#include <sys/types.h>
#include <dirent.h>

#include "cache.h"
#include "commit.h"
#include "tree.h"
#include "blob.h"
#include "tag.h"

#define REACHABLE 0x0001

static int show_root = 0;
static int show_tags = 0;
static int show_unreachable = 0;
static unsigned char head_sha1[20];

static void check_connectivity(void)
{
        int i;

        /* Look up all the requirements, warn about missing objects.. */
        for (i = 0; i < nr_objs; i++) {
                struct object *obj = objs[i];
                struct object_list *refs;

                if (!obj->parsed) {
                        printf("missing %s %s\n", obj->type, sha1_to_hex(obj->sha1));
                        continue;
                }

                for (refs = obj->refs; refs; refs = refs->next) {
                        if (refs->item->parsed)
                                continue;
                        printf("broken link from %7s %s\n",
                               obj->type, sha1_to_hex(obj->sha1));
                        printf("              to %7s %s\n",
                               obj->type, sha1_to_hex(refs->item->sha1));
                }

                /* Don't bother with tag reachability. */
                if (obj->type == tag_type)
                        continue;

                if (show_unreachable && !(obj->flags & REACHABLE)) {
                        printf("unreachable %s %s\n", obj->type, sha1_to_hex(obj->sha1));
                        continue;
                }

                if (!obj->used) {
                        printf("dangling %s %s\n", obj->type, 
                               sha1_to_hex(obj->sha1));
                }
        }
}

static int fsck_tree(struct tree *item)
{
        if (item->has_full_path) {
                fprintf(stderr, "warning: fsck-cache: tree %s "
                        "has full pathnames in it\n", 
                        sha1_to_hex(item->object.sha1));
        }
        return 0;
}

static int fsck_commit(struct commit *commit)
{
        if (!commit->tree)
                return -1;
        if (!commit->parents && show_root)
                printf("root %s\n", sha1_to_hex(commit->object.sha1));
        if (!commit->date)
                printf("bad commit date in %s\n", 
                       sha1_to_hex(commit->object.sha1));
        return 0;
}

static int fsck_tag(struct tag *tag)
{
        if (!show_tags)
                return 0;

        printf("tagged %s %s",
               tag->tagged->type,
               sha1_to_hex(tag->tagged->sha1));
        printf(" (%s) in %s\n",
               tag->tag, sha1_to_hex(tag->object.sha1));
        return 0;
}

static int fsck_name(char *hex)
{
        unsigned char sha1[20];
        if (!get_sha1_hex(hex, sha1)) {
                struct object *obj = parse_object(sha1);
                if (!obj)
                        return -1;
                if (obj->type == blob_type)
                        return 0;
                if (obj->type == tree_type)
                        return fsck_tree((struct tree *) obj);
                if (obj->type == commit_type)
                        return fsck_commit((struct commit *) obj);
                if (obj->type == tag_type)
                        return fsck_tag((struct tag *) obj);
        }
        return -1;
}

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

        if (!dir) {
                return error("missing sha1 directory '%s'", path);
        }

        while ((de = readdir(dir)) != NULL) {
                char name[100];
                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 (!fsck_name(name))
                                continue;
                }
                fprintf(stderr, "bad sha1 file: %s/%s\n", path, de->d_name);
        }
        closedir(dir);
        return 0;
}

int main(int argc, char **argv)
{
        int i, heads;
        char *sha1_dir;

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

                if (!strcmp(arg, "--unreachable")) {
                        show_unreachable = 1;
                        continue;
                }
                if (!strcmp(arg, "--tags")) {
                        show_tags = 1;
                        continue;
                }
                if (!strcmp(arg, "--root")) {
                        show_root = 1;
                        continue;
                }
                if (*arg == '-')
                        usage("fsck-cache [--tags] [[--unreachable] <head-sha1>*]");
        }

        sha1_dir = getenv(DB_ENVIRONMENT) ? : DEFAULT_DB_ENVIRONMENT;
        for (i = 0; i < 256; i++) {
                static char dir[4096];
                sprintf(dir, "%s/%02x", sha1_dir, i);
                fsck_dir(i, dir);
        }

        heads = 0;
        for (i = 1; i < argc; i++) {
                const char *arg = argv[i]; 

                if (*arg == '-')
                        continue;

                if (!get_sha1_hex(arg, head_sha1)) {
                        struct commit *commit = lookup_commit(head_sha1);
                        struct object *obj;

                        /* Error is printed by lookup_commit(). */
                        if (!commit)
                                continue;

                        obj = &commit->object;
                        obj->used = 1;
                        mark_reachable(obj, REACHABLE);
                        heads++;
                        continue;
                }
                error("expected sha1, got %s", arg);
        }

        if (!heads) {
                if (show_unreachable) {
                        fprintf(stderr, "unable to do reachability without a head\n");
                        show_unreachable = 0; 
                }
                fprintf(stderr, "expect dangling commits - potential heads - due to lack of head information\n");
        }

        check_connectivity();
        return 0;
}