#ifndef window_hh_INCLUDED
#define window_hh_INCLUDED

#include <functional>

#include "buffer.hh"
#include "dynamic_buffer_iterator.hh"
#include "display_buffer.hh"
#include "filter.hh"

namespace Kakoune
{

struct Selection
{
    Selection(const BufferIterator& first, const BufferIterator& last)
        : m_first(first), m_last(last) {}

    BufferIterator begin() const;
    BufferIterator end() const;

    const BufferIterator& first() const { return m_first; }
    const BufferIterator& last()  const { return m_last; }

    void merge_with(const Selection& selection);

private:
    DynamicBufferIterator m_first;
    DynamicBufferIterator m_last;
};

typedef std::vector<Selection> SelectionList;

class IncrementalInserter;

class Window
{
public:
    typedef BufferString String;
    typedef std::function<Selection (const BufferIterator&)> Selector;

    void erase();
    void insert(const String& string);
    void append(const String& string);

    const BufferCoord& position() const { return m_position; }
    DisplayCoord   cursor_position() const;
    BufferIterator cursor_iterator() const;

    Buffer& buffer() const { return m_buffer; }

    BufferIterator iterator_at(const DisplayCoord& window_pos) const;
    DisplayCoord   line_and_column_at(const BufferIterator& iterator) const;

    void move_cursor(const DisplayCoord& offset, bool append = false);
    void move_cursor_to(const BufferIterator& iterator);

    void clear_selections();
    void select(const Selector& selector, bool append = false);
    BufferString selection_content() const;

    void set_dimensions(const DisplayCoord& dimensions);

    const DisplayBuffer& display_buffer() const { return m_display_buffer; }

    void update_display_buffer();

    bool undo();
    bool redo();

    std::string status_line() const;

    struct filter_id_not_unique : public runtime_error
    {
        filter_id_not_unique(const std::string& id)
            : runtime_error("filter id not unique: " + id) {}
    };

    void add_filter(FilterAndId&& filter);
    void remove_filter(const std::string& id);

private:
    friend class Buffer;

    Window(Buffer& buffer);
    Window(const Window&) = delete;

    void check_invariant() const;
    void scroll_to_keep_cursor_visible_ifn();

    void erase_noundo();
    void insert_noundo(const String& string);
    void append_noundo(const String& string);

    friend class IncrementalInserter;
    IncrementalInserter* m_current_inserter;

    friend class HighlightSelections;

    Buffer&       m_buffer;
    BufferCoord   m_position;
    DisplayCoord  m_dimensions;
    SelectionList m_selections;
    DisplayBuffer m_display_buffer;

    typedef std::vector<FilterAndId> FilterList;
    FilterList m_filters;
};

class IncrementalInserter
{
public:
    enum class Mode
    {
        Insert,
        Append,
        Change,
        InsertAtLineBegin,
        AppendAtLineEnd,
        OpenLineBelow,
        OpenLineAbove
    };

    IncrementalInserter(Window& window, Mode mode = Mode::Insert);
    ~IncrementalInserter();

    void insert(const Window::String& string);
    void erase();
    void move_cursor(const DisplayCoord& offset);

private:
    Window&                     m_window;
};

}

#endif // window_hh_INCLUDED