#pragma once

#include <string>
#include <vector>
#include <map>
#include <memory>
#include <functional>
#include <chrono>
#include <optional>

namespace lumacs {

/// @brief Represents a single key in a key sequence.
struct Key {
    std::string name;           ///< Key name (e.g., "a", "Return", "F1").
    bool ctrl = false;          ///< Ctrl modifier active.
    bool meta = false;          ///< Meta/Alt modifier active.
    bool shift = false;         ///< Shift modifier active.
    
    Key() = default;
    explicit Key(const std::string& key_name);
    
    /// @brief Parse a key string like "C-x" or "M-S-a" into a Key structure.
    static Key parse(const std::string& key_str);
    
    /// @brief Convert Key back to canonical string representation.
    std::string to_string() const;
    
    bool operator==(const Key& other) const;
    bool operator<(const Key& other) const;
};

/// @brief Represents a sequence of keys (e.g., "C-x C-f").
class KeySequence {
public:
    KeySequence() = default;
    explicit KeySequence(const std::vector<Key>& keys);
    explicit KeySequence(const std::string& key_sequence_str);
    
    /// @brief Add a key to the sequence.
    void add_key(const Key& key);
    void add_key(const std::string& key_str);
    
    /// @brief Get the keys in this sequence.
    const std::vector<Key>& keys() const { return keys_; }
    
    /// @brief Check if this sequence is empty.
    bool empty() const { return keys_.empty(); }
    
    /// @brief Get the length of the sequence.
    size_t length() const { return keys_.size(); }
    
    /// @brief Check if this sequence is a prefix of another sequence.
    bool is_prefix_of(const KeySequence& other) const;
    
    /// @brief Check if this sequence has the given sequence as a prefix.
    bool has_prefix(const KeySequence& prefix) const;
    
    /// @brief Get string representation like "C-x 2".
    std::string to_string() const;
    
    /// @brief Clear the sequence.
    void clear();
    
    /// @brief Get a subsequence starting from index.
    KeySequence subsequence(size_t start_index) const;
    
    bool operator==(const KeySequence& other) const;
    bool operator<(const KeySequence& other) const;

private:
    std::vector<Key> keys_;
};

/// @brief Function type for key binding callbacks.
using KeyBindingFunction = std::function<bool()>;

/// @brief Represents a key binding with its associated function.
struct KeyBinding {
    KeySequence sequence;       ///< The key sequence that triggers this binding.
    KeyBindingFunction function;///< The function to execute.
    std::string description;    ///< Human-readable description.
    
    KeyBinding() = default;
    KeyBinding(const KeySequence& seq, KeyBindingFunction func, std::string desc = "");
    KeyBinding(const std::string& key_str, KeyBindingFunction func, std::string desc = "");
};

/// @brief Result of processing a key in the binding manager.
enum class KeyResult {
    Unbound,        ///< No binding found, key not handled.
    Executed,       ///< Binding found and executed successfully.
    Failed,         ///< Binding found but execution failed.
    Partial,        ///< Key is part of a multi-key sequence, waiting for more keys.
    Timeout         ///< Partial sequence timed out.
};

/// @brief Central manager for all key bindings.
/// 
/// Handles:
/// - Registration of global key bindings.
/// - Processing of key input (single and multi-key sequences).
/// - Prefix key logic (e.g., C-x waiting for next key).
class KeyBindingManager {
public:
    KeyBindingManager();
    ~KeyBindingManager() = default;
    
    /// @brief Bind a key sequence to a function.
    void bind(const KeySequence& sequence, KeyBindingFunction function, const std::string& description = "");
    void bind(const std::string& key_str, KeyBindingFunction function, const std::string& description = "");
    
    /// @brief Unbind a key sequence.
    void unbind(const KeySequence& sequence);
    void unbind(const std::string& key_str);
    
    /// @brief Process a single key press.
    /// @return Result indicating if key was bound, partial, etc.
    KeyResult process_key(const Key& key);
    KeyResult process_key(const std::string& key_str);
    
    /// @brief Check if a sequence has any bindings (exact or partial).
    bool has_binding(const KeySequence& sequence) const;
    
    /// @brief Check if a sequence has an exact binding.
    bool has_exact_binding(const KeySequence& sequence) const;
    
    /// @brief Check if a sequence is a prefix for other bindings.
    bool has_prefix_bindings(const KeySequence& sequence) const;
    
    /// @brief Clear current partial sequence (e.g., on timeout or escape).
    void clear_partial_sequence();
    
    /// @brief Get current partial sequence for display purposes.
    const KeySequence& current_partial_sequence() const { return current_sequence_; }
    
    /// @brief Check if we're currently building a multi-key sequence.
    bool is_building_sequence() const;
    
    /// @brief Get string representation of current sequence for display.
    std::string current_sequence_display() const;
    
    /// @brief Get all registered bindings (for debugging/help).
    std::vector<KeyBinding> get_all_bindings() const;
    
    /// @brief Set timeout for multi-key sequences.
    void set_sequence_timeout(std::chrono::milliseconds timeout);
    
    /// @brief Check if current partial sequence has timed out.
    bool has_sequence_timed_out() const;

private:
    std::map<KeySequence, KeyBinding> bindings_;
    KeySequence current_sequence_;
    std::chrono::steady_clock::time_point sequence_start_time_;
    std::chrono::milliseconds sequence_timeout_;
    
    std::optional<KeyBinding> find_exact_binding(const KeySequence& sequence) const;
    bool has_prefix_bindings_impl(const KeySequence& sequence) const;
};

} // namespace lumacs