#pragma once
#include <exception>
#include <optional>
#include "type.hpp"
#include "location.hh"
#include "parse_driver.hpp"

using maybe_location = std::optional<yy::location>;

struct type_error : std::exception {
    std::string description;
    std::optional<yy::location> loc;

    type_error(std::string d, maybe_location l = std::nullopt)
        : description(std::move(d)), loc(std::move(l)) {}

    const char* what() const noexcept override;
    void pretty_print(std::ostream& to, parse_driver& drv);
};

struct unification_error : public type_error {
    type_ptr left;
    type_ptr right;

    unification_error(type_ptr l, type_ptr r, maybe_location loc = std::nullopt)
        : left(std::move(l)), right(std::move(r)), 
            type_error("failed to unify types", std::move(loc)) {}

    void pretty_print(std::ostream& to, parse_driver& drv, type_mgr& mgr);
};