#pragma once

#include <QAbstractItemModel>
#include <QModelIndex>
#include <QVariant>
#include <QVector>
#include <QDateTime>
#include <QDate>
#include "core/mailitem.h"

class EmailTreeModel : public QAbstractItemModel
{
    Q_OBJECT

public:
    enum Columns {
        ColSubject = 0,
        ColSender = 1,
        ColDate = 2,
        ColCount = 3
    };

    enum Roles {
        MailIdRole = Qt::UserRole + 1,
        IsGroupRole = Qt::UserRole + 2,
        GroupNameRole = Qt::UserRole + 3,
        GroupIndexRole = Qt::UserRole + 4,
        MailIndexRole = Qt::UserRole + 5,
        IsThreadRole = Qt::UserRole + 6,
        ThreadIdRole = Qt::UserRole + 7,
        IsThreadExpandedRole = Qt::UserRole + 8
    };

    explicit EmailTreeModel(QObject *parent = nullptr);
    ~EmailTreeModel() override;

    // Basic model interface
    QModelIndex index(int row, int column, const QModelIndex &parent = QModelIndex()) const override;
    QModelIndex parent(const QModelIndex &child) const override;
    int rowCount(const QModelIndex &parent = QModelIndex()) const override;
    int columnCount(const QModelIndex &parent = QModelIndex()) const override;
    QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override;
    QVariant headerData(int section, Qt::Orientation orientation, int role = Qt::DisplayRole) const override;
    Qt::ItemFlags flags(const QModelIndex &index) const override;

    // Email data management
    void setEmails(const QVector<MailItem> &emails);
    void clear();

    // Grouping
    enum GroupMode {
        NoGrouping = 0,
        GroupByDate = 1,
        GroupByThread = 2,
        GroupBySender = 3
    };
    void setGroupMode(GroupMode mode);
    GroupMode groupMode() const { return m_groupMode; }

    // Thread expansion
    void setThreadExpanded(const QString& threadId, bool expanded);
    bool isThreadExpanded(const QString& threadId) const;

private:
    struct TreeItem {
        enum Type { Group, Mail, Thread } type;
        QString groupName;          // for Group type
        QString threadId;           // for Thread type
        int groupIndex = -1;        // for Group type
        int mailIndex = -1;         // for Mail type (index in m_emails)
        QVector<TreeItem*> children;
        TreeItem* parent = nullptr;
        int row = -1;
        bool expanded = true;       // for Thread type

        TreeItem(Type t, TreeItem* p = nullptr) : type(t), parent(p) {}
        ~TreeItem() { qDeleteAll(children); }
    };

    GroupMode m_groupMode = NoGrouping;
    QVector<MailItem> m_emails;
    TreeItem* m_rootItem = nullptr;
    QSet<QString> m_expandedThreads;

    void setupModelData();
    void buildGroups();
    void buildThreads();
    void buildSenderGroups();
    QString groupNameForDate(const QDateTime &date) const;
    int groupIndexForDate(const QDateTime &date) const;
    void deleteTree(TreeItem* item);
    void buildThreadTree();
    QString extractThreadId(const MailItem& mail) const;
};