/*
 * Builtin "git clone"
 *
 * Copyright (c) 2007 Kristian Høgsberg <krh@redhat.com>,
 *               2008 Daniel Barkalow <barkalow@iabervon.org>
 * Based on git-commit.sh by Junio C Hamano and Linus Torvalds
 *
 * Clone a repository into a different directory that does not yet exist.
 */

#include "cache.h"
#include "parse-options.h"
#include "fetch-pack.h"
#include "refs.h"
#include "tree.h"
#include "tree-walk.h"
#include "unpack-trees.h"
#include "transport.h"
#include "strbuf.h"
#include "dir.h"
#include "pack-refs.h"
#include "sigchain.h"

/*
 * Overall FIXMEs:
 *  - respect DB_ENVIRONMENT for .git/objects.
 *
 * Implementation notes:
 *  - dropping use-separate-remote and no-separate-remote compatibility
 *
 */
static const char * const builtin_clone_usage[] = {
        "git clone [options] [--] <repo> [<dir>]",
        NULL
};

static int option_quiet, option_no_checkout, option_bare, option_mirror;
static int option_local, option_no_hardlinks, option_shared;
static char *option_template, *option_reference, *option_depth;
static char *option_origin = NULL;
static char *option_upload_pack = "git-upload-pack";
static int option_verbose;

static struct option builtin_clone_options[] = {
        OPT__QUIET(&option_quiet),
        OPT__VERBOSE(&option_verbose),
        OPT_BOOLEAN('n', "no-checkout", &option_no_checkout,
                    "don't create a checkout"),
        OPT_BOOLEAN(0, "bare", &option_bare, "create a bare repository"),
        OPT_BOOLEAN(0, "naked", &option_bare, "create a bare repository"),
        OPT_BOOLEAN(0, "mirror", &option_mirror,
                    "create a mirror repository (implies bare)"),
        OPT_BOOLEAN('l', "local", &option_local,
                    "to clone from a local repository"),
        OPT_BOOLEAN(0, "no-hardlinks", &option_no_hardlinks,
                    "don't use local hardlinks, always copy"),
        OPT_BOOLEAN('s', "shared", &option_shared,
                    "setup as shared repository"),
        OPT_STRING(0, "template", &option_template, "path",
                   "path the template repository"),
        OPT_STRING(0, "reference", &option_reference, "repo",
                   "reference repository"),
        OPT_STRING('o', "origin", &option_origin, "branch",
                   "use <branch> instead of 'origin' to track upstream"),
        OPT_STRING('u', "upload-pack", &option_upload_pack, "path",
                   "path to git-upload-pack on the remote"),
        OPT_STRING(0, "depth", &option_depth, "depth",
                    "create a shallow clone of that depth"),

        OPT_END()
};

static char *get_repo_path(const char *repo, int *is_bundle)
{
        static char *suffix[] = { "/.git", ".git", "" };
        static char *bundle_suffix[] = { ".bundle", "" };
        struct stat st;
        int i;

        for (i = 0; i < ARRAY_SIZE(suffix); i++) {
                const char *path;
                path = mkpath("%s%s", repo, suffix[i]);
                if (is_directory(path)) {
                        *is_bundle = 0;
                        return xstrdup(make_nonrelative_path(path));
                }
        }

        for (i = 0; i < ARRAY_SIZE(bundle_suffix); i++) {
                const char *path;
                path = mkpath("%s%s", repo, bundle_suffix[i]);
                if (!stat(path, &st) && S_ISREG(st.st_mode)) {
                        *is_bundle = 1;
                        return xstrdup(make_nonrelative_path(path));
                }
        }

        return NULL;
}

static char *guess_dir_name(const char *repo, int is_bundle, int is_bare)
{
        const char *end = repo + strlen(repo), *start;

        /*
         * Strip trailing slashes and /.git
         */
        while (repo < end && is_dir_sep(end[-1]))
                end--;
        if (end - repo > 5 && is_dir_sep(end[-5]) &&
            !strncmp(end - 4, ".git", 4)) {
                end -= 5;
                while (repo < end && is_dir_sep(end[-1]))
                        end--;
        }

        /*
         * Find last component, but be prepared that repo could have
         * the form  "remote.example.com:foo.git", i.e. no slash
         * in the directory part.
         */
        start = end;
        while (repo < start && !is_dir_sep(start[-1]) && start[-1] != ':')
                start--;

        /*
         * Strip .{bundle,git}.
         */
        if (is_bundle) {
                if (end - start > 7 && !strncmp(end - 7, ".bundle", 7))
                        end -= 7;
        } else {
                if (end - start > 4 && !strncmp(end - 4, ".git", 4))
                        end -= 4;
        }

        if (is_bare) {
                struct strbuf result = STRBUF_INIT;
                strbuf_addf(&result, "%.*s.git", (int)(end - start), start);
                return strbuf_detach(&result, 0);
        }

        return xstrndup(start, end - start);
}

static void strip_trailing_slashes(char *dir)
{
        char *end = dir + strlen(dir);

        while (dir < end - 1 && is_dir_sep(end[-1]))
                end--;
        *end = '\0';
}

static void setup_reference(const char *repo)
{
        const char *ref_git;
        char *ref_git_copy;

        struct remote *remote;
        struct transport *transport;
        const struct ref *extra;

        ref_git = make_absolute_path(option_reference);

        if (is_directory(mkpath("%s/.git/objects", ref_git)))
                ref_git = mkpath("%s/.git", ref_git);
        else if (!is_directory(mkpath("%s/objects", ref_git)))
                die("reference repository '%s' is not a local directory.",
                    option_reference);

        ref_git_copy = xstrdup(ref_git);

        add_to_alternates_file(ref_git_copy);

        remote = remote_get(ref_git_copy);
        transport = transport_get(remote, ref_git_copy);
        for (extra = transport_get_remote_refs(transport); extra;
             extra = extra->next)
                add_extra_ref(extra->name, extra->old_sha1, 0);

        transport_disconnect(transport);

        free(ref_git_copy);
}

static void copy_or_link_directory(struct strbuf *src, struct strbuf *dest)
{
        struct dirent *de;
        struct stat buf;
        int src_len, dest_len;
        DIR *dir;

        dir = opendir(src->buf);
        if (!dir)
                die("failed to open %s", src->buf);

        if (mkdir(dest->buf, 0777)) {
                if (errno != EEXIST)
                        die("failed to create directory %s", dest->buf);
                else if (stat(dest->buf, &buf))
                        die("failed to stat %s", dest->buf);
                else if (!S_ISDIR(buf.st_mode))
                        die("%s exists and is not a directory", dest->buf);
        }

        strbuf_addch(src, '/');
        src_len = src->len;
        strbuf_addch(dest, '/');
        dest_len = dest->len;

        while ((de = readdir(dir)) != NULL) {
                strbuf_setlen(src, src_len);
                strbuf_addstr(src, de->d_name);
                strbuf_setlen(dest, dest_len);
                strbuf_addstr(dest, de->d_name);
                if (stat(src->buf, &buf)) {
                        warning ("failed to stat %s\n", src->buf);
                        continue;
                }
                if (S_ISDIR(buf.st_mode)) {
                        if (de->d_name[0] != '.')
                                copy_or_link_directory(src, dest);
                        continue;
                }

                if (unlink(dest->buf) && errno != ENOENT)
                        die("failed to unlink %s", dest->buf);
                if (!option_no_hardlinks) {
                        if (!link(src->buf, dest->buf))
                                continue;
                        if (option_local)
                                die("failed to create link %s", dest->buf);
                        option_no_hardlinks = 1;
                }
                if (copy_file(dest->buf, src->buf, 0666))
                        die("failed to copy file to %s", dest->buf);
        }
        closedir(dir);
}

static const struct ref *clone_local(const char *src_repo,
                                     const char *dest_repo)
{
        const struct ref *ret;
        struct strbuf src = STRBUF_INIT;
        struct strbuf dest = STRBUF_INIT;
        struct remote *remote;
        struct transport *transport;

        if (option_shared)
                add_to_alternates_file(src_repo);
        else {
                strbuf_addf(&src, "%s/objects", src_repo);
                strbuf_addf(&dest, "%s/objects", dest_repo);
                copy_or_link_directory(&src, &dest);
                strbuf_release(&src);
                strbuf_release(&dest);
        }

        remote = remote_get(src_repo);
        transport = transport_get(remote, src_repo);
        ret = transport_get_remote_refs(transport);
        transport_disconnect(transport);
        return ret;
}

static const char *junk_work_tree;
static const char *junk_git_dir;
pid_t junk_pid;

static void remove_junk(void)
{
        struct strbuf sb = STRBUF_INIT;
        if (getpid() != junk_pid)
                return;
        if (junk_git_dir) {
                strbuf_addstr(&sb, junk_git_dir);
                remove_dir_recursively(&sb, 0);
                strbuf_reset(&sb);
        }
        if (junk_work_tree) {
                strbuf_addstr(&sb, junk_work_tree);
                remove_dir_recursively(&sb, 0);
                strbuf_reset(&sb);
        }
}

static void remove_junk_on_signal(int signo)
{
        remove_junk();
        sigchain_pop(signo);
        raise(signo);
}

static const struct ref *locate_head(const struct ref *refs,
                                     const struct ref *mapped_refs,
                                     const struct ref **remote_head_p)
{
        const struct ref *remote_head = NULL;
        const struct ref *remote_master = NULL;
        const struct ref *r;
        for (r = refs; r; r = r->next)
                if (!strcmp(r->name, "HEAD"))
                        remote_head = r;

        for (r = mapped_refs; r; r = r->next)
                if (!strcmp(r->name, "refs/heads/master"))
                        remote_master = r;

        if (remote_head_p)
                *remote_head_p = remote_head;

        /* If there's no HEAD value at all, never mind. */
        if (!remote_head)
                return NULL;

        /* If refs/heads/master could be right, it is. */
        if (remote_master && !hashcmp(remote_master->old_sha1,
                                      remote_head->old_sha1))
                return remote_master;

        /* Look for another ref that points there */
        for (r = mapped_refs; r; r = r->next)
                if (r != remote_head &&
                    !hashcmp(r->old_sha1, remote_head->old_sha1))
                        return r;

        /* Nothing is the same */
        return NULL;
}

static struct ref *write_remote_refs(const struct ref *refs,
                struct refspec *refspec, const char *reflog)
{
        struct ref *local_refs = NULL;
        struct ref **tail = &local_refs;
        struct ref *r;

        get_fetch_map(refs, refspec, &tail, 0);
        if (!option_mirror)
                get_fetch_map(refs, tag_refspec, &tail, 0);

        for (r = local_refs; r; r = r->next)
                add_extra_ref(r->peer_ref->name, r->old_sha1, 0);

        pack_refs(PACK_REFS_ALL);
        clear_extra_refs();

        return local_refs;
}

static void install_branch_config(const char *local,
                                  const char *origin,
                                  const char *remote)
{
        struct strbuf key = STRBUF_INIT;
        strbuf_addf(&key, "branch.%s.remote", local);
        git_config_set(key.buf, origin);
        strbuf_reset(&key);
        strbuf_addf(&key, "branch.%s.merge", local);
        git_config_set(key.buf, remote);
        strbuf_release(&key);
}

int cmd_clone(int argc, const char **argv, const char *prefix)
{
        int is_bundle = 0;
        struct stat buf;
        const char *repo_name, *repo, *work_tree, *git_dir;
        char *path, *dir;
        int dest_exists;
        const struct ref *refs, *head_points_at, *remote_head, *mapped_refs;
        struct strbuf key = STRBUF_INIT, value = STRBUF_INIT;
        struct strbuf branch_top = STRBUF_INIT, reflog_msg = STRBUF_INIT;
        struct transport *transport = NULL;
        char *src_ref_prefix = "refs/heads/";

        struct refspec refspec;

        junk_pid = getpid();

        argc = parse_options(argc, argv, builtin_clone_options,
                             builtin_clone_usage, 0);

        if (argc == 0)
                die("You must specify a repository to clone.");

        if (option_mirror)
                option_bare = 1;

        if (option_bare) {
                if (option_origin)
                        die("--bare and --origin %s options are incompatible.",
                            option_origin);
                option_no_checkout = 1;
        }

        if (!option_origin)
                option_origin = "origin";

        repo_name = argv[0];

        path = get_repo_path(repo_name, &is_bundle);
        if (path)
                repo = xstrdup(make_nonrelative_path(repo_name));
        else if (!strchr(repo_name, ':'))
                repo = xstrdup(make_absolute_path(repo_name));
        else
                repo = repo_name;

        if (argc == 2)
                dir = xstrdup(argv[1]);
        else
                dir = guess_dir_name(repo_name, is_bundle, option_bare);
        strip_trailing_slashes(dir);

        dest_exists = !stat(dir, &buf);
        if (dest_exists && !is_empty_dir(dir))
                die("destination path '%s' already exists and is not "
                        "an empty directory.", dir);

        strbuf_addf(&reflog_msg, "clone: from %s", repo);

        if (option_bare)
                work_tree = NULL;
        else {
                work_tree = getenv("GIT_WORK_TREE");
                if (work_tree && !stat(work_tree, &buf))
                        die("working tree '%s' already exists.", work_tree);
        }

        if (option_bare || work_tree)
                git_dir = xstrdup(dir);
        else {
                work_tree = dir;
                git_dir = xstrdup(mkpath("%s/.git", dir));
        }

        if (!option_bare) {
                junk_work_tree = work_tree;
                if (safe_create_leading_directories_const(work_tree) < 0)
                        die("could not create leading directories of '%s': %s",
                                        work_tree, strerror(errno));
                if (!dest_exists && mkdir(work_tree, 0755))
                        die("could not create work tree dir '%s': %s.",
                                        work_tree, strerror(errno));
                set_git_work_tree(work_tree);
        }
        junk_git_dir = git_dir;
        atexit(remove_junk);
        sigchain_push_common(remove_junk_on_signal);

        setenv(CONFIG_ENVIRONMENT, xstrdup(mkpath("%s/config", git_dir)), 1);

        if (safe_create_leading_directories_const(git_dir) < 0)
                die("could not create leading directories of '%s'", git_dir);
        set_git_dir(make_absolute_path(git_dir));

        init_db(option_template, option_quiet ? INIT_DB_QUIET : 0);

        /*
         * At this point, the config exists, so we do not need the
         * environment variable.  We actually need to unset it, too, to
         * re-enable parsing of the global configs.
         */
        unsetenv(CONFIG_ENVIRONMENT);

        if (option_reference)
                setup_reference(git_dir);

        git_config(git_default_config, NULL);

        if (option_bare) {
                if (option_mirror)
                        src_ref_prefix = "refs/";
                strbuf_addstr(&branch_top, src_ref_prefix);

                git_config_set("core.bare", "true");
        } else {
                strbuf_addf(&branch_top, "refs/remotes/%s/", option_origin);
        }

        if (option_mirror || !option_bare) {
                /* Configure the remote */
                if (option_mirror) {
                        strbuf_addf(&key, "remote.%s.mirror", option_origin);
                        git_config_set(key.buf, "true");
                        strbuf_reset(&key);
                }

                strbuf_addf(&key, "remote.%s.url", option_origin);
                git_config_set(key.buf, repo);
                        strbuf_reset(&key);

                strbuf_addf(&key, "remote.%s.fetch", option_origin);
                strbuf_addf(&value, "+%s*:%s*", src_ref_prefix, branch_top.buf);
                git_config_set_multivar(key.buf, value.buf, "^$", 0);
                strbuf_reset(&key);
                strbuf_reset(&value);
        }

        refspec.force = 0;
        refspec.pattern = 1;
        refspec.src = src_ref_prefix;
        refspec.dst = branch_top.buf;

        if (path && !is_bundle)
                refs = clone_local(path, git_dir);
        else {
                struct remote *remote = remote_get(argv[0]);
                transport = transport_get(remote, remote->url[0]);

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

                transport_set_option(transport, TRANS_OPT_KEEP, "yes");

                if (option_depth)
                        transport_set_option(transport, TRANS_OPT_DEPTH,
                                             option_depth);

                if (option_quiet)
                        transport->verbose = -1;
                else if (option_verbose)
                        transport->progress = 1;

                if (option_upload_pack)
                        transport_set_option(transport, TRANS_OPT_UPLOADPACK,
                                             option_upload_pack);

                refs = transport_get_remote_refs(transport);
                if(refs)
                        transport_fetch_refs(transport, refs);
        }

        if (refs) {
                clear_extra_refs();

                mapped_refs = write_remote_refs(refs, &refspec, reflog_msg.buf);

                head_points_at = locate_head(refs, mapped_refs, &remote_head);
        }
        else {
                warning("You appear to have cloned an empty repository.");
                head_points_at = NULL;
                remote_head = NULL;
                option_no_checkout = 1;
                if (!option_bare)
                        install_branch_config("master", option_origin,
                                              "refs/heads/master");
        }

        if (head_points_at) {
                /* Local default branch link */
                create_symref("HEAD", head_points_at->name, NULL);

                if (!option_bare) {
                        struct strbuf head_ref = STRBUF_INIT;
                        const char *head = head_points_at->name;

                        if (!prefixcmp(head, "refs/heads/"))
                                head += 11;

                        /* Set up the initial local branch */

                        /* Local branch initial value */
                        update_ref(reflog_msg.buf, "HEAD",
                                   head_points_at->old_sha1,
                                   NULL, 0, DIE_ON_ERR);

                        strbuf_addstr(&head_ref, branch_top.buf);
                        strbuf_addstr(&head_ref, "HEAD");

                        /* Remote branch link */
                        create_symref(head_ref.buf,
                                      head_points_at->peer_ref->name,
                                      reflog_msg.buf);

                        install_branch_config(head, option_origin,
                                              head_points_at->name);
                }
        } else if (remote_head) {
                /* Source had detached HEAD pointing somewhere. */
                if (!option_bare)
                        update_ref(reflog_msg.buf, "HEAD",
                                   remote_head->old_sha1,
                                   NULL, REF_NODEREF, DIE_ON_ERR);
        } else {
                /* Nothing to checkout out */
                if (!option_no_checkout)
                        warning("remote HEAD refers to nonexistent ref, "
                                "unable to checkout.\n");
                option_no_checkout = 1;
        }

        if (transport)
                transport_unlock_pack(transport);

        if (!option_no_checkout) {
                struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
                struct unpack_trees_options opts;
                struct tree *tree;
                struct tree_desc t;
                int fd;

                /* We need to be in the new work tree for the checkout */
                setup_work_tree();

                fd = hold_locked_index(lock_file, 1);

                memset(&opts, 0, sizeof opts);
                opts.update = 1;
                opts.merge = 1;
                opts.fn = oneway_merge;
                opts.verbose_update = !option_quiet;
                opts.src_index = &the_index;
                opts.dst_index = &the_index;

                tree = parse_tree_indirect(remote_head->old_sha1);
                parse_tree(tree);
                init_tree_desc(&t, tree->buffer, tree->size);
                unpack_trees(1, &t, &opts);

                if (write_cache(fd, active_cache, active_nr) ||
                    commit_locked_index(lock_file))
                        die("unable to write new index file");
        }

        strbuf_release(&reflog_msg);
        strbuf_release(&branch_top);
        strbuf_release(&key);
        strbuf_release(&value);
        junk_pid = 0;
        return 0;
}