4 files changed, 389 insertions, 141 deletions

diff --git a/src/openvic-simulation/map/Map.cpp b/src/openvic-simulation/map/Map.cpp
index 1e68cc6..ec4691d 100644
--- a/src/openvic-simulation/map/Map.cpp
+++ b/src/openvic-simulation/map/Map.cpp
@@ -25,6 +25,10 @@ Mapmode::base_stripe_t Mapmode::get_base_stripe_colours(Map const& map, Province
 	return colour_func ? colour_func(map, province) : NULL_COLOUR;
 }
 
+Map::Map()
+  : width { 0 }, height { 0 }, max_provinces { Province::MAX_INDEX }, selected_province_index { Province::NULL_INDEX },
+  	highest_province_population { 0 }, total_map_population { 0 } {}
+
 bool Map::add_province(std::string_view identifier, colour_t colour) {
 	if (provinces.size() >= max_provinces) {
 		Logger::error(
@@ -69,7 +73,7 @@ bool Map::set_water_province(std::string_view identifier) {
 		Logger::error("Unrecognised water province identifier: ", identifier);
 		return false;
 	}
-	if (province->get_water()) {
+	if (province->is_water()) {
 		Logger::warning("Province ", identifier, " is already a water province!");
 		return true;
 	}
@@ -172,41 +176,21 @@ bool Map::set_max_provinces(Province::index_t new_max_provinces) {
 	return true;
 }
 
-Province::index_t Map::get_max_provinces() const {
-	return max_provinces;
-}
-
 void Map::set_selected_province(Province::index_t index) {
 	if (index > get_province_count()) {
 		Logger::error(
 			"Trying to set selected province to an invalid index ", index, " (max index is ", get_province_count(), ")"
 		);
-		selected_province = Province::NULL_INDEX;
+		selected_province_index = Province::NULL_INDEX;
 	} else {
-		selected_province = index;
+		selected_province_index = index;
 	}
 }
 
-Province::index_t Map::get_selected_province_index() const {
-	return selected_province;
-}
-
 Province const* Map::get_selected_province() const {
 	return get_province_by_index(get_selected_province_index());
 }
 
-size_t Map::get_width() const {
-	return width;
-}
-
-size_t Map::get_height() const {
-	return height;
-}
-
-std::vector<Map::shape_pixel_t> const& Map::get_province_shape_image() const {
-	return province_shape_image;
-}
-
 bool Map::add_mapmode(std::string_view identifier, Mapmode::colour_func_t colour_func) {
 	if (identifier.empty()) {
 		Logger::error("Invalid mapmode identifier - empty!");
@@ -265,10 +249,6 @@ void Map::update_highest_province_population() {
 	}
 }
 
-Pop::pop_size_t Map::get_highest_province_population() const {
-	return highest_province_population;
-}
-
 void Map::update_total_map_population() {
 	total_map_population = 0;
 	for (Province const& province : provinces.get_items()) {
@@ -276,10 +256,6 @@ void Map::update_total_map_population() {
 	}
 }
 
-Pop::pop_size_t Map::get_total_map_population() const {
-	return total_map_population;
-}
-
 bool Map::reset(BuildingTypeManager const& building_type_manager) {
 	bool ret = true;
 	for (Province& province : provinces.get_items()) {
@@ -291,7 +267,7 @@ bool Map::reset(BuildingTypeManager const& building_type_manager) {
 bool Map::apply_history_to_provinces(ProvinceHistoryManager const& history_manager, Date date) {
 	bool ret = true;
 	for (Province& province : provinces.get_items()) {
-		if (!province.get_water()) {
+		if (!province.is_water()) {
 			ProvinceHistoryMap const* history_map = history_manager.get_province_history(&province);
 			if (history_map != nullptr) {
 				ProvinceHistoryEntry const* pop_history_entry = nullptr;
@@ -496,46 +472,39 @@ bool Map::load_map_images(fs::path const& province_path, fs::path const& terrain
 	uint8_t const* province_data = province_bmp.get_pixel_data().data();
 	uint8_t const* terrain_data = terrain_bmp.get_pixel_data().data();
 
-	std::vector<bool> province_checklist(provinces.size());
 	std::vector<fixed_point_map_t<TerrainType const*>> terrain_type_pixels_list(provinces.size());
+
 	bool ret = true;
 	std::unordered_set<colour_t> unrecognised_province_colours;
-	
+
 	std::vector<fixed_point_t> pixels_per_province(provinces.size());
-	std::vector<fixed_point_t> x_sum_per_province(provinces.size());
-	std::vector<fixed_point_t> y_sum_per_province(provinces.size());
+	std::vector<fvec2_t> pixel_position_sum_per_province(provinces.size());
 
-	for (size_t y = 0; y < height; ++y) {
-		for (size_t x = 0; x < width; ++x) {
+	for (int32_t y = 0; y < height; ++y) {
+		for (int32_t x = 0; x < width; ++x) {
 			const size_t pixel_index = x + y * width;
 			const colour_t province_colour = colour_at(province_data, pixel_index);
+			Province::index_t province_index = Province::NULL_INDEX;
 
 			if (x > 0) {
 				const size_t jdx = pixel_index - 1;
 				if (colour_at(province_data, jdx) == province_colour) {
-					province_shape_image[pixel_index].index = province_shape_image[jdx].index;
-					goto set_terrain;
+					province_index = province_shape_image[jdx].index;
+					goto index_found;
 				}
 			}
 
 			if (y > 0) {
 				const size_t jdx = pixel_index - width;
 				if (colour_at(province_data, jdx) == province_colour) {
-					province_shape_image[pixel_index].index = province_shape_image[jdx].index;
-					goto set_terrain;
+					province_index = province_shape_image[jdx].index;
+					goto index_found;
 				}
 			}
 
-			{
-				const Province::index_t province_index = get_index_from_colour(province_colour);
-				if (province_index != Province::NULL_INDEX) {
-					province_checklist[province_index - 1] = true;
-					province_shape_image[pixel_index].index = province_index;
-					goto set_terrain;
-				}
-			}
+			province_index = get_index_from_colour(province_colour);
 
-			if (!unrecognised_province_colours.contains(province_colour)) {
+			if (province_index == Province::NULL_INDEX && !unrecognised_province_colours.contains(province_colour)) {
 				unrecognised_province_colours.insert(province_colour);
 				if (detailed_errors) {
 					Logger::warning(
@@ -544,27 +513,26 @@ bool Map::load_map_images(fs::path const& province_path, fs::path const& terrain
 				}
 			}
 
-			province_shape_image[pixel_index].index = Province::NULL_INDEX;
+		index_found:
+			province_shape_image[pixel_index].index = province_index;
 
-		set_terrain:
-			const Province::index_t province_index = province_shape_image[pixel_index].index;			
 			if (province_index != Province::NULL_INDEX) {
-				const uint16_t array_index = province_index - 1;
+				const Province::index_t array_index = province_index - 1;
 				pixels_per_province[array_index]++;
-				x_sum_per_province[array_index] += x;
-				y_sum_per_province[array_index] += y;
+				pixel_position_sum_per_province[array_index] += static_cast<fvec2_t>(ivec2_t { x, y });
 			}
 
 			const TerrainTypeMapping::index_t terrain = terrain_data[pixel_index];
 			TerrainTypeMapping const* mapping = terrain_type_manager.get_terrain_type_mapping_for(terrain);
 			if (mapping != nullptr) {
-
 				if (province_index != Province::NULL_INDEX) {
 					terrain_type_pixels_list[province_index - 1][&mapping->get_type()]++;
 				}
-
-				province_shape_image[pixel_index].terrain =
-					mapping->get_has_texture() && terrain < terrain_type_manager.get_terrain_texture_limit() ? terrain + 1 : 0;
+				if (mapping->get_has_texture() && terrain < terrain_type_manager.get_terrain_texture_limit()) {
+					province_shape_image[pixel_index].terrain = terrain + 1;
+				} else {
+					province_shape_image[pixel_index].terrain = 0;
+				}
 			} else {
 				province_shape_image[pixel_index].terrain = 0;
 			}
@@ -576,23 +544,19 @@ bool Map::load_map_images(fs::path const& province_path, fs::path const& terrain
 	}
 
 	size_t missing = 0;
-	for (size_t array_index = 0; array_index < province_checklist.size(); ++array_index) {
+	for (size_t array_index = 0; array_index < provinces.size(); ++array_index) {
 		Province* province = provinces.get_item_by_index(array_index);
+
+		fixed_point_map_t<TerrainType const*> const& terrain_type_pixels = terrain_type_pixels_list[array_index];
+		const fixed_point_map_const_iterator_t<TerrainType const*> largest = get_largest_item(terrain_type_pixels);
+		province->default_terrain_type = largest != terrain_type_pixels.end() ? largest->first : nullptr;
+
 		const fixed_point_t pixel_count = pixels_per_province[array_index];
-		if(pixel_count > 0) {
-			const fixed_point_t x = x_sum_per_province[array_index] / pixel_count;
-			const fixed_point_t y = y_sum_per_province[array_index] / pixel_count;
-			const fvec2_t center { x, y };
-			province->positions.center = center;
-		}
-		else {
-			Logger::warning("Province ",province->index," has no pixels");
-		}
+		province->on_map = pixel_count > 0;
 
-		const fixed_point_map_const_iterator_t<TerrainType const*> largest = get_largest_item(terrain_type_pixels_list[array_index]);
-		province->default_terrain_type = largest != terrain_type_pixels_list[array_index].end() ? largest->first : nullptr;
-		province->on_map = province_checklist[array_index];
-		if (!province->on_map) {
+		if (province->on_map) {
+			province->positions.centre = pixel_position_sum_per_province[array_index] / pixel_count;
+		} else {
 			if (detailed_errors) {
 				Logger::warning("Province missing from shape image: ", province->to_string());
 			}
@@ -609,15 +573,13 @@ bool Map::load_map_images(fs::path const& province_path, fs::path const& terrain
 /* REQUIREMENTS:
  * MAP-19, MAP-84
  */
-bool Map::_generate_province_adjacencies() {
+bool Map::_generate_standard_province_adjacencies() {
 	bool changed = false;
 
-	auto generate_adjacency = [&](Province* current, size_t x, size_t y) -> bool {
+	const auto generate_adjacency = [this, &changed](Province* current, size_t x, size_t y) -> bool {
 		Province* neighbour = get_province_by_index(province_shape_image[x + y * width].index);
-		if (neighbour != nullptr && current != neighbour) {
-			const Province::distance_t distance = current->calculate_distance_to(neighbour);
-			const Province::flags_t flags = 0;
-			return current->add_adjacency(neighbour, distance, flags) | neighbour->add_adjacency(current, distance, flags);
+		if (neighbour != nullptr) {
+			return Province::add_standard_adjacency(*current, *neighbour);
 		}
 		return false;
 	};
@@ -638,8 +600,64 @@ bool Map::_generate_province_adjacencies() {
 	return changed;
 }
 
-bool Map::generate_and_load_province_adjacencies(std::vector<ovdl::csv::LineObject> const& additional_adjacencies) {
-	bool ret = _generate_province_adjacencies();
-	// TODO - DEV TASK: read additional adjacencies
+bool Map::generate_and_load_province_adjacencies(std::vector<LineObject> const& additional_adjacencies) {
+	bool ret = _generate_standard_province_adjacencies();
+	if (!ret) {
+		Logger::error("Failed to generate standard province adjacencies!");
+	}
+	/* Skip first line containing column headers */
+	if (additional_adjacencies.size() <= 1) {
+		Logger::error("No entries in province adjacencies file!");
+		return false;
+	}
+	std::for_each(
+		additional_adjacencies.begin() + 1, additional_adjacencies.end(), [this, &ret](LineObject const& adjacency) -> void {
+			const std::string_view from_str = adjacency.get_value_for(0);
+			if (from_str.empty() || from_str.front() == '#') {
+				return;
+			}
+			Province* const from = get_province_by_identifier(from_str);
+			if (from == nullptr) {
+				Logger::error("Unrecognised adjacency from province identifier: \"", from_str, "\"");
+				ret = false;
+				return;
+			}
+
+			const std::string_view to_str = adjacency.get_value_for(1);
+			Province* const to = get_province_by_identifier(to_str);
+			if (to == nullptr) {
+				Logger::error("Unrecognised adjacency to province identifier: \"", to_str, "\"");
+				ret = false;
+				return;
+			}
+
+			using enum Province::adjacency_t::type_t;
+			static const string_map_t<Province::adjacency_t::type_t> type_map {
+				{ "land", LAND }, { "sea", STRAIT }, { "impassable", IMPASSABLE }, { "canal", CANAL }
+			};
+			const std::string_view type_str = adjacency.get_value_for(2);
+			const string_map_t<Province::adjacency_t::type_t>::const_iterator it = type_map.find(type_str);
+			if (it == type_map.end()) {
+				Logger::error("Invalid adjacency type: \"", type_str, "\"");
+				ret = false;
+				return;
+			}
+			const Province::adjacency_t::type_t type = it->second;
+
+			Province const* const through = get_province_by_identifier(adjacency.get_value_for(3));
+
+			const std::string_view data_str = adjacency.get_value_for(4);
+			bool successful = false;
+			const uint64_t data_uint = StringUtils::string_to_uint64(data_str, &successful);
+			if (!successful || data_uint > std::numeric_limits<Province::adjacency_t::data_t>::max()) {
+				Logger::error("Invalid adjacency data: \"", data_str, "\"");
+				ret = false;
+				return;
+			}
+			const Province::adjacency_t::data_t data = data_uint;
+
+			ret &= Province::add_special_adjacency(*from, *to, type, through, data);
+		}
+	);
 	return ret;
 }
diff --git a/src/openvic-simulation/map/Map.hpp b/src/openvic-simulation/map/Map.hpp
index 16d12a8..185e99e 100644
--- a/src/openvic-simulation/map/Map.hpp
+++ b/src/openvic-simulation/map/Map.hpp
@@ -59,20 +59,24 @@ namespace OpenVic {
 		ProvinceSet water_provinces;
 		TerrainTypeManager PROPERTY_REF(terrain_type_manager);
 
-		size_t width = 0, height = 0;
-		std::vector<shape_pixel_t> province_shape_image;
+		int32_t PROPERTY(width);
+		int32_t PROPERTY(height);
+		std::vector<shape_pixel_t> PROPERTY(province_shape_image);
 		colour_index_map_t colour_index_map;
 
-		Province::index_t max_provinces = Province::MAX_INDEX;
-		Province::index_t selected_province = Province::NULL_INDEX;
-		Pop::pop_size_t highest_province_population, total_map_population;
+		Province::index_t PROPERTY(max_provinces);
+		Province::index_t PROPERTY(selected_province_index);
+		Pop::pop_size_t PROPERTY(highest_province_population)
+		Pop::pop_size_t PROPERTY(total_map_population);
 
 		Province::index_t get_index_from_colour(colour_t colour) const;
-		bool _generate_province_adjacencies();
+		bool _generate_standard_province_adjacencies();
 
 		StateManager PROPERTY_REF(state_manager);
 
 	public:
+		Map();
+
 		bool add_province(std::string_view identifier, colour_t colour);
 		IDENTIFIER_REGISTRY_NON_CONST_ACCESSORS_CUSTOM_INDEX_OFFSET(province, 1);
 
@@ -82,15 +86,9 @@ namespace OpenVic {
 
 		Province::index_t get_province_index_at(size_t x, size_t y) const;
 		bool set_max_provinces(Province::index_t new_max_provinces);
-		Province::index_t get_max_provinces() const;
 		void set_selected_province(Province::index_t index);
-		Province::index_t get_selected_province_index() const;
 		Province const* get_selected_province() const;
 
-		size_t get_width() const;
-		size_t get_height() const;
-		std::vector<shape_pixel_t> const& get_province_shape_image() const;
-
 		bool add_region(std::string_view identifier, std::vector<std::string_view> const& province_identifiers);
 		IDENTIFIER_REGISTRY_NON_CONST_ACCESSORS(region)
 
@@ -107,14 +105,13 @@ namespace OpenVic {
 		bool apply_history_to_provinces(ProvinceHistoryManager const& history_manager, Date date);
 
 		void update_highest_province_population();
-		Pop::pop_size_t get_highest_province_population() const;
 		void update_total_map_population();
-		Pop::pop_size_t get_total_map_population() const;
 
 		void update_state(Date today);
 		void tick(Date today);
 
 		bool load_province_definitions(std::vector<ovdl::csv::LineObject> const& lines);
+		/* Must be loaded after adjacencies so we know what provinces are coastal, and so can have a port */
 		bool load_province_positions(BuildingTypeManager const& building_type_manager, ast::NodeCPtr root);
 		bool load_region_file(ast::NodeCPtr root);
 		bool load_map_images(fs::path const& province_path, fs::path const& terrain_path, bool detailed_errors);
diff --git a/src/openvic-simulation/map/Province.cpp b/src/openvic-simulation/map/Province.cpp
index 717ef35..6f1a0f6 100644
--- a/src/openvic-simulation/map/Province.cpp
+++ b/src/openvic-simulation/map/Province.cpp
@@ -7,14 +7,18 @@ using namespace OpenVic::NodeTools;
 
 Province::Province(
 	std::string_view new_identifier, colour_t new_colour, index_t new_index
-) : HasIdentifierAndColour { new_identifier, new_colour, true, false }, index { new_index },
-	region { nullptr }, on_map { false }, has_region { false }, water { false }, default_terrain_type { nullptr },
-	positions {}, terrain_type { nullptr }, life_rating { 0 }, colony_status { colony_status_t::STATE }, owner { nullptr },
-	controller { nullptr }, slave { false }, crime { nullptr }, rgo { nullptr }, buildings { "buildings", false },
-	total_population { 0 } {
+) : HasIdentifierAndColour { new_identifier, new_colour, true, false }, index { new_index }, region { nullptr },
+	on_map { false }, has_region { false }, water { false }, coastal { false }, port { false },
+	default_terrain_type { nullptr }, positions {}, terrain_type { nullptr }, life_rating { 0 },
+	colony_status { colony_status_t::STATE }, state { nullptr }, owner { nullptr }, controller { nullptr }, slave { false },
+	crime { nullptr }, rgo { nullptr }, buildings { "buildings", false }, total_population { 0 } {
 	assert(index != NULL_INDEX);
 }
 
+bool Province::operator==(Province const& other) const {
+	return this == &other;
+}
+
 std::string Province::to_string() const {
 	std::stringstream stream;
 	stream << "(#" << std::to_string(index) << ", " << get_identifier() << ", 0x" << colour_to_hex_string() << ")";
@@ -22,7 +26,7 @@ std::string Province::to_string() const {
 }
 
 bool Province::load_positions(BuildingTypeManager const& building_type_manager, ast::NodeCPtr root) {
-	return expect_dictionary_keys(
+	const bool ret = expect_dictionary_keys(
 		"text_position", ZERO_OR_ONE, expect_fvec2(assign_variable_callback(positions.text)),
 		"text_rotation", ZERO_OR_ONE, expect_fixed_point(assign_variable_callback(positions.text_rotation)),
 		"text_scale", ZERO_OR_ONE, expect_fixed_point(assign_variable_callback(positions.text_scale)),
@@ -48,6 +52,10 @@ bool Province::load_positions(BuildingTypeManager const& building_type_manager,
 		"railroad_visibility", ZERO_OR_ONE, success_callback,
 		"building_nudge", ZERO_OR_ONE, success_callback
 	)(root);
+
+	port = coastal && positions.building_position.contains(building_type_manager.get_port_building_type());
+
+	return ret;
 }
 
 bool Province::expand_building(std::string_view building_type_identifier) {
@@ -59,7 +67,7 @@ bool Province::expand_building(std::string_view building_type_identifier) {
 }
 
 bool Province::add_pop(Pop&& pop) {
-	if (!get_water()) {
+	if (!is_water()) {
 		pops.push_back(std::move(pop));
 		return true;
 	} else {
@@ -69,7 +77,7 @@ bool Province::add_pop(Pop&& pop) {
 }
 
 bool Province::add_pop_vec(std::vector<Pop> const& pop_vec) {
-	if (!get_water()) {
+	if (!is_water()) {
 		pops.reserve(pops.size() + pop_vec.size());
 		for (Pop const& pop : pop_vec) {
 			pops.push_back(pop);
@@ -116,57 +124,241 @@ void Province::tick(Date today) {
 	}
 }
 
-Province::adjacency_t::adjacency_t(Province const* province, distance_t distance, flags_t flags)
-	: province { province }, distance { distance }, flags { flags } {
-	assert(province != nullptr);
+Province::adjacency_t::adjacency_t(
+	Province const* new_to, distance_t new_distance, type_t new_type, Province const* new_through, data_t new_data
+) : to { new_to }, distance { new_distance }, type { new_type }, through { new_through }, data { new_data } {}
+
+std::string_view Province::adjacency_t::get_type_name(type_t type) {
+	switch (type) {
+	case type_t::LAND: return "Land";
+	case type_t::WATER: return "Water";
+	case type_t::COASTAL: return "Coastal";
+	case type_t::IMPASSABLE: return "Impassable";
+	case type_t::STRAIT: return "Strait";
+	case type_t::CANAL: return "Canal";
+	default: return "Invalid Adjacency Type";
+	}
+}
+
+Province::adjacency_t* Province::get_adjacency_to(Province const* province) {
+	const std::vector<adjacency_t>::iterator it = std::find_if(adjacencies.begin(), adjacencies.end(),
+		[province](adjacency_t const& adj) -> bool { return adj.get_to() == province; }
+	);
+	if (it != adjacencies.end()) {
+		return &*it;
+	} else {
+		return nullptr;
+	}
+}
+
+Province::adjacency_t const* Province::get_adjacency_to(Province const* province) const {
+	const std::vector<adjacency_t>::const_iterator it = std::find_if(adjacencies.begin(), adjacencies.end(),
+		[province](adjacency_t const& adj) -> bool { return adj.get_to() == province; }
+	);
+	if (it != adjacencies.end()) {
+		return &*it;
+	} else {
+		return nullptr;
+	}
 }
 
 bool Province::is_adjacent_to(Province const* province) const {
-	for (adjacency_t adj : adjacencies) {
-		if (adj.province == province) {
-			return true;
+	return province != nullptr && std::any_of(adjacencies.begin(), adjacencies.end(),
+		[province](adjacency_t const& adj) -> bool { return adj.get_to() == province; }
+	);
+}
+
+std::vector<Province::adjacency_t const*> Province::get_adjacencies_going_through(Province const* province) const {
+	std::vector<adjacency_t const*> ret;
+	for (adjacency_t const& adj : adjacencies) {
+		if (adj.get_through() == province) {
+			ret.push_back(&adj);
 		}
 	}
-	return false;
+	return ret;
+}
+
+bool Province::has_adjacency_going_through(Province const* province) const {
+	return province != nullptr && std::any_of(adjacencies.begin(), adjacencies.end(),
+		[province](adjacency_t const& adj) -> bool { return adj.get_through() == province; }
+	);
 }
 
-bool Province::add_adjacency(Province const* province, distance_t distance, flags_t flags) {
-	if (province == nullptr) {
-		Logger::error("Tried to create null adjacency province for province ", get_identifier(), "!");
+/* This is called for all adjacent pixel pairs and returns whether or not a new adjacency was add,
+ * hence the lack of error messages in the false return cases. */
+bool Province::add_standard_adjacency(Province& from, Province& to) {
+	if (from == to) {
 		return false;
 	}
-	if (is_adjacent_to(province)) {
+
+	const bool from_needs_adjacency = !from.is_adjacent_to(&to);
+	const bool to_needs_adjacency = !to.is_adjacent_to(&from);
+
+	if (!from_needs_adjacency && !to_needs_adjacency) {
 		return false;
 	}
-	adjacencies.push_back({ province, distance, flags });
+
+	const distance_t distance = calculate_distance_between(from, to);
+
+	using enum adjacency_t::type_t;
+
+	/* Default land-to-land adjacency */
+	adjacency_t::type_t type = LAND;
+	if (from.is_water() != to.is_water()) {
+		/* Land-to-water adjacency */
+		type = COASTAL;
+
+		/* Mark the land province as coastal */
+		from.coastal = !from.is_water();
+		to.coastal = !to.is_water();
+	} else if (from.is_water()) {
+		/* Water-to-water adjacency */
+		type = WATER;
+	}
+
+	if (from_needs_adjacency) {
+		from.adjacencies.emplace_back(&to, distance, type, nullptr, 0);
+	}
+	if (to_needs_adjacency) {
+		to.adjacencies.emplace_back(&from, distance, type, nullptr, 0);
+	}
 	return true;
 }
 
+bool Province::add_special_adjacency(
+	Province& from, Province& to, adjacency_t::type_t type, Province const* through, adjacency_t::data_t data
+) {
+	if (from == to) {
+		Logger::error("Trying to add ", adjacency_t::get_type_name(type), " adjacency from province ", from, " to itself!");
+		return false;
+	}
+
+	using enum adjacency_t::type_t;
+
+	/* Check end points */
+	switch (type) {
+	case LAND:
+	case IMPASSABLE:
+	case STRAIT:
+		if (from.is_water() || to.is_water()) {
+			Logger::error(adjacency_t::get_type_name(type), " adjacency from ", from, " to ", to, " has water endpoint(s)!");
+			return false;
+		}
+		break;
+	case WATER:
+	case CANAL:
+		if (!from.is_water() || !to.is_water()) {
+			Logger::error(adjacency_t::get_type_name(type), " adjacency from ", from, " to ", to, " has land endpoint(s)!");
+			return false;
+		}
+		break;
+	case COASTAL:
+		if (from.is_water() == to.is_water()) {
+			Logger::error("Coastal adjacency from ", from, " to ", to, " has both land or water endpoints!");
+			return false;
+		}
+		break;
+	default:
+		Logger::error("Invalid adjacency type ", static_cast<uint32_t>(type));
+		return false;
+	}
+
+	/* Check through province */
+	if (type == STRAIT || type == CANAL) {
+		const bool water_expected = type == STRAIT;
+		if (through == nullptr || through->is_water() != water_expected) {
+			Logger::error(
+				adjacency_t::get_type_name(type), " adjacency from ", from, " to ", to, " has a ",
+				(through == nullptr ? "null" : water_expected ? "land" : "water"), " through province ", through
+			);
+			return false;
+		}
+	} else if (through != nullptr) {
+		Logger::warning(
+			adjacency_t::get_type_name(type), " adjacency from ", from, " to ", to, " has a non-null through province ",
+			through
+		);
+		through = nullptr;
+	}
+
+	/* Check canal data */
+	if (data != adjacency_t::NO_CANAL && type != CANAL) {
+		Logger::warning(
+			adjacency_t::get_type_name(type), " adjacency from ", from, " to ", to, " has invalid data ",
+			static_cast<uint32_t>(data)
+		);
+		data = adjacency_t::NO_CANAL;
+	}
+
+	const distance_t distance = calculate_distance_between(from, to);
+
+	const auto add_adjacency = [distance, type, through, data](Province& from, Province const& to) -> bool {
+		adjacency_t* existing_adjacency = from.get_adjacency_to(&to);
+		if (existing_adjacency != nullptr) {
+			if (type == existing_adjacency->get_type()) {
+				Logger::warning(
+					"Adjacency from ", from, " to ", to, " already has type ", adjacency_t::get_type_name(type), "!"
+				);
+				if (type != STRAIT && type != CANAL) {
+					/* Straits and canals might change through or data, otherwise we can exit early */
+					return true;
+				}
+			}
+			if (type != IMPASSABLE && type != STRAIT && type != CANAL) {
+				Logger::error(
+					"Provinces ", from, " and ", to, " already have an existing ",
+					adjacency_t::get_type_name(existing_adjacency->get_type()), " adjacency, cannot create a ",
+					adjacency_t::get_type_name(type), " adjacency!"
+				);
+				return false;
+			}
+			if (type != existing_adjacency->get_type() && existing_adjacency->get_type() != (type == CANAL ? WATER : LAND)) {
+				Logger::error(
+					"Cannot convert ", adjacency_t::get_type_name(existing_adjacency->get_type()), " adjacency from ", from,
+					" to ", to, " to type ", adjacency_t::get_type_name(type), "!"
+				);
+				return false;
+			}
+			*existing_adjacency = { &to, distance, type, through, data };
+			return true;
+		} else if (type == IMPASSABLE) {
+			Logger::warning(
+				"Provinces ", from, " and ", to, " do not have an existing adjacency to make impassable!"
+			);
+			return true;
+		} else {
+			from.adjacencies.emplace_back(&to, distance, type, through, data);
+			return true;
+		}
+	};
+
+	return add_adjacency(from, to) & add_adjacency(to, from);
+}
+
 fvec2_t Province::get_unit_position() const {
-	return positions.unit.value_or(positions.center);
+	return positions.unit.value_or(positions.centre);
 }
 
-Province::distance_t Province::calculate_distance_to(Province const* province) const {
-	const fvec2_t my_unit_position = get_unit_position();
-	const fvec2_t other_unit_position = province->get_unit_position();
-	const fvec2_t distance_vector = other_unit_position - my_unit_position;
-	const fixed_point_t distance = distance_vector.length_squared();
-	return static_cast<Province::distance_t>(distance);
+Province::distance_t Province::calculate_distance_between(Province const& from, Province const& to) {
+	const fvec2_t distance_vector = to.get_unit_position() - from.get_unit_position();
+	return distance_vector.length_squared(); // TODO - replace with length using deterministic fixed point square root
 }
 
 bool Province::reset(BuildingTypeManager const& building_type_manager) {
 	terrain_type = default_terrain_type;
 	life_rating = 0;
 	colony_status = colony_status_t::STATE;
+	state = nullptr;
 	owner = nullptr;
 	controller = nullptr;
 	cores.clear();
 	slave = false;
+	crime = nullptr;
 	rgo = nullptr;
 
 	buildings.reset();
 	bool ret = true;
-	if (!get_water()) {
+	if (!is_water()) {
 		if (building_type_manager.building_types_are_locked()) {
 			for (BuildingType const& building_type : building_type_manager.get_building_types()) {
 				if (building_type.get_in_province()) {
@@ -232,6 +424,6 @@ bool Province::apply_history_to_province(ProvinceHistoryEntry const* entry) {
 		}
 	}
 	// TODO: load state buildings
-	// TODO: party loyalties for each POP when implemented on POP side#
+	// TODO: party loyalties for each POP when implemented on POP side
 	return ret;
 }
diff --git a/src/openvic-simulation/map/Province.hpp b/src/openvic-simulation/map/Province.hpp
index 2f8068e..844ca63 100644
--- a/src/openvic-simulation/map/Province.hpp
+++ b/src/openvic-simulation/map/Province.hpp
@@ -27,26 +27,52 @@ namespace OpenVic {
 		using index_t = uint16_t;
 		using life_rating_t = int8_t;
 		using distance_t = fixed_point_t;
-		using flags_t = uint16_t;
 
 		enum struct colony_status_t : uint8_t { STATE, PROTECTORATE, COLONY };
 
 		struct adjacency_t {
-			friend struct Province;
+			using data_t = uint8_t;
+			static constexpr data_t NO_CANAL = 0;
 
-		private:
-			Province const* const province;
-			const distance_t PROPERTY(distance);
-			flags_t PROPERTY(flags);
+			enum struct type_t : uint8_t {
+				LAND,       /* Between two land provinces */
+				WATER,      /* Between two water provinces */
+				COASTAL,    /* Between a land province and a water province */
+				IMPASSABLE, /* Between two land provinces (non-traversable) */
+				STRAIT,     /* Between two land provinces with a water through province */
+				CANAL       /* Between two water provinces with a land through province */
+			};
+
+			/* Type display name used for logging */
+			static std::string_view get_type_name(type_t type);
 
-			adjacency_t(Province const* province, distance_t distance, flags_t flags);
+		private:
+			Province const* PROPERTY(to);
+			Province const* PROPERTY(through);
+			distance_t PROPERTY(distance);
+			type_t PROPERTY(type);
+			data_t PROPERTY(data); // represents canal index, 0 for non-canal adjacencies
+
+		public:
+			adjacency_t(
+				Province const* new_to, distance_t new_distance, type_t new_type, Province const* new_through, data_t new_data
+			);
+			adjacency_t(adjacency_t const&) = delete;
+			adjacency_t(adjacency_t&&) = default;
+			adjacency_t& operator=(adjacency_t const&) = delete;
+			adjacency_t& operator=(adjacency_t&&) = default;
 		};
 
 		struct province_positions_t {
-			fvec2_t center;
+			/* Calculated average */
+			fvec2_t centre;
+
+			/* Province name placement */
 			fvec2_t text;
 			fixed_point_t text_rotation;
 			fixed_point_t text_scale;
+
+			/* Model positions */
 			std::optional<fvec2_t> unit;
 			fvec2_t city;
 			fvec2_t factory;
@@ -59,21 +85,25 @@ namespace OpenVic {
 		static constexpr index_t NULL_INDEX = 0, MAX_INDEX = std::numeric_limits<index_t>::max();
 
 	private:
+		/* Immutable attributes (unchanged after initial game load) */
 		const index_t PROPERTY(index);
 		Region* PROPERTY(region);
-		State const* PROPERTY_RW(state);
 		bool PROPERTY(on_map);
 		bool PROPERTY(has_region);
-		bool PROPERTY(water);
+		bool PROPERTY_CUSTOM_PREFIX(water, is);
+		bool PROPERTY_CUSTOM_PREFIX(coastal, is);
+		bool PROPERTY_CUSTOM_PREFIX(port, has);
 		/* Terrain type calculated from terrain image */
 		TerrainType const* PROPERTY(default_terrain_type);
 
 		std::vector<adjacency_t> PROPERTY(adjacencies);
 		province_positions_t PROPERTY(positions);
 
+		/* Mutable attributes (reset before loading history) */
 		TerrainType const* PROPERTY(terrain_type);
 		life_rating_t PROPERTY(life_rating);
 		colony_status_t PROPERTY(colony_status);
+		State const* PROPERTY_RW(state);
 		Country const* PROPERTY(owner);
 		Country const* PROPERTY(controller);
 		std::vector<Country const*> PROPERTY(cores);
@@ -90,13 +120,12 @@ namespace OpenVic {
 		fixed_point_map_t<Culture const*> PROPERTY(culture_distribution);
 		fixed_point_map_t<Religion const*> PROPERTY(religion_distribution);
 
-		fvec2_t get_unit_position() const;
-
 		Province(std::string_view new_identifier, colour_t new_colour, index_t new_index);
 
 	public:
 		Province(Province&&) = default;
 
+		bool operator==(Province const& other) const;
 		std::string to_string() const;
 
 		bool load_positions(BuildingTypeManager const& building_type_manager, ast::NodeCPtr root);
@@ -111,10 +140,22 @@ namespace OpenVic {
 		void update_state(Date today);
 		void tick(Date today);
 
+	private:
+		adjacency_t* get_adjacency_to(Province const* province);
+
+	public:
+		adjacency_t const* get_adjacency_to(Province const* province) const;
 		bool is_adjacent_to(Province const* province) const;
-		bool add_adjacency(Province const* province, distance_t distance, flags_t flags);
+		std::vector<adjacency_t const*> get_adjacencies_going_through(Province const* province) const;
+		bool has_adjacency_going_through(Province const* province) const;
+
+		static bool add_standard_adjacency(Province& from, Province& to);
+		static bool add_special_adjacency(
+			Province& from, Province& to, adjacency_t::type_t type, Province const* through, adjacency_t::data_t data
+		);
 
-		distance_t calculate_distance_to(Province const* province) const;
+		fvec2_t get_unit_position() const;
+		static distance_t calculate_distance_between(Province const& from, Province const& to);
 
 		bool reset(BuildingTypeManager const& building_type_manager);
 		bool apply_history_to_province(ProvinceHistoryEntry const* entry);