#pragma once

#include "lumacs/buffer.hpp"
#include "lumacs/window.hpp"
#include "lumacs/kill_ring.hpp"
#include "lumacs/theme.hpp"
#include "lumacs/config.hpp"
#include "lumacs/keybinding.hpp"
#include "lumacs/modeline.hpp"
// #include "lumacs/minibuffer_manager.hpp" // Changed to forward declaration below
#include "lumacs/ui_interface.hpp" // Include for EditorEvent
#include <memory>
#include <functional>
#include <vector>
#include <list>
#include <unordered_map>
#include <chrono> // For std::chrono::steady_clock
#include <optional> // For std::optional

namespace lumacs {

class LuaApi; // Forward declaration
class CommandSystem; // Forward declaration
class CompletionSystem; // Forward declaration
class MinibufferManager; // Forward declaration

/// @brief Represents a node in the window layout tree.
struct LayoutNode {
    enum class Type { Leaf, HorizontalSplit, VerticalSplit };
    Type type;
    
    // If Leaf
    std::shared_ptr<Window> window;
    
    // If Split
    std::shared_ptr<LayoutNode> child1;
    std::shared_ptr<LayoutNode> child2;
    float ratio = 0.5f; // Split ratio (0.0 to 1.0)
    
    LayoutNode(std::shared_ptr<Window> w) : type(Type::Leaf), window(w) {}
    LayoutNode(Type t, std::shared_ptr<LayoutNode> c1, std::shared_ptr<LayoutNode> c2)
        : type(t), child1(c1), child2(c2) {}
};

/// @brief Core logic of the Lumacs editor, independent of the UI framework.
/// 
/// This class acts as the central controller/facade for the editor's logic.
/// It manages buffers, windows, the kill ring, registers, macros, configuration,
/// and subsystems like the command system and Lua API.
/// It emits events to notify the UI (IEditorView) of state changes.
class EditorCore {
public:
    EditorCore();
    ~EditorCore();

    // Disable copy, allow move
    EditorCore(const EditorCore&) = delete;
    EditorCore& operator=(const EditorCore&) = delete;
    EditorCore(EditorCore&&) noexcept = default;
    EditorCore& operator=(EditorCore&&) noexcept = default;

    // === Message System ===

    /// @brief Display a message to the user (usually in the minibuffer).
    /// @param msg The message string to display.
    void set_message(std::string msg) {
        last_message_ = std::move(msg);
        message_clear_time_ = std::chrono::steady_clock::now() + std::chrono::seconds(5); // Clear after 5 seconds
        emit_event(EditorEvent::Message); // Use this for transient messages
    }

    /// @brief Get the last set message.
    const std::string& last_message() const { return last_message_; }

    /// @brief Check if a message is set and if its display time has expired.
    /// Clears the message if expired.
    void check_and_clear_message() {
        if (message_clear_time_.has_value() && std::chrono::steady_clock::now() > message_clear_time_.value()) {
            last_message_.clear();
            message_clear_time_.reset();
            emit_event(EditorEvent::TransientMessageCleared); // Notify UI
        }
    }

    // === Actions ===
    // These methods trigger specific input modes in the UI.

    void enter_command_mode() { emit_event(EditorEvent::CommandMode); }
    void enter_buffer_switch_mode() { emit_event(EditorEvent::BufferSwitchMode); }
    void enter_kill_buffer_mode() { emit_event(EditorEvent::KillBufferMode); }
    void enter_find_file_mode() { emit_event(EditorEvent::FindFileMode); }
    void enter_theme_selection_mode() { emit_event(EditorEvent::ThemeSelectionMode); }
    void enter_isearch_mode() { emit_event(EditorEvent::ISearchMode); }
    void enter_isearch_backward_mode() { emit_event(EditorEvent::ISearchBackwardMode); }

    // === Buffer Management ===

    /// @brief Get the active buffer (associated with the active window).
    [[nodiscard]] const Buffer& buffer() const noexcept;
    [[nodiscard]] Buffer& buffer() noexcept;

    /// @brief Load a file into a buffer and display it in the active window.
    /// @param path Filesystem path to load.
    /// @return true if successful, false otherwise.
    bool load_file(const std::filesystem::path& path);

    /// @brief Create a new empty buffer (e.g., *scratch*) and display it.
    /// @param name The name of the new buffer.
    void new_buffer(std::string name = "*scratch*");

    /// @brief Get a list of names of all open buffers.
    [[nodiscard]] std::vector<std::string> get_buffer_names() const;

    /// @brief Find a buffer by its name.
    /// @return Shared pointer to the buffer, or nullptr if not found.
    [[nodiscard]] std::shared_ptr<Buffer> get_buffer_by_name(const std::string& name);

    /// @brief Switch the active window to display the specified buffer.
    /// @param name The name of the buffer to switch to.
    /// @return true if successful.
    bool switch_buffer_in_window(const std::string& name);

    /// @brief Close (kill) a buffer.
    /// @param name The name of the buffer to close.
    /// @return true if closed, false if it doesn't exist or is the last buffer.
    bool close_buffer(const std::string& name);

    /// @brief Structure containing summary information about a buffer.
    struct BufferInfo {
        std::string name;
        size_t size;
        bool modified;
        std::string mode;
        std::optional<std::filesystem::path> filepath;
    };

    /// @brief Get detailed information about all buffers.
    [[nodiscard]] std::vector<BufferInfo> get_all_buffer_info() const;

    // === Window Management ===

    /// @brief Split the active window horizontally (active becomes top).
    void split_horizontally();

    /// @brief Split the active window vertically (active becomes left).
    void split_vertically();

    /// @brief Close the active window and remove it from the layout tree.
    void close_active_window();

    /// @brief Move focus to the next window in the tree traversal order.
    void next_window();
    
    /// @brief Safe version of next_window (deprecated, alias for next_window).
    void next_window_safe();

    /// @brief Get the currently focused window.
    std::shared_ptr<Window> active_window() const { return active_window_; }
    
    /// @brief Set the active window explicitly (must exist in the tree).
    bool set_active_window(std::shared_ptr<Window> window);

    /// @brief Get the root node of the window layout tree.
    std::shared_ptr<LayoutNode> root_layout() const { return root_node_; }

    // === Cursor Management (Proxies to active window) ===

    [[nodiscard]] Position cursor() const noexcept;
    void set_cursor(Position pos);

    // === Cursor Movement (Proxies to active window) ===

    void move_up();
    void move_down();
    void move_left();
    void move_right();
    void move_to_line_start();
    void move_to_line_end();
    void move_forward_word();
    void move_backward_word();
    void page_up();
    void page_down();
    void goto_beginning();
    void goto_end();
    void goto_line(size_t line);

    // === Viewport Management (Proxies to active window) ===
    
    const Viewport& viewport() const noexcept;
    void set_viewport_size(int width, int height);
    void adjust_scroll();
    std::pair<size_t, size_t> visible_line_range() const;

    // === Event Callbacks ===

    using EventCallback = std::function<void(EditorEvent)>;

    /// @brief Register a callback to be notified of editor events.
    void on_event(EventCallback callback) {
        event_callbacks_.push_back(std::move(callback));
    }

    /// @brief Clear all registered event callbacks.
    void clear_event_callbacks() {
        event_callbacks_.clear();
    }

    // === Actions ===

    /// @brief Request the application to quit.
    void request_quit() {
        emit_event(EditorEvent::Quit);
    }

    // === Undo/Redo ===

    bool undo();
    bool redo();
    bool can_undo() const;
    bool can_redo() const;

    // === Kill Ring ===

    /// @brief Access the global Kill Ring (clipboard history).
    [[nodiscard]] KillRing& kill_ring() noexcept { return kill_ring_; }
    [[nodiscard]] const KillRing& kill_ring() const noexcept { return kill_ring_; }

    // === Registers ===

    /// @brief Save text to a named register.
    void copy_to_register(char register_name, const std::string& text);
    
    /// @brief Insert text from a named register.
    bool insert_register(char register_name);
    
    /// @brief Copy the active region to a register (C-x r s).
    void copy_region_to_register(char register_name);
    
    /// @brief Insert text from a register (C-x r i).
    bool yank_from_register(char register_name);

    // === Keyboard Macros ===

    /// @brief Start recording a keyboard macro (F3).
    void start_kbd_macro();

    /// @brief Stop recording or execute the last macro (F4).
    void end_kbd_macro_or_call();

    /// @brief Record a key sequence if macro recording is active.
    void record_key_sequence(const std::string& key_sequence);

    /// @brief Check if macro recording is currently active.
    [[nodiscard]] bool is_recording_macro() const noexcept { return recording_macro_; }

    // === Rectangles ===

    /// @brief Kill (cut) a rectangular region (C-x r k).
    void kill_rectangle();

    /// @brief Yank (paste) the last killed rectangle (C-x r y).
    void yank_rectangle();

    /// @brief Replace a rectangular region with a string (C-x r t).
    void string_rectangle(const std::string& text);

    // === Standard Editing Commands ===

    /// @brief Kill text from cursor to end of line (C-k).
    void kill_line();

    /// @brief Kill the text in the active region (C-w).
    void kill_region();

    /// @brief Copy the active region to the kill ring (M-w).
    void copy_region_as_kill();

    /// @brief Yank (paste) from the kill ring (C-y).
    void yank();

    /// @brief Replace the just-yanked text with the next item in kill ring (M-y).
    void yank_pop();

    /// @brief Kill word forward (M-d).
    void kill_word();

    /// @brief Kill word backward (M-Backspace).
    void backward_kill_word();

    // === Theme Management ===

    [[nodiscard]] ThemeManager& theme_manager() noexcept { return theme_manager_; }
    [[nodiscard]] const ThemeManager& theme_manager() const noexcept { return theme_manager_; }

    /// @brief Set the active theme by name.
    void set_theme(const std::string& name) { theme_manager_.set_active_theme(name); }

    /// @brief Get the currently active theme.
    [[nodiscard]] std::shared_ptr<Theme> active_theme() const { return theme_manager_.active_theme(); }

    // === Configuration ===

    [[nodiscard]] Config& config() noexcept { return config_; }
    [[nodiscard]] const Config& config() const noexcept { return config_; }

    // === Key Binding System ===                                                                                                                                 
    [[nodiscard]] KeyBindingManager& keybinding_manager() noexcept { return keybinding_manager_; }                                                                
    [[nodiscard]] const KeyBindingManager& keybinding_manager() const noexcept { return keybinding_manager_; }                                                    
                                                                                                                                                                  
    // === Lua API ===                                                                                                                                            
    [[nodiscard]] LuaApi* lua_api() const { return lua_api_.get(); }
    
    // === Command System ===
    [[nodiscard]] CommandSystem& command_system() noexcept { return *command_system_; }
    [[nodiscard]] const CommandSystem& command_system() const noexcept { return *command_system_; }

    // === Modeline Manager ===
    [[nodiscard]] ModelineManager& modeline_manager() noexcept { return modeline_manager_; }
    [[nodiscard]] const ModelineManager& modeline_manager() const noexcept { return modeline_manager_; }

    // === Minibuffer Manager ===
    [[nodiscard]] MinibufferManager& minibuffer_manager() noexcept { return *minibuffer_manager_; }
    [[nodiscard]] const MinibufferManager& minibuffer_manager() const noexcept { return *minibuffer_manager_; }

    // === Completion System ===
    [[nodiscard]] CompletionSystem& completion_system() noexcept { return *completion_system_; }
    [[nodiscard]] const CompletionSystem& completion_system() const noexcept { return *completion_system_; }

private:
    std::list<std::shared_ptr<Buffer>> buffers_;

    // Word movement helpers
    Position calculate_forward_word_pos(Position start_pos);
    Position calculate_backward_word_pos(Position start_pos);

    // Window layout
    std::shared_ptr<LayoutNode> root_node_;
    std::shared_ptr<Window> active_window_;

    std::string last_message_;
    std::optional<std::chrono::steady_clock::time_point> message_clear_time_;

    std::vector<EventCallback> event_callbacks_;

    // Kill ring for cut/copy/paste
    KillRing kill_ring_;

    // Last yank position (for yank-pop)
    std::optional<Position> last_yank_start_;
    std::optional<Position> last_yank_end_;

    // Registers for storing text (a-z, A-Z, 0-9)
    std::unordered_map<char, std::string> registers_;

    // Keyboard macros
    std::vector<std::string> current_macro_;
    std::vector<std::string> last_macro_;
    bool recording_macro_ = false;

    // Rectangle storage
    std::vector<std::string> rectangle_kill_ring_;

    // Subsystems
    ThemeManager theme_manager_;
    Config config_;
    std::unique_ptr<CommandSystem> command_system_; // Must be declared before KeyBindingManager
    KeyBindingManager keybinding_manager_;
    std::unique_ptr<LuaApi> lua_api_;
    ModelineManager modeline_manager_;

    void emit_event(EditorEvent event);
    
    // Helper to find a node containing the active window
    LayoutNode* find_parent_node(LayoutNode* root, std::shared_ptr<Window> target);
    
    // Helper to collect all windows in traversal order
    void collect_windows(LayoutNode* node, std::vector<std::shared_ptr<Window>>& windows);
};

} // namespace lumacs