#include "builtin.h"
#include "cache.h"
#include "commit.h"
#include "tree.h"
#include "blob.h"
#include "tag.h"
#include "refs.h"
#include "pack.h"
#include "cache-tree.h"
#include "tree-walk.h"
#include "fsck.h"
#include "parse-options.h"
#include "dir.h"
#include "progress.h"
#include "streaming.h"
#include "decorate.h"

#define REACHABLE 0x0001
#define SEEN      0x0002
#define HAS_OBJ   0x0004

static int show_root;
static int show_tags;
static int show_unreachable;
static int include_reflogs = 1;
static int check_full = 1;
static int connectivity_only;
static int check_strict;
static int keep_cache_objects;
static struct fsck_options fsck_walk_options = FSCK_OPTIONS_DEFAULT;
static struct fsck_options fsck_obj_options = FSCK_OPTIONS_DEFAULT;
static struct object_id head_oid;
static const char *head_points_at;
static int errors_found;
static int write_lost_and_found;
static int verbose;
static int show_progress = -1;
static int show_dangling = 1;
static int name_objects;
#define ERROR_OBJECT 01
#define ERROR_REACHABLE 02
#define ERROR_PACK 04
#define ERROR_REFS 010

static const char *describe_object(struct object *obj)
{
        static struct strbuf buf = STRBUF_INIT;
        char *name = name_objects ?
                lookup_decoration(fsck_walk_options.object_names, obj) : NULL;

        strbuf_reset(&buf);
        strbuf_addstr(&buf, oid_to_hex(&obj->oid));
        if (name)
                strbuf_addf(&buf, " (%s)", name);

        return buf.buf;
}

static int fsck_config(const char *var, const char *value, void *cb)
{
        if (strcmp(var, "fsck.skiplist") == 0) {
                const char *path;
                struct strbuf sb = STRBUF_INIT;

                if (git_config_pathname(&path, var, value))
                        return 1;
                strbuf_addf(&sb, "skiplist=%s", path);
                free((char *)path);
                fsck_set_msg_types(&fsck_obj_options, sb.buf);
                strbuf_release(&sb);
                return 0;
        }

        if (skip_prefix(var, "fsck.", &var)) {
                fsck_set_msg_type(&fsck_obj_options, var, value);
                return 0;
        }

        return git_default_config(var, value, cb);
}

static void objreport(struct object *obj, const char *msg_type,
                        const char *err)
{
        fprintf(stderr, "%s in %s %s: %s\n",
                msg_type, typename(obj->type), describe_object(obj), err);
}

static int objerror(struct object *obj, const char *err)
{
        errors_found |= ERROR_OBJECT;
        objreport(obj, "error", err);
        return -1;
}

static int fsck_error_func(struct fsck_options *o,
        struct object *obj, int type, const char *message)
{
        objreport(obj, (type == FSCK_WARN) ? "warning" : "error", message);
        return (type == FSCK_WARN) ? 0 : 1;
}

static struct object_array pending;

static int mark_object(struct object *obj, int type, void *data, struct fsck_options *options)
{
        struct object *parent = data;

        /*
         * The only case data is NULL or type is OBJ_ANY is when
         * mark_object_reachable() calls us.  All the callers of
         * that function has non-NULL obj hence ...
         */
        if (!obj) {
                /* ... these references to parent->fld are safe here */
                printf("broken link from %7s %s\n",
                           typename(parent->type), describe_object(parent));
                printf("broken link from %7s %s\n",
                           (type == OBJ_ANY ? "unknown" : typename(type)), "unknown");
                errors_found |= ERROR_REACHABLE;
                return 1;
        }

        if (type != OBJ_ANY && obj->type != type)
                /* ... and the reference to parent is safe here */
                objerror(parent, "wrong object type in link");

        if (obj->flags & REACHABLE)
                return 0;
        obj->flags |= REACHABLE;
        if (!(obj->flags & HAS_OBJ)) {
                if (parent && !has_object_file(&obj->oid)) {
                        printf("broken link from %7s %s\n",
                                 typename(parent->type), describe_object(parent));
                        printf("              to %7s %s\n",
                                 typename(obj->type), describe_object(obj));
                        errors_found |= ERROR_REACHABLE;
                }
                return 1;
        }

        add_object_array(obj, NULL, &pending);
        return 0;
}

static void mark_object_reachable(struct object *obj)
{
        mark_object(obj, OBJ_ANY, NULL, NULL);
}

static int traverse_one_object(struct object *obj)
{
        int result;
        struct tree *tree = NULL;

        if (obj->type == OBJ_TREE) {
                tree = (struct tree *)obj;
                if (parse_tree(tree) < 0)
                        return 1; /* error already displayed */
        }
        result = fsck_walk(obj, obj, &fsck_walk_options);
        if (tree)
                free_tree_buffer(tree);
        return result;
}

static int traverse_reachable(void)
{
        struct progress *progress = NULL;
        unsigned int nr = 0;
        int result = 0;
        if (show_progress)
                progress = start_progress_delay(_("Checking connectivity"), 0, 0, 2);
        while (pending.nr) {
                struct object_array_entry *entry;
                struct object *obj;

                entry = pending.objects + --pending.nr;
                obj = entry->item;
                result |= traverse_one_object(obj);
                display_progress(progress, ++nr);
        }
        stop_progress(&progress);
        return !!result;
}

static int mark_used(struct object *obj, int type, void *data, struct fsck_options *options)
{
        if (!obj)
                return 1;
        obj->used = 1;
        return 0;
}

/*
 * Check a single reachable object
 */
static void check_reachable_object(struct object *obj)
{
        /*
         * We obviously want the object to be parsed,
         * except if it was in a pack-file and we didn't
         * do a full fsck
         */
        if (!(obj->flags & HAS_OBJ)) {
                if (has_sha1_pack(obj->oid.hash))
                        return; /* it is in pack - forget about it */
                printf("missing %s %s\n", typename(obj->type),
                        describe_object(obj));
                errors_found |= ERROR_REACHABLE;
                return;
        }
}

/*
 * Check a single unreachable object
 */
static void check_unreachable_object(struct object *obj)
{
        /*
         * Missing unreachable object? Ignore it. It's not like
         * we miss it (since it can't be reached), nor do we want
         * to complain about it being unreachable (since it does
         * not exist).
         */
        if (!(obj->flags & HAS_OBJ))
                return;

        /*
         * Unreachable object that exists? Show it if asked to,
         * since this is something that is prunable.
         */
        if (show_unreachable) {
                printf("unreachable %s %s\n", typename(obj->type),
                        describe_object(obj));
                return;
        }

        /*
         * "!used" means that nothing at all points to it, including
         * other unreachable objects. In other words, it's the "tip"
         * of some set of unreachable objects, usually a commit that
         * got dropped.
         *
         * Such starting points are more interesting than some random
         * set of unreachable objects, so we show them even if the user
         * hasn't asked for _all_ unreachable objects. If you have
         * deleted a branch by mistake, this is a prime candidate to
         * start looking at, for example.
         */
        if (!obj->used) {
                if (show_dangling)
                        printf("dangling %s %s\n", typename(obj->type),
                               describe_object(obj));
                if (write_lost_and_found) {
                        char *filename = git_pathdup("lost-found/%s/%s",
                                obj->type == OBJ_COMMIT ? "commit" : "other",
                                describe_object(obj));
                        FILE *f;

                        if (safe_create_leading_directories_const(filename)) {
                                error("Could not create lost-found");
                                free(filename);
                                return;
                        }
                        if (!(f = fopen(filename, "w")))
                                die_errno("Could not open '%s'", filename);
                        if (obj->type == OBJ_BLOB) {
                                if (stream_blob_to_fd(fileno(f), &obj->oid, NULL, 1))
                                        die_errno("Could not write '%s'", filename);
                        } else
                                fprintf(f, "%s\n", describe_object(obj));
                        if (fclose(f))
                                die_errno("Could not finish '%s'",
                                          filename);
                        free(filename);
                }
                return;
        }

        /*
         * Otherwise? It's there, it's unreachable, and some other unreachable
         * object points to it. Ignore it - it's not interesting, and we showed
         * all the interesting cases above.
         */
}

static void check_object(struct object *obj)
{
        if (verbose)
                fprintf(stderr, "Checking %s\n", describe_object(obj));

        if (obj->flags & REACHABLE)
                check_reachable_object(obj);
        else
                check_unreachable_object(obj);
}

static void check_connectivity(void)
{
        int i, max;

        /* Traverse the pending reachable objects */
        traverse_reachable();

        /* Look up all the requirements, warn about missing objects.. */
        max = get_max_object_index();
        if (verbose)
                fprintf(stderr, "Checking connectivity (%d objects)\n", max);

        for (i = 0; i < max; i++) {
                struct object *obj = get_indexed_object(i);

                if (obj)
                        check_object(obj);
        }
}

static int fsck_obj(struct object *obj)
{
        if (obj->flags & SEEN)
                return 0;
        obj->flags |= SEEN;

        if (verbose)
                fprintf(stderr, "Checking %s %s\n",
                        typename(obj->type), describe_object(obj));

        if (fsck_walk(obj, NULL, &fsck_obj_options))
                objerror(obj, "broken links");
        if (fsck_object(obj, NULL, 0, &fsck_obj_options))
                return -1;

        if (obj->type == OBJ_TREE) {
                struct tree *item = (struct tree *) obj;

                free_tree_buffer(item);
        }

        if (obj->type == OBJ_COMMIT) {
                struct commit *commit = (struct commit *) obj;

                free_commit_buffer(commit);

                if (!commit->parents && show_root)
                        printf("root %s\n", describe_object(&commit->object));
        }

        if (obj->type == OBJ_TAG) {
                struct tag *tag = (struct tag *) obj;

                if (show_tags && tag->tagged) {
                        printf("tagged %s %s", typename(tag->tagged->type),
                                describe_object(tag->tagged));
                        printf(" (%s) in %s\n", tag->tag,
                                describe_object(&tag->object));
                }
        }

        return 0;
}

static int fsck_sha1(const unsigned char *sha1)
{
        struct object *obj = parse_object(sha1);
        if (!obj) {
                errors_found |= ERROR_OBJECT;
                return error("%s: object corrupt or missing",
                             sha1_to_hex(sha1));
        }
        obj->flags |= HAS_OBJ;
        return fsck_obj(obj);
}

static int fsck_obj_buffer(const unsigned char *sha1, enum object_type type,
                           unsigned long size, void *buffer, int *eaten)
{
        /*
         * Note, buffer may be NULL if type is OBJ_BLOB. See
         * verify_packfile(), data_valid variable for details.
         */
        struct object *obj;
        obj = parse_object_buffer(sha1, type, size, buffer, eaten);
        if (!obj) {
                errors_found |= ERROR_OBJECT;
                return error("%s: object corrupt or missing", sha1_to_hex(sha1));
        }
        obj->flags = HAS_OBJ;
        return fsck_obj(obj);
}

static int default_refs;

static void fsck_handle_reflog_sha1(const char *refname, unsigned char *sha1,
        unsigned long timestamp)
{
        struct object *obj;

        if (!is_null_sha1(sha1)) {
                obj = lookup_object(sha1);
                if (obj) {
                        if (timestamp && name_objects)
                                add_decoration(fsck_walk_options.object_names,
                                        obj,
                                        xstrfmt("%s@{%ld}", refname, timestamp));
                        obj->used = 1;
                        mark_object_reachable(obj);
                } else {
                        error("%s: invalid reflog entry %s", refname, sha1_to_hex(sha1));
                        errors_found |= ERROR_REACHABLE;
                }
        }
}

static int fsck_handle_reflog_ent(unsigned char *osha1, unsigned char *nsha1,
                const char *email, unsigned long timestamp, int tz,
                const char *message, void *cb_data)
{
        const char *refname = cb_data;

        if (verbose)
                fprintf(stderr, "Checking reflog %s->%s\n",
                        sha1_to_hex(osha1), sha1_to_hex(nsha1));

        fsck_handle_reflog_sha1(refname, osha1, 0);
        fsck_handle_reflog_sha1(refname, nsha1, timestamp);
        return 0;
}

static int fsck_handle_reflog(const char *logname, const struct object_id *oid,
                              int flag, void *cb_data)
{
        for_each_reflog_ent(logname, fsck_handle_reflog_ent, (void *)logname);
        return 0;
}

static int fsck_handle_ref(const char *refname, const struct object_id *oid,
                           int flag, void *cb_data)
{
        struct object *obj;

        obj = parse_object(oid->hash);
        if (!obj) {
                error("%s: invalid sha1 pointer %s", refname, oid_to_hex(oid));
                errors_found |= ERROR_REACHABLE;
                /* We'll continue with the rest despite the error.. */
                return 0;
        }
        if (obj->type != OBJ_COMMIT && is_branch(refname)) {
                error("%s: not a commit", refname);
                errors_found |= ERROR_REFS;
        }
        default_refs++;
        obj->used = 1;
        if (name_objects)
                add_decoration(fsck_walk_options.object_names,
                        obj, xstrdup(refname));
        mark_object_reachable(obj);

        return 0;
}

static void get_default_heads(void)
{
        if (head_points_at && !is_null_oid(&head_oid))
                fsck_handle_ref("HEAD", &head_oid, 0, NULL);
        for_each_rawref(fsck_handle_ref, NULL);
        if (include_reflogs)
                for_each_reflog(fsck_handle_reflog, NULL);

        /*
         * Not having any default heads isn't really fatal, but
         * it does mean that "--unreachable" no longer makes any
         * sense (since in this case everything will obviously
         * be unreachable by definition.
         *
         * Showing dangling objects is valid, though (as those
         * dangling objects are likely lost heads).
         *
         * So we just print a warning about it, and clear the
         * "show_unreachable" flag.
         */
        if (!default_refs) {
                fprintf(stderr, "notice: No default references\n");
                show_unreachable = 0;
        }
}

static int fsck_loose(const unsigned char *sha1, const char *path, void *data)
{
        if (fsck_sha1(sha1))
                errors_found |= ERROR_OBJECT;
        return 0;
}

static int fsck_cruft(const char *basename, const char *path, void *data)
{
        if (!starts_with(basename, "tmp_obj_"))
                fprintf(stderr, "bad sha1 file: %s\n", path);
        return 0;
}

static int fsck_subdir(int nr, const char *path, void *progress)
{
        display_progress(progress, nr + 1);
        return 0;
}

static void fsck_object_dir(const char *path)
{
        struct progress *progress = NULL;

        if (verbose)
                fprintf(stderr, "Checking object directory\n");

        if (show_progress)
                progress = start_progress(_("Checking object directories"), 256);

        for_each_loose_file_in_objdir(path, fsck_loose, fsck_cruft, fsck_subdir,
                                      progress);
        display_progress(progress, 256);
        stop_progress(&progress);
}

static int fsck_head_link(void)
{
        int null_is_error = 0;

        if (verbose)
                fprintf(stderr, "Checking HEAD link\n");

        head_points_at = resolve_ref_unsafe("HEAD", 0, head_oid.hash, NULL);
        if (!head_points_at) {
                errors_found |= ERROR_REFS;
                return error("Invalid HEAD");
        }
        if (!strcmp(head_points_at, "HEAD"))
                /* detached HEAD */
                null_is_error = 1;
        else if (!starts_with(head_points_at, "refs/heads/")) {
                errors_found |= ERROR_REFS;
                return error("HEAD points to something strange (%s)",
                             head_points_at);
        }
        if (is_null_oid(&head_oid)) {
                if (null_is_error) {
                        errors_found |= ERROR_REFS;
                        return error("HEAD: detached HEAD points at nothing");
                }
                fprintf(stderr, "notice: HEAD points to an unborn branch (%s)\n",
                        head_points_at + 11);
        }
        return 0;
}

static int fsck_cache_tree(struct cache_tree *it)
{
        int i;
        int err = 0;

        if (verbose)
                fprintf(stderr, "Checking cache tree\n");

        if (0 <= it->entry_count) {
                struct object *obj = parse_object(it->sha1);
                if (!obj) {
                        error("%s: invalid sha1 pointer in cache-tree",
                              sha1_to_hex(it->sha1));
                        errors_found |= ERROR_REFS;
                        return 1;
                }
                obj->used = 1;
                if (name_objects)
                        add_decoration(fsck_walk_options.object_names,
                                obj, xstrdup(":"));
                mark_object_reachable(obj);
                if (obj->type != OBJ_TREE)
                        err |= objerror(obj, "non-tree in cache-tree");
        }
        for (i = 0; i < it->subtree_nr; i++)
                err |= fsck_cache_tree(it->down[i]->cache_tree);
        return err;
}

static void mark_object_for_connectivity(const unsigned char *sha1)
{
        struct object *obj = lookup_object(sha1);

        /*
         * Setting the object type here isn't strictly necessary for a
         * connectivity check. In most cases, our walk will expect a certain
         * type (e.g., a tree referencing a blob) and will use lookup_blob() to
         * assign the type. But doing it here has two advantages:
         *
         *   1. When the fsck_walk code looks at objects that _don't_ come from
         *      links (e.g., the tip of a ref), it may complain about the
         *      "unknown object type".
         *
         *   2. This serves as a nice cross-check that the graph links are
         *      sane. So --connectivity-only does not check that the bits of
         *      blobs are not corrupted, but it _does_ check that 100644 tree
         *      entries point to blobs, and so forth.
         *
         * Unfortunately we can't just use parse_object() here, because the
         * whole point of --connectivity-only is to avoid reading the object
         * data more than necessary.
         */
        if (!obj || obj->type == OBJ_NONE) {
                enum object_type type = sha1_object_info(sha1, NULL);
                switch (type) {
                case OBJ_BAD:
                        error("%s: unable to read object type",
                              sha1_to_hex(sha1));
                        break;
                case OBJ_COMMIT:
                        obj = (struct object *)lookup_commit(sha1);
                        break;
                case OBJ_TREE:
                        obj = (struct object *)lookup_tree(sha1);
                        break;
                case OBJ_BLOB:
                        obj = (struct object *)lookup_blob(sha1);
                        break;
                case OBJ_TAG:
                        obj = (struct object *)lookup_tag(sha1);
                        break;
                default:
                        error("%s: unknown object type %d",
                              sha1_to_hex(sha1), type);
                }

                if (!obj || obj->type == OBJ_NONE) {
                        errors_found |= ERROR_OBJECT;
                        return;
                }
        }

        obj->flags |= HAS_OBJ;
}

static int mark_loose_for_connectivity(const unsigned char *sha1,
                                       const char *path,
                                       void *data)
{
        mark_object_for_connectivity(sha1);
        return 0;
}

static int mark_packed_for_connectivity(const unsigned char *sha1,
                                        struct packed_git *pack,
                                        uint32_t pos,
                                        void *data)
{
        mark_object_for_connectivity(sha1);
        return 0;
}

static char const * const fsck_usage[] = {
        N_("git fsck [<options>] [<object>...]"),
        NULL
};

static struct option fsck_opts[] = {
        OPT__VERBOSE(&verbose, N_("be verbose")),
        OPT_BOOL(0, "unreachable", &show_unreachable, N_("show unreachable objects")),
        OPT_BOOL(0, "dangling", &show_dangling, N_("show dangling objects")),
        OPT_BOOL(0, "tags", &show_tags, N_("report tags")),
        OPT_BOOL(0, "root", &show_root, N_("report root nodes")),
        OPT_BOOL(0, "cache", &keep_cache_objects, N_("make index objects head nodes")),
        OPT_BOOL(0, "reflogs", &include_reflogs, N_("make reflogs head nodes (default)")),
        OPT_BOOL(0, "full", &check_full, N_("also consider packs and alternate objects")),
        OPT_BOOL(0, "connectivity-only", &connectivity_only, N_("check only connectivity")),
        OPT_BOOL(0, "strict", &check_strict, N_("enable more strict checking")),
        OPT_BOOL(0, "lost-found", &write_lost_and_found,
                                N_("write dangling objects in .git/lost-found")),
        OPT_BOOL(0, "progress", &show_progress, N_("show progress")),
        OPT_BOOL(0, "name-objects", &name_objects, N_("show verbose names for reachable objects")),
        OPT_END(),
};

int cmd_fsck(int argc, const char **argv, const char *prefix)
{
        int i, heads;
        struct alternate_object_database *alt;

        errors_found = 0;
        check_replace_refs = 0;

        argc = parse_options(argc, argv, prefix, fsck_opts, fsck_usage, 0);

        fsck_walk_options.walk = mark_object;
        fsck_obj_options.walk = mark_used;
        fsck_obj_options.error_func = fsck_error_func;
        if (check_strict)
                fsck_obj_options.strict = 1;

        if (show_progress == -1)
                show_progress = isatty(2);
        if (verbose)
                show_progress = 0;

        if (write_lost_and_found) {
                check_full = 1;
                include_reflogs = 0;
        }

        if (name_objects)
                fsck_walk_options.object_names =
                        xcalloc(1, sizeof(struct decoration));

        git_config(fsck_config, NULL);

        fsck_head_link();
        if (connectivity_only) {
                for_each_loose_object(mark_loose_for_connectivity, NULL, 0);
                for_each_packed_object(mark_packed_for_connectivity, NULL, 0);
        } else {
                fsck_object_dir(get_object_directory());

                prepare_alt_odb();
                for (alt = alt_odb_list; alt; alt = alt->next)
                        fsck_object_dir(alt->path);

                if (check_full) {
                        struct packed_git *p;
                        uint32_t total = 0, count = 0;
                        struct progress *progress = NULL;

                        prepare_packed_git();

                        if (show_progress) {
                                for (p = packed_git; p; p = p->next) {
                                        if (open_pack_index(p))
                                                continue;
                                        total += p->num_objects;
                                }

                                progress = start_progress(_("Checking objects"), total);
                        }
                        for (p = packed_git; p; p = p->next) {
                                /* verify gives error messages itself */
                                if (verify_pack(p, fsck_obj_buffer,
                                                progress, count))
                                        errors_found |= ERROR_PACK;
                                count += p->num_objects;
                        }
                        stop_progress(&progress);
                }
        }

        heads = 0;
        for (i = 0; i < argc; i++) {
                const char *arg = argv[i];
                unsigned char sha1[20];
                if (!get_sha1(arg, sha1)) {
                        struct object *obj = lookup_object(sha1);

                        /* Error is printed by lookup_object(). */
                        if (!obj)
                                continue;

                        obj->used = 1;
                        if (name_objects)
                                add_decoration(fsck_walk_options.object_names,
                                        obj, xstrdup(arg));
                        mark_object_reachable(obj);
                        heads++;
                        continue;
                }
                error("invalid parameter: expected sha1, got '%s'", arg);
        }

        /*
         * If we've not been given any explicit head information, do the
         * default ones from .git/refs. We also consider the index file
         * in this case (ie this implies --cache).
         */
        if (!heads) {
                get_default_heads();
                keep_cache_objects = 1;
        }

        if (keep_cache_objects) {
                read_cache();
                for (i = 0; i < active_nr; i++) {
                        unsigned int mode;
                        struct blob *blob;
                        struct object *obj;

                        mode = active_cache[i]->ce_mode;
                        if (S_ISGITLINK(mode))
                                continue;
                        blob = lookup_blob(active_cache[i]->oid.hash);
                        if (!blob)
                                continue;
                        obj = &blob->object;
                        obj->used = 1;
                        if (name_objects)
                                add_decoration(fsck_walk_options.object_names,
                                        obj,
                                        xstrfmt(":%s", active_cache[i]->name));
                        mark_object_reachable(obj);
                }
                if (active_cache_tree)
                        fsck_cache_tree(active_cache_tree);
        }

        check_connectivity();
        return errors_found;
}