Added std::variant and Visitor for all IQ Stanza errors

library/include/larra/client/client.hpp

@@ -84,14 +84,12 @@ struct Client {
 
     auto set_bind_response = co_await connection.template Read<Iq<::iq::Bind>>();
     std::visit(utempl::Overloaded(
-                   [](auto error) {
-                     throw "Error response on IQ: Set::Bind: ''";  // TODO(unknown): Add exact error parsing
-                   },
                    [&](::iq::ResultBind r) {
                      jid.resource = std::move(r.payload.jid->resource);
                      SPDLOG_INFO("Allocated resource: {}", jid.resource);
-                   }),
-               set_bind_response);
+                   },
+                   IqErrThrowVisitor<::iq::Bind>{"Error response on IQ: Set::Bind"}),
+               std::move(set_bind_response));
     co_return;
   }
 
@@ -101,14 +99,12 @@ struct Client {
 
     const auto get_roster_response = co_await connection.template Read<Iq<::iq::Roster>>();
     std::visit(utempl::Overloaded(
-                   [](auto error) {
-                     throw "Error response on IQ: Get::Roster: ''";  // TODO(unknown): Add exact error parsing
-                   },
                    [&](::iq::ResultRoster r) {
                      roster = std::move(r.payload);
                      SPDLOG_INFO("New roster: {}", ToString(roster));
-                   }),
-               get_roster_response);
+                   },
+                   IqErrThrowVisitor<::iq::Roster>{"Error response on IQ: Get::Roster"}),
+               std::move(get_roster_response));
     co_return;
   }
 

library/include/larra/iq.hpp

@@ -1,9 +1,12 @@
 #pragma once
+#include <spdlog/spdlog.h>
+
+#include <larra/iq_error.hpp>
 #include <larra/jid.hpp>
 #include <larra/serialization.hpp>
-#include <larra/stream_error.hpp>
 #include <larra/utils.hpp>
 #include <optional>
+#include <stdexcept>
 #include <string>
 
 namespace larra::xmpp {
@@ -115,7 +118,40 @@ using Error = BaseImplWithPayload<kErrorName, Payload>;
 
 }  // namespace iq
 
+using IqError = iq::Error<iq::error::IqError>;
+
 template <typename Payload>
-using Iq = std::variant<iq::Get<Payload>, iq::Set<Payload>, iq::Result<Payload>, iq::Error<Payload>>;
+using Iq = std::variant<iq::Get<Payload>, iq::Set<Payload>, iq::Result<Payload>, IqError>;
+
+template <typename Payload>
+struct IqErrThrowVisitor {
+  constexpr IqErrThrowVisitor(std::string_view baseErrorMsg) : baseErrorMsg(baseErrorMsg) {
+  }
+
+  void operator()(const iq::Get<Payload>&) {
+    static constexpr std::string_view getErrorMsg = ": 'Get' is an invalid type for IQ result. Expected 'Result' or 'Error'";
+
+    auto finalErrorMsg = std::string(baseErrorMsg).append(getErrorMsg);
+    SPDLOG_ERROR(finalErrorMsg);
+    throw std::runtime_error{finalErrorMsg};
+  }
+  void operator()(const iq::Set<Payload>&) {
+    static constexpr std::string_view getErrorMsg = ": 'Set' is an invalid type for IQ result. Expected 'Result' or 'Error'";
+
+    auto finalErrorMsg = std::string(baseErrorMsg).append(getErrorMsg);
+    SPDLOG_ERROR(finalErrorMsg);
+    throw std::runtime_error{finalErrorMsg};
+  }
+  void operator()(IqError err) {
+    SPDLOG_ERROR(baseErrorMsg);
+    std::visit(
+        [](auto exception) {
+          throw exception;
+        },
+        std::move(err.payload));
+  }
+
+  std::string_view baseErrorMsg;
+};
 
 }  // namespace larra::xmpp

library/include/larra/iq_error.hpp

@@ -0,0 +1,152 @@
+#pragma once
+#include <libxml++/libxml++.h>
+
+#include <larra/utils.hpp>
+#include <optional>
+#include <variant>
+
+namespace larra::xmpp::iq::error {
+
+namespace impl {
+
+struct IqBaseError : std::exception {};
+
+// DO NOT MOVE TO ANOTHER NAMESPACE(where no heirs). VIA friend A FUNCTION IS ADDED THAT VIA ADL WILL BE SEARCHED FOR HEIRS
+// C++20 modules very unstable in clangd :(
+template <typename T>
+struct IqErrorImpl : IqBaseError {
+  static constexpr auto kDefaultName = "error";
+  static constexpr auto kDefaultNamespace = "urn:ietf:params:xml:ns:xmpp-stanzas";
+  static inline const auto kKebabCaseName = static_cast<std::string>(utils::ToKebabCaseName<T>());
+
+  static constexpr auto kErrorMessage = [] -> std::string_view {
+    static constexpr auto name = nameof::nameof_short_type<T>();
+    static constexpr auto str = [] {
+      return std::array{std::string_view{"Stanza IQ Error: "}, std::string_view{name}, std::string_view{"\0", 1}} | std::views::join;
+    };
+    static constexpr auto array = str() | std::ranges::to<utils::RangeToWrapper<std::array<char, std::ranges::distance(str())>>>();
+    return {array.data(), array.size() - 1};
+  }();
+
+  std::optional<std::string> by{};
+  std::string type;
+
+  // TODO(unknown): Add "optional text children" support for stanza error. Check  "XML Stanzas" -> "Syntax" for more details
+  static constexpr auto TryParse(xmlpp::Element* element) -> std::optional<T> {
+    if(not element) {
+      return std::nullopt;
+    }
+
+    auto by = element->get_attribute("by");
+    auto type = element->get_attribute("type");
+    if(not type) {
+      return std::nullopt;
+    }
+
+    auto node = element->get_first_child(kKebabCaseName);
+    if(not node) {
+      return std::nullopt;
+    }
+
+    T obj;
+    obj.type = type->get_value();
+    if(by) {
+      obj.by = std::optional{by->get_value()};
+    }
+    return obj;
+  }
+  static constexpr auto Parse(xmlpp::Element* element) -> T {
+    return TryParse(element).value();
+  }
+  friend constexpr auto operator<<(xmlpp::Element* element, const T& obj) -> void {
+    element->set_attribute("type", obj.type);
+    if(obj.by) {
+      element->set_attribute("by", *obj.by);
+    }
+
+    auto node = element->add_child_element(kKebabCaseName);
+    node->set_namespace_declaration(kDefaultNamespace);
+  }
+  constexpr auto operator==(const IqErrorImpl<T>&) const -> bool {
+    return true;
+  };
+  [[nodiscard]] constexpr auto what() const noexcept -> const char* override {
+    return kErrorMessage.data();
+  }
+};
+
+// Helper class to prevent parsing response stream into an expected return type if its name is an 'error'
+struct UnknownIqError : IqBaseError {
+  static constexpr auto kDefaultName = "stream:error";
+  static constexpr std::string_view kErrorMessage = "Unknown XMPP stream error";
+
+  static constexpr auto TryParse(xmlpp::Element* element) {
+    return std::optional{UnknownIqError{}};
+  }
+  static constexpr auto Parse(xmlpp::Element* element) {
+    return TryParse(element).value();
+  }
+  friend constexpr auto operator<<(xmlpp::Element* element, const UnknownIqError& obj) -> void {
+    throw std::format("'{}' must never be written into the real stream!", kErrorMessage);
+  }
+  constexpr auto operator==(const UnknownIqError&) const -> bool {
+    return true;
+  };
+  [[nodiscard]] constexpr auto what() const noexcept -> const char* override {
+    return kErrorMessage.data();
+  }
+};
+
+struct BadRequest : IqErrorImpl<BadRequest> {};
+struct Conflict : IqErrorImpl<Conflict> {};
+struct FeatureNotImplemented : IqErrorImpl<FeatureNotImplemented> {};
+struct Forbidden : IqErrorImpl<Forbidden> {};
+struct Gone : IqErrorImpl<Gone> {};
+struct InternalServerError : IqErrorImpl<InternalServerError> {};
+struct ItemNotFound : IqErrorImpl<ItemNotFound> {};
+struct JidMalformed : IqErrorImpl<JidMalformed> {};
+struct NotAcceptable : IqErrorImpl<NotAcceptable> {};
+struct NotAllowed : IqErrorImpl<NotAllowed> {};
+struct NotAuthorized : IqErrorImpl<NotAuthorized> {};
+struct PolicyViolation : IqErrorImpl<PolicyViolation> {};
+struct RecipientUnavailable : IqErrorImpl<RecipientUnavailable> {};
+struct Redirect : IqErrorImpl<Redirect> {};
+struct RegistrationRequired : IqErrorImpl<RegistrationRequired> {};
+struct RemoteServerNotFound : IqErrorImpl<RemoteServerNotFound> {};
+struct RemoteServerTimeout : IqErrorImpl<RemoteServerTimeout> {};
+struct ResourceConstraint : IqErrorImpl<ResourceConstraint> {};
+struct ServiceUnavailable : IqErrorImpl<ServiceUnavailable> {};
+struct SubscriptionRequired : IqErrorImpl<SubscriptionRequired> {};
+struct UndefinedCondition : IqErrorImpl<UndefinedCondition> {};
+struct UnexpectedRequest : IqErrorImpl<UnexpectedRequest> {};
+
+}  // namespace impl
+
+using IqError = std::variant<impl::BadRequest,
+                             impl::Conflict,
+                             impl::FeatureNotImplemented,
+                             impl::Forbidden,
+                             impl::Gone,
+                             impl::InternalServerError,
+                             impl::ItemNotFound,
+                             impl::JidMalformed,
+                             impl::NotAcceptable,
+                             impl::NotAllowed,
+                             impl::NotAuthorized,
+                             impl::PolicyViolation,
+                             impl::RecipientUnavailable,
+                             impl::Redirect,
+                             impl::RegistrationRequired,
+                             impl::RemoteServerNotFound,
+                             impl::RemoteServerTimeout,
+                             impl::ResourceConstraint,
+                             impl::ServiceUnavailable,
+                             impl::SubscriptionRequired,
+                             impl::UndefinedCondition,
+                             impl::UnexpectedRequest,
+                             impl::UnknownIqError>;
+
+static_assert(!std::is_same_v<typename std::variant_alternative_t<std::variant_size_v<IqError> - 1, IqError>, IqError>,
+              "'UnknownIqError' must be at the end of 'IqError' variant");
+
+}  // namespace larra::xmpp::iq::error

library/src/bind.cpp

@@ -2,7 +2,7 @@
 
 namespace larra::xmpp::iq {
 auto operator<<(xmlpp::Element* element, const Bind& bind) -> void {
-  element->set_attribute("xmlns", Bind::kDefaultNamespace);
+  element->set_namespace_declaration(Bind::kDefaultNamespace);
 
   if(bind.jid) {
     auto* jid_el = element->add_child_element("jid");

library/src/roster.cpp

@@ -21,7 +21,7 @@ auto RosterItem::Parse(xmlpp::Element* element) -> RosterItem {
 }
 
 auto operator<<(xmlpp::Element* element, const Roster& self) -> void {
-  element->set_attribute("xmlns", Roster::kDefaultNamespace);
+  element->set_namespace_declaration(Roster::kDefaultNamespace);
   S::Serialize(element, self);
 }
 auto Roster::Parse(xmlpp::Element* element) -> Roster {