1 files changed, 148 insertions, 0 deletions
diff --git a/src/discord/json.hpp b/src/discord/json.hpp
new file mode 100644
index 0000000..837080b
--- /dev/null
+++ b/src/discord/json.hpp
@@ -0,0 +1,148 @@
+#pragma once
+#include <nlohmann/json.hpp>
+#include <optional>
+#include "util.hpp"
+
+namespace detail { // more or less because idk what to name this stuff
+template<typename T>
+inline void json_direct(const ::nlohmann::json &j, const char *key, T &val) {
+    if constexpr (::util::is_optional<T>::value)
+        val = j.at(key).get<typename T::value_type>();
+    else
+        j.at(key).get_to(val);
+}
+
+template<typename T>
+inline void json_optional(const ::nlohmann::json &j, const char *key, T &val) {
+    if constexpr (::util::is_optional<T>::value) {
+        if (j.contains(key))
+            val = j.at(key).get<typename T::value_type>();
+        else
+            val = ::std::nullopt;
+    } else {
+        if (j.contains(key))
+            j.at(key).get_to(val);
+    }
+}
+
+template<typename T>
+inline void json_nullable(const ::nlohmann::json &j, const char *key, T &val) {
+    if constexpr (::util::is_optional<T>::value) {
+        const auto &at = j.at(key);
+        if (!at.is_null())
+            val = at.get<typename T::value_type>();
+        else
+            val = ::std::nullopt;
+    } else {
+        const auto &at = j.at(key);
+        if (!at.is_null())
+            at.get_to(val);
+    }
+}
+
+template<typename T>
+inline void json_optional_nullable(const ::nlohmann::json &j, const char *key, T &val) {
+    if constexpr (::util::is_optional<T>::value) {
+        if (j.contains(key)) {
+            const auto &at = j.at(key);
+            if (!at.is_null())
+                val = at.get<typename T::value_type>();
+            else
+                val = ::std::nullopt;
+        } else {
+            val = ::std::nullopt;
+        }
+    } else {
+        if (j.contains(key)) {
+            const auto &at = j.at(key);
+            if (!at.is_null())
+                at.get_to(val);
+        }
+    }
+}
+
+template<typename T>
+inline void json_update_optional_nullable(const ::nlohmann::json &j, const char *key, T &val) {
+    if constexpr (::util::is_optional<T>::value) {
+        if (j.contains(key)) {
+            const auto &at = j.at(key);
+            if (!at.is_null())
+                val = at.get<typename T::value_type>();
+            else
+                val = ::std::nullopt;
+        }
+    } else {
+        if (j.contains(key)) {
+            const auto &at = j.at(key);
+            if (!at.is_null())
+                at.get_to(val);
+            else
+                val = T();
+        }
+    }
+}
+
+template<typename T, typename U>
+inline void json_update_optional_nullable_default(const ::nlohmann::json &j, const char *key, T &val, const U &fallback) {
+    if constexpr (::util::is_optional<T>::value) {
+        if (j.contains(key)) {
+            const auto &at = j.at(key);
+            if (at.is_null())
+                val = fallback;
+            else
+                val = at.get<typename T::value_type>();
+        }
+    } else {
+        if (j.contains(key)) {
+            const auto &at = j.at(key);
+            if (at.is_null())
+                val = fallback;
+            else
+                at.get_to(val);
+        }
+    }
+}
+} // namespace detail
+
+// get a json value that is guaranteed to be present and non-null
+#define JS_D(k, t)                    \
+    do {                              \
+        detail::json_direct(j, k, t); \
+    } while (0)
+
+// get a json value that may not be present
+#define JS_O(k, t)                      \
+    do {                                \
+        detail::json_optional(j, k, t); \
+    } while (0)
+
+// get a json value that may be null
+#define JS_N(k, t)                      \
+    do {                                \
+        detail::json_nullable(j, k, t); \
+    } while (0)
+
+// get a json value that may not be present or may be null
+#define JS_ON(k, t)                              \
+    do {                                         \
+        detail::json_optional_nullable(j, k, t); \
+    } while (0)
+
+// set from a json value only if it is present. null will assign default-constructed value
+#define JS_RD(k, t)                                     \
+    do {                                                \
+        detail::json_update_optional_nullable(j, k, t); \
+    } while (0)
+
+// set from a json value only if it is present. null will assign the given default
+#define JS_RV(k, t, d)                                             \
+    do {                                                           \
+        detail::json_update_optional_nullable_default(j, k, t, d); \
+    } while (0)
+
+// set a json value from a std::optional only if it has a value
+#define JS_IF(k, v)        \
+    do {                   \
+        if (v.has_value()) \
+            j[k] = *v;     \
+    } while (0)