#pragma once
#include "model/FileRecord.h"
#include <QThread>
#include <QString>
#include <QList>
#include <QSet>
#include <atomic>

namespace whittle {

// Direct-write, one-way copier run on its own thread. Copies each record to
// <usbMount>/<relPath>, creating the full path (mkdir -p) so /a/photos is
// reproduced. Preserves mode/owner/mtime/xattrs where the target FS allows.
// Skips (and reports) files with FAT-illegal names or case-collisions and
// individual IO/permission errors. If the USB disappears mid-run it STOPS
// and waits, rather than skipping -- that is a device event, not a file error.
class MergeController : public QThread {
    Q_OBJECT
public:
    enum class Skip { IllegalName, CaseCollision, IoError };

    MergeController(QList<FileRecord> items, QString usbMount,
                    QObject* parent = nullptr);
    void cancel() { m_cancel.store(true, std::memory_order_relaxed); }

    qint64 totalBytes() const { return m_totalBytes; }
    int    fileCount()  const { return m_fileCount;  }

signals:
    void progress(QString currentRel, qint64 bytesDone, int filesDone);
    void skipped(QString relPath, int reason);   // reason = Skip
    void deviceLost();
    void done(bool canceled);

protected:
    void run() override;

private:
    enum class Result { Ok, IllegalName, CaseCollision, IoError, DeviceLost };
    Result copyFile(const FileRecord& rec, const QString& dest,
                    qint64& bytesDone, int filesDone, bool caseInsensitive);
    Result makeDir (const FileRecord& rec, const QString& dest);
    bool deviceGone() const;

    QList<FileRecord> m_items;
    QString m_usbMount;
    qint64  m_totalBytes = 0;
    int     m_fileCount  = 0;
    bool    m_fatNames = false;
    QSet<QString> m_writtenLower;   // in-run case-collision tracking
    std::atomic<bool> m_cancel{false};
};

} // namespace whittle