/**
 * @file pcan_modbus_server.h
 * @brief Modbus register windows transported in one classic ProtoCAN frame.
 */
#ifndef PCAN_MODBUS_SERVER_H
#define PCAN_MODBUS_SERVER_H

#include <stdbool.h>
#include <stdint.h>

#include "pcan_frame.h"

#ifdef __cplusplus
extern "C" {
#endif

typedef enum {
    PCAN_MODBUS_COIL = 0x4U,
    PCAN_MODBUS_DISCRETE = 0x5U,
    PCAN_MODBUS_HOLDING = 0x6U,
    PCAN_MODBUS_INPUT = 0x7U
} pcan_modbus_bank_t;

typedef bool (*pcan_modbus_read_fn)(void *user, pcan_modbus_bank_t bank,
                                    uint16_t address, uint16_t *value);
typedef bool (*pcan_modbus_write_fn)(void *user, pcan_modbus_bank_t bank,
                                     uint16_t address, uint16_t value);

typedef struct {
    uint8_t device_type;
    uint8_t device_id;
    pcan_modbus_read_fn read;
    pcan_modbus_write_fn write;
    void *user;
    uint32_t requests;
    uint32_t responses;
    uint32_t rejected;
} pcan_modbus_server_t;

typedef enum {
    PCAN_MODBUS_NOT_FOR_US = 0,
    PCAN_MODBUS_HANDLED_NO_RESPONSE,
    PCAN_MODBUS_RESPONSE
} pcan_modbus_result_t;

bool pcan_modbus_server_init(pcan_modbus_server_t *server,
                             uint8_t device_type, uint8_t device_id,
                             pcan_modbus_read_fn read,
                             pcan_modbus_write_fn write, void *user);

/** Zero DLC reads; data writes COIL/HOLDING. Register words are little-endian. */
pcan_modbus_result_t pcan_modbus_server_handle(pcan_modbus_server_t *server,
                                                const pcan_frame_t *request,
                                                pcan_frame_t *response);

#ifdef __cplusplus
}
#endif

#endif /* PCAN_MODBUS_SERVER_H */