TFileLog.h

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//------------------------------------------------------------------------------
// Module:        CTFileLog
// Description:   Mirrors Circle log output into an SD-card backed log file.
// Author:        R. Zuehlsdorff, ralf.zuehlsdorff@t-online.de
// Created:       2026-01-24
// License:       MIT License (https://opensource.org/license/mit/)
//------------------------------------------------------------------------------
// Change Log:
// 2026-01-24     R. Zuehlsdorff        Initial creation
//------------------------------------------------------------------------------
 
#pragma once
 
#include <circle/device.h>
#include <circle/string.h>
#include <circle/types.h>
#include <fatfs/ff.h>
 
class CLogger;
 
class CTFileLog : public CDevice
{
public:
    static CTFileLog *Get();
 
    bool Initialize(CLogger &logger, const char *fileName, CDevice *fallbackTarget);
    void SetFallback(CDevice *fallbackTarget);
    bool Start();
    void Stop();
 
    int Write(const void *buffer, size_t count) override;
 
private:
    CTFileLog();
    ~CTFileLog();
 
    bool OpenFile(const char *fileName);
    void CloseFile();
    void WriteHeader();
    void Flush();
 
private:
    static CTFileLog *s_pInstance;
 
    CLogger *m_pLogger;
    CDevice *m_pFallback;
    FIL m_File;
    bool m_FileOpen;
    bool m_Initialized;
    bool m_Active;
    CString m_FilePath;
    unsigned m_PendingFlushBytes;
    unsigned m_PendingFlushLines;
 
    static constexpr unsigned FlushByteThreshold = 1024;
    static constexpr unsigned FlushLineThreshold = 8;
};