// SPDX-License-Identifier: MIT
#include "dbc_tree_model.h"
#include <QVariantList>
#include <QVariantMap>
#include <limits>
#include <stdexcept>

namespace {
    QVariantList ToVariantList(const ValueDescriptions &values) {
        QVariantList descriptions;
        for (const ValueDescriptions::value_type &entry : values) {
            QVariantMap pair;
            if (const std::int64_t *number = std::get_if<std::int64_t>(&entry.first))
                pair.insert("value", QVariant::fromValue(static_cast<qlonglong>(*number)));
            else
                pair.insert("value", QVariant::fromValue(
                                         static_cast<qulonglong>(std::get<std::uint64_t>(entry.first))));
            pair.insert("description", QString::fromStdString(entry.second));
            descriptions.append(pair);
        }
        return descriptions;
    }
} // namespace

DbcTreeModel::DbcTreeModel(QObject *parent) : QAbstractItemModel(parent) {}

void DbcTreeModel::SetTree(std::unique_ptr<TreeNode> root) {
    if (root && (root->GetType() != NodeType::Root || root->GetParent()))
        throw std::invalid_argument("Model requires a detached root node");
    beginResetModel();
    m_root = std::move(root);
    endResetModel();
}

const TreeNode *DbcTreeModel::Node(const QModelIndex &index) const {
    if (!index.isValid() || index.model() != this || index.column() < 0 ||
        index.column() >= ColumnCount || index.row() < 0)
        return nullptr;
    return static_cast<const TreeNode *>(index.internalPointer());
}

QModelIndex DbcTreeModel::index(int row, int column, const QModelIndex &parentIndex) const {
    if (row < 0 || column < 0 || column >= ColumnCount ||
        (parentIndex.isValid() && parentIndex.column() != 0))
        return {};
    const TreeNode *owner = parentIndex.isValid() ? Node(parentIndex) : m_root.get();
    if (!owner)
        return {};
    const TreeNode *child = owner->GetChild(static_cast<std::size_t>(row));
    return child ? createIndex(row, column, const_cast<TreeNode *>(child)) : QModelIndex();
}

QModelIndex DbcTreeModel::parent(const QModelIndex &childIndex) const {
    const TreeNode *child = Node(childIndex);
    const TreeNode *owner = child ? child->GetParent() : nullptr;
    if (!owner || owner == m_root.get())
        return {};
    return createIndex(static_cast<int>(owner->GetRow()), 0, const_cast<TreeNode *>(owner));
}

int DbcTreeModel::rowCount(const QModelIndex &parentIndex) const {
    if (parentIndex.isValid() && parentIndex.column() != 0)
        return 0;
    const TreeNode *owner = parentIndex.isValid() ? Node(parentIndex) : m_root.get();
    if (!owner)
        return 0;
    return static_cast<int>(qMin(owner->GetChildCount(), static_cast<std::size_t>(std::numeric_limits<int>::max())));
}

int DbcTreeModel::columnCount(const QModelIndex &parentIndex) const {
    return parentIndex.isValid() && !Node(parentIndex) ? 0 : ColumnCount;
}

QVariant DbcTreeModel::data(const QModelIndex &item, int role) const {
    const TreeNode *node = Node(item);
    if (!node)
        return {};
    const FrameInfo *frame = node->GetFrame();
    const SignalInfo *signal = node->GetSignal();
    QString comment;
    if (frame != nullptr)
        comment = QString::fromStdString(frame->comment);
    else if (signal != nullptr)
        comment = QString::fromStdString(signal->comment);
    if (role == Qt::ToolTipRole || role == CommentRole)
        return comment;
    if (role == NodeTypeRole)
        return static_cast<int>(node->GetType());
    if (role == ValueDescriptionsRole && signal) {
        return ToVariantList(signal->valueDescriptions);
    }
    if (frame) {
        if (role == CanIdRole)
            return frame->canId;
        if (role == PayloadLengthRole)
            return static_cast<int>(frame->dlc);
        if (role == ExtendedRole)
            return frame->isExtended;
    }
    if (signal) {
        if (role == StartBitRole)
            return signal->startBit;
        if (role == BitLengthRole)
            return signal->length;
        if (role == LittleEndianRole)
            return signal->isLittleEndian;
        if (role == SignedRole)
            return signal->isSigned;
        if (role == UnitRole)
            return QString::fromStdString(signal->unit);
    }
    if (role != Qt::DisplayRole)
        return {};
    switch (item.column()) {
        case Name:
            return QString::fromStdString(node->GetName());
        case CanId:
            return frame ? QVariant(QString("0x%1").arg(frame->canId, 0, 16).toUpper()) : QVariant();
        case PayloadLength:
            return frame ? QVariant(static_cast<int>(frame->dlc)) : QVariant();
        case StartBit:
            return signal ? QVariant(signal->startBit) : QVariant();
        case BitLength:
            return signal ? QVariant(signal->length) : QVariant();
        case ByteOrder:
            return signal ? QVariant(signal->isLittleEndian ? "Intel" : "Motorola") : QVariant();
        case Signed:
            return signal ? QVariant(signal->isSigned ? "Signed" : "Unsigned") : QVariant();
        case Unit:
            return signal ? QVariant(QString::fromStdString(signal->unit)) : QVariant();
        case Comment:
            return comment;
        default:
            return {};
    }
}

QVariant DbcTreeModel::headerData(int section, Qt::Orientation orientation, int role) const {
    static const char *const headers[] = {"Name", "CAN ID", "Payload (bytes)", "Start bit", "Length (bits)", "Byte order", "Signedness", "Unit", "Comment"};
    if (orientation != Qt::Horizontal || role != Qt::DisplayRole || section < 0 || section >= ColumnCount)
        return {};
    return QString::fromLatin1(headers[section]);
}

Qt::ItemFlags DbcTreeModel::flags(const QModelIndex &item) const {
    return Node(item) ? Qt::ItemIsEnabled | Qt::ItemIsSelectable : Qt::NoItemFlags;
}