#include "cache.h"
#include "commit.h"
#include "tag.h"
#include "pkt-line.h"

static int is_shallow = -1;
static struct stat shallow_stat;
static char *alternate_shallow_file;

void set_alternate_shallow_file(const char *path)
{
        if (is_shallow != -1)
                die("BUG: is_repository_shallow must not be called before set_alternate_shallow_file");
        free(alternate_shallow_file);
        alternate_shallow_file = path ? xstrdup(path) : NULL;
}

int register_shallow(const unsigned char *sha1)
{
        struct commit_graft *graft =
                xmalloc(sizeof(struct commit_graft));
        struct commit *commit = lookup_commit(sha1);

        hashcpy(graft->sha1, sha1);
        graft->nr_parent = -1;
        if (commit && commit->object.parsed)
                commit->parents = NULL;
        return register_commit_graft(graft, 0);
}

int is_repository_shallow(void)
{
        FILE *fp;
        char buf[1024];
        const char *path = alternate_shallow_file;

        if (is_shallow >= 0)
                return is_shallow;

        if (!path)
                path = git_path("shallow");
        /*
         * fetch-pack sets '--shallow-file ""' as an indicator that no
         * shallow file should be used. We could just open it and it
         * will likely fail. But let's do an explicit check instead.
         */
        if (!*path ||
            stat(path, &shallow_stat) ||
            (fp = fopen(path, "r")) == NULL) {
                is_shallow = 0;
                return is_shallow;
        }
        is_shallow = 1;

        while (fgets(buf, sizeof(buf), fp)) {
                unsigned char sha1[20];
                if (get_sha1_hex(buf, sha1))
                        die("bad shallow line: %s", buf);
                register_shallow(sha1);
        }
        fclose(fp);
        return is_shallow;
}

struct commit_list *get_shallow_commits(struct object_array *heads, int depth,
                int shallow_flag, int not_shallow_flag)
{
        int i = 0, cur_depth = 0;
        struct commit_list *result = NULL;
        struct object_array stack = OBJECT_ARRAY_INIT;
        struct commit *commit = NULL;

        while (commit || i < heads->nr || stack.nr) {
                struct commit_list *p;
                if (!commit) {
                        if (i < heads->nr) {
                                commit = (struct commit *)
                                        deref_tag(heads->objects[i++].item, NULL, 0);
                                if (!commit || commit->object.type != OBJ_COMMIT) {
                                        commit = NULL;
                                        continue;
                                }
                                if (!commit->util)
                                        commit->util = xmalloc(sizeof(int));
                                *(int *)commit->util = 0;
                                cur_depth = 0;
                        } else {
                                commit = (struct commit *)
                                        stack.objects[--stack.nr].item;
                                cur_depth = *(int *)commit->util;
                        }
                }
                if (parse_commit(commit))
                        die("invalid commit");
                cur_depth++;
                if (cur_depth >= depth) {
                        commit_list_insert(commit, &result);
                        commit->object.flags |= shallow_flag;
                        commit = NULL;
                        continue;
                }
                commit->object.flags |= not_shallow_flag;
                for (p = commit->parents, commit = NULL; p; p = p->next) {
                        if (!p->item->util) {
                                int *pointer = xmalloc(sizeof(int));
                                p->item->util = pointer;
                                *pointer =  cur_depth;
                        } else {
                                int *pointer = p->item->util;
                                if (cur_depth >= *pointer)
                                        continue;
                                *pointer = cur_depth;
                        }
                        if (p->next)
                                add_object_array(&p->item->object,
                                                NULL, &stack);
                        else {
                                commit = p->item;
                                cur_depth = *(int *)commit->util;
                        }
                }
        }

        return result;
}

void check_shallow_file_for_update(void)
{
        struct stat st;

        if (!is_shallow)
                return;
        else if (is_shallow == -1)
                die("BUG: shallow must be initialized by now");

        if (stat(git_path("shallow"), &st))
                die("shallow file was removed during fetch");
        else if (st.st_mtime != shallow_stat.st_mtime
#ifdef USE_NSEC
                 || ST_MTIME_NSEC(st) != ST_MTIME_NSEC(shallow_stat)
#endif
                   )
                die("shallow file was changed during fetch");
}

struct write_shallow_data {
        struct strbuf *out;
        int use_pack_protocol;
        int count;
};

static int write_one_shallow(const struct commit_graft *graft, void *cb_data)
{
        struct write_shallow_data *data = cb_data;
        const char *hex = sha1_to_hex(graft->sha1);
        if (graft->nr_parent != -1)
                return 0;
        data->count++;
        if (data->use_pack_protocol)
                packet_buf_write(data->out, "shallow %s", hex);
        else {
                strbuf_addstr(data->out, hex);
                strbuf_addch(data->out, '\n');
        }
        return 0;
}

int write_shallow_commits(struct strbuf *out, int use_pack_protocol)
{
        struct write_shallow_data data;
        data.out = out;
        data.use_pack_protocol = use_pack_protocol;
        data.count = 0;
        for_each_commit_graft(write_one_shallow, &data);
        return data.count;
}

char *setup_temporary_shallow(void)
{
        struct strbuf sb = STRBUF_INIT;
        int fd;

        if (write_shallow_commits(&sb, 0)) {
                struct strbuf path = STRBUF_INIT;
                strbuf_addstr(&path, git_path("shallow_XXXXXX"));
                fd = xmkstemp(path.buf);
                if (write_in_full(fd, sb.buf, sb.len) != sb.len)
                        die_errno("failed to write to %s",
                                  path.buf);
                close(fd);
                strbuf_release(&sb);
                return strbuf_detach(&path, NULL);
        }
        /*
         * is_repository_shallow() sees empty string as "no shallow
         * file".
         */
        return xstrdup("");
}

void setup_alternate_shallow(struct lock_file *shallow_lock,
                             const char **alternate_shallow_file)
{
        struct strbuf sb = STRBUF_INIT;
        int fd;

        check_shallow_file_for_update();
        fd = hold_lock_file_for_update(shallow_lock, git_path("shallow"),
                                       LOCK_DIE_ON_ERROR);
        if (write_shallow_commits(&sb, 0)) {
                if (write_in_full(fd, sb.buf, sb.len) != sb.len)
                        die_errno("failed to write to %s",
                                  shallow_lock->filename);
                *alternate_shallow_file = shallow_lock->filename;
        } else
                /*
                 * is_repository_shallow() sees empty string as "no
                 * shallow file".
                 */
                *alternate_shallow_file = "";
        strbuf_release(&sb);
}