/*
 * logger.c
 *
 *  Created on: Jul 4, 2021
 *      Author: Andreas Berthoud
 */

#include <stdarg.h>
#include <string.h>

#include "usbd_cdc_if.h"
#include "logger.h"

#define BUFFER_MAX                      512
#define COMMAND_HEADER_SIZE             4
#define LOG_COMMAND_HEADER_SIZE         1
#define HEADER_SIZE                     (COMMAND_HEADER_SIZE + LOG_COMMAND_HEADER_SIZE)
#define MESSAGE_BUFFER_START            (COMMAND_HEADER_SIZE + LOG_COMMAND_HEADER_SIZE)
#define MAX_LOG_MESSAGE_SIZE            (BUFFER_MAX - COMMAND_HEADER_SIZE - LOG_COMMAND_HEADER_SIZE - 1)

#define min(a,b) \
   ({ __typeof__ (a) _a = (a); \
       __typeof__ (b) _b = (b); \
     _a < _b ? _a : _b; })


typedef struct
{
    uint8_t LOG_LEVEL_DEBUG;
    uint8_t LOG_LEVEL_INFO;
    uint8_t LOG_LEVEL_WARNING;
    uint8_t LOG_LEVEL_ERROR;
} LOGGER_SEVERTITY_T;

LOGGER_SEVERTITY_T LOGGER_SEVERTITY = {
        .LOG_LEVEL_DEBUG = 10,
        .LOG_LEVEL_INFO = 20,
        .LOG_LEVEL_WARNING = 30,
        .LOG_LEVEL_ERROR = 40,
};

/*
 * A command is 4 bytes long
 *
 * | 1 byte     | 2 bytes   | 1 byte    | N bytes | 1 byte    |
 * | command ID | length N  | reserved  | data    | stop byte |
 * */

/*
 * command length = N
 * | 1 byte    | N-1 bytes |
 * | severtity | message   |
 * */
char buffer[BUFFER_MAX];

void log_message(uint8_t severtiy) {
    int message_length = min(strlen(buffer + MESSAGE_BUFFER_START), MAX_LOG_MESSAGE_SIZE);
    int command_length = message_length + 1;
    buffer[0] = 0xFF;  // log command
    buffer[1] = (command_length & 0x0000FF00) >> 8;
    buffer[2] = command_length & 0x000000FF;
    buffer[3] = 0x00;  // reserved
    buffer[4] = severtiy;
    buffer[5 + message_length] = 0xFF;  // stop byte
    CDC_Transmit_FS((uint8_t*)buffer, (uint16_t)(HEADER_SIZE + message_length + 1));
}

void log_debug(const char * format, int nargs, ...) {
    va_list args;
    va_start(args, nargs);
    vsnprintf(
            buffer + MESSAGE_BUFFER_START,
            MAX_LOG_MESSAGE_SIZE,
            format,
            args
            );
    va_end(args);
    log_message(LOGGER_SEVERTITY.LOG_LEVEL_DEBUG);
}

void log_info(const char * format, int nargs, ...) {
    va_list args;
    va_start(args, nargs);
    vsnprintf(
            buffer + MESSAGE_BUFFER_START,
            MAX_LOG_MESSAGE_SIZE,
            format,
            args
            );
    va_end(args);
    log_message(LOGGER_SEVERTITY.LOG_LEVEL_INFO);
}

void log_warning(const char * format, int nargs, ...) {
    va_list args;
    va_start(args, nargs);
    vsnprintf(
            buffer + MESSAGE_BUFFER_START,
            MAX_LOG_MESSAGE_SIZE,
            format,
            args
            );
    va_end(args);
    log_message(LOGGER_SEVERTITY.LOG_LEVEL_WARNING);
}

void log_error(const char * format, int nargs, ...) {
    va_list args;
    va_start(args, nargs);
    vsnprintf(
            buffer + MESSAGE_BUFFER_START,
            MAX_LOG_MESSAGE_SIZE,
            format,
            args
            );
    va_end(args);
    log_message(LOGGER_SEVERTITY.LOG_LEVEL_ERROR);
}