#include <string>
#include <vector>
#include <unordered_map>
#include <variant>
#include <exception>
#include <memory>
#include <functional>



namespace Pilang3 {
    using integer_type = int64_t;

    namespace exceptions {
        class langException : public std::exception {};
        class BadInteger : public langException {};
        class BadArgs : public langException {};
        class NoSuchCommand : public langException {};
        class NoSuchVariable : public langException {};
    }

    class Environment;
    class Evaluation;
    struct Variable;
    using SharedVariable = std::shared_ptr<Variable>;
    using SharedEvaluation = std::shared_ptr<Evaluation>;

    struct Variable {
        enum Type {
            id_string,
            id_integer,
            id_reference,
            id_evaluation,
            id_type [[maybe_unused]],
            id_any [[maybe_unused]],
            id_null [[maybe_unused]]
        } type;

        using Data = std::variant<std::string, integer_type, SharedVariable, Type, SharedEvaluation>;
        Data data;
    };

    using Cmdargs = std::vector<Variable>;
    using Cmdfnc = std::function<Variable (Environment&, Cmdargs&)>;
    using Cmddesc = std::tuple<Cmdfnc, uint16_t, std::vector<Variable::Type>, bool>;

    extern std::unordered_map<std::string, Cmddesc> builtinCmds;

    class Environment {
    public:
        std::unordered_map<std::string, SharedVariable> globalVars;
        void *anybuf = nullptr;
    };

    class Evaluation {
    public:
        Cmdargs arguments;
        Cmdfnc command = nullptr;
        std::string command_name;
        ssize_t exprlen;

        Evaluation(Environment& env, const std::string &expression, const bool autoeval = true);

        Variable execute(Environment& env);
    };
};