Support Pokemon style experience gain.

src/Battling/Library/ExperienceLibrary.cpp

@@ -0,0 +1,23 @@
+#include "ExperienceLibrary.hpp"
+#include "../PkmnScriptHook.hpp"
+#include "../Pokemon/Pokemon.hpp"
+
+void PkmnLib::Battling::ExperienceLibrary::HandleExperienceGain(
+    CreatureLib::Battling::Creature* faintedMon,
+    const std::unordered_set<CreatureLib::Battling::Creature*>& opponents) const {
+
+    auto fainted = dynamic_cast<Pokemon*>(faintedMon);
+    auto expGain = fainted->GetPokemonSpecies()->GetExperienceGains();
+    auto level = fainted->GetLevel();
+    // TODO exp share
+
+    auto v1 = (expGain * level) / 5;
+
+    for (auto op : opponents) {
+        auto v2 = pow(2 * level + 10, 2.5) / pow(level + op->GetLevel() + 10, 2.5);
+        uint32_t experienceGain = v1 * v2 + 1;
+        // TODO: Check owner and international
+        PKMN_HOOK(ModifyExperienceGain, op, faintedMon, op, experienceGain);
+        op->AddExperience(experienceGain);
+    }
+}