// SPDX-License-Identifier: MIT
#ifndef DBC_TREE_MODEL_H
#define DBC_TREE_MODEL_H

#include "tree_node.h"
#include <QAbstractItemModel>

/** Read-only model. Owns an immutable tree; all indexes expire on SetTree().
 * Use QPersistentModelIndex to observe reset invalidation. Call on the model thread.
 */
class DbcTreeModel : public QAbstractItemModel {
public:
    /** @brief Display columns for frame and signal metadata. */
    enum Column { Name,
                  CanId,
                  PayloadLength,
                  StartBit,
                  BitLength,
                  ByteOrder,
                  Signed,
                  Unit,
                  Comment,
                  ColumnCount };
    // Metadata roles apply on every column; inapplicable roles return invalid QVariant.
    /** @brief Typed metadata roles in addition to Qt display roles. */
    enum Role { NodeTypeRole = Qt::UserRole + 1,
                CanIdRole,
                PayloadLengthRole,
                StartBitRole,
                BitLengthRole,
                LittleEndianRole,
                SignedRole,
                UnitRole,
                CommentRole,
                ValueDescriptionsRole,
                ExtendedRole };

    /** @brief Create an empty read-only model. */
    explicit DbcTreeModel(QObject *parent = nullptr);
    /** @brief Replace the tree and invalidate indexes; reject roots with a parent or non-root type. */
    void SetTree(std::unique_ptr<TreeNode> root);
    /** @brief Return a child index; only column zero can have children. */
    QModelIndex index(int row, int column, const QModelIndex &parent = QModelIndex()) const override;
    /** @brief Return the parent in column zero, or an invalid index for frames. */
    QModelIndex parent(const QModelIndex &child) const override;
    /** @brief Return the child count, capped at the Qt integer limit. */
    int rowCount(const QModelIndex &parent = QModelIndex()) const override;
    /** @brief Return the fixed metadata column count for this model. */
    int columnCount(const QModelIndex &parent = QModelIndex()) const override;
    /** @brief Return display text or typed metadata for an index. */
    QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override;
    /** @brief Return horizontal display column titles. */
    QVariant headerData(int section, Qt::Orientation orientation, int role = Qt::DisplayRole) const override;
    /** @brief Allow selecting and enabling valid indexes without editing. */
    Qt::ItemFlags flags(const QModelIndex &index) const override;

private:
    const TreeNode *Node(const QModelIndex &index) const;
    std::unique_ptr<TreeNode> m_root;
};
#endif