#pragma once

#include <functional>
#include <vector>
#include <variant>
#include <unordered_map>
#include <memory>
#include "xutil.h"


class SeqMatcher {
public:
	using Callback = std::function<void()>;

	struct SymSequence {
		std::vector<x::Keysym> syms;
		Callback callback;
	};

	SeqMatcher(Display *dpy);

	// Initialise with an initial list of sequences.
	SeqMatcher(Display *dpy, std::vector<SymSequence> seqs);

	// Register a key sequence
	void addSequence(const std::vector<x::Keysym> &syms, Callback callback);

	// Returns bel()-running callback if unrecognised sequence is given
	std::optional<Callback> observe(const XKeyEvent &ev);

	// Cancel any running sequence and restart from the beginning
	void reset();

private:
	struct Node;
	using NodeMap = std::unordered_map<x::Keycode, std::unique_ptr<Node>>;
	struct Node {
		std::variant<NodeMap, Callback> v;
	};

	Display *const dpy;
	Node rootNode;
	Node *curNode = &rootNode;
};