--strict")) {
                        strict = 1;
                        continue;
                }
                if (!prefixcmp(arg, "--timeout=")) {
                        timeout = atoi(arg+10);
                        continue;
                }
                if (!strcmp(arg, "--")) {
                        i++;
                        break;
                }
        }

        if (i != argc-1)
                usage(upload_pack_usage);

        setup_path(NULL);

        dir = argv[i];

        if (!enter_repo(dir, strict))
                die("'%s': unable to chdir or not a git archive", dir);
        if (is_repository_shallow())
                die("attempt to fetch/clone from a shallow repository");
        upload_pack();
        return 0;
}