XPlor/libs/dsl/recompiler.h

#ifndef RECOMPILER_H
#define RECOMPILER_H

#include "operationjournal.h"
#include "../compression/compression.h"
#include <QObject>
#include <QByteArray>
#include <QVariantMap>
#include <QDataStream>
#include <QSet>

/**
 * @brief The Recompiler class walks an operation journal and produces binary output.
 *
 * Given a journal (recorded during parsing) and a set of modified values,
 * the Recompiler produces a QByteArray representing the recompiled binary.
 *
 * For write-back to work, the journal must be "exportable" (no random access,
 * no unsupported compression, etc.).
 */
class Recompiler : public QObject {
    Q_OBJECT

public:
    explicit Recompiler(QObject* parent = nullptr);

    /**
     * @brief Recompile a structure to bytes using journal and values.
     * @param journalId The journal ID from parsing
     * @param values The current values (may be modified from original)
     * @return The recompiled binary data
     * @throws std::runtime_error if recompilation fails or journal not exportable
     */
    QByteArray recompile(int journalId, const QVariantMap& values);

    /**
     * @brief Check if a journal can be recompiled.
     * @param journalId The journal ID to check
     * @return true if recompilation is possible
     */
    bool canRecompile(int journalId) const;

    /**
     * @brief Get human-readable reason why recompilation is not possible.
     * @param journalId The journal ID to check
     * @return Empty string if exportable, otherwise the reason
     */
    QString whyNotRecompilable(int journalId) const;

    /**
     * @brief Recompile and return both the bytes and any errors/warnings.
     * @param journalId The journal ID
     * @param values The values to use
     * @param outErrors Output parameter for error messages
     * @return The recompiled bytes (empty if failed)
     */
    QByteArray recompileWithErrors(int journalId, const QVariantMap& values, QStringList& outErrors);

signals:
    /**
     * @brief Emitted during recompilation to report progress.
     * @param percent Progress percentage (0-100)
     * @param stage Description of current stage
     */
    void progressChanged(int percent, const QString& stage);

private:
    /**
     * @brief Write a scalar value to the output stream.
     * @param out Output stream
     * @param type Scalar type
     * @param order Byte order
     * @param value Value to write
     */
    void writeScalar(QDataStream& out, ScalarType type, ByteOrder order, const QVariant& value);

    /**
     * @brief Write raw bytes to the output stream.
     * @param out Output stream
     * @param data Bytes to write
     */
    void writeBytes(QDataStream& out, const QByteArray& data);

    /**
     * @brief Write a null-terminated C string.
     * @param out Output stream
     * @param str String to write
     */
    void writeCString(QDataStream& out, const QString& str);

    /**
     * @brief Write a null-terminated wide string (UTF-16).
     * @param out Output stream
     * @param str String to write
     * @param order Byte order (LE or BE)
     */
    void writeWString(QDataStream& out, const QString& str, ByteOrder order);

    /**
     * @brief Write padding/skip bytes.
     * @param out Output stream
     * @param count Number of bytes to skip (writes zeros)
     * @param originalBytes Original bytes to use (if available)
     */
    void writeSkip(QDataStream& out, qint64 count, const QByteArray& originalBytes = QByteArray());

    /**
     * @brief Get the value for a field, using modified value if present, otherwise original.
     * @param values Modified values map
     * @param entry Journal entry with original value
     * @return The value to use for recompilation
     */
    QVariant getValueForField(const QVariantMap& values, const JournalEntry& entry) const;

    /**
     * @brief Recursively recompile a nested structure.
     * @param nestedJournalId The nested journal ID
     * @param parentValues Values from parent (may contain nested values)
     * @param fieldName The field name for the nested structure
     * @param outErrors Output for error messages
     * @return The recompiled bytes for the nested structure
     */
    QByteArray recompileNested(int nestedJournalId, const QVariantMap& parentValues,
                               const QString& fieldName, QStringList& outErrors);

    /**
     * @brief Extract nested values from parent values map.
     * @param parentValues The parent values map
     * @param fieldName The field name for the nested structure
     * @param nestedJournal The nested journal (to get original values)
     * @return Values map for the nested structure
     */
    QVariantMap extractNestedValues(const QVariantMap& parentValues, const QString& fieldName,
                                    const OperationJournal* nestedJournal) const;

    /**
     * @brief Compress data using the specified compression type.
     * @param data The uncompressed data
     * @param compressionType The compression algorithm ("zlib", "deflate", "xmem", "oodle")
     * @param params Algorithm-specific parameters (e.g., compression level, window size)
     * @return The compressed data
     */
    QByteArray compress(const QByteArray& data, const QString& compressionType,
                        const QByteArray& params = QByteArray()) const;

    /**
     * @brief Check if a compression type is supported for write-back.
     * @param compressionType The compression type name
     * @return true if compression is supported
     */
    bool isCompressionSupported(const QString& compressionType) const;

    // Track visited journals to prevent infinite recursion
    QSet<int> m_visitedJournals;
};

#endif // RECOMPILER_H