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{"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{"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/jid.hpp>
 #include <larra/serialization.hpp>
-#include <larra/stream_error.hpp>
+#include <larra/stanza_error.hpp>
 #include <larra/utils.hpp>
 #include <optional>
+#include <stdexcept>
 #include <string>
 
 namespace larra::xmpp {
@@ -115,7 +118,41 @@ using Error = BaseImplWithPayload<kErrorName, Payload>;
 
 }  // namespace iq
 
+using IqError = iq::Error<stanza::error::StanzaError>;
+
 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>;
+
+struct IqErrThrowVisitor {
+  constexpr IqErrThrowVisitor(std::string_view baseErrorMsg) : baseErrorMsg(baseErrorMsg) {
+  }
+
+  template <typename Payload>
+  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};
+  }
+  template <typename Payload>
+  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/stanza_error.hpp

@@ -0,0 +1,148 @@
+#pragma once
+#include <libxml++/libxml++.h>
+
+#include <larra/utils.hpp>
+#include <optional>
+#include <variant>
+
+namespace larra::xmpp::stanza::error {
+
+struct StanzaBaseError : 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 StanzaErrorImpl : StanzaBaseError {
+  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 StanzaErrorImpl<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 UnknownStanzaError : StanzaBaseError {
+  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{UnknownStanzaError{}};
+  }
+  static constexpr auto Parse(xmlpp::Element* element) {
+    return TryParse(element).value();
+  }
+  friend constexpr auto operator<<(xmlpp::Element* element, const UnknownStanzaError& obj) -> void {
+    throw std::runtime_error{std::format("'{}' must never be written into the real stream!", kErrorMessage)};
+  }
+  constexpr auto operator==(const UnknownStanzaError&) const -> bool {
+    return true;
+  };
+  [[nodiscard]] constexpr auto what() const noexcept -> const char* override {
+    return kErrorMessage.data();
+  }
+};
+
+struct BadRequest : StanzaErrorImpl<BadRequest> {};
+struct Conflict : StanzaErrorImpl<Conflict> {};
+struct FeatureNotImplemented : StanzaErrorImpl<FeatureNotImplemented> {};
+struct Forbidden : StanzaErrorImpl<Forbidden> {};
+struct Gone : StanzaErrorImpl<Gone> {};
+struct InternalServerError : StanzaErrorImpl<InternalServerError> {};
+struct ItemNotFound : StanzaErrorImpl<ItemNotFound> {};
+struct JidMalformed : StanzaErrorImpl<JidMalformed> {};
+struct NotAcceptable : StanzaErrorImpl<NotAcceptable> {};
+struct NotAllowed : StanzaErrorImpl<NotAllowed> {};
+struct NotAuthorized : StanzaErrorImpl<NotAuthorized> {};
+struct PolicyViolation : StanzaErrorImpl<PolicyViolation> {};
+struct RecipientUnavailable : StanzaErrorImpl<RecipientUnavailable> {};
+struct Redirect : StanzaErrorImpl<Redirect> {};
+struct RegistrationRequired : StanzaErrorImpl<RegistrationRequired> {};
+struct RemoteServerNotFound : StanzaErrorImpl<RemoteServerNotFound> {};
+struct RemoteServerTimeout : StanzaErrorImpl<RemoteServerTimeout> {};
+struct ResourceConstraint : StanzaErrorImpl<ResourceConstraint> {};
+struct ServiceUnavailable : StanzaErrorImpl<ServiceUnavailable> {};
+struct SubscriptionRequired : StanzaErrorImpl<SubscriptionRequired> {};
+struct UndefinedCondition : StanzaErrorImpl<UndefinedCondition> {};
+struct UnexpectedRequest : StanzaErrorImpl<UnexpectedRequest> {};
+
+using StanzaError = std::variant<BadRequest,
+                                 Conflict,
+                                 FeatureNotImplemented,
+                                 Forbidden,
+                                 Gone,
+                                 InternalServerError,
+                                 ItemNotFound,
+                                 JidMalformed,
+                                 NotAcceptable,
+                                 NotAllowed,
+                                 NotAuthorized,
+                                 PolicyViolation,
+                                 RecipientUnavailable,
+                                 Redirect,
+                                 RegistrationRequired,
+                                 RemoteServerNotFound,
+                                 RemoteServerTimeout,
+                                 ResourceConstraint,
+                                 ServiceUnavailable,
+                                 SubscriptionRequired,
+                                 UndefinedCondition,
+                                 UnexpectedRequest,
+                                 UnknownStanzaError>;
+
+static_assert(std::is_same_v<typename std::variant_alternative_t<std::variant_size_v<StanzaError> - 1, StanzaError>, UnknownStanzaError>,
+              "'UnknownStanzaError' must be at the end of 'StanzaError' variant");
+
+}  // namespace larra::xmpp::stanza::error

library/include/larra/stream_error.hpp

@@ -52,7 +52,7 @@ struct UnknownXmppError : BaseError {
     return TryParse(element).value();
   }
   friend constexpr auto operator<<(xmlpp::Element* element, const UnknownXmppError& obj) -> void {
-    throw std::format("'{}' must never be written into the real stream!", kErrorMessage);
+    throw std::runtime_error{std::format("'{}' must never be written into the real stream!", kErrorMessage)};
   }
   [[nodiscard]] constexpr auto what() const noexcept -> const char* override {
     return kErrorMessage.data();
@@ -112,7 +112,8 @@ using StreamError = std::variant<error::stream::BadFormat,
                                  error::stream::UnsupportedVersion,
                                  error::stream::UnknownXmppError>;
 
-static_assert(!std::is_same_v<typename std::variant_alternative_t<std::variant_size_v<StreamError> - 1, StreamError>, StreamError>,
-              "'UnknownXmppError' must be at the end of 'StreamError' variant");
+static_assert(
+    std::is_same_v<typename std::variant_alternative_t<std::variant_size_v<StreamError> - 1, StreamError>, error::stream::UnknownXmppError>,
+    "'UnknownXmppError' must be at the end of 'StreamError' variant");
 
 }  // namespace larra::xmpp

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 {