Lumacs/include/lumacs/window.hpp

#pragma once

#include "lumacs/buffer.hpp"
#include <memory>
#include <utility>
#include <algorithm>

namespace lumacs {

struct Viewport {
    int width = 0;
    int height = 0;
    int scroll_offset = 0;        // Vertical scroll (line offset)
    int horizontal_offset = 0;    // Horizontal scroll (column offset)
};

class Window {
public:
    Window(std::shared_ptr<Buffer> buffer);

    void set_buffer(std::shared_ptr<Buffer> buffer);
    
    // Accessors
    std::shared_ptr<Buffer> buffer_ptr() const { return buffer_; }
    Buffer& buffer() { return *buffer_; }
    const Buffer& buffer() const { return *buffer_; }

    void set_cursor(Position pos);
    Position cursor() const { return cursor_; }

    // Movement
    void move_up();
    void move_down();
    void move_left();
    void move_right();
    void move_to_line_start();
    void move_to_line_end();

    // Viewport
    void set_viewport_size(int width, int height);
    const Viewport& viewport() const { return viewport_; }
    
    void adjust_scroll();
    
    // Explicit scrolling (moves view, and cursor if necessary)
    void scroll_lines(int lines); // + for down, - for up
    
    std::pair<size_t, size_t> visible_line_range() const;

private:
    void clamp_cursor();

    std::shared_ptr<Buffer> buffer_;
    Position cursor_;
    Viewport viewport_;
    
    static constexpr int SCROLL_MARGIN = 3;
};

} // namespace lumacs