/**
 * \file netconf.h
 * \author Radek Krejci <rkrejci@cesnet.cz>
 * \brief libnetconf2's general public functions and structures definitions.
 *
 * Copyright (c) 2015 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_NETCONF_H_
#define NC_NETCONF_H_

#include <time.h>

#ifdef __cplusplus
extern "C" {
#endif

#define NC_NS_BASE  "urn:ietf:params:xml:ns:netconf:base:1.0"
#define NC_NS_NOTIF "urn:ietf:params:xml:ns:netconf:notification:1.0"

/** @brief Default NETCONF over SSH port */
#define NC_PORT_SSH 830
/** @brief Default NETCONF over SSH Call Home port */
#define NC_PORT_CH_SSH 6666

/** @brief Default NETCONF over TLS port */
#define NC_PORT_TLS 6513
/** @brief Default NETCONF over TLS Call Home port */
#define NC_PORT_CH_TLS 6667

/** @brief Microseconds after which tasks are repeated until the full timeout elapses */
#define NC_TIMEOUT_STEP 100

/**
 * @brief Enumeration of reasons of the NETCONF session termination as defined in RFC 6470.
 */
typedef enum NC_SESSION_TERM_REASON {
    NC_SESSION_TERM_NONE = 0,     /**< session still running */
    NC_SESSION_TERM_CLOSED,       /**< closed by client in a normal fashion */
    NC_SESSION_TERM_KILLED,       /**< session was terminated by \<kill-session\> operation */
    NC_SESSION_TERM_DROPPED,      /**< transport layer connection was unexpectedly closed */
    NC_SESSION_TERM_TIMEOUT,      /**< terminated because of inactivity */
    NC_SESSION_TERM_BADHELLO,     /**< \<hello\> message was invalid */
    NC_SESSION_TERM_OTHER         /**< terminated for some other reason */
} NC_SESSION_TERM_REASON;

/**
 * @brief Enumeration of NETCONF message types.
 */
typedef enum NC_MSG_TYPE {
    NC_MSG_ERROR,       /**< error return value */
    NC_MSG_WOULDBLOCK,  /**< timeout return value */
    NC_MSG_NONE,        /**< no message at input or message was processed internally */
    NC_MSG_HELLO,       /**< \<hello\> message */
    NC_MSG_RPC,         /**< \<rpc\> message */
    NC_MSG_REPLY,       /**< \<rpc-reply\> message */
    NC_MSG_NOTIF        /**< \<notification\> message */
} NC_MSG_TYPE;

/**
 * @brief Enumeration of the supported types of datastores defined by NETCONF
 */
typedef enum NC_DATASTORE_TYPE {
    NC_DATASTORE_ERROR = 0, /**< error state of functions returning the datastore type */
    NC_DATASTORE_CONFIG,    /**< value describing that the datastore is set as config */
    NC_DATASTORE_URL,       /**< value describing that the datastore data should be given from the URL */
    NC_DATASTORE_RUNNING,   /**< base NETCONF's datastore containing the current device configuration */
    NC_DATASTORE_STARTUP,   /**< separated startup datastore as defined in Distinct Startup Capability */
    NC_DATASTORE_CANDIDATE  /**< separated working datastore as defined in Candidate Configuration Capability */
} NC_DATASTORE;

/**
 * @brief Enumeration of NETCONF with-defaults capability modes.
 */
typedef enum NC_WITHDEFAULTS_MODE {
    NC_WD_UNKNOWN = 0,    /**< invalid mode */
    NC_WD_ALL = 0x01,     /**< report-all mode */
    NC_WD_ALL_TAG = 0x02, /**< report-all-tagged mode */
    NC_WD_TRIM = 0x04,    /**< trim mode */
    NC_WD_EXPLICIT = 0x08 /**< explicit mode */
} NC_WD_MODE;

/**
 * @brief Enumeration of NETCONF (both server and client) rpc-reply types.
 */
typedef enum NC_REPLY {
    NC_RPL_OK,    /**< OK rpc-reply */
    NC_RPL_DATA,  /**< DATA rpc-reply */
    NC_RPL_ERROR, /**< ERROR rpc-reply */
    NC_RPL_NOTIF  /**< notification (client-only) */
} NC_RPL;

/**
 * @brief Enumeration of function parameter treatments.
 */
typedef enum NC_PARAMTYPE {
    NC_PARAMTYPE_CONST,       /**< use the parameter directly, do not free */
    NC_PARAMTYPE_FREE,        /**< use the parameter directly, free afterwards */
    NC_PARAMTYPE_DUP_AND_FREE /**< make a copy of the argument, free afterwards */
} NC_PARAMTYPE;

#if defined(NC_ENABLED_SSH) || defined(NC_ENABLED_TLS)

/**
 * @brief Free all the dynamically allocated thread-specific libssl/libcrypto
 *        resources.
 *
 *        This function should be called only if any of #nc_ssh_init(), #nc_tls_init(),
 *        or #nc_ssh_tls_init() was called. Call it in every thread your application
 *        creates just before the thread exits. In the last thread (usually the main one)
 *        call only #nc_ssh_destroy(), #nc_ssh_tls_destroy(), or #nc_tls_destroy,
 *        depending on what you used for initialization.
 */
void nc_thread_destroy(void);

#endif /* NC_ENABLED_SSH || NC_ENABLED_TLS */

#if defined(NC_ENABLED_SSH) && defined(NC_ENABLED_TLS)

/**
 * @brief Initialize both libssh and libssl/libcrypto libraries for thread-safe usage.
 *        Call this function even if you, for instance, will use only SSH transport,
 *        but want to use some libssl/libcrypto functions in your application.
 *
 *        Must be called before calling any libnetconf2 SSH and/or TLS function.
 */
void nc_ssh_tls_init(void);

/**
 * @brief Free all the dynamically allocated libssh and libssl/libcrypto resources.
 *
 *        No libnetconf2 SSH/TLS, libssh, and libcrypto/libssl function should be
 *        called afterwards.
 */
void nc_ssh_tls_destroy(void);

#endif /* NC_ENABLED_SSH && NC_ENABLED_TLS */

#ifdef NC_ENABLED_SSH

/**
 * @brief Initialize libssh for thread-safe usage. If you plan to use libcrypto/
 *        /libssl in your application as well, please call #nc_ssh_tls_init()
 *        instead.
 *
 *        Must be called before calling any libnetconf2 SSH function.
 */
void nc_ssh_init(void);

/**
 * @brief Free all the dynamically allocated libssh resources.
 *
 *        No libnetconf2 SSH and libssh function should be called afterwards.
 */
void nc_ssh_destroy(void);

#endif /* NC_ENABLED_SSH */

#ifdef NC_ENABLED_TLS

/**
 * @brief Initialize libssl/libcrypto for thread-safe usage. If you plan to use libssh
 *        in your application as well, please call #nc_ssh_tls_init() instead.
 *
 *        Must be called before calling any libnetconf2 TLS function.
 */
void nc_tls_init(void);

/**
 * @brief Free all the dynamically allocated libssl/libcrypto resources.
 *
 *        No libnetconf2 TLS and libssl/libcrypto function should be called afterwards.
 */
void nc_tls_destroy(void);

#endif /* NC_ENABLED_TLS */

/**
 * @brief Transform given time_t (seconds since the epoch) into the RFC 3339 format
 * accepted by NETCONF functions.
 *
 * This is a reverse function to nc_datetime2time().
 *
 * @param[in] time time_t type value returned e.g. by time().
 * @param[in] tz timezone name for the result. See tzselect(1) for list of
 * correct values. If not specified (NULL), the result is provided in UTC (Zulu).
 * @return Printed string in a format compliant to RFC 3339. It is up to the
 * caller to free the returned string.
 */
char* nc_time2datetime(time_t time, const char* tz);

/**
 * @brief Transform given string in RFC 3339 compliant format to the time_t
 * (seconds since the epoch) accepted by most Linux functions.
 *
 * This is a reverse function to nc_time2datetime().
 *
 * @param[in] datetime Time structure returned e.g. by localtime().
 * @return time_t value of the given string.
 */
time_t nc_datetime2time(const char* datetime);

#ifdef __cplusplus
}
#endif

#endif /* NC_NETCONF_H_ */