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

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

#define REACHABLE 0x0001

static int show_root = 0;
static int show_tags = 0;
static int show_unreachable = 0;
static int standalone = 0;
static int check_full = 0;
static int check_strict = 0;
static int keep_cache_objects = 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) {
                        if (!standalone && has_sha1_file(obj->sha1))
                                ; /* it is in pack */
                        else
                                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 ||
                            (!standalone && has_sha1_file(refs->item->sha1)))
                                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));
                }

                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".
 */
#define TREE_UNORDERED (-1)
#define TREE_HAS_DUPS  (-2)

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 TREE_UNORDERED;

        /*
         * 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 && !c2)
                /*
                 * git-write-tree used to write out a nonsense tree that has
                 * entries with the same name, one blob and one tree.  Make
                 * sure we do not have duplicate entries.
                 */
                return TREE_HAS_DUPS;
        if (!c1 && a->directory)
                c1 = '/';
        if (!c2 && b->directory)
                c2 = '/';
        return c1 < c2 ? 0 : TREE_UNORDERED;
}

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;

                switch (entry->mode) {
                /*
                 * Standard modes.. 
                 */
                case S_IFREG | 0755:
                case S_IFREG | 0644:
                case S_IFLNK:
                case S_IFDIR:
                        break;
                /*
                 * This is nonstandard, but we had a few of these
                 * early on when we honored the full set of mode
                 * bits..
                 */
                case S_IFREG | 0664:
                        if (!check_strict)
                                break;
                default:
                        printf("tree %s has entry %o %s\n",
                                sha1_to_hex(item->object.sha1),
                                entry->mode, entry->name);
                }

                if (last) {
                        switch (verify_ordered(last, entry)) {
                        case TREE_UNORDERED:
                                fprintf(stderr, "tree %s not ordered\n",
                                        sha1_to_hex(item->object.sha1));
                                return -1;
                        case TREE_HAS_DUPS:
                                fprintf(stderr, "tree %s has duplicate entries for '%s'\n",
                                        sha1_to_hex(item->object.sha1),
                                        entry->name);
                                return -1;
                        default:
                                break;
                        }
                }

                last = entry;
        }

        if (has_full_path) {
                fprintf(stderr, "warning: git-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)
{
        char *buffer = commit->buffer;
        unsigned char sha1[20];

        if (memcmp(buffer, "tree ", 5))
                return -1;
        if (get_sha1_hex(buffer+5, sha1) || buffer[45] != '\n')
                return -1;
        buffer += 46;
        while (!memcmp(buffer, "parent ", 7)) {
                if (get_sha1_hex(buffer+7, sha1) || buffer[47] != '\n')
                        return -1;
                buffer += 48;
        }
        if (memcmp(buffer, "author ", 7))
                return -1;
        free(commit->buffer);
        commit->buffer = NULL;
        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;
}

static int default_refs = 0;

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

        obj = lookup_object(sha1);
        if (!obj) {
                if (!standalone && has_sha1_file(sha1)) {
                        default_refs++;
                        return 0; /* it is in a pack */
                }
                error("%s: invalid sha1 pointer %s", refname, sha1_to_hex(sha1));
                /* We'll continue with the rest despite the error.. */
                return 0;
        }
        default_refs++;
        obj->used = 1;
        mark_reachable(obj, REACHABLE);
        return 0;
}

static void get_default_heads(void)
{
        for_each_ref(fsck_handle_ref);
        if (!default_refs)
                die("No default references");
}

static void fsck_object_dir(const char *path)
{
        int i;
        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)
{
        int fd, count;
        char hex[40];
        unsigned char sha1[20];
        static char path[PATH_MAX], link[PATH_MAX];
        const char *git_dir = gitenv(GIT_DIR_ENVIRONMENT) ? : DEFAULT_GIT_DIR_ENVIRONMENT;

        snprintf(path, sizeof(path), "%s/HEAD", git_dir);
        if (readlink(path, link, sizeof(link)) < 0)
                return error("HEAD is not a symlink");
        if (strncmp("refs/heads/", link, 11))
                return error("HEAD points to something strange (%s)", link);
        fd = open(path, O_RDONLY);
        if (fd < 0)
                return error("HEAD: %s", strerror(errno));
        count = read(fd, hex, sizeof(hex));
        close(fd);
        if (count < 0)
                return error("HEAD: %s", strerror(errno));
        if (count < 40 || get_sha1_hex(hex, sha1))
                return error("HEAD: not a valid git pointer");
        return 0;
}

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

        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 (!strcmp(arg, "--cache")) {
                        keep_cache_objects = 1;
                        continue;
                }
                if (!strcmp(arg, "--standalone")) {
                        standalone = 1;
                        continue;
                }
                if (!strcmp(arg, "--full")) {
                        check_full = 1;
                        continue;
                }
                if (!strcmp(arg, "--strict")) {
                        check_strict = 1;
                        continue;
                }
                if (*arg == '-')
                        usage("git-fsck-cache [--tags] [[--unreachable] [--cache] [--standalone | --full] <head-sha1>*]");
        }

        if (standalone && check_full)
                die("Only one of --standalone or --full can be used.");
        if (standalone)
                unsetenv("GIT_ALTERNATE_OBJECT_DIRECTORIES");

        fsck_head_link();
        fsck_object_dir(get_object_directory());
        if (check_full) {
                int j;
                struct packed_git *p;
                prepare_alt_odb();
                for (j = 0; alt_odb[j].base; j++) {
                        char namebuf[PATH_MAX];
                        int namelen = alt_odb[j].name - alt_odb[j].base;
                        memcpy(namebuf, alt_odb[j].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, 0);

                for (p = packed_git; p; p = p->next) {
                        int num = num_packed_objects(p);
                        for (i = 0; i < num; i++) {
                                unsigned char sha1[20];
                                nth_packed_object_sha1(p, i, sha1);
                                if (fsck_sha1(sha1) < 0)
                                        fprintf(stderr, "bad sha1 entry '%s'\n", sha1_to_hex(sha1));

                        }
                }
        }

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

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

                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_reachable(obj, REACHABLE);
                        heads++;
                        continue;
                }
                error("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) {
                int i;
                read_cache();
                for (i = 0; i < active_nr; i++) {
                        struct blob *blob = lookup_blob(active_cache[i]->sha1);
                        struct object *obj;
                        if (!blob)
                                continue;
                        obj = &blob->object;
                        obj->used = 1;
                        mark_reachable(obj, REACHABLE);
                }
        }

        check_connectivity();
        return 0;
}