#include <stdio.h>
#include <stdint.h>

// Function Pointer Jump Table Architecture
typedef void (*CommandHandler)(const char* arg);

void handle_start(const char* arg) { printf("System starting: %s
", arg); }
void handle_stop(const char* arg)  { printf("System stopping: %s
", arg); }

typedef struct {
    const char* command_name;
    CommandHandler handler;
} CommandEntry;

const CommandEntry command_table[] = {
    {"START", handle_start},
    {"STOP",  handle_stop},
    {NULL,    NULL}
};

// Hardware Network Protocol Header with Bitfields and Explicit Packing
#pragma pack(push, 1) // Enforces 1-byte strict alignment with 0 padding bytes
typedef struct {
    uint8_t  version : 4;      // 4 bits: IP Version (e.g. 4 or 6)
    uint8_t  ihl : 4;          // 4 bits: Internet Header Length
    uint8_t  type_of_service;  // 8 bits
    uint16_t total_length;     // 16 bits (Stored in Big-Endian network byte order)
    uint16_t identification;   // 16 bits
    uint16_t flags_fragment;   // 16 bits
    uint8_t  time_to_live;     // 8 bits (TTL)
    uint8_t  protocol;         // 8 bits (e.g. 6 for TCP, 17 for UDP)
    uint16_t header_checksum;  // 16 bits
    uint32_t src_ip;           // 32 bits
    uint32_t dst_ip;           // 32 bits
} IPv4Header;
#pragma pack(pop)

// X-Macro Pattern: Generate synchronized enums and string mapping tables
#define ERROR_CODES_LIST(X)     X(ERR_SUCCESS,        0, "Operation completed successfully")     X(ERR_NOT_FOUND,      404, "Requested resource not found")     X(ERR_ACCESS_DENIED,  403, "Permission denied")     X(ERR_SERVER_PANIC,   500, "Internal hardware fault")

// 1. Generate Enum Identifiers
typedef enum {
    #define AS_ENUM(name, code, desc) name = code,
    ERROR_CODES_LIST(AS_ENUM)
    #undef AS_ENUM
} StatusCode;

// 2. Generate Description Lookup Function
const char* get_error_description(StatusCode code) {
    switch (code) {
        #define AS_CASE(name, code, desc) case name: return desc;
        ERROR_CODES_LIST(AS_CASE)
        #undef AS_CASE
        default: return "Unknown status code";
    }
}