#include "fetch.h"

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

const char *write_ref = NULL;

const unsigned char *current_ref = NULL;

int get_tree = 0;
int get_history = 0;
int get_all = 0;
int get_verbosely = 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_entry_list *entry;

        if (parse_tree(tree))
                return -1;

        entry = tree->entries;
        tree->entries = NULL;
        while (entry) {
                struct tree_entry_list *next = entry->next;
                if (process(entry->item.any))
                        return -1;
                free(entry);
                entry = next;
        }
        return 0;
}

#define COMPLETE        1U
#define TO_FETCH        2U
#define TO_SCAN         4U
#define SCANNED         8U
#define SEEN            16U

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->flags & SCANNED)
                return 0;
        obj->flags |= SCANNED;

        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)) {
                parse_object(obj->sha1);
                /* We already have it, so we should scan it now. */
                if (obj->flags & (SCANNED | TO_SCAN))
                        return 0;
                object_list_insert(obj, process_queue_end);
                process_queue_end = &(*process_queue_end)->next;
                obj->flags |= TO_SCAN;
                return 0;
        }
        if (obj->flags & (COMPLETE | TO_FETCH))
                return 0;
        object_list_insert(obj, process_queue_end);
        process_queue_end = &(*process_queue_end)->next;
        obj->flags |= TO_FETCH;

        prefetch(obj->sha1);
                
        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 (!has_sha1_file(obj->sha1) && 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];
        int fd = -1;

        save_commit_buffer = 0;
        if (write_ref && current_ref) {
                fd = lock_ref_sha1(write_ref, current_ref);
                if (fd < 0)
                        return -1;
        }

        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) {
                if (current_ref) {
                        write_ref_sha1(write_ref, fd, sha1);
                } else {
                        write_ref_sha1_unlocked(write_ref, sha1);
                }
        }
        return 0;
}