/**
 * @file messages_server.h
 * @author Michal Vasko <mvasko@cesnet.cz>
 * @brief libnetconf2's functions and structures of server NETCONF messages.
 *
 * @copyright
 * Copyright (c) 2015-2021 CESNET, z.s.p.o.
 *
 * This source code is licensed under BSD 3-Clause License (the "License").
 * You may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     https://opensource.org/licenses/BSD-3-Clause
 */

#ifndef NC_MESSAGES_SERVER_H_
#define NC_MESSAGES_SERVER_H_

#ifdef __cplusplus
extern "C" {
#endif

#include <stdarg.h>
#include <stdint.h>

#include <libyang/libyang.h>

#include "netconf.h"
#include "session.h"

/**
 * @defgroup server_msg Server Messages
 * @ingroup server
 *
 * @brief Functions to create NETCONF Event notifications and replies to the NETCONF RPCs (or actions).
 * @{
 */

/**
 * @brief Enumeration of NETCONF errors
 */
typedef enum NC_ERROR {
    NC_ERR_UNKNOWN = 0,      /**< unknown error */
    NC_ERR_IN_USE,           /**< in-use error */
    NC_ERR_INVALID_VALUE,    /**< invalid-value error */
    NC_ERR_TOO_BIG,          /**< too-big error */
    NC_ERR_MISSING_ATTR,     /**< missing-attribute error */
    NC_ERR_BAD_ATTR,         /**< bad-attribute error */
    NC_ERR_UNKNOWN_ATTR,     /**< unknown-attribute error */
    NC_ERR_MISSING_ELEM,     /**< missing-element error */
    NC_ERR_BAD_ELEM,         /**< bad-element error */
    NC_ERR_UNKNOWN_ELEM,     /**< unknown-element error */
    NC_ERR_UNKNOWN_NS,       /**< unknown-namespace error */
    NC_ERR_ACCESS_DENIED,    /**< access-denied error */
    NC_ERR_LOCK_DENIED,      /**< lock-denied error */
    NC_ERR_RES_DENIED,       /**< resource-denied error */
    NC_ERR_ROLLBACK_FAILED,  /**< rollback-failed error */
    NC_ERR_DATA_EXISTS,      /**< data-exists error */
    NC_ERR_DATA_MISSING,     /**< data-missing error */
    NC_ERR_OP_NOT_SUPPORTED, /**< operation-not-supported error */
    NC_ERR_OP_FAILED,        /**< operation-failed error */
    NC_ERR_MALFORMED_MSG     /**< malformed-message error */
} NC_ERR;

/**
 * @brief Enumeration of NETCONF error type (layer)
 */
typedef enum NC_ERROR_TYPE {
    NC_ERR_TYPE_UNKNOWN = 0, /**< unknown layer */
    NC_ERR_TYPE_TRAN,        /**< transport layer */
    NC_ERR_TYPE_RPC,         /**< RPC layer */
    NC_ERR_TYPE_PROT,        /**< protocol layer */
    NC_ERR_TYPE_APP          /**< application layer */
} NC_ERR_TYPE;

/**
 * @brief NETCONF server rpc-reply object
 */
struct nc_server_reply;

/**
 * @brief NETCONF server Event Notification object
 */
struct nc_server_notif;

/**
 * @brief NETCONF server error structure
 */
struct nc_server_error;

/**
 * @brief Create an OK rpc-reply object.
 *
 * @return rpc-reply object, NULL on error.
 */
struct nc_server_reply *nc_server_reply_ok(void);

/**
 * @brief Create a DATA rpc-reply object.
 *
 * @param[in] data Reply data tree pointing to the RPC/action itself. This tree must be valid according to
 * the RPC output of the RPC this is a reply to.
 * @param[in] wd with-default mode if applicable
 * @param[in] paramtype Determines how the @p data parameter is treated.
 * @return rpc-reply object, NULL on error.
 */
struct nc_server_reply *nc_server_reply_data(struct lyd_node *data, NC_WD_MODE wd, NC_PARAMTYPE paramtype);

/**
 * @brief Create an ERROR rpc-reply object.
 *
 * @param[in] err Errors created by nc_err(). It will be freed with the returned object.
 * @return rpc-reply object, NULL on error.
 */
struct nc_server_reply *nc_server_reply_err(struct lyd_node *err);

/**
 * @brief Add another error opaque data node tree to an ERROR rpc-reply object.
 *
 * @param[in] reply ERROR reply to add to.
 * @param[in] err Error created by nc_err(). It will be freed with the returned object.
 * @return 0 on success, -1 on errror.
 */
int nc_server_reply_add_err(struct nc_server_reply *reply, struct lyd_node *err);

/**
 * @brief Get last error from an ERROR rpc-reply object.
 *
 * @param[in] reply ERROR reply to read from.
 * @return Last error opaque data tree, NULL on failure.
 */
const struct lyd_node *nc_server_reply_get_last_err(const struct nc_server_reply *reply);

/**
 * @brief Create a server error structure. Its \<error-message\> is filled with
 * a general description of the specific error.
 *
 * @param[in] ctx libyang context to use.
 * @param[in] tag \<error-tag\> of the server error specified as #NC_ERR value. According to the tag, the
 * specific additional parameters are required:
 * - #NC_ERR_IN_USE
 * - #NC_ERR_INVALID_VALUE
 * - #NC_ERR_ACCESS_DENIED
 * - #NC_ERR_ROLLBACK_FAILED
 * - #NC_ERR_OP_NOT_SUPPORTED
 * - #NC_ERR_TOO_BIG
 * - #NC_ERR_RES_DENIED
 * - #NC_ERR_OP_FAILED
 *   - `NC_ERR_TYPE type;` - type (layer) of the error.
 * - #NC_ERR_MISSING_ATTR
 * - #NC_ERR_BAD_ATTR
 * - #NC_ERR_UNKNOWN_ATTR
 *   - `NC_ERR_TYPE type;` - type (layer) of the error.
 *   - `const char *attr_name;` - error \<bad-attribute\> value.
 *   - `const char *elem_name;` - error \<bad-element\> value.
 * - #NC_ERR_MISSING_ELEM
 * - #NC_ERR_BAD_ELEM
 * - #NC_ERR_UNKNOWN_ELEM
 *   - `NC_ERR_TYPE type;` - type (layer) of the error.
 *   - `const char *elem_name;` - error \<bad-element\> value.
 * - #NC_ERR_UNKNOWN_NS
 *   - `NC_ERR_TYPE type;` - type (layer) of the error.
 *   - `const char *elem_name;` - error \<bad-element\> value.
 *   - `const char *nc_name;` - error \<bad-namespace\> value.
 * - #NC_ERR_LOCK_DENIED
 *   - `uint32_t session_id;` - error \<session-id\> value.
 * - #NC_ERR_DATA_EXISTS
 * - #NC_ERR_DATA_MISSING
 * - #NC_ERR_MALFORMED_MSG
 *   - no additional arguments
 * @param[in] ... Additional arguments depending on the @p tag used.
 * @return Opaque data node tree representing the error.
 */
struct lyd_node *nc_err(const struct ly_ctx *ctx, NC_ERR tag, ...);

/**
 * @brief Get the \<error-type\> of a server error.
 *
 * @param[in] err Error opaque data node tree to read from.
 * @return Server error type, 0 on error.
 */
NC_ERR_TYPE nc_err_get_type(const struct lyd_node *err);

/**
 * @brief Get the \<error-tag\> of a server error.
 *
 * @param[in] err Error opaque data node tree to read from.
 * @return Server error tag, 0 on error.
 */
NC_ERR nc_err_get_tag(const struct lyd_node *err);

/**
 * @brief Set the \<error-app-tag\> element of an error. Any previous value will be overwritten.
 *
 * @param[in] err Error opaque data node tree to modify.
 * @param[in] error_app_tag New value of \<error-app-tag\>.
 * @return 0 on success, -1 on error.
 */
int nc_err_set_app_tag(struct lyd_node *err, const char *error_app_tag);

/**
 * @brief Get the \<error-app-tag\> of a server error.
 *
 * @param[in] err Error opaque data node tree to read from.
 * @return Server error app tag, NULL on error.
 */
const char *nc_err_get_app_tag(const struct lyd_node *err);

/**
 * @brief Set the \<error-path\> element of an error. Any previous value will be overwritten.
 *
 * @param[in] err Error opaque data node tree to modify.
 * @param[in] error_path New value of \<error-path\>.
 * @return 0 on success, -1 on error.
 */
int nc_err_set_path(struct lyd_node *err, const char *error_path);

/**
 * @brief Get the \<error-path\> of a server error.
 *
 * @param[in] err Error opaque data node tree to read from.
 * @return Server error path, NULL on error.
 */
const char *nc_err_get_path(const struct lyd_node *err);

/**
 * @brief Set the \<error-message\> element of an error. Any previous value will be overwritten.
 *
 * @param[in] err Error opaque data node tree to modify.
 * @param[in] error_message New value of \<error-message\>.
 * @param[in] lang Optional language of @p error_message.
 * @return 0 on success, -1 on error.
 */
int nc_err_set_msg(struct lyd_node *err, const char *error_message, const char *lang);

/**
 * @brief Get the \<error-message\> of a server error.
 *
 * @param[in] err Error opaque data node tree to read from.
 * @return Server error message, NULL on error.
 */
const char *nc_err_get_msg(const struct lyd_node *err);

/**
 * @brief Set the \<session-id\> element of an error. Any previous value will be overwritten.
 *
 * @param[in] err Error opaque data node tree to modify.
 * @param[in] session_id New value of \<session-id\>.
 * @return 0 on success, -1 on error.
 */
int nc_err_set_sid(struct lyd_node *err, uint32_t session_id);

/**
 * @brief Add a \<bad-attribute\> element to an error.
 *
 * @param[in] err Error opaque data node tree to modify.
 * @param[in] attr_name Value of the new \<bad-attribute\> element.
 * @return 0 on success, -1 on error.
 */
int nc_err_add_bad_attr(struct lyd_node *err, const char *attr_name);

/**
 * @brief Add a \<bad-element\> element to an error.
 *
 * @param[in] err Error opaque data node tree to modify.
 * @param[in] elem_name Value of the new \<bad-element\> element.
 * @return 0 on success, -1 on error.
 */
int nc_err_add_bad_elem(struct lyd_node *err, const char *elem_name);

/**
 * @brief Add a \<bad-namespace\> element to an error.
 *
 * @param[in] err Error opaque data node tree to modify.
 * @param[in] ns_name Value of the new \<bad-namespace\> element.
 * @return 0 on success, -1 on error.
 */
int nc_err_add_bad_ns(struct lyd_node *err, const char *ns_name);

/**
 * @brief Add an additional custom element to an error.
 *
 * @param[in] err Error opaque data node tree to modify.
 * @param[in] other Other error opaque data node tree.
 * @return 0 on success, -1 on error.
 */
int nc_err_add_info_other(struct lyd_node *err, struct lyd_node *other);

/**
 * @brief Free a server rpc-reply object.
 *
 * @param[in] reply Server rpc-reply object to free.
 */
void nc_server_reply_free(struct nc_server_reply *reply);

/**
 * @brief Create Event Notification object to be sent to the subscribed client(s).
 *
 * @param[in] event Notification data tree (valid as LYD_OPT_NOTIF) from libyang. The tree is directly used in created
 * object, so the caller is supposed to not free the tree on its own, but only via freeng the created object.
 * @param[in] eventtime YANG dateTime format value of the time when the event was generated by the event source.
 * Caller can use nc_timespec2datetime() to create the value from a timespec value.
 * @param[in] paramtype How to further manage data parameters.
 * @return Newly created structure of the Event Notification object to be sent to the clients via nc_server_send_notif()
 * and freed using nc_server_notif_free().
 */
struct nc_server_notif *nc_server_notif_new(struct lyd_node *event, char *eventtime, NC_PARAMTYPE paramtype);

/**
 * @brief Send NETCONF Event Notification via the session.
 *
 * @param[in] session NETCONF session where the Event Notification will be written.
 * @param[in] notif NETCOFN Notification object to send via specified session. Object can be created by
 *            nc_notif_new() function.
 * @param[in] timeout Timeout for writing in milliseconds. Use negative value for infinite
 *            waiting and 0 for return if data cannot be sent immediately.
 * @return #NC_MSG_NOTIF on success,
 *         #NC_MSG_WOULDBLOCK in case of a busy session, and
 *         #NC_MSG_ERROR on error.
 */
NC_MSG_TYPE nc_server_notif_send(struct nc_session *session, struct nc_server_notif *notif, int timeout);

/**
 * @brief Free a server Event Notification object.
 *
 * @param[in] notif Server Event Notification object to free.
 */
void nc_server_notif_free(struct nc_server_notif *notif);

/**
 * @brief Get the notification timestamp.
 *
 * @param[in] notif Server notification to read from.
 * @return Datetime timestamp of the notification, NULL on error.
 */
const char *nc_server_notif_get_time(const struct nc_server_notif *notif);

/** @} Client Messages */

#ifdef __cplusplus
}
#endif

#endif /* NC_MESSAGES_SERVER_H_ */