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

/*
 * reflog expire
 */

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

static unsigned long default_reflog_expire;
static unsigned long default_reflog_expire_unreachable;

struct cmd_reflog_expire_cb {
        struct rev_info revs;
        int dry_run;
        int stalefix;
        int verbose;
        unsigned long expire_total;
        unsigned long expire_unreachable;
};

struct expire_reflog_cb {
        FILE *newlog;
        const char *ref;
        struct commit *ref_commit;
        struct cmd_reflog_expire_cb *cmd;
};

#define INCOMPLETE      (1u<<10)
#define STUDYING        (1u<<11)

static int tree_is_complete(const unsigned char *sha1)
{
        struct tree_desc desc;
        struct name_entry entry;
        int complete;
        struct tree *tree;

        tree = lookup_tree(sha1);
        if (!tree)
                return 0;
        if (tree->object.flags & SEEN)
                return 1;
        if (tree->object.flags & INCOMPLETE)
                return 0;

        desc.buf = tree->buffer;
        desc.size = tree->size;
        if (!desc.buf) {
                char type[20];
                void *data = read_sha1_file(sha1, type, &desc.size);
                if (!data) {
                        tree->object.flags |= INCOMPLETE;
                        return 0;
                }
                desc.buf = data;
                tree->buffer = data;
        }
        complete = 1;
        while (tree_entry(&desc, &entry)) {
                if (!has_sha1_file(entry.sha1) ||
                    (S_ISDIR(entry.mode) && !tree_is_complete(entry.sha1))) {
                        tree->object.flags |= INCOMPLETE;
                        complete = 0;
                }
        }
        free(tree->buffer);
        tree->buffer = NULL;

        if (complete)
                tree->object.flags |= SEEN;
        return complete;
}

static int commit_is_complete(struct commit *commit)
{
        struct object_array study;
        struct object_array found;
        int is_incomplete = 0;
        int i;

        /* early return */
        if (commit->object.flags & SEEN)
                return 1;
        if (commit->object.flags & INCOMPLETE)
                return 0;
        /*
         * Find all commits that are reachable and are not marked as
         * SEEN.  Then make sure the trees and blobs contained are
         * complete.  After that, mark these commits also as SEEN.
         * If some of the objects that are needed to complete this
         * commit are missing, mark this commit as INCOMPLETE.
         */
        memset(&study, 0, sizeof(study));
        memset(&found, 0, sizeof(found));
        add_object_array(&commit->object, NULL, &study);
        add_object_array(&commit->object, NULL, &found);
        commit->object.flags |= STUDYING;
        while (study.nr) {
                struct commit *c;
                struct commit_list *parent;

                c = (struct commit *)study.objects[--study.nr].item;
                if (!c->object.parsed && !parse_object(c->object.sha1))
                        c->object.flags |= INCOMPLETE;

                if (c->object.flags & INCOMPLETE) {
                        is_incomplete = 1;
                        break;
                }
                else if (c->object.flags & SEEN)
                        continue;
                for (parent = c->parents; parent; parent = parent->next) {
                        struct commit *p = parent->item;
                        if (p->object.flags & STUDYING)
                                continue;
                        p->object.flags |= STUDYING;
                        add_object_array(&p->object, NULL, &study);
                        add_object_array(&p->object, NULL, &found);
                }
        }
        if (!is_incomplete) {
                /*
                 * make sure all commits in "found" array have all the
                 * necessary objects.
                 */
                for (i = 0; i < found.nr; i++) {
                        struct commit *c =
                                (struct commit *)found.objects[i].item;
                        if (!tree_is_complete(c->tree->object.sha1)) {
                                is_incomplete = 1;
                                c->object.flags |= INCOMPLETE;
                        }
                }
                if (!is_incomplete) {
                        /* mark all found commits as complete, iow SEEN */
                        for (i = 0; i < found.nr; i++)
                                found.objects[i].item->flags |= SEEN;
                }
        }
        /* clear flags from the objects we traversed */
        for (i = 0; i < found.nr; i++)
                found.objects[i].item->flags &= ~STUDYING;
        if (is_incomplete)
                commit->object.flags |= INCOMPLETE;
        else {
                /*
                 * If we come here, we have (1) traversed the ancestry chain
                 * from the "commit" until we reach SEEN commits (which are
                 * known to be complete), and (2) made sure that the commits
                 * encountered during the above traversal refer to trees that
                 * are complete.  Which means that we know *all* the commits
                 * we have seen during this process are complete.
                 */
                for (i = 0; i < found.nr; i++)
                        found.objects[i].item->flags |= SEEN;
        }
        /* free object arrays */
        free(study.objects);
        free(found.objects);
        return !is_incomplete;
}

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

        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.
         *
         * We have walked all the objects reachable from the refs
         * and cache earlier.  The commits reachable by this commit
         * must meet SEEN commits -- and then we should mark them as
         * SEEN as well.
         */
        if (!commit_is_complete(commit))
                return 0;
        *it = commit;
        return 1;
}

static int expire_reflog_ent(unsigned char *osha1, unsigned char *nsha1,
                const char *email, unsigned long timestamp, int tz,
                const char *message, void *cb_data)
{
        struct expire_reflog_cb *cb = cb_data;
        struct commit *old, *new;

        if (timestamp < cb->cmd->expire_total)
                goto prune;

        old = new = NULL;
        if (cb->cmd->stalefix &&
            (!keep_entry(&old, osha1) || !keep_entry(&new, nsha1)))
                goto prune;

        if (timestamp < cb->cmd->expire_unreachable) {
                if (!cb->ref_commit)
                        goto prune;
                if (!old && !is_null_sha1(osha1))
                        old = lookup_commit_reference_gently(osha1, 1);
                if (!new && !is_null_sha1(nsha1))
                        new = lookup_commit_reference_gently(nsha1, 1);
                if ((old && !in_merge_bases(old, cb->ref_commit)) ||
                    (new && !in_merge_bases(new, cb->ref_commit)))
                        goto prune;
        }

        if (cb->newlog) {
                char sign = (tz < 0) ? '-' : '+';
                int zone = (tz < 0) ? (-tz) : tz;
                fprintf(cb->newlog, "%s %s %s %lu %c%04d\t%s",
                        sha1_to_hex(osha1), sha1_to_hex(nsha1),
                        email, timestamp, sign, zone,
                        message);
        }
        if (cb->cmd->verbose)
                printf("keep %s", message);
        return 0;
 prune:
        if (!cb->newlog || cb->cmd->verbose)
                printf("%sprune %s", cb->newlog ? "" : "would ", message);
        return 0;
}

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);
        cb.ref = ref;
        cb.cmd = cmd;
        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 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;

        /*
         * We can trust the commits and objects reachable from refs
         * even in older repository.  We cannot trust what's reachable
         * from reflog if the repository was pruned with older git.
         */

        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, "--stale-fix"))
                        cb.stalefix = 1;
                else if (!strcmp(arg, "--all"))
                        do_all = 1;
                else if (!strcmp(arg, "--verbose"))
                        cb.verbose = 1;
                else if (!strcmp(arg, "--")) {
                        i++;
                        break;
                }
                else if (arg[0] == '-')
                        usage(reflog_expire_usage);
                else
                        break;
        }
        if (cb.stalefix) {
                init_revisions(&cb.revs, prefix);
                if (cb.verbose)
                        printf("Marking reachable objects...");
                mark_reachable_objects(&cb.revs, 0);
                if (cb.verbose)
                        putchar('\n');
        }

        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;
}

/*
 * main "reflog"
 */

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);
}