// AuditWriter: durable per-event security log interface.

#pragma once

#include <string>

struct AuditEvent {

  std::string userId;      // acting user identifier

  std::string action;      // name of the audited action

  std::string resourceId;  // target resource identifier

  long long   timestampMs; // event time in milliseconds since epoch

};

// Writes security audit events to a local log file.

// Each event is serialised as a newline-delimited JSON object.

// Thread-safe: concurrent callers must hold an external lock.

class AuditWriter {

public:

  // Parameters:

  //   path - filesystem path to the audit log file (opened in append mode)

  // Returns: new AuditWriter; check isOpen() before first use

  explicit AuditWriter(const std::string& path);

  ~AuditWriter();

  // Parameters:

  //   event - fully populated audit event to append to the log

  // Returns: true if the event was fully written successfully, false on any I/O error

  bool logEvent(const AuditEvent& event);

  // Parameters: none

  // Returns: true if the underlying file descriptor is open and ready

  bool isOpen() const { return fd_ >= 0; }

private:

  int fd_ = -1; // underlying file descriptor; -1 means closed

  // Parameters:

  //   event - audit event to format

  // Returns: newline-terminated JSON representation of the event

  std::string formatEvent(const AuditEvent& event) const;

};