#ifndef REFS_H
#define REFS_H

/*
 * A ref_transaction represents a collection of ref updates
 * that should succeed or fail together.
 *
 * Calling sequence
 * ----------------
 * - Allocate and initialize a `struct ref_transaction` by calling
 *   `ref_transaction_begin()`.
 *
 * - List intended ref updates by calling functions like
 *   `ref_transaction_update()` and `ref_transaction_create()`.
 *
 * - Call `ref_transaction_commit()` to execute the transaction.
 *   If this succeeds, the ref updates will have taken place and
 *   the transaction cannot be rolled back.
 *
 * - At any time call `ref_transaction_free()` to discard the
 *   transaction and free associated resources.  In particular,
 *   this rolls back the transaction if it has not been
 *   successfully committed.
 *
 * Error handling
 * --------------
 *
 * On error, transaction functions append a message about what
 * went wrong to the 'err' argument.  The message mentions what
 * ref was being updated (if any) when the error occurred so it
 * can be passed to 'die' or 'error' as-is.
 *
 * The message is appended to err without first clearing err.
 * err will not be '\n' terminated.
 */
struct ref_transaction;

/*
 * Bit values set in the flags argument passed to each_ref_fn():
 */

/* Reference is a symbolic reference. */
#define REF_ISSYMREF 0x01

/* Reference is a packed reference. */
#define REF_ISPACKED 0x02

/*
 * Reference cannot be resolved to an object name: dangling symbolic
 * reference (directly or indirectly), corrupt reference file,
 * reference exists but name is bad, or symbolic reference refers to
 * ill-formatted reference name.
 */
#define REF_ISBROKEN 0x04

/*
 * Reference name is not well formed.
 *
 * See git-check-ref-format(1) for the definition of well formed ref names.
 */
#define REF_BAD_NAME 0x08

/*
 * The signature for the callback function for the for_each_*()
 * functions below.  The memory pointed to by the refname and sha1
 * arguments is only guaranteed to be valid for the duration of a
 * single callback invocation.
 */
typedef int each_ref_fn(const char *refname,
                        const struct object_id *oid, int flags, void *cb_data);

/*
 * The following functions invoke the specified callback function for
 * each reference indicated.  If the function ever returns a nonzero
 * value, stop the iteration and return that value.  Please note that
 * it is not safe to modify references while an iteration is in
 * progress, unless the same callback function invocation that
 * modifies the reference also returns a nonzero value to immediately
 * stop the iteration.
 */
extern int head_ref(each_ref_fn, void *);
extern int for_each_ref(each_ref_fn, void *);
extern int for_each_ref_in(const char *, each_ref_fn, void *);
extern int for_each_tag_ref(each_ref_fn, void *);
extern int for_each_branch_ref(each_ref_fn, void *);
extern int for_each_remote_ref(each_ref_fn, void *);
extern int for_each_replace_ref(each_ref_fn, void *);
extern int for_each_glob_ref(each_ref_fn, const char *pattern, void *);
extern int for_each_glob_ref_in(each_ref_fn, const char *pattern, const char* prefix, void *);

extern int head_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data);
extern int for_each_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data);
extern int for_each_ref_in_submodule(const char *submodule, const char *prefix,
                each_ref_fn fn, void *cb_data);
extern int for_each_tag_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data);
extern int for_each_branch_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data);
extern int for_each_remote_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data);

extern int head_ref_namespaced(each_ref_fn fn, void *cb_data);
extern int for_each_namespaced_ref(each_ref_fn fn, void *cb_data);

static inline const char *has_glob_specials(const char *pattern)
{
        return strpbrk(pattern, "?*[");
}

/* can be used to learn about broken ref and symref */
extern int for_each_rawref(each_ref_fn, void *);

extern void warn_dangling_symref(FILE *fp, const char *msg_fmt, const char *refname);
extern void warn_dangling_symrefs(FILE *fp, const char *msg_fmt, const struct string_list *refnames);

/*
 * Lock the packed-refs file for writing.  Flags is passed to
 * hold_lock_file_for_update().  Return 0 on success.
 * Errno is set to something meaningful on error.
 */
extern int lock_packed_refs(int flags);

/*
 * Add a reference to the in-memory packed reference cache.  This may
 * only be called while the packed-refs file is locked (see
 * lock_packed_refs()).  To actually write the packed-refs file, call
 * commit_packed_refs().
 */
extern void add_packed_ref(const char *refname, const unsigned char *sha1);

/*
 * Write the current version of the packed refs cache from memory to
 * disk.  The packed-refs file must already be locked for writing (see
 * lock_packed_refs()).  Return zero on success.
 * Sets errno to something meaningful on error.
 */
extern int commit_packed_refs(void);

/*
 * Rollback the lockfile for the packed-refs file, and discard the
 * in-memory packed reference cache.  (The packed-refs file will be
 * read anew if it is needed again after this function is called.)
 */
extern void rollback_packed_refs(void);

/*
 * Flags for controlling behaviour of pack_refs()
 * PACK_REFS_PRUNE: Prune loose refs after packing
 * PACK_REFS_ALL:   Pack _all_ refs, not just tags and already packed refs
 */
#define PACK_REFS_PRUNE 0x0001
#define PACK_REFS_ALL   0x0002

/*
 * Write a packed-refs file for the current repository.
 * flags: Combination of the above PACK_REFS_* flags.
 */
int pack_refs(unsigned int flags);

/*
 * Rewrite the packed-refs file, omitting any refs listed in
 * 'refnames'. On error, packed-refs will be unchanged, the return
 * value is nonzero, and a message about the error is written to the
 * 'err' strbuf.
 *
 * The refs in 'refnames' needn't be sorted. `err` must not be NULL.
 */
extern int repack_without_refs(struct string_list *refnames,
                               struct strbuf *err);

extern int ref_exists(const char *);

extern int is_branch(const char *refname);

/*
 * If refname is a non-symbolic reference that refers to a tag object,
 * and the tag can be (recursively) dereferenced to a non-tag object,
 * store the SHA1 of the referred-to object to sha1 and return 0.  If
 * any of these conditions are not met, return a non-zero value.
 * Symbolic references are considered unpeelable, even if they
 * ultimately resolve to a peelable tag.
 */
extern int peel_ref(const char *refname, unsigned char *sha1);

/*
 * Flags controlling ref_transaction_update(), ref_transaction_create(), etc.
 * REF_NODEREF: act on the ref directly, instead of dereferencing
 *              symbolic references.
 *
 * Other flags are reserved for internal use.
 */
#define REF_NODEREF     0x01

/*
 * Setup reflog before using. Set errno to something meaningful on failure.
 */
int log_ref_setup(const char *refname, struct strbuf *logfile);

/** Reads log for the value of ref during at_time. **/
extern int read_ref_at(const char *refname, unsigned int flags,
                       unsigned long at_time, int cnt,
                       unsigned char *sha1, char **msg,
                       unsigned long *cutoff_time, int *cutoff_tz, int *cutoff_cnt);

/** Check if a particular reflog exists */
extern int reflog_exists(const char *refname);

/*
 * Delete the specified reference. If old_sha1 is non-NULL and not
 * NULL_SHA1, then verify that the current value of the reference is
 * old_sha1 before deleting it. If old_sha1 is NULL or NULL_SHA1,
 * delete the reference if it exists, regardless of its old value.
 * flags is passed through to ref_transaction_delete().
 */
extern int delete_ref(const char *refname, const unsigned char *old_sha1,
                      unsigned int flags);

/** Delete a reflog */
extern int delete_reflog(const char *refname);

/* iterate over reflog entries */
typedef int each_reflog_ent_fn(unsigned char *osha1, unsigned char *nsha1, const char *, unsigned long, int, const char *, void *);
int for_each_reflog_ent(const char *refname, each_reflog_ent_fn fn, void *cb_data);
int for_each_reflog_ent_reverse(const char *refname, each_reflog_ent_fn fn, void *cb_data);

/*
 * Calls the specified function for each reflog file until it returns nonzero,
 * and returns the value
 */
extern int for_each_reflog(each_ref_fn, void *);

#define REFNAME_ALLOW_ONELEVEL 1
#define REFNAME_REFSPEC_PATTERN 2

/*
 * Return 0 iff refname has the correct format for a refname according
 * to the rules described in Documentation/git-check-ref-format.txt.
 * If REFNAME_ALLOW_ONELEVEL is set in flags, then accept one-level
 * reference names.  If REFNAME_REFSPEC_PATTERN is set in flags, then
 * allow a "*" wildcard character in place of one of the name
 * components.  No leading or repeated slashes are accepted.
 */
extern int check_refname_format(const char *refname, int flags);

extern const char *prettify_refname(const char *refname);
extern char *shorten_unambiguous_ref(const char *refname, int strict);

/** rename ref, return 0 on success **/
extern int rename_ref(const char *oldref, const char *newref, const char *logmsg);

/**
 * Resolve refname in the nested "gitlink" repository that is located
 * at path.  If the resolution is successful, return 0 and set sha1 to
 * the name of the object; otherwise, return a non-zero value.
 */
extern int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *sha1);

enum action_on_err {
        UPDATE_REFS_MSG_ON_ERR,
        UPDATE_REFS_DIE_ON_ERR,
        UPDATE_REFS_QUIET_ON_ERR
};

/*
 * Begin a reference transaction.  The reference transaction must
 * be freed by calling ref_transaction_free().
 */
struct ref_transaction *ref_transaction_begin(struct strbuf *err);

/*
 * Reference transaction updates
 *
 * The following four functions add a reference check or update to a
 * ref_transaction.  They have some common similar parameters:
 *
 *     transaction -- a pointer to an open ref_transaction, obtained
 *         from ref_transaction_begin().
 *
 *     refname -- the name of the reference to be affected.
 *
 *     flags -- flags affecting the update, passed to
 *         update_ref_lock(). Can be REF_NODEREF, which means that
 *         symbolic references should not be followed.
 *
 *     msg -- a message describing the change (for the reflog).
 *
 *     err -- a strbuf for receiving a description of any error that
 *         might have occured.
 *
 * The functions make internal copies of refname and msg, so the
 * caller retains ownership of these parameters.
 *
 * The functions return 0 on success and non-zero on failure. A
 * failure means that the transaction as a whole has failed and needs
 * to be rolled back.
 */

/*
 * Add a reference update to transaction. new_sha1 is the value that
 * the reference should have after the update, or null_sha1 if it
 * should be deleted. If new_sha1 is NULL, then the reference is not
 * changed at all. old_sha1 is the value that the reference must have
 * before the update, or null_sha1 if it must not have existed
 * beforehand. The old value is checked after the lock is taken to
 * prevent races. If the old value doesn't agree with old_sha1, the
 * whole transaction fails. If old_sha1 is NULL, then the previous
 * value is not checked.
 *
 * See the above comment "Reference transaction updates" for more
 * information.
 */
int ref_transaction_update(struct ref_transaction *transaction,
                           const char *refname,
                           const unsigned char *new_sha1,
                           const unsigned char *old_sha1,
                           unsigned int flags, const char *msg,
                           struct strbuf *err);

/*
 * Add a reference creation to transaction. new_sha1 is the value that
 * the reference should have after the update; it must not be
 * null_sha1. It is verified that the reference does not exist
 * already.
 *
 * See the above comment "Reference transaction updates" for more
 * information.
 */
int ref_transaction_create(struct ref_transaction *transaction,
                           const char *refname,
                           const unsigned char *new_sha1,
                           unsigned int flags, const char *msg,
                           struct strbuf *err);

/*
 * Add a reference deletion to transaction. If old_sha1 is non-NULL,
 * then it holds the value that the reference should have had before
 * the update (which must not be null_sha1).
 *
 * See the above comment "Reference transaction updates" for more
 * information.
 */
int ref_transaction_delete(struct ref_transaction *transaction,
                           const char *refname,
                           const unsigned char *old_sha1,
                           unsigned int flags, const char *msg,
                           struct strbuf *err);

/*
 * Verify, within a transaction, that refname has the value old_sha1,
 * or, if old_sha1 is null_sha1, then verify that the reference
 * doesn't exist. old_sha1 must be non-NULL.
 *
 * See the above comment "Reference transaction updates" for more
 * information.
 */
int ref_transaction_verify(struct ref_transaction *transaction,
                           const char *refname,
                           const unsigned char *old_sha1,
                           unsigned int flags,
                           struct strbuf *err);

/*
 * Commit all of the changes that have been queued in transaction, as
 * atomically as possible.
 *
 * Returns 0 for success, or one of the below error codes for errors.
 */
/* Naming conflict (for example, the ref names A and A/B conflict). */
#define TRANSACTION_NAME_CONFLICT -1
/* All other errors. */
#define TRANSACTION_GENERIC_ERROR -2
int ref_transaction_commit(struct ref_transaction *transaction,
                           struct strbuf *err);

/*
 * Free an existing transaction and all associated data.
 */
void ref_transaction_free(struct ref_transaction *transaction);

/**
 * Lock, update, and unlock a single reference. This function
 * basically does a transaction containing a single call to
 * ref_transaction_update(). The parameters to this function have the
 * same meaning as the corresponding parameters to
 * ref_transaction_update(). Handle errors as requested by the `onerr`
 * argument.
 */
int update_ref(const char *msg, const char *refname,
               const unsigned char *new_sha1, const unsigned char *old_sha1,
               unsigned int flags, enum action_on_err onerr);

extern int parse_hide_refs_config(const char *var, const char *value, const char *);
extern int ref_is_hidden(const char *);

enum expire_reflog_flags {
        EXPIRE_REFLOGS_DRY_RUN = 1 << 0,
        EXPIRE_REFLOGS_UPDATE_REF = 1 << 1,
        EXPIRE_REFLOGS_VERBOSE = 1 << 2,
        EXPIRE_REFLOGS_REWRITE = 1 << 3
};

/*
 * The following interface is used for reflog expiration. The caller
 * calls reflog_expire(), supplying it with three callback functions,
 * of the following types. The callback functions define the
 * expiration policy that is desired.
 *
 * reflog_expiry_prepare_fn -- Called once after the reference is
 *     locked.
 *
 * reflog_expiry_should_prune_fn -- Called once for each entry in the
 *     existing reflog. It should return true iff that entry should be
 *     pruned.
 *
 * reflog_expiry_cleanup_fn -- Called once before the reference is
 *     unlocked again.
 */
typedef void reflog_expiry_prepare_fn(const char *refname,
                                      const unsigned char *sha1,
                                      void *cb_data);
typedef int reflog_expiry_should_prune_fn(unsigned char *osha1,
                                          unsigned char *nsha1,
                                          const char *email,
                                          unsigned long timestamp, int tz,
                                          const char *message, void *cb_data);
typedef void reflog_expiry_cleanup_fn(void *cb_data);

/*
 * Expire reflog entries for the specified reference. sha1 is the old
 * value of the reference. flags is a combination of the constants in
 * enum expire_reflog_flags. The three function pointers are described
 * above. On success, return zero.
 */
extern int reflog_expire(const char *refname, const unsigned char *sha1,
                         unsigned int flags,
                         reflog_expiry_prepare_fn prepare_fn,
                         reflog_expiry_should_prune_fn should_prune_fn,
                         reflog_expiry_cleanup_fn cleanup_fn,
                         void *policy_cb_data);

#endif /* REFS_H */