#ifndef CHATBLOCKMODEL_H
#define CHATBLOCKMODEL_H

#include <QAbstractListModel>
#include <QList>
#include <QString>
#include <QStringList>
#include <QRegularExpression>
#include <QHash>
#include <QSet>
#include <QVariantList>

class QNetworkAccessManager;
class QNetworkReply;

namespace KSyntaxHighlighting {
class Repository;
}

// A segment within a block — either text or a diagram
struct BlockSegment {
    enum Type { Text, Diagram };
    Type type = Text;
    QString html;           // For Text: rendered HTML; for Diagram: highlighted source HTML
    QString diagramLang;    // For Diagram: language (plantuml, mermaid)
    QString diagramSource;  // For Diagram: raw source code
    QString diagramSvg;     // For Diagram: base64 SVG data URI, or empty if loading/error
    QString diagramError;   // For Diagram: error message if failed
    bool diagramLoading = false;  // For Diagram: true if still loading
};

struct ChatBlock {
    enum Type {
        User,
        Assistant,
        Reasoning,
        Call,
        Tool,
        Error,
        Info,
        Retry,
        Interrupt,
        Default
    };

    Type type = Default;
    QString name;
    QString content;
    QString renderedHtml;  // Legacy: full HTML (kept for compatibility)
    QList<BlockSegment> segments;  // Structured segments for interactive rendering
};

class ChatBlockModel : public QAbstractListModel
{
    Q_OBJECT
    Q_PROPERTY(int count READ rowCount NOTIFY countChanged)

public:
    // Two-state parser for [[[blockname]]] ... [[[end]]] blocks.
    enum class State {
        BlockStart, // Waiting for a block header
        BlockEnd    // Collecting content until [[[end]]]
    };

    enum Roles {
        BlockTypeRole = Qt::UserRole + 1,
        BlockNameRole,
        ContentRole,
        RenderedHtmlRole,
        SegmentsRole,  // QVariantList of segment maps
    };

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

    int rowCount(const QModelIndex &parent = QModelIndex()) const override;
    QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override;
    QHash<int, QByteArray> roleNames() const override;

    Q_INVOKABLE void appendData(const QString &text);
    Q_INVOKABLE void reset();
    Q_INVOKABLE void trimFront(int keepCount);
    Q_INVOKABLE void clearDiagramCache();

signals:
    void countChanged();

private slots:
    void onDiagramReply(QNetworkReply *reply);

private:
    void processLine(const QString &line);
    void appendContent(const QString &line);
    void rebuildBlockHtml(int blockIndex);

    QString highlightCode(const QString &code, const QString &language) const;
    QString escapeForHtml(const QString &text) const;
    QString getDefaultTextColor() const;
    
    // Diagram rendering
    bool isDiagramLanguage(const QString &lang) const;
    void requestDiagram(const QString &lang, const QString &code, int blockIndex);
    QString diagramPlaceholder(const QString &lang) const;
    QString diagramErrorHtml(const QString &error) const;
    QString diagramSvgHtml(const QByteArray &svg) const;
    QString diagramPngHtml(const QByteArray &png) const;
    QString diagramJpegHtml(const QByteArray &jpeg) const;
    
    // Convert segments to QVariantList for QML
    QVariantList segmentsToVariant(const QList<BlockSegment> &segments) const;

    State m_state = State::BlockStart;
    KSyntaxHighlighting::Repository *m_repo = nullptr;
    QNetworkAccessManager *m_netManager = nullptr;

    QList<ChatBlock> m_blocks;
    QString m_lineBuffer;

    // Code fence state (for streaming)
    bool m_inCodeFence = false;
    QString m_fenceLanguage;
    QString m_fenceContent;
    
    // Diagram cache: hash of (lang + code) -> SVG data
    QHash<QString, QByteArray> m_diagramCache;
    // Pending requests: hash -> block indices waiting for this diagram
    QHash<QString, QList<int>> m_pendingDiagrams;
    // Track which requests are in flight
    QSet<QString> m_inFlightRequests;

    static const QRegularExpression s_headerRe;
    static const QRegularExpression s_endRe;
    static const QRegularExpression s_fenceOpenRe;
    static const QRegularExpression s_fenceCloseRe;
};

#endif // CHATBLOCKMODEL_H