#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"

#define REACHABLE 0x0001
#define SEEN      0x0002

static int show_root;
static int show_tags;
static int show_unreachable;
static int include_reflogs = 1;
static int check_full;
static int check_strict;
static int keep_cache_objects;
static unsigned char head_sha1[20];
static int errors_found;
static int write_lost_and_found;
static int verbose;
#define ERROR_OBJECT 01
#define ERROR_REACHABLE 02

#ifdef NO_D_INO_IN_DIRENT
#define SORT_DIRENT 0
#define DIRENT_SORT_HINT(de) 0
#else
#define SORT_DIRENT 1
#define DIRENT_SORT_HINT(de) ((de)->d_ino)
#endif

static void objreport(struct object *obj, const char *severity,
                      const char *err, va_list params)
{
        fprintf(stderr, "%s in %s %s: ",
                severity, typename(obj->type), sha1_to_hex(obj->sha1));
        vfprintf(stderr, err, params);
        fputs("\n", stderr);
}

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

static int fsck_error_func(struct object *obj, int type, const char *err, ...)
{
        va_list params;
        va_start(params, err);
        objreport(obj, (type == FSCK_WARN) ? "warning" : "error", err, params);
        va_end(params);
        return (type == FSCK_WARN) ? 0 : 1;
}

static int mark_object(struct object *obj, int type, void *data)
{
        struct tree *tree = NULL;
        struct object *parent = data;
        int result;

        if (!obj) {
                printf("broken link from %7s %s\n",
                           typename(parent->type), sha1_to_hex(parent->sha1));
                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)
                objerror(parent, "wrong object type in link");

        if (obj->flags & REACHABLE)
                return 0;
        obj->flags |= REACHABLE;
        if (!obj->parsed) {
                if (parent && !has_sha1_file(obj->sha1)) {
                        printf("broken link from %7s %s\n",
                                 typename(parent->type), sha1_to_hex(parent->sha1));
                        printf("              to %7s %s\n",
                                 typename(obj->type), sha1_to_hex(obj->sha1));
                        errors_found |= ERROR_REACHABLE;
                }
                return 1;
        }

        if (obj->type == OBJ_TREE) {
                obj->parsed = 0;
                tree = (struct tree *)obj;
                if (parse_tree(tree) < 0)
                        return 1; /* error already displayed */
        }
        result = fsck_walk(obj, mark_object, obj);
        if (tree) {
                free(tree->buffer);
                tree->buffer = NULL;
        }
        if (result < 0)
                result = 1;

        return result;
}

static void mark_object_reachable(struct object *obj)
{
        mark_object(obj, OBJ_ANY, 0);
}

static int mark_used(struct object *obj, int type, void *data)
{
        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->parsed) {
                if (has_sha1_pack(obj->sha1, NULL))
                        return; /* it is in pack - forget about it */
                printf("missing %s %s\n", typename(obj->type), sha1_to_hex(obj->sha1));
                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->parsed)
                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), sha1_to_hex(obj->sha1));
                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) {
                printf("dangling %s %s\n", typename(obj->type),
                       sha1_to_hex(obj->sha1));
                if (write_lost_and_found) {
                        char *filename = git_path("lost-found/%s/%s",
                                obj->type == OBJ_COMMIT ? "commit" : "other",
                                sha1_to_hex(obj->sha1));
                        FILE *f;

                        if (safe_create_leading_directories(filename)) {
                                error("Could not create lost-found");
                                return;
                        }
                        if (!(f = fopen(filename, "w")))
                                die("Could not open %s", filename);
                        if (obj->type == OBJ_BLOB) {
                                enum object_type type;
                                unsigned long size;
                                char *buf = read_sha1_file(obj->sha1,
                                                &type, &size);
                                if (buf) {
                                        fwrite(buf, size, 1, f);
                                        free(buf);
                                }
                        } else
                                fprintf(f, "%s\n", sha1_to_hex(obj->sha1));
                        fclose(f);
                }
                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", sha1_to_hex(obj->sha1));

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

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

        /* 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_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));
        }
        if (obj->flags & SEEN)
                return 0;
        obj->flags |= SEEN;

        if (verbose)
                fprintf(stderr, "Checking %s %s\n",
                        typename(obj->type), sha1_to_hex(obj->sha1));

        if (fsck_walk(obj, mark_used, 0))
                objerror(obj, "broken links");
        if (fsck_object(obj, check_strict, fsck_error_func))
                return -1;

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

                free(item->buffer);
                item->buffer = NULL;
        }

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

                free(commit->buffer);
                commit->buffer = NULL;

                if (!commit->parents && show_root)
                        printf("root %s\n", sha1_to_hex(commit->object.sha1));
        }

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

                if (show_tags && tag->tagged) {
                        printf("tagged %s %s", typename(tag->tagged->type), sha1_to_hex(tag->tagged->sha1));
                        printf(" (%s) in %s\n", tag->tag, sha1_to_hex(tag->object.sha1));
                }
        }

        return 0;
}

/*
 * This is the sorting chunk size: make it reasonably
 * big so that we can sort well..
 */
#define MAX_SHA1_ENTRIES (1024)

struct sha1_entry {
        unsigned long ino;
        unsigned char sha1[20];
};

static struct {
        unsigned long nr;
        struct sha1_entry *entry[MAX_SHA1_ENTRIES];
} sha1_list;

static int ino_compare(const void *_a, const void *_b)
{
        const struct sha1_entry *a = _a, *b = _b;
        unsigned long ino1 = a->ino, ino2 = b->ino;
        return ino1 < ino2 ? -1 : ino1 > ino2 ? 1 : 0;
}

static void fsck_sha1_list(void)
{
        int i, nr = sha1_list.nr;

        if (SORT_DIRENT)
                qsort(sha1_list.entry, nr,
                      sizeof(struct sha1_entry *), ino_compare);
        for (i = 0; i < nr; i++) {
                struct sha1_entry *entry = sha1_list.entry[i];
                unsigned char *sha1 = entry->sha1;

                sha1_list.entry[i] = NULL;
                fsck_sha1(sha1);
                free(entry);
        }
        sha1_list.nr = 0;
}

static void add_sha1_list(unsigned char *sha1, unsigned long ino)
{
        struct sha1_entry *entry = xmalloc(sizeof(*entry));
        int nr;

        entry->ino = ino;
        hashcpy(entry->sha1, sha1);
        nr = sha1_list.nr;
        if (nr == MAX_SHA1_ENTRIES) {
                fsck_sha1_list();
                nr = 0;
        }
        sha1_list.entry[nr] = entry;
        sha1_list.nr = ++nr;
}

static void fsck_dir(int i, char *path)
{
        DIR *dir = opendir(path);
        struct dirent *de;

        if (!dir)
                return;

        if (verbose)
                fprintf(stderr, "Checking directory %s\n", path);

        while ((de = readdir(dir)) != NULL) {
                char name[100];
                unsigned char sha1[20];
                int len = strlen(de->d_name);

                switch (len) {
                case 2:
                        if (de->d_name[1] != '.')
                                break;
                case 1:
                        if (de->d_name[0] != '.')
                                break;
                        continue;
                case 38:
                        sprintf(name, "%02x", i);
                        memcpy(name+2, de->d_name, len+1);
                        if (get_sha1_hex(name, sha1) < 0)
                                break;
                        add_sha1_list(sha1, DIRENT_SORT_HINT(de));
                        continue;
                }
                if (prefixcmp(de->d_name, "tmp_obj_"))
                        continue;
                fprintf(stderr, "bad sha1 file: %s/%s\n", path, de->d_name);
        }
        closedir(dir);
}

static int default_refs;

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)
{
        struct object *obj;

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

        if (!is_null_sha1(osha1)) {
                obj = lookup_object(osha1);
                if (obj) {
                        obj->used = 1;
                        mark_object_reachable(obj);
                }
        }
        obj = lookup_object(nsha1);
        if (obj) {
                obj->used = 1;
                mark_object_reachable(obj);
        }
        return 0;
}

static int fsck_handle_reflog(const char *logname, const unsigned char *sha1, int flag, void *cb_data)
{
        for_each_reflog_ent(logname, fsck_handle_reflog_ent, NULL);
        return 0;
}

static int is_branch(const char *refname)
{
        return !strcmp(refname, "HEAD") || !prefixcmp(refname, "refs/heads/");
}

static int fsck_handle_ref(const char *refname, const unsigned char *sha1, int flag, void *cb_data)
{
        struct object *obj;

        obj = parse_object(sha1);
        if (!obj) {
                error("%s: invalid sha1 pointer %s", refname, sha1_to_hex(sha1));
                /* 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);
        default_refs++;
        obj->used = 1;
        mark_object_reachable(obj);

        return 0;
}

static void get_default_heads(void)
{
        for_each_ref(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 void fsck_object_dir(const char *path)
{
        int i;

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

        for (i = 0; i < 256; i++) {
                static char dir[4096];
                sprintf(dir, "%s/%02x", path, i);
                fsck_dir(i, dir);
        }
        fsck_sha1_list();
}

static int fsck_head_link(void)
{
        unsigned char sha1[20];
        int flag;
        int null_is_error = 0;
        const char *head_points_at = resolve_ref("HEAD", sha1, 0, &flag);

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

        if (!head_points_at)
                return error("Invalid HEAD");
        if (!strcmp(head_points_at, "HEAD"))
                /* detached HEAD */
                null_is_error = 1;
        else if (prefixcmp(head_points_at, "refs/heads/"))
                return error("HEAD points to something strange (%s)",
                             head_points_at);
        if (is_null_sha1(sha1)) {
                if (null_is_error)
                        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));
                        return 1;
                }
                mark_object_reachable(obj);
                obj->used = 1;
                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 char const * const fsck_usage[] = {
        "git fsck [options] [<object>...]",
        NULL
};

static struct option fsck_opts[] = {
        OPT__VERBOSE(&verbose),
        OPT_BOOLEAN(0, "unreachable", &show_unreachable, "show unreachable objects"),
        OPT_BOOLEAN(0, "tags", &show_tags, "report tags"),
        OPT_BOOLEAN(0, "root", &show_root, "report root nodes"),
        OPT_BOOLEAN(0, "cache", &keep_cache_objects, "make index objects head nodes"),
        OPT_BOOLEAN(0, "reflogs", &include_reflogs, "make reflogs head nodes (default)"),
        OPT_BOOLEAN(0, "full", &check_full, "also consider alternate objects"),
        OPT_BOOLEAN(0, "strict", &check_strict, "enable more strict checking"),
        OPT_BOOLEAN(0, "lost-found", &write_lost_and_found,
                                "write dangling objects in .git/lost-found"),
        OPT_END(),
};

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

        errors_found = 0;

        argc = parse_options(argc, argv, fsck_opts, fsck_usage, 0);
        if (write_lost_and_found) {
                check_full = 1;
                include_reflogs = 0;
        }

        fsck_head_link();
        fsck_object_dir(get_object_directory());
        if (check_full) {
                struct alternate_object_database *alt;
                struct packed_git *p;
                prepare_alt_odb();
                for (alt = alt_odb_list; alt; alt = alt->next) {
                        char namebuf[PATH_MAX];
                        int namelen = alt->name - alt->base;
                        memcpy(namebuf, alt->base, namelen);
                        namebuf[namelen - 1] = 0;
                        fsck_object_dir(namebuf);
                }
                prepare_packed_git();
                for (p = packed_git; p; p = p->next)
                        /* verify gives error messages itself */
                        verify_pack(p);

                for (p = packed_git; p; p = p->next) {
                        uint32_t j, num;
                        if (open_pack_index(p))
                                continue;
                        num = p->num_objects;
                        for (j = 0; j < num; j++)
                                fsck_sha1(nth_packed_object_sha1(p, j));
                }
        }

        heads = 0;
        for (i = 1; i < argc; i++) {
                const char *arg = argv[i];
                if (!get_sha1(arg, head_sha1)) {
                        struct object *obj = lookup_object(head_sha1);

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

                        obj->used = 1;
                        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]->sha1);
                        if (!blob)
                                continue;
                        obj = &blob->object;
                        obj->used = 1;
                        mark_object_reachable(obj);
                }
                if (active_cache_tree)
                        fsck_cache_tree(active_cache_tree);
        }

        check_connectivity();
        return errors_found;
}