/*
 * Copyright © Stéphane Raimbault <stephane.raimbault@gmail.com>
 *
 * SPDX-License-Identifier: LGPL-2.1-or-later
 */

#ifndef MODBUS_PRIVATE_H
#define MODBUS_PRIVATE_H

// clang-format off
#ifndef _MSC_VER
# include <stdint.h>
# include <sys/time.h>
#else
# include "stdint.h"
# include <time.h>
typedef int ssize_t;
#endif
// clang-format on
#include <config.h>
#include <sys/types.h>

#include "modbus.h"

MODBUS_BEGIN_DECLS

/* It's not really the minimal length (the real one is report slave ID
 * in RTU (4 bytes)) but it's a convenient size to use in RTU or TCP
 * communications to read many values or write a single one.
 * Maximum between :
 * - HEADER_LENGTH_TCP (7) + function (1) + address (2) + number (2)
 * - HEADER_LENGTH_RTU (1) + function (1) + address (2) + number (2) + CRC (2)
 */
#define _MIN_REQ_LENGTH 12

#define _REPORT_SLAVE_ID 180

#define _MODBUS_EXCEPTION_RSP_LENGTH 5

/* Timeouts in microsecond (0.5 s) */
#define _RESPONSE_TIMEOUT 500000
#define _BYTE_TIMEOUT     500000

typedef enum {
    _MODBUS_BACKEND_TYPE_RTU = 0,
    _MODBUS_BACKEND_TYPE_TCP
} modbus_backend_type_t;

/*
 *  ---------- Request     Indication ----------
 *  | Client | ---------------------->| Server |
 *  ---------- Confirmation  Response ----------
 */
typedef enum {
    /* Request message on the server side */
    MSG_INDICATION,
    /* Request message on the client side */
    MSG_CONFIRMATION
} msg_type_t;

/* This structure reduces the number of params in functions and so
 * optimizes the speed of execution (~ 37%). */
typedef struct _sft {
    int slave;
    int function;
    int t_id;
} sft_t;

typedef struct _modbus_backend {
    unsigned int backend_type;
    unsigned int header_length;
    unsigned int checksum_length;
    unsigned int max_adu_length;
    int (*set_slave)(modbus_t *ctx, int slave);
    int (*build_request_basis)(
        modbus_t *ctx, int function, int addr, int nb, uint8_t *req);
    int (*build_response_basis)(sft_t *sft, uint8_t *rsp);
    int (*prepare_response_tid)(const uint8_t *req, int *req_length);
    int (*send_msg_pre)(uint8_t *req, int req_length);
    ssize_t (*send)(modbus_t *ctx, const uint8_t *req, int req_length);
    int (*receive)(modbus_t *ctx, uint8_t *req);
    ssize_t (*recv)(modbus_t *ctx, uint8_t *rsp, int rsp_length);
    int (*check_integrity)(modbus_t *ctx, uint8_t *msg, const int msg_length);
    int (*pre_check_confirmation)(modbus_t *ctx,
                                  const uint8_t *req,
                                  const uint8_t *rsp,
                                  int rsp_length);
    int (*connect)(modbus_t *ctx);
    unsigned int (*is_connected)(modbus_t *ctx);
    void (*close)(modbus_t *ctx);
    int (*flush)(modbus_t *ctx);
    int (*select)(modbus_t *ctx, fd_set *rset, struct timeval *tv, int msg_length);
    void (*free)(modbus_t *ctx);
} modbus_backend_t;

struct _modbus {
    /* Slave address */
    int slave;
    /* Socket or file descriptor */
    int s;
    int debug;
    int error_recovery;
    int quirks;
    struct timeval response_timeout;
    struct timeval byte_timeout;
    struct timeval indication_timeout;
    const modbus_backend_t *backend;
    void *backend_data;
};

void _modbus_init_common(modbus_t *ctx);
void _error_print(modbus_t *ctx, const char *context);
int _modbus_receive_msg(modbus_t *ctx, uint8_t *msg, msg_type_t msg_type);

#ifndef HAVE_STRLCPY
size_t strlcpy(char *dest, const char *src, size_t dest_size);
#endif

MODBUS_END_DECLS

#endif /* MODBUS_PRIVATE_H */