Add placeholder game action to recruit units

src/openvic-simulation/map/ProvinceInstance.cpp

@@ -1,6 +1,8 @@
 #include "ProvinceInstance.hpp"
 #include "ProvinceInstanceDeps.hpp"
 
+#include <type_traits>
+
 #include "openvic-simulation/country/CountryDefinition.hpp"
 #include "openvic-simulation/country/CountryInstance.hpp"
 #include "openvic-simulation/defines/MilitaryDefines.hpp"
@@ -518,4 +520,21 @@ void ProvinceInstance::setup_pop_test_values(IssueManager const& issue_manager)
 
 memory::colony<Pop>& ProvinceInstance::get_mutable_pops() {
 	return pops;
-}
+}
+
+template<typename T>
+std::conditional_t<std::is_const_v<T>, Pop const*, Pop*> ProvinceInstance::_find_pop_by_id(T& self, const pop_id_in_province_t pop_id) {
+	if (pop_id.is_null()) {
+		return nullptr;
+	}
+
+	for (std::conditional_t<std::is_const_v<T>, Pop const&, Pop&>& pop : self.pops) {
+		if (pop.id_in_province == pop_id) {
+			return &pop;
+		}
+	}
+
+	return nullptr;
+}
+Pop* ProvinceInstance::find_pop_by_id(const pop_id_in_province_t pop_id) { return _find_pop_by_id(*this, pop_id); }
+Pop const* ProvinceInstance::find_pop_by_id(const pop_id_in_province_t pop_id) const { return _find_pop_by_id(*this, pop_id); }

src/openvic-simulation/map/ProvinceInstance.hpp

@@ -224,5 +224,11 @@ namespace OpenVic {
 
 		void setup_pop_test_values(IssueManager const& issue_manager);
 		memory::colony<Pop>& get_mutable_pops();
+	private:
+		template<typename T>
+		static std::conditional_t<std::is_const_v<T>, Pop const*, Pop*> _find_pop_by_id(T& self, const pop_id_in_province_t pop_id);
+	public:
+		Pop* find_pop_by_id(const pop_id_in_province_t pop_id);
+		Pop const* find_pop_by_id(const pop_id_in_province_t pop_id) const;
 	};
 }

src/openvic-simulation/misc/GameAction.cpp

@@ -1,8 +1,9 @@
 #include "GameAction.hpp"
 
+#include "openvic-simulation/core/Typedefs.hpp"
 #include "openvic-simulation/DefinitionManager.hpp"
 #include "openvic-simulation/InstanceManager.hpp"
-#include "openvic-simulation/core/Typedefs.hpp"
+#include "openvic-simulation/map/ProvinceInstance.hpp"
 
 using namespace OpenVic;
 
@@ -374,3 +375,36 @@ bool GameActionManager::VariantVisitor::operator() (set_mobilise_argument_t cons
 
 	return old_mobilise != country->is_mobilised();
 }
+
+bool GameActionManager::VariantVisitor::operator() (start_land_unit_recruitment_argument_t const& argument) const {
+	const auto [regiment_type_index, province_index, pop_id_in_province] = argument;
+
+	RegimentType const* const regiment_type = instance_manager.definition_manager
+		.get_military_manager()
+		.get_unit_type_manager()
+		.get_regiment_type_by_index(regiment_type_index);
+	if (OV_unlikely(regiment_type == nullptr)) {
+		spdlog::error_s("GAME_ACTION_START_LAND_UNIT_RECRUITMENT called with invalid regiment type index: {}", regiment_type_index);
+		return false;
+	}
+
+	ProvinceInstance* province = instance_manager
+		.get_map_instance()
+		.get_province_instance_by_index(province_index);
+	if (OV_unlikely(province == nullptr)) {
+		spdlog::error_s("GAME_ACTION_START_LAND_UNIT_RECRUITMENT called with invalid province index: {}", province_index);
+		return false;
+	}
+
+	Pop* pop = province->find_pop_by_id(pop_id_in_province);
+	if (OV_unlikely(pop == nullptr)) {
+		spdlog::error_s("GAME_ACTION_START_LAND_UNIT_RECRUITMENT called with invalid pop_id_in_province: {}", pop_id_in_province);
+		return false;
+	}
+
+	//these TODO's should be implemented in ProvinceInstance and/or some military type
+	//TODO verify pop's cultural status is acceptable for regiment type
+	//TODO verify pop is recruitable and has enough size (pop.try_recruit())
+	//TODO actually instantiate a regiment in recruitment state
+	return false;
+}

src/openvic-simulation/misc/GameAction.hpp

@@ -8,6 +8,7 @@
 
 #include <type_safe/strong_typedef.hpp>
 
+#include "openvic-simulation/population/PopIdInProvince.hpp"
 #include "openvic-simulation/types/fixed_point/FixedPoint.hpp"
 #include "openvic-simulation/types/TypedIndices.hpp"
 #include "openvic-simulation/types/UniqueId.hpp"
@@ -85,7 +86,8 @@ X(create_leader, country_index_t, unit_branch_t) \
 X(set_use_leader, unique_id_t, bool) \
 X(set_auto_create_leaders, country_index_t, bool) \
 X(set_auto_assign_leaders, country_index_t, bool) \
-X(set_mobilise, country_index_t, bool)
+X(set_mobilise, country_index_t, bool) \
+X(start_land_unit_recruitment, regiment_type_index_t, province_index_t, pop_id_in_province_t)
 // <--- ADD NEW GAME ACTIONS HERE (copy/edit an X(...) line)
 
 //the argument type alias for each game action

src/openvic-simulation/population/PopIdInProvince.hpp

@@ -13,6 +13,9 @@ namespace OpenVic {
 		type_safe::strong_typedef_op::relational_comparison<pop_id_in_province_t>,
 		type_safe::strong_typedef_op::integer_arithmetic<pop_id_in_province_t> {
 		using strong_typedef::strong_typedef;
+
+		constexpr bool is_null() const { return type_safe::get(*this) == 0; }
+    	constexpr bool operator!() const { return is_null(); }
 	};
 }
 namespace std {