#include "cache.h"
#include "refs.h"
#include "commit.h"

static void show_new(char *type, unsigned char *sha1_new)
{
        fprintf(stderr, "  %s: %s\n", type,
                find_unique_abbrev(sha1_new, DEFAULT_ABBREV));
}

static int update_ref(const char *action,
                      const char *refname,
                      unsigned char *sha1,
                      unsigned char *oldval)
{
        int len;
        char msg[1024];
        char *rla = getenv("GIT_REFLOG_ACTION");
        static struct ref_lock *lock;

        if (!rla)
                rla = "(reflog update)";
        len = snprintf(msg, sizeof(msg), "%s: %s", rla, action);
        if (sizeof(msg) <= len)
                die("insanely long action");
        lock = lock_any_ref_for_update(refname, oldval);
        if (!lock)
                return 1;
        if (write_ref_sha1(lock, sha1, msg) < 0)
                return 1;
        return 0;
}

static int update_local_ref(const char *name,
                            const char *new_head,
                            const char *note,
                            int verbose, int force)
{
        char type[20];
        unsigned char sha1_old[20], sha1_new[20];
        char oldh[41], newh[41];
        struct commit *current, *updated;

        if (get_sha1_hex(new_head, sha1_new))
                die("malformed object name %s", new_head);
        if (sha1_object_info(sha1_new, type, NULL))
                die("object %s not found", new_head);

        if (!*name) {
                /* Not storing */
                if (verbose) {
                        fprintf(stderr, "* fetched %s\n", note);
                        show_new(type, sha1_new);
                }
                return 0;
        }

        if (get_sha1(name, sha1_old)) {
                char *msg;
        just_store:
                /* new ref */
                if (!strncmp(name, "refs/tags/", 10))
                        msg = "storing tag";
                else
                        msg = "storing head";
                fprintf(stderr, "* %s: storing %s\n",
                        name, note);
                show_new(type, sha1_new);
                return update_ref(msg, name, sha1_new, NULL);
        }

        if (!hashcmp(sha1_old, sha1_new)) {
                if (verbose) {
                        fprintf(stderr, "* %s: same as %s\n", name, note);
                        show_new(type, sha1_new);
                }
                return 0;
        }

        if (!strncmp(name, "refs/tags/", 10)) {
                fprintf(stderr, "* %s: updating with %s\n", name, note);
                show_new(type, sha1_new);
                return update_ref("updating tag", name, sha1_new, NULL);
        }

        current = lookup_commit_reference(sha1_old);
        updated = lookup_commit_reference(sha1_new);
        if (!current || !updated)
                goto just_store;

        strcpy(oldh, find_unique_abbrev(current->object.sha1, DEFAULT_ABBREV));
        strcpy(newh, find_unique_abbrev(sha1_new, DEFAULT_ABBREV));

        if (in_merge_bases(current, &updated, 1)) {
                fprintf(stderr, "* %s: fast forward to %s\n",
                        name, note);
                fprintf(stderr, "  old..new: %s..%s\n", oldh, newh);
                return update_ref("fast forward", name, sha1_new, sha1_old);
        }
        if (!force) {
                fprintf(stderr,
                        "* %s: not updating to non-fast forward %s\n",
                        name, note);
                fprintf(stderr,
                        "  old...new: %s...%s\n", oldh, newh);
                return 1;
        }
        fprintf(stderr,
                "* %s: forcing update to non-fast forward %s\n",
                name, note);
        fprintf(stderr, "  old...new: %s...%s\n", oldh, newh);
        return update_ref("forced-update", name, sha1_new, sha1_old);
}

static int append_fetch_head(FILE *fp,
                             const char *head, const char *remote,
                             const char *remote_name, const char *remote_nick,
                             const char *local_name, int not_for_merge,
                             int verbose, int force)
{
        struct commit *commit;
        int remote_len, i, note_len;
        unsigned char sha1[20];
        char note[1024];
        const char *what, *kind;

        if (get_sha1(head, sha1))
                return error("Not a valid object name: %s", head);
        commit = lookup_commit_reference(sha1);
        if (!commit)
                not_for_merge = 1;

        if (!strcmp(remote_name, "HEAD")) {
                kind = "";
                what = "";
        }
        else if (!strncmp(remote_name, "refs/heads/", 11)) {
                kind = "branch";
                what = remote_name + 11;
        }
        else if (!strncmp(remote_name, "refs/tags/", 10)) {
                kind = "tag";
                what = remote_name + 10;
        }
        else if (!strncmp(remote_name, "refs/remotes/", 13)) {
                kind = "remote branch";
                what = remote_name + 13;
        }
        else {
                kind = "";
                what = remote_name;
        }

        remote_len = strlen(remote);
        for (i = remote_len - 1; remote[i] == '/' && 0 <= i; i--)
                ;
        remote_len = i + 1;
        if (4 < i && !strncmp(".git", remote + i - 3, 4))
                remote_len = i - 3;
        note_len = sprintf(note, "%s\t%s\t",
                           sha1_to_hex(commit ? commit->object.sha1 : sha1),
                           not_for_merge ? "not-for-merge" : "");
        if (*what) {
                if (*kind)
                        note_len += sprintf(note + note_len, "%s ", kind);
                note_len += sprintf(note + note_len, "'%s' of ", what);
        }
        note_len += sprintf(note + note_len, "%.*s", remote_len, remote);
        fprintf(fp, "%s\n", note);
        return update_local_ref(local_name, head, note, verbose, force);
}

int cmd_fetch__tool(int argc, const char **argv, const char *prefix)
{
        int verbose = 0;
        int force = 0;

        while (1 < argc) {
                const char *arg = argv[1];
                if (!strcmp("-v", arg))
                        verbose = 1;
                else if (!strcmp("-f", arg))
                        force = 1;
                else
                        break;
                argc--;
                argv++;
        }

        if (argc <= 1)
                return error("Missing subcommand");

        if (!strcmp("append-fetch-head", argv[1])) {
                int result;
                FILE *fp;

                if (argc != 8)
                        return error("append-fetch-head takes 6 args");
                fp = fopen(git_path("FETCH_HEAD"), "a");
                result = append_fetch_head(fp, argv[2], argv[3],
                                           argv[4], argv[5],
                                           argv[6], !!argv[7][0],
                                           verbose, force);
                fclose(fp);
                return result;
        }
        if (!strcmp("update-local-ref", argv[1])) {
                if (argc != 5)
                        return error("update-local-ref takes 3 args");
                return update_local_ref(argv[2], argv[3], argv[4],
                                        verbose, force);
        }
        return error("Unknown subcommand: %s", argv[1]);
}