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



namespace Pilang3 {
    using integer_type = int64_t;

    namespace exceptions {
        class langException : public std::exception {public: const char *what() const noexcept {return "Runtime error";}};
        class emptyExpr : public langException {public: const char *what() const noexcept {return "Empty expression";}};
        class BadInteger : public langException {public: const char *what() const noexcept {return "Bad integer";}};
        class BadArgs : public langException {public: const char *what() const noexcept {return "Bad arguments";}};
        class NoSuchCommand : public langException {public: const char *what() const noexcept {return "No such command";}};
        class NoSuchVariable : public langException {public: const char *what() const noexcept {return "No such variable";}};
        class UnexpectedEndOfExpression : public langException {public: const char *what() const noexcept {return "Unexpected end of expression";}};
        class exit : public langException {public: int code; const char *what() const noexcept {return "Interpreter exit";} exit(int code) {this->code = code;}};
    }

    class Environment;
    class Evaluation;
    class Function;
    class Condition;
    struct Variable;
    using SharedEnvironment = std::shared_ptr<Environment>;
    using SharedVariable = std::shared_ptr<Variable>;
    using SharedEvaluation = std::shared_ptr<Evaluation>;
    using SharedFunction = std::shared_ptr<Function>;
    using SharedEvaluationWBool = std::tuple<SharedEvaluation, bool>;

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

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

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

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

    class Environment {
    public:
        using Scope = std::unordered_map<std::string, SharedVariable>;

        std::stack<Scope> variableScope;
        Scope *globalScope;
        void *anybuf = nullptr;

        Environment() {
            variableScope.push({});
            globalScope = &variableScope.top();
        }

        Scope &currScope() {
            return variableScope.top();
        }
    };

    class Evaluation {
    public:
        Cmdargs arguments;
        std::tuple<std::string /*Command name in case cmddesc was not found in eval time*/, Cmddesc> command = {"", {nullptr, {}, false}};
        std::string command_name;
        ssize_t exprlen = -1;

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

        void derefer(SharedEnvironment env);
        Variable execute(SharedEnvironment env);
    };

    class Function {
    public:
        std::vector<SharedEvaluation> evalChain;
        std::vector<std::string> argumentNames;
        bool new_scope = false;

        Variable execute(SharedEnvironment env, Cmdargs& args);
    };

    class Condition {
    public:
        enum {
            // Condition special types
            id_equals,
            id_notequals,
            id_biggerthan,
            id_smallerthan
        };

        ssize_t exprlen = -1;
        std::vector<std::string*> arr;

        Condition(const std::string& expression);
    };
};