#include "MapDefinition.hpp"

#include <cstdint>
#include <vector>

#include "openvic-simulation/types/Colour.hpp"
#include "openvic-simulation/types/OrderedContainers.hpp"
#include "openvic-simulation/types/Vector.hpp"
#include "openvic-simulation/utility/BMP.hpp"
#include "openvic-simulation/utility/Logger.hpp"

using namespace OpenVic;
using namespace OpenVic::NodeTools;

MapDefinition::MapDefinition() : dims { 0, 0 }, max_provinces { ProvinceDefinition::MAX_INDEX } {}

RiverSegment::RiverSegment(uint8_t new_size, std::vector<ivec2_t>&& new_points)
	: size { new_size }, points { std::move(new_points) } {}

bool MapDefinition::add_province_definition(std::string_view identifier, colour_t colour) {
	if (province_definitions.size() >= max_provinces) {
		Logger::error(
			"The map's province list is full - maximum number of provinces is ", max_provinces, " (this can be at most ",
			ProvinceDefinition::MAX_INDEX, ")"
		);
		return false;
	}
	if (identifier.empty()) {
		Logger::error("Invalid province identifier - empty!");
		return false;
	}
	if (!valid_basic_identifier(identifier)) {
		Logger::error(
			"Invalid province identifier: ", identifier, " (can only contain alphanumeric characters and underscores)"
		);
		return false;
	}
	if (colour.is_null()) {
		Logger::error("Invalid province colour for ", identifier, " - null! (", colour, ")");
		return false;
	}
	ProvinceDefinition new_province {
		identifier, colour, static_cast<ProvinceDefinition::index_t>(province_definitions.size() + 1)
	};
	const ProvinceDefinition::index_t index = get_index_from_colour(colour);
	if (index != ProvinceDefinition::NULL_INDEX) {
		Logger::error(
			"Duplicate province colours: ", get_province_definition_by_index(index)->to_string(), " and ",
			new_province.to_string()
		);
		return false;
	}
	colour_index_map[new_province.get_colour()] = new_province.get_index();
	return province_definitions.add_item(std::move(new_province));
}

ProvinceDefinition::distance_t MapDefinition::calculate_distance_between(
	ProvinceDefinition const& from, ProvinceDefinition const& to
) const {
	const fvec2_t to_pos = to.get_unit_position();
	const fvec2_t from_pos = from.get_unit_position();

	const fixed_point_t min_x = std::min(
		(to_pos.x - from_pos.x).abs(),
		std::min(
			(to_pos.x - from_pos.x + get_width()).abs(),
			(to_pos.x - from_pos.x - get_width()).abs()
		)
	);

	return fvec2_t { min_x, to_pos.y - from_pos.y }.length_squared().sqrt();
}

using adjacency_t = ProvinceDefinition::adjacency_t;

/* 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 MapDefinition::add_standard_adjacency(ProvinceDefinition& from, ProvinceDefinition& to) const {
	if (from == to) {
		return false;
	}

	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;
	}

	const ProvinceDefinition::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 MapDefinition::add_special_adjacency(
	ProvinceDefinition& from, ProvinceDefinition& to, adjacency_t::type_t type, ProvinceDefinition const* through,
	adjacency_t::data_t data
) const {
	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 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;
	case IMPASSABLE:
		/* Impassable is valid for all combinations of land and water:
		 * - land-land = replace existing land adjacency with impassable adjacency (blue borders)
		 * - land-water = delete existing coastal adjacency, preventing armies and navies from moving between the provinces
		 * - water-water = delete existing water adjacency, preventing navies from moving between the provinces */
		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 ProvinceDefinition::distance_t distance = calculate_distance_between(from, to);

	const auto add_adjacency = [distance, type, through, data](
		ProvinceDefinition& from, ProvinceDefinition const& to
	) -> bool {
		const std::vector<adjacency_t>::iterator existing_adjacency = std::find_if(
			from.adjacencies.begin(), from.adjacencies.end(),
			[&to](adjacency_t const& adj) -> bool { return adj.get_to() == &to; }
		);
		if (existing_adjacency != from.adjacencies.end()) {
			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) {
				if (existing_adjacency->get_type() == WATER || existing_adjacency->get_type() == COASTAL) {
					from.adjacencies.erase(existing_adjacency);
					return true;
				}
			} else {
				if (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);
}

bool MapDefinition::set_water_province(std::string_view identifier) {
	if (water_provinces.is_locked()) {
		Logger::error("The map's water provinces have already been locked!");
		return false;
	}

	ProvinceDefinition* province = get_province_definition_by_identifier(identifier);

	if (province == nullptr) {
		Logger::error("Unrecognised water province identifier: ", identifier);
		return false;
	}
	if (province->has_region()) {
		Logger::error("Province ", identifier, " cannot be water as it belongs to region \"", province->get_region(), "\"");
		return false;
	}
	if (province->is_water()) {
		Logger::warning("Province ", identifier, " is already a water province!");
		return true;
	}
	if (!water_provinces.add_province(province)) {
		Logger::error("Failed to add province ", identifier, " to water province set!");
		return false;
	}
	province->water = true;
	return true;
}

bool MapDefinition::set_water_province_list(std::vector<std::string_view> const& list) {
	if (water_provinces.is_locked()) {
		Logger::error("The map's water provinces have already been locked!");
		return false;
	}
	bool ret = true;
	water_provinces.reserve_more(list.size());
	for (std::string_view const& identifier : list) {
		ret &= set_water_province(identifier);
	}
	lock_water_provinces();
	return ret;
}

void MapDefinition::lock_water_provinces() {
	water_provinces.lock();
	Logger::info("Locked water provinces after registering ", water_provinces.size());
}

bool MapDefinition::add_region(std::string_view identifier, std::vector<ProvinceDefinition const*>&& provinces, colour_t colour) {
	if (identifier.empty()) {
		Logger::error("Invalid region identifier - empty!");
		return false;
	}

	bool ret = true;

	std::erase_if(provinces, [identifier, &ret](ProvinceDefinition const* province) -> bool {
		if (province->is_water()) {
			Logger::error(
				"Province ", province->get_identifier(), " cannot be added to region \"", identifier,
				"\" as it is a water province!"
			);
			ret = false;
			return true;
		} else {
			return false;
		}
	});

	const bool meta = provinces.empty() || std::any_of(
		provinces.begin(), provinces.end(), std::bind_front(&ProvinceDefinition::has_region)
	);

	Region region { identifier, colour, meta };
	ret &= region.add_provinces(provinces);
	region.lock();
	if (regions.add_item(std::move(region))) {
		if (!meta) {
			Region const& last_region = regions.get_items().back();
			for (ProvinceDefinition const* province : last_region.get_provinces()) {
				remove_province_definition_const(province)->region = &last_region;
			}
		}
	} else {
		ret = false;
	}
	return ret;
}

ProvinceDefinition::index_t MapDefinition::get_index_from_colour(colour_t colour) const {
	const colour_index_map_t::const_iterator it = colour_index_map.find(colour);
	if (it != colour_index_map.end()) {
		return it->second;
	}
	return ProvinceDefinition::NULL_INDEX;
}

ProvinceDefinition::index_t MapDefinition::get_province_index_at(ivec2_t pos) const {
	if (pos.nonnegative() && pos.less_than(dims)) {
		return province_shape_image[get_pixel_index_from_pos(pos)].index;
	}
	return ProvinceDefinition::NULL_INDEX;
}

ProvinceDefinition* MapDefinition::get_province_definition_at(ivec2_t pos) {
	return get_province_definition_by_index(get_province_index_at(pos));
}

ProvinceDefinition const* MapDefinition::get_province_definition_at(ivec2_t pos) const {
	return get_province_definition_by_index(get_province_index_at(pos));
}

bool MapDefinition::set_max_provinces(ProvinceDefinition::index_t new_max_provinces) {
	if (new_max_provinces <= ProvinceDefinition::NULL_INDEX) {
		Logger::error(
			"Trying to set max province count to an invalid value ", new_max_provinces, " (must be greater than ",
			ProvinceDefinition::NULL_INDEX, ")"
		);
		return false;
	}
	if (!province_definitions.empty() || province_definitions.is_locked()) {
		Logger::error(
			"Trying to set max province count to ", new_max_provinces, " after provinces have already been added and/or locked"
		);
		return false;
	}
	max_provinces = new_max_provinces;
	return true;
}

using namespace ovdl::csv;

static bool _validate_province_definitions_header(LineObject const& header) {
	static const std::vector<std::string> standard_header { "province", "red", "green", "blue" };
	for (size_t i = 0; i < standard_header.size(); ++i) {
		const std::string_view val = header.get_value_for(i);
		if (i == 0 && val.empty()) {
			break;
		}
		if (val != standard_header[i]) {
			return false;
		}
	}
	return true;
}

static bool _parse_province_colour(colour_t& colour, std::array<std::string_view, 3> components) {
	bool ret = true;
	for (size_t i = 0; i < 3; ++i) {
		std::string_view& component = components[i];
		if (component.ends_with('.')) {
			component.remove_suffix(1);
		}
		bool successful = false;
		const uint64_t val = StringUtils::string_to_uint64(component, &successful, 10);
		if (successful && val <= colour_t::max_value) {
			colour[i] = val;
		} else {
			ret = false;
		}
	}
	return ret;
}

bool MapDefinition::load_province_definitions(std::vector<LineObject> const& lines) {
	if (lines.empty()) {
		Logger::error("No header or entries in province definition file!");
		return false;
	}

	{
		LineObject const& header = lines.front();
		if (!_validate_province_definitions_header(header)) {
			Logger::error(
				"Non-standard province definition file header - make sure this is not a province definition: ", header
			);
		}
	}

	if (lines.size() <= 1) {
		Logger::error("No entries in province definition file!");
		return false;
	}

	reserve_more_province_definitions(lines.size() - 1);

	bool ret = true;
	std::for_each(lines.begin() + 1, lines.end(), [this, &ret](LineObject const& line) -> void {
		const std::string_view identifier = line.get_value_for(0);
		if (!identifier.empty()) {
			colour_t colour = colour_t::null();
			if (!_parse_province_colour(colour, { line.get_value_for(1), line.get_value_for(2), line.get_value_for(3) })) {
				Logger::error("Error reading colour in province definition: ", line);
				ret = false;
			}
			ret &= add_province_definition(identifier, colour);
		}
	});

	lock_province_definitions();

	return ret;
}

bool MapDefinition::load_province_positions(BuildingTypeManager const& building_type_manager, ast::NodeCPtr root) {
	return expect_province_definition_dictionary(
		[this, &building_type_manager](ProvinceDefinition& province, ast::NodeCPtr node) -> bool {
			return province.load_positions(*this, building_type_manager, node);
		}
	)(root);
}

bool MapDefinition::load_region_colours(ast::NodeCPtr root, std::vector<colour_t>& colours) {
	return expect_dictionary_reserve_length(
		colours,
		[&colours](std::string_view key, ast::NodeCPtr value) -> bool {
			if (key != "color") {
				Logger::error("Invalid key in region colours: \"", key, "\"");
				return false;
			}
			return expect_colour(vector_callback(colours))(value);
	})(root);
}

bool MapDefinition::load_region_file(ast::NodeCPtr root, std::vector<colour_t> const& colours) {
	const bool ret = expect_dictionary_reserve_length(
		regions,
		[this, &colours](std::string_view region_identifier, ast::NodeCPtr region_node) -> bool {
			std::vector<ProvinceDefinition const*> provinces;

			bool ret = expect_list_reserve_length(
				provinces, expect_province_definition_identifier(vector_callback_pointer(provinces))
			)(region_node);

			ret &= add_region(region_identifier, std::move(provinces), colours[regions.size() % colours.size()]);

			return ret;
		}
	)(root);

	lock_regions();

	return ret;
}

static constexpr colour_t colour_at(uint8_t const* colour_data, int32_t idx) {
	/* colour_data is filled with BGR byte triplets - to get pixel idx as a
	 * single RGB value, multiply idx by 3 to get the index of the corresponding
	 * triplet, then combine the bytes in reverse order.
	 */
	idx *= 3;
	return { colour_data[idx + 2], colour_data[idx + 1], colour_data[idx] };
}

bool MapDefinition::load_map_images(fs::path const& province_path, fs::path const& terrain_path, fs::path const& rivers_path, bool detailed_errors) {
	if (!province_definitions_are_locked()) {
		Logger::error("Province index image cannot be generated until after provinces are locked!");
		return false;
	}
	if (!terrain_type_manager.terrain_type_mappings_are_locked()) {
		Logger::error("Province index image cannot be generated until after terrain type mappings are locked!");
		return false;
	}

	static constexpr uint16_t expected_province_bpp = 24;
	static constexpr uint16_t expected_terrain_rivers_bpp = 8;

	BMP province_bmp;
	if (!(province_bmp.open(province_path) && province_bmp.read_header() && province_bmp.read_pixel_data())) {
		Logger::error("Failed to read BMP for compatibility mode province image: ", province_path);
		return false;
	}
	if (province_bmp.get_bits_per_pixel() != expected_province_bpp) {
		Logger::error(
			"Invalid province BMP bits per pixel: ", province_bmp.get_bits_per_pixel(), " (expected ", expected_province_bpp,
			")"
		);
		return false;
	}

	BMP terrain_bmp;
	if (!(terrain_bmp.open(terrain_path) && terrain_bmp.read_header() && terrain_bmp.read_pixel_data())) {
		Logger::error("Failed to read BMP for compatibility mode terrain image: ", terrain_path);
		return false;
	}
	if (terrain_bmp.get_bits_per_pixel() != expected_terrain_rivers_bpp) {
		Logger::error(
			"Invalid terrain BMP bits per pixel: ", terrain_bmp.get_bits_per_pixel(), " (expected ", expected_terrain_rivers_bpp, ")"
		);
		return false;
	}

	BMP rivers_bmp;
	if (!(rivers_bmp.open(rivers_path) && rivers_bmp.read_header() && rivers_bmp.read_pixel_data())) {
		Logger::error("Failed to read BMP for compatibility mode river image: ", rivers_path);
		return false;
	}
	if (rivers_bmp.get_bits_per_pixel() != expected_terrain_rivers_bpp) {
		Logger::error(
			"Invalid rivers BMP bits per pixel: ", rivers_bmp.get_bits_per_pixel(), " (expected ", expected_terrain_rivers_bpp, ")"
		);
		return false;
	}

	if (province_bmp.get_width() != terrain_bmp.get_width() ||
		province_bmp.get_height() != terrain_bmp.get_height() ||
		province_bmp.get_width() != rivers_bmp.get_width() ||
		province_bmp.get_height() != rivers_bmp.get_height()
	) {
		Logger::error(
			"Mismatched map BMP dims: provinces:", province_bmp.get_width(), "x", province_bmp.get_height(), ", terrain: ",
			terrain_bmp.get_width(), "x", terrain_bmp.get_height(), ", rivers: ", rivers_bmp.get_width(), "x", rivers_bmp.get_height()
		);
		return false;
	}

	dims.x = province_bmp.get_width();
	dims.y = province_bmp.get_height();
	province_shape_image.resize(dims.x * dims.y);

	uint8_t const* province_data = province_bmp.get_pixel_data().data();
	uint8_t const* terrain_data = terrain_bmp.get_pixel_data().data();

	std::vector<fixed_point_map_t<TerrainType const*>> terrain_type_pixels_list(province_definitions.size());

	bool ret = true;
	ordered_set<colour_t> unrecognised_province_colours;

	std::vector<fixed_point_t> pixels_per_province(province_definitions.size());
	std::vector<fvec2_t> pixel_position_sum_per_province(province_definitions.size());

	for (ivec2_t pos {}; pos.y < get_height(); ++pos.y) {
		for (pos.x = 0; pos.x < get_width(); ++pos.x) {
			const size_t pixel_index = get_pixel_index_from_pos(pos);
			const colour_t province_colour = colour_at(province_data, pixel_index);
			ProvinceDefinition::index_t province_index = ProvinceDefinition::NULL_INDEX;

			if (pos.x > 0) {
				const size_t jdx = pixel_index - 1;
				if (colour_at(province_data, jdx) == province_colour) {
					province_index = province_shape_image[jdx].index;
					goto index_found;
				}
			}

			if (pos.y > 0) {
				const size_t jdx = pixel_index - get_width();
				if (colour_at(province_data, jdx) == province_colour) {
					province_index = province_shape_image[jdx].index;
					goto index_found;
				}
			}

			province_index = get_index_from_colour(province_colour);

			if (province_index == ProvinceDefinition::NULL_INDEX && !unrecognised_province_colours.contains(province_colour)) {
				unrecognised_province_colours.insert(province_colour);
				if (detailed_errors) {
					Logger::warning(
						"Unrecognised province colour ", province_colour, " at ", pos
					);
				}
			}

		index_found:
			province_shape_image[pixel_index].index = province_index;

			if (province_index != ProvinceDefinition::NULL_INDEX) {
				const ProvinceDefinition::index_t array_index = province_index - 1;
				pixels_per_province[array_index]++;
				pixel_position_sum_per_province[array_index] += static_cast<fvec2_t>(pos);
			}

			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 != ProvinceDefinition::NULL_INDEX) {
					terrain_type_pixels_list[province_index - 1][&mapping->get_type()]++;
				}
				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;
			}
		}
	}

	if (!unrecognised_province_colours.empty()) {
		Logger::warning("Province image contains ", unrecognised_province_colours.size(), " unrecognised province colours");
	}

	size_t missing = 0;
	for (size_t array_index = 0; array_index < province_definitions.size(); ++array_index) {
		ProvinceDefinition* province = province_definitions.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];
		province->on_map = pixel_count > 0;

		if (province->on_map) {
			province->centre = pixel_position_sum_per_province[array_index] / pixel_count;
		} else {
			if (detailed_errors) {
				Logger::warning("Province missing from shape image: ", province->to_string());
			}
			missing++;
		}
	}
	if (missing > 0) {
		Logger::warning("Province image is missing ", missing, " province colours");
	}

	// Constants in the River BMP Palette
	static constexpr uint8_t START_COLOUR = 0;
	static constexpr uint8_t MERGE_COLOUR = 1;
	static constexpr uint8_t RIVER_SIZE_1 = 2;
	static constexpr uint8_t RIVER_SIZE_2 = 3;
	static constexpr uint8_t RIVER_SIZE_3 = 4;
	static constexpr uint8_t RIVER_SIZE_4 = 5;
	static constexpr uint8_t RIVER_SIZE_5 = 6;
	static constexpr uint8_t RIVER_SIZE_6 = 7;
	static constexpr uint8_t RIVER_SIZE_7 = 8;
	static constexpr uint8_t RIVER_SIZE_8 = 9;
	static constexpr uint8_t RIVER_SIZE_9 = 10;
	static constexpr uint8_t RIVER_SIZE_10 = 11;

	uint8_t const* river_data = rivers_bmp.get_pixel_data().data();

	/** Generating River Segments
		1. check pixels up, right, down, and left from last_segment_end for a colour <12
		2. add first point
		3. set size of segment based on color value at first point
		4. loop, adding adjacent points until the colour value changes (to make sure we don't backtrack, last_segment_direction provides a pixel to automatically ignore)
				last_segment_direction:
				0 -> start, ignore nothing
				1 -> ignore up
				2 -> ignore down
				3 -> ignore left
				4 -> ignore right
		5. if the colour value changes to MERGE_COLOUR, add the point & finish the segment
		6. if there is no further point, finish the segment
		7. if the colour value changes to a different river size (>1 && <12), recursively call this function on the next segment
	*/
	const std::function<void(ivec2_t, uint8_t, river_t&)> next_segment = [&river_data, &rivers_bmp, &next_segment](ivec2_t last_segment_end, uint8_t last_segment_direction, river_t& river) {
		size_t idx = last_segment_end.x + last_segment_end.y * rivers_bmp.get_width();

		std::vector<ivec2_t> points;
		uint8_t direction = 0;

		// check pixel above
		if (last_segment_end.y > 0 && last_segment_direction != 1) { // check for bounds & ignore direction
			if (river_data[idx - rivers_bmp.get_width()] < 12) {
				points.push_back({ last_segment_end.x, last_segment_end.y - 1 });
				direction = 2;
			}
		}
		// check pixel to right
		if (last_segment_end.x < rivers_bmp.get_width() - 1 && last_segment_direction != 4) {
			if (river_data[idx + 1] < 12) {
				points.push_back({ last_segment_end.x + 1, last_segment_end.y });
				direction = 3;
			}
		}
		// check pixel below
		if (last_segment_end.y < rivers_bmp.get_height() - 1 && last_segment_direction != 2) {
			if (river_data[idx + rivers_bmp.get_width()] < 12) {
				points.push_back({ last_segment_end.x, last_segment_end.y + 1 });
				direction = 1;
			}
		}
		// check pixel to left
		if (last_segment_end.x > 0 && last_segment_direction != 3) {
			if (river_data[idx - 1] < 12) {
				points.push_back({ last_segment_end.x - 1, last_segment_end.y });
				direction = 4;
			}
		}

		if (points.empty()) {
			Logger::error("River analysis failed: single-pixel river @ (", last_segment_end.x, ", ", last_segment_end.y, ").");
			return;
		}
		uint8_t size = river_data[points.front().x + points.front().y * rivers_bmp.get_width()] - 1; // size of river from 1 - 10 determined by colour

		bool river_complete = false;
		ivec2_t new_point;

		size_t limit = 0; // stops infinite loop

		while (true) {
			limit++;
			if (limit == 4096) {
				Logger::error("River segment starting at (", points.front().x, ", ", points.front().y, ") is longer than limit 4096, check for misplaced pixels or other definition errors!");
				river_complete = true;
				break;
			}

			idx = points.back().x + points.back().y * rivers_bmp.get_width();

			ivec2_t merge_location;
			bool merge = false;

			// check pixel above
			if (points.back().y > 0 && direction != 1) { // check for bounds & ignore direction
				if (river_data[idx - rivers_bmp.get_width()] == size + 1) { // now checking if size changes too
					points.push_back({ points.back().x, points.back().y - 1 });
					direction = 2;
					continue;
				} else if (river_data[idx - rivers_bmp.get_width()] == MERGE_COLOUR) { // check for merge node
					merge_location = { points.back().x, points.back().y - 1 };
					merge = true;
				} else if (river_data[idx - rivers_bmp.get_width()] > 1 && river_data[idx - rivers_bmp.get_width()] < 12) { // new segment
					new_point = { points.back().x, points.back().y - 1 };
					direction = 2;
					break;
				}
			}
			// check pixel to right
			if (points.back().x < rivers_bmp.get_width() - 1 && direction != 4) {
				if (river_data[idx + 1] == size + 1) {
					points.push_back({ points.back().x + 1, points.back().y });
					direction = 3;
					continue;
				} else if (river_data[idx + 1] == MERGE_COLOUR) {
					merge_location = { points.back().x + 1, points.back().y };
					merge = true;
				} else if (river_data[idx + 1] > 1 && river_data[idx + 1] < 12) { // new segment
					new_point = { points.back().x + 1, points.back().y };
					direction = 3;
					break;
				}
			}
			// check pixel below
			if (points.back().y < rivers_bmp.get_height() - 1 && direction != 2) {
				if (river_data[idx + rivers_bmp.get_width()] == size + 1) {
					points.push_back({ points.back().x, points.back().y + 1 });
					direction = 1;
					continue;
				} else if (river_data[idx + rivers_bmp.get_width()] == MERGE_COLOUR) {
					merge_location = { points.back().x, points.back().y + 1 };
					merge = true;
				} else if (river_data[idx + rivers_bmp.get_width()] > 1 && river_data[idx + rivers_bmp.get_width()] < 12) { // new segment
					new_point = { points.back().x, points.back().y + 1 };
					direction = 1;
					break;
				}
			}
			// check pixel to left
			if (points.back().x > 0 && direction != 3) {
				if (river_data[idx - 1] == size + 1) {
					points.push_back({ points.back().x - 1, points.back().y });
					direction = 4;
					continue;
				} else if (river_data[idx - 1] == MERGE_COLOUR) {
					merge_location = { points.back().x - 1, points.back().y };
					merge = true;
				} else if (river_data[idx - 1] > 1 && river_data[idx - 1] < 12) { // new segment
					new_point = { points.back().x - 1, points.back().y };
					direction = 4;
					break;
				}
			}

			// no further points
			if (merge) points.push_back(merge_location);
			river_complete = true;
			break;
		}

		// save memory & simplify by storing only start, corner, and end points.
		const auto is_corner_point = [](ivec2_t previous, ivec2_t current, ivec2_t next) {
			return ((current.x - previous.x) * (next.y - current.y)) != ((current.y - previous.y) * (next.x - current.x)); // slope is fun
		};
		std::vector<ivec2_t> simplified_points;
		simplified_points.push_back(points.front()); // add starting point
		for (int i = 1; i < points.size()-1; ++i) {
			if (is_corner_point(points[i-1], points[i], points[i+1])) { // add corner points
				simplified_points.push_back(points[i]);
			}
		}
		simplified_points.push_back(points.back());

		// add segment then recursively call if neeeded
		river.push_back({ size, std::move(simplified_points) });
		if (river_complete) return;
		next_segment(new_point, direction, river);
	};

	// find every river source and then run the segment algorithm.
	for (int y = 0; y < rivers_bmp.get_height(); ++y) {
		for (int x = 0; x < rivers_bmp.get_width(); ++x) {
			if (river_data[x + y * rivers_bmp.get_width()] == START_COLOUR) { // start of a river
				river_t river;

				next_segment({ x, y }, 0, river);

				rivers.push_back(std::move(river));
			}
		}
	}
	Logger::info("Generated ", rivers.size(), " rivers.");

	return ret;
}

/* REQUIREMENTS:
 * MAP-19, MAP-84
 */
bool MapDefinition::_generate_standard_province_adjacencies() {
	bool changed = false;

	const auto generate_adjacency = [this](ProvinceDefinition* current, ivec2_t pos) -> bool {
		ProvinceDefinition* neighbour = get_province_definition_at(pos);
		if (neighbour != nullptr) {
			return add_standard_adjacency(*current, *neighbour);
		}
		return false;
	};

	for (ivec2_t pos {}; pos.y < get_height(); ++pos.y) {
		for (pos.x = 0; pos.x < get_width(); ++pos.x) {
			ProvinceDefinition* cur = get_province_definition_at(pos);

			if (cur != nullptr) {
				changed |= generate_adjacency(cur, { (pos.x + 1) % get_width(), pos.y });
				changed |= generate_adjacency(cur, { pos.x, pos.y + 1 });
			}
		}
	}

	return changed;
}

bool MapDefinition::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;
			}
			ProvinceDefinition* const from = get_province_definition_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);
			ProvinceDefinition* const to = get_province_definition_by_identifier(to_str);
			if (to == nullptr) {
				Logger::error("Unrecognised adjacency to province identifier: \"", to_str, "\"");
				ret = false;
				return;
			}

			using enum adjacency_t::type_t;
			static const string_map_t<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<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 adjacency_t::type_t type = it->second;

			ProvinceDefinition const* const through = get_province_definition_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<adjacency_t::data_t>::max()) {
				Logger::error("Invalid adjacency data: \"", data_str, "\"");
				ret = false;
				return;
			}
			const adjacency_t::data_t data = data_uint;

			ret &= add_special_adjacency(*from, *to, type, through, data);
		}
	);
	return ret;
}

bool MapDefinition::load_climate_file(ModifierManager const& modifier_manager, ast::NodeCPtr root) {
	bool ret = expect_dictionary_reserve_length(
		climates,
		[this, &modifier_manager](std::string_view identifier, ast::NodeCPtr node) -> bool {
			if (identifier.empty()) {
				Logger::error("Invalid climate identifier - empty!");
				return false;
			}

			bool ret = true;
			Climate* cur_climate = climates.get_item_by_identifier(identifier);
			if (cur_climate == nullptr) {
				ModifierValue values;
				ret &= modifier_manager.expect_modifier_value(move_variable_callback(values))(node);
				ret &= climates.add_item({ identifier, std::move(values) });
			} else {
				ret &= expect_list_reserve_length(*cur_climate, expect_province_definition_identifier(
					[cur_climate, &identifier](ProvinceDefinition& province) {
						if (province.climate != cur_climate) {
							cur_climate->add_province(&province);
							if (province.climate != nullptr) {
								Climate* old_climate = const_cast<Climate*>(province.climate);
								old_climate->remove_province(&province);
								Logger::warning(
									"Province with id ", province.get_identifier(),
									" found in multiple climates: ", identifier,
									" and ", old_climate->get_identifier()
								);
							}
							province.climate = cur_climate;
						} else {
							Logger::warning(
								"Province with id ", province.get_identifier(),
								" defined twice in climate ", identifier
							);
						}
						return true;
					}
				))(node);
			}
			return ret;
		}
	)(root);

	for (Climate& climate : climates.get_items()) {
		climate.lock();
	}

	lock_climates();

	return ret;
}

bool MapDefinition::load_continent_file(ModifierManager const& modifier_manager, ast::NodeCPtr root) {
	bool ret = expect_dictionary_reserve_length(
		continents,
		[this, &modifier_manager](std::string_view identifier, ast::NodeCPtr node) -> bool {
			if (identifier.empty()) {
				Logger::error("Invalid continent identifier - empty!");
				return false;
			}

			ModifierValue values;
			std::vector<ProvinceDefinition const*> prov_list;
			bool ret = modifier_manager.expect_modifier_value_and_keys(move_variable_callback(values),
				"provinces", ONE_EXACTLY, expect_list_reserve_length(prov_list, expect_province_definition_identifier(
					[&prov_list](ProvinceDefinition const& province) -> bool {
						if (province.continent == nullptr) {
							prov_list.emplace_back(&province);
						} else {
							Logger::warning("Province ", province, " found in multiple continents");
						}
						return true;
					}
				))
			)(node);

			Continent continent = { identifier, std::move(values) };
			continent.add_provinces(prov_list);
			continent.lock();

			if (continents.add_item(std::move(continent))) {
				Continent const& moved_continent = continents.get_items().back();
				for (ProvinceDefinition const* prov : moved_continent.get_provinces()) {
					remove_province_definition_const(prov)->continent = &moved_continent;
				}
			} else {
				ret = false;
			}

			return ret;
		}
	)(root);

	lock_continents();

	return ret;
}