#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",
                               refs->item->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));
                }
        }
}

/*
 * The entries in a tree are ordered in the _path_ order,
 * which means that a directory entry is ordered by adding
 * a slash to the end of it.
 *
 * So a directory called "a" is ordered _after_ a file
 * called "a.c", because "a/" sorts after "a.c".
 */
static int verify_ordered(struct tree_entry_list *a, struct tree_entry_list *b)
{
        int len1 = strlen(a->name);
        int len2 = strlen(b->name);
        int len = len1 < len2 ? len1 : len2;
        unsigned char c1, c2;
        int cmp;

        cmp = memcmp(a->name, b->name, len);
        if (cmp < 0)
                return 0;
        if (cmp > 0)
                return -1;

        /*
         * Ok, the first <len> characters are the same.
         * Now we need to order the next one, but turn
         * a '\0' into a '/' for a directory entry.
         */
        c1 = a->name[len];
        c2 = b->name[len];
        if (!c1 && a->directory)
                c1 = '/';
        if (!c2 && b->directory)
                c2 = '/';
        return c1 < c2 ? 0 : -1;
}

static int fsck_tree(struct tree *item)
{
        int has_full_path = 0;
        struct tree_entry_list *entry, *last;

        last = NULL;
        for (entry = item->entries; entry; entry = entry->next) {
                if (strchr(entry->name, '/'))
                        has_full_path = 1;

                if (last) {
                        if (verify_ordered(last, entry) < 0) {
                                fprintf(stderr, "tree %s not ordered\n",
                                        sha1_to_hex(item->object.sha1));
                                return -1;
                        }
                }

                last = entry;
        }

        if (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)
{
        struct object *tagged = tag->tagged;

        if (!tagged) {
                printf("bad object in tag %s\n", sha1_to_hex(tag->object.sha1));
                return -1;
        }
        if (!show_tags)
                return 0;

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

static int fsck_sha1(unsigned char *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;
}

/*
 * 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;

        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;
                if (fsck_sha1(sha1) < 0)
                        fprintf(stderr, "bad sha1 entry '%s'\n", sha1_to_hex(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;
        memcpy(entry->sha1, sha1, 20);
        nr = sha1_list.nr;
        if (nr == MAX_SHA1_ENTRIES) {
                fsck_sha1_list();
                nr = 0;
        }
        sha1_list.entry[nr] = entry;
        sha1_list.nr = ++nr;
}

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];
                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, de->d_ino);
                        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);
        }
        fsck_sha1_list();

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

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

                if (!get_sha1(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;
}