#include "cache.h"
#include "builtin.h"
#include "commit.h"
#include "refs.h"
#include "dir.h"
#include "tree-walk.h"

static unsigned long default_reflog_expire;
static unsigned long default_reflog_expire_unreachable;

struct expire_reflog_cb {
        FILE *newlog;
        const char *ref;
        struct commit *ref_commit;
        unsigned long expire_total;
        unsigned long expire_unreachable;
};

static int tree_is_complete(const unsigned char *sha1)
{
        struct tree_desc desc;
        void *buf;
        char type[20];

        buf = read_sha1_file(sha1, type, &desc.size);
        if (!buf)
                return 0;
        desc.buf = buf;
        while (desc.size) {
                const unsigned char *elem;
                const char *name;
                unsigned mode;

                elem = tree_entry_extract(&desc, &name, &mode);
                if (!has_sha1_file(elem) ||
                    (S_ISDIR(mode) && !tree_is_complete(elem))) {
                        free(buf);
                        return 0;
                }
                update_tree_entry(&desc);
        }
        free(buf);
        return 1;
}

static int keep_entry(struct commit **it, unsigned char *sha1)
{
        struct commit *commit;

        *it = NULL;
        if (is_null_sha1(sha1))
                return 1;
        commit = lookup_commit_reference_gently(sha1, 1);
        if (!commit)
                return 0;

        /* Make sure everything in this commit exists. */
        parse_object(commit->object.sha1);
        if (!tree_is_complete(commit->tree->object.sha1))
                return 0;
        *it = commit;
        return 1;
}

static int expire_reflog_ent(unsigned char *osha1, unsigned char *nsha1,
                             char *data, void *cb_data)
{
        struct expire_reflog_cb *cb = cb_data;
        unsigned long timestamp;
        char *cp, *ep;
        struct commit *old, *new;

        cp = strchr(data, '>');
        if (!cp || *++cp != ' ')
                goto prune;
        timestamp = strtoul(cp, &ep, 10);
        if (*ep != ' ')
                goto prune;
        if (timestamp < cb->expire_total)
                goto prune;

        if (!keep_entry(&old, osha1) || !keep_entry(&new, nsha1))
                goto prune;

        if ((timestamp < cb->expire_unreachable) &&
            (!cb->ref_commit ||
             (old && !in_merge_bases(old, cb->ref_commit)) ||
             (new && !in_merge_bases(new, cb->ref_commit))))
                goto prune;

        if (cb->newlog)
                fprintf(cb->newlog, "%s %s %s",
                        sha1_to_hex(osha1), sha1_to_hex(nsha1), data);
        return 0;
 prune:
        if (!cb->newlog)
                fprintf(stderr, "would prune %s", data);
        return 0;
}

struct cmd_reflog_expire_cb {
        int dry_run;
        unsigned long expire_total;
        unsigned long expire_unreachable;
};

static int expire_reflog(const char *ref, const unsigned char *sha1, int unused, void *cb_data)
{
        struct cmd_reflog_expire_cb *cmd = cb_data;
        struct expire_reflog_cb cb;
        struct ref_lock *lock;
        char *newlog_path = NULL;
        int status = 0;

        if (strncmp(ref, "refs/", 5))
                return error("not a ref '%s'", ref);

        memset(&cb, 0, sizeof(cb));
        /* we take the lock for the ref itself to prevent it from
         * getting updated.
         */
        lock = lock_ref_sha1(ref + 5, sha1);
        if (!lock)
                return error("cannot lock ref '%s'", ref);
        if (!file_exists(lock->log_file))
                goto finish;
        if (!cmd->dry_run) {
                newlog_path = xstrdup(git_path("logs/%s.lock", ref));
                cb.newlog = fopen(newlog_path, "w");
        }

        cb.ref_commit = lookup_commit_reference_gently(sha1, 1);
        if (!cb.ref_commit)
                fprintf(stderr,
                        "warning: ref '%s' does not point at a commit\n", ref);
        cb.ref = ref;
        cb.expire_total = cmd->expire_total;
        cb.expire_unreachable = cmd->expire_unreachable;
        for_each_reflog_ent(ref, expire_reflog_ent, &cb);
 finish:
        if (cb.newlog) {
                if (fclose(cb.newlog))
                        status |= error("%s: %s", strerror(errno),
                                        newlog_path);
                if (rename(newlog_path, lock->log_file)) {
                        status |= error("cannot rename %s to %s",
                                        newlog_path, lock->log_file);
                        unlink(newlog_path);
                }
        }
        free(newlog_path);
        unlock_ref(lock);
        return status;
}

static int reflog_expire_config(const char *var, const char *value)
{
        if (!strcmp(var, "gc.reflogexpire"))
                default_reflog_expire = approxidate(value);
        else if (!strcmp(var, "gc.reflogexpireunreachable"))
                default_reflog_expire_unreachable = approxidate(value);
        else
                return git_default_config(var, value);
        return 0;
}

static const char reflog_expire_usage[] =
"git-reflog expire [--dry-run] [--expire=<time>] [--expire-unreachable=<time>] [--all] <refs>...";

static int cmd_reflog_expire(int argc, const char **argv, const char *prefix)
{
        struct cmd_reflog_expire_cb cb;
        unsigned long now = time(NULL);
        int i, status, do_all;

        git_config(reflog_expire_config);

        save_commit_buffer = 0;
        do_all = status = 0;
        memset(&cb, 0, sizeof(cb));

        if (!default_reflog_expire_unreachable)
                default_reflog_expire_unreachable = now - 30 * 24 * 3600;
        if (!default_reflog_expire)
                default_reflog_expire = now - 90 * 24 * 3600;
        cb.expire_total = default_reflog_expire;
        cb.expire_unreachable = default_reflog_expire_unreachable;

        for (i = 1; i < argc; i++) {
                const char *arg = argv[i];
                if (!strcmp(arg, "--dry-run") || !strcmp(arg, "-n"))
                        cb.dry_run = 1;
                else if (!strncmp(arg, "--expire=", 9))
                        cb.expire_total = approxidate(arg + 9);
                else if (!strncmp(arg, "--expire-unreachable=", 21))
                        cb.expire_unreachable = approxidate(arg + 21);
                else if (!strcmp(arg, "--all"))
                        do_all = 1;
                else if (!strcmp(arg, "--")) {
                        i++;
                        break;
                }
                else if (arg[0] == '-')
                        usage(reflog_expire_usage);
                else
                        break;
        }
        if (do_all)
                status |= for_each_ref(expire_reflog, &cb);
        while (i < argc) {
                const char *ref = argv[i++];
                unsigned char sha1[20];
                if (!resolve_ref(ref, sha1, 1, NULL)) {
                        status |= error("%s points nowhere!", ref);
                        continue;
                }
                status |= expire_reflog(ref, sha1, 0, &cb);
        }
        return status;
}

static const char reflog_usage[] =
"git-reflog (expire | ...)";

int cmd_reflog(int argc, const char **argv, const char *prefix)
{
        if (argc < 2)
                usage(reflog_usage);
        else if (!strcmp(argv[1], "expire"))
                return cmd_reflog_expire(argc - 1, argv + 1, prefix);
        else
                usage(reflog_usage);
}