#include "cache.h"
#include "refs.h"
#include "tag.h"
#include "commit.h"
#include "tree.h"
#include "blob.h"
#include "tree-walk.h"
#include "diff.h"
#include "revision.h"
#include "builtin.h"
#include "cache-tree.h"

static const char prune_usage[] = "git-prune [-n]";
static int show_only;
static struct rev_info revs;

static int prune_object(char *path, const char *filename, const unsigned char *sha1)
{
        if (show_only) {
                printf("would prune %s/%s\n", path, filename);
                return 0;
        }
        unlink(mkpath("%s/%s", path, filename));
        rmdir(path);
        return 0;
}

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

        if (!dir)
                return 0;

        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;

                        /*
                         * Do we know about this object?
                         * It must have been reachable
                         */
                        if (lookup_object(sha1))
                                continue;

                        prune_object(path, de->d_name, sha1);
                        continue;
                }
                fprintf(stderr, "bad sha1 file: %s/%s\n", path, de->d_name);
        }
        closedir(dir);
        return 0;
}

static void prune_object_dir(const char *path)
{
        int i;
        for (i = 0; i < 256; i++) {
                static char dir[4096];
                sprintf(dir, "%s/%02x", path, i);
                prune_dir(i, dir);
        }
}

static void process_blob(struct blob *blob,
                         struct object_array *p,
                         struct name_path *path,
                         const char *name)
{
        struct object *obj = &blob->object;

        if (obj->flags & SEEN)
                return;
        obj->flags |= SEEN;
        /* Nothing to do, really .. The blob lookup was the important part */
}

static void process_tree(struct tree *tree,
                         struct object_array *p,
                         struct name_path *path,
                         const char *name)
{
        struct object *obj = &tree->object;
        struct tree_desc desc;
        struct name_entry entry;
        struct name_path me;

        if (obj->flags & SEEN)
                return;
        obj->flags |= SEEN;
        if (parse_tree(tree) < 0)
                die("bad tree object %s", sha1_to_hex(obj->sha1));
        name = xstrdup(name);
        add_object(obj, p, path, name);
        me.up = path;
        me.elem = name;
        me.elem_len = strlen(name);

        desc.buf = tree->buffer;
        desc.size = tree->size;

        while (tree_entry(&desc, &entry)) {
                if (S_ISDIR(entry.mode))
                        process_tree(lookup_tree(entry.sha1), p, &me, entry.path);
                else
                        process_blob(lookup_blob(entry.sha1), p, &me, entry.path);
        }
        free(tree->buffer);
        tree->buffer = NULL;
}

static void process_tag(struct tag *tag, struct object_array *p, const char *name)
{
        struct object *obj = &tag->object;
        struct name_path me;

        if (obj->flags & SEEN)
                return;
        obj->flags |= SEEN;

        me.up = NULL;
        me.elem = "tag:/";
        me.elem_len = 5;

        if (parse_tag(tag) < 0)
                die("bad tag object %s", sha1_to_hex(obj->sha1));
        add_object(tag->tagged, p, NULL, name);
}

static void walk_commit_list(struct rev_info *revs)
{
        int i;
        struct commit *commit;
        struct object_array objects = { 0, 0, NULL };

        /* Walk all commits, process their trees */
        while ((commit = get_revision(revs)) != NULL)
                process_tree(commit->tree, &objects, NULL, "");

        /* Then walk all the pending objects, recursively processing them too */
        for (i = 0; i < revs->pending.nr; i++) {
                struct object_array_entry *pending = revs->pending.objects + i;
                struct object *obj = pending->item;
                const char *name = pending->name;
                if (obj->type == OBJ_TAG) {
                        process_tag((struct tag *) obj, &objects, name);
                        continue;
                }
                if (obj->type == OBJ_TREE) {
                        process_tree((struct tree *)obj, &objects, NULL, name);
                        continue;
                }
                if (obj->type == OBJ_BLOB) {
                        process_blob((struct blob *)obj, &objects, NULL, name);
                        continue;
                }
                die("unknown pending object %s (%s)", sha1_to_hex(obj->sha1), name);
        }
}

static int add_one_ref(const char *path, const unsigned char *sha1, int flag, void *cb_data)
{
        struct object *object = parse_object(sha1);
        if (!object)
                die("bad object ref: %s:%s", path, sha1_to_hex(sha1));
        add_pending_object(&revs, object, "");
        return 0;
}

static void add_one_tree(const unsigned char *sha1)
{
        struct tree *tree = lookup_tree(sha1);
        add_pending_object(&revs, &tree->object, "");
}

static void add_cache_tree(struct cache_tree *it)
{
        int i;

        if (it->entry_count >= 0)
                add_one_tree(it->sha1);
        for (i = 0; i < it->subtree_nr; i++)
                add_cache_tree(it->down[i]->cache_tree);
}

static void add_cache_refs(void)
{
        int i;

        read_cache();
        for (i = 0; i < active_nr; i++) {
                lookup_blob(active_cache[i]->sha1);
                /*
                 * We could add the blobs to the pending list, but quite
                 * frankly, we don't care. Once we've looked them up, and
                 * added them as objects, we've really done everything
                 * there is to do for a blob
                 */
        }
        if (active_cache_tree)
                add_cache_tree(active_cache_tree);
}

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

        for (i = 1; i < argc; i++) {
                const char *arg = argv[i];
                if (!strcmp(arg, "-n")) {
                        show_only = 1;
                        continue;
                }
                usage(prune_usage);
        }

        /*
         * Set up revision parsing, and mark us as being interested
         * in all object types, not just commits.
         */
        init_revisions(&revs, prefix);
        revs.tag_objects = 1;
        revs.blob_objects = 1;
        revs.tree_objects = 1;

        /* Add all external refs */
        for_each_ref(add_one_ref, NULL);

        /* Add all refs from the index file */
        add_cache_refs();

        /*
         * Set up the revision walk - this will move all commits
         * from the pending list to the commit walking list.
         */
        prepare_revision_walk(&revs);

        walk_commit_list(&revs);

        prune_object_dir(get_object_directory());

        return 0;
}