#include "cache.h"
#include "walker.h"
#include "commit.h"
#include "tree.h"
#include "tree-walk.h"
#include "tag.h"
#include "blob.h"
#include "refs.h"

static unsigned char current_commit_sha1[20];

void walker_say(struct walker *walker, const char *fmt, const char *hex)
{
        if (walker->get_verbosely)
                fprintf(stderr, fmt, hex);
}

static void report_missing(const struct object *obj)
{
        fprintf(stderr, "Cannot obtain needed %s %s\n",
                obj->type ? typename(obj->type): "object",
                sha1_to_hex(obj->sha1));
        if (!is_null_sha1(current_commit_sha1))
                fprintf(stderr, "while processing commit %s.\n",
                        sha1_to_hex(current_commit_sha1));
}

static int process(struct walker *walker, struct object *obj);

static int process_tree(struct walker *walker, struct tree *tree)
{
        struct tree_desc desc;
        struct name_entry entry;

        if (parse_tree(tree))
                return -1;

        init_tree_desc(&desc, tree->buffer, tree->size);
        while (tree_entry(&desc, &entry)) {
                struct object *obj = NULL;

                /* submodule commits are not stored in the superproject */
                if (S_ISGITLINK(entry.mode))
                        continue;
                if (S_ISDIR(entry.mode)) {
                        struct tree *tree = lookup_tree(entry.sha1);
                        if (tree)
                                obj = &tree->object;
                }
                else {
                        struct blob *blob = lookup_blob(entry.sha1);
                        if (blob)
                                obj = &blob->object;
                }
                if (!obj || process(walker, obj))
                        return -1;
        }
        free_tree_buffer(tree);
        return 0;
}

/* Remember to update object flag allocation in object.h */
#define COMPLETE        (1U << 0)
#define SEEN            (1U << 1)
#define TO_SCAN         (1U << 2)

static struct commit_list *complete = NULL;

static int process_commit(struct walker *walker, struct commit *commit)
{
        if (parse_commit(commit))
                return -1;

        while (complete && complete->item->date >= commit->date) {
                pop_most_recent_commit(&complete, COMPLETE);
        }

        if (commit->object.flags & COMPLETE)
                return 0;

        hashcpy(current_commit_sha1, commit->object.sha1);

        walker_say(walker, "walk %s\n", sha1_to_hex(commit->object.sha1));

        if (walker->get_tree) {
                if (process(walker, &commit->tree->object))
                        return -1;
                if (!walker->get_all)
                        walker->get_tree = 0;
        }
        if (walker->get_history) {
                struct commit_list *parents = commit->parents;
                for (; parents; parents = parents->next) {
                        if (process(walker, &parents->item->object))
                                return -1;
                }
        }
        return 0;
}

static int process_tag(struct walker *walker, struct tag *tag)
{
        if (parse_tag(tag))
                return -1;
        return process(walker, tag->tagged);
}

static struct object_list *process_queue = NULL;
static struct object_list **process_queue_end = &process_queue;

static int process_object(struct walker *walker, struct object *obj)
{
        if (obj->type == OBJ_COMMIT) {
                if (process_commit(walker, (struct commit *)obj))
                        return -1;
                return 0;
        }
        if (obj->type == OBJ_TREE) {
                if (process_tree(walker, (struct tree *)obj))
                        return -1;
                return 0;
        }
        if (obj->type == OBJ_BLOB) {
                return 0;
        }
        if (obj->type == OBJ_TAG) {
                if (process_tag(walker, (struct tag *)obj))
                        return -1;
                return 0;
        }
        return error("Unable to determine requirements "
                     "of type %s for %s",
                     typename(obj->type), sha1_to_hex(obj->sha1));
}

static int process(struct walker *walker, struct object *obj)
{
        if (obj->flags & SEEN)
                return 0;
        obj->flags |= SEEN;

        if (has_sha1_file(obj->sha1)) {
                /* We already have it, so we should scan it now. */
                obj->flags |= TO_SCAN;
        }
        else {
                if (obj->flags & COMPLETE)
                        return 0;
                walker->prefetch(walker, obj->sha1);
        }

        object_list_insert(obj, process_queue_end);
        process_queue_end = &(*process_queue_end)->next;
        return 0;
}

static int loop(struct walker *walker)
{
        struct object_list *elem;

        while (process_queue) {
                struct object *obj = process_queue->item;
                elem = process_queue;
                process_queue = elem->next;
                free(elem);
                if (!process_queue)
                        process_queue_end = &process_queue;

                /* If we are not scanning this object, we placed it in
                 * the queue because we needed to fetch it first.
                 */
                if (! (obj->flags & TO_SCAN)) {
                        if (walker->fetch(walker, obj->sha1)) {
                                report_missing(obj);
                                return -1;
                        }
                }
                if (!obj->type)
                        parse_object(obj->sha1);
                if (process_object(walker, obj))
                        return -1;
        }
        return 0;
}

static int interpret_target(struct walker *walker, char *target, unsigned char *sha1)
{
        if (!get_sha1_hex(target, sha1))
                return 0;
        if (!check_refname_format(target, 0)) {
                struct ref *ref = alloc_ref(target);
                if (!walker->fetch_ref(walker, ref)) {
                        hashcpy(sha1, ref->old_sha1);
                        free(ref);
                        return 0;
                }
                free(ref);
        }
        return -1;
}

static int mark_complete(const char *path, const struct object_id *oid,
                         int flag, void *cb_data)
{
        struct commit *commit = lookup_commit_reference_gently(oid->hash, 1);

        if (commit) {
                commit->object.flags |= COMPLETE;
                commit_list_insert(commit, &complete);
        }
        return 0;
}

int walker_targets_stdin(char ***target, const char ***write_ref)
{
        int targets = 0, targets_alloc = 0;
        struct strbuf buf = STRBUF_INIT;
        *target = NULL; *write_ref = NULL;
        while (1) {
                char *rf_one = NULL;
                char *tg_one;

                if (strbuf_getline(&buf, stdin, '\n') == EOF)
                        break;
                tg_one = buf.buf;
                rf_one = strchr(tg_one, '\t');
                if (rf_one)
                        *rf_one++ = 0;

                if (targets >= targets_alloc) {
                        targets_alloc = targets_alloc ? targets_alloc * 2 : 64;
                        REALLOC_ARRAY(*target, targets_alloc);
                        REALLOC_ARRAY(*write_ref, targets_alloc);
                }
                (*target)[targets] = xstrdup(tg_one);
                (*write_ref)[targets] = xstrdup_or_null(rf_one);
                targets++;
        }
        strbuf_release(&buf);
        return targets;
}

void walker_targets_free(int targets, char **target, const char **write_ref)
{
        while (targets--) {
                free(target[targets]);
                if (write_ref)
                        free((char *) write_ref[targets]);
        }
}

int walker_fetch(struct walker *walker, int targets, char **target,
                 const char **write_ref, const char *write_ref_log_details)
{
        struct strbuf refname = STRBUF_INIT;
        struct strbuf err = STRBUF_INIT;
        struct ref_transaction *transaction = NULL;
        unsigned char *sha1 = xmalloc(targets * 20);
        char *msg = NULL;
        int i, ret = -1;

        save_commit_buffer = 0;

        if (write_ref) {
                transaction = ref_transaction_begin(&err);
                if (!transaction) {
                        error("%s", err.buf);
                        goto done;
                }
        }

        if (!walker->get_recover) {
                for_each_ref(mark_complete, NULL);
                commit_list_sort_by_date(&complete);
        }

        for (i = 0; i < targets; i++) {
                if (interpret_target(walker, target[i], &sha1[20 * i])) {
                        error("Could not interpret response from server '%s' as something to pull", target[i]);
                        goto done;
                }
                if (process(walker, lookup_unknown_object(&sha1[20 * i])))
                        goto done;
        }

        if (loop(walker))
                goto done;
        if (!write_ref) {
                ret = 0;
                goto done;
        }
        if (write_ref_log_details) {
                msg = xstrfmt("fetch from %s", write_ref_log_details);
        } else {
                msg = NULL;
        }
        for (i = 0; i < targets; i++) {
                if (!write_ref[i])
                        continue;
                strbuf_reset(&refname);
                strbuf_addf(&refname, "refs/%s", write_ref[i]);
                if (ref_transaction_update(transaction, refname.buf,
                                           &sha1[20 * i], NULL, 0,
                                           msg ? msg : "fetch (unknown)",
                                           &err)) {
                        error("%s", err.buf);
                        goto done;
                }
        }
        if (ref_transaction_commit(transaction, &err)) {
                error("%s", err.buf);
                goto done;
        }

        ret = 0;

done:
        ref_transaction_free(transaction);
        free(msg);
        free(sha1);
        strbuf_release(&err);
        strbuf_release(&refname);
        return ret;
}

void walker_free(struct walker *walker)
{
        walker->cleanup(walker);
        free(walker);
}