#include "fetch.h"

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

const char *write_ref = NULL;

int get_tree = 0;
int get_history = 0;
int get_all = 0;
int get_verbosely = 0;
int get_recover = 0;
static unsigned char current_commit_sha1[20];

void pull_say(const char *fmt, const char *hex) 
{
        if (get_verbosely)
                fprintf(stderr, fmt, hex);
}

static void report_missing(const char *what, const unsigned char *missing)
{
        char missing_hex[41];

        strcpy(missing_hex, sha1_to_hex(missing));;
        fprintf(stderr,
                "Cannot obtain needed %s %s\nwhile processing commit %s.\n",
                what, missing_hex, sha1_to_hex(current_commit_sha1));
}

static int process(struct object *obj);

static int process_tree(struct tree *tree)
{
        struct tree_desc desc;

        if (parse_tree(tree))
                return -1;

        desc.buf = tree->buffer;
        desc.size = tree->size;
        while (desc.size) {
                unsigned mode;
                const char *name;
                const unsigned char *sha1;

                sha1 = tree_entry_extract(&desc, &name, &mode);
                update_tree_entry(&desc);

                if (S_ISDIR(mode)) {
                        struct tree *tree = lookup_tree(sha1);
                        process_tree(tree);
                } else {
                        struct blob *blob = lookup_blob(sha1);
                        process(&blob->object);
                }
        }
        free(tree->buffer);
        tree->buffer = NULL;
        tree->size = 0;
        return 0;
}

#define COMPLETE        (1U << 0)
#define SEEN            (1U << 1)
#define TO_SCAN         (1U << 2)

static struct commit_list *complete = NULL;

static int process_commit(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;

        memcpy(current_commit_sha1, commit->object.sha1, 20);

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

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

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

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

static int process_object(struct object *obj)
{
        if (obj->type == commit_type) {
                if (process_commit((struct commit *)obj))
                        return -1;
                return 0;
        }
        if (obj->type == tree_type) {
                if (process_tree((struct tree *)obj))
                        return -1;
                return 0;
        }
        if (obj->type == blob_type) {
                return 0;
        }
        if (obj->type == tag_type) {
                if (process_tag((struct tag *)obj))
                        return -1;
                return 0;
        }
        return error("Unable to determine requirements "
                     "of type %s for %s",
                     obj->type, sha1_to_hex(obj->sha1));
}

static int process(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;
                prefetch(obj->sha1);
        }
                
        object_list_insert(obj, process_queue_end);
        process_queue_end = &(*process_queue_end)->next;
        return 0;
}

static int loop(void)
{
        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 (fetch(obj->sha1)) {
                                report_missing(obj->type
                                               ? obj->type
                                               : "object", obj->sha1);
                                return -1;
                        }
                }
                if (!obj->type)
                        parse_object(obj->sha1);
                if (process_object(obj))
                        return -1;
        }
        return 0;
}

static int interpret_target(char *target, unsigned char *sha1)
{
        if (!get_sha1_hex(target, sha1))
                return 0;
        if (!check_ref_format(target)) {
                if (!fetch_ref(target, sha1)) {
                        return 0;
                }
        }
        return -1;
}

static int mark_complete(const char *path, const unsigned char *sha1)
{
        struct commit *commit = lookup_commit_reference_gently(sha1, 1);
        if (commit) {
                commit->object.flags |= COMPLETE;
                insert_by_date(commit, &complete);
        }
        return 0;
}

int pull(char *target)
{
        unsigned char sha1[20];

        save_commit_buffer = 0;
        track_object_refs = 0;

        if (!get_recover)
                for_each_ref(mark_complete);

        if (interpret_target(target, sha1))
                return error("Could not interpret %s as something to pull",
                             target);
        if (process(lookup_unknown_object(sha1)))
                return -1;
        if (loop())
                return -1;
        
        if (write_ref)
                write_ref_sha1_unlocked(write_ref, sha1);
        return 0;
}