package net.minecraft.world.level.biome;

import com.google.common.annotations.VisibleForTesting;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Lists;
import com.mojang.datafixers.util.Pair;
import com.mojang.serialization.Codec;
import com.mojang.serialization.DataResult;
import com.mojang.serialization.MapCodec;
import com.mojang.serialization.codecs.RecordCodecBuilder;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Comparator;
import java.util.Iterator;
import java.util.List;
import java.util.Locale;
import java.util.stream.Collectors;
import net.minecraft.core.BlockPos;
import net.minecraft.core.QuartPos;
import net.minecraft.util.ExtraCodecs;
import net.minecraft.util.Mth;
import net.minecraft.world.level.biome.Climate.RTree.Leaf;
import net.minecraft.world.level.biome.Climate.RTree.Node;
import net.minecraft.world.level.biome.Climate.RTree.SubTree;
import net.minecraft.world.level.biome.Climate.SpawnFinder.Result;
import net.minecraft.world.level.levelgen.DensityFunction;
import net.minecraft.world.level.levelgen.DensityFunctions;
import net.minecraft.world.level.levelgen.DensityFunction.SinglePointContext;
import org.jetbrains.annotations.Nullable;

public class Climate {
	private static final boolean DEBUG_SLOW_BIOME_SEARCH = false;
	private static final float QUANTIZATION_FACTOR = 10000.0F;
	@VisibleForTesting
	protected static final int PARAMETER_COUNT = 7;

	public static Climate.TargetPoint target(float temperature, float humidity, float continentalness, float erosion, float depth, float weirdness) {
		return new Climate.TargetPoint(
			quantizeCoord(temperature), quantizeCoord(humidity), quantizeCoord(continentalness), quantizeCoord(erosion), quantizeCoord(depth), quantizeCoord(weirdness)
		);
	}

	public static Climate.ParameterPoint parameters(
		float temperature, float humidity, float continentalness, float erosion, float depth, float weirdness, float offset
	) {
		return new Climate.ParameterPoint(
			Climate.Parameter.point(temperature),
			Climate.Parameter.point(humidity),
			Climate.Parameter.point(continentalness),
			Climate.Parameter.point(erosion),
			Climate.Parameter.point(depth),
			Climate.Parameter.point(weirdness),
			quantizeCoord(offset)
		);
	}

	public static Climate.ParameterPoint parameters(
		Climate.Parameter temperature,
		Climate.Parameter humidity,
		Climate.Parameter continentalness,
		Climate.Parameter erosion,
		Climate.Parameter depth,
		Climate.Parameter weirdness,
		float offset
	) {
		return new Climate.ParameterPoint(temperature, humidity, continentalness, erosion, depth, weirdness, quantizeCoord(offset));
	}

	public static long quantizeCoord(float coord) {
		return (long)(coord * 10000.0F);
	}

	public static float unquantizeCoord(long coord) {
		return (float)coord / 10000.0F;
	}

	public static Climate.Sampler empty() {
		DensityFunction densityFunction = DensityFunctions.zero();
		return new Climate.Sampler(densityFunction, densityFunction, densityFunction, densityFunction, densityFunction, densityFunction, List.of());
	}

	public static BlockPos findSpawnPosition(List<Climate.ParameterPoint> points, Climate.Sampler sampler) {
		return (new Climate.SpawnFinder(points, sampler)).result.location();
	}

	interface DistanceMetric<T> {
		long distance(Node<T> node, long[] ls);
	}

	public record Parameter(long min, long max) {
		public static final Codec<Climate.Parameter> CODEC = ExtraCodecs.intervalCodec(
			Codec.floatRange(-2.0F, 2.0F),
			"min",
			"max",
			(float_, float2) -> float_.compareTo(float2) > 0
				? DataResult.error(() -> "Cannon construct interval, min > max (" + float_ + " > " + float2 + ")")
				: DataResult.success(new Climate.Parameter(Climate.quantizeCoord(float_), Climate.quantizeCoord(float2))),
			parameter -> Climate.unquantizeCoord(parameter.min()),
			parameter -> Climate.unquantizeCoord(parameter.max())
		);

		public static Climate.Parameter point(float value) {
			return span(value, value);
		}

		public static Climate.Parameter span(float min, float max) {
			if (min > max) {
				throw new IllegalArgumentException("min > max: " + min + " " + max);
			} else {
				return new Climate.Parameter(Climate.quantizeCoord(min), Climate.quantizeCoord(max));
			}
		}

		public static Climate.Parameter span(Climate.Parameter min, Climate.Parameter max) {
			if (min.min() > max.max()) {
				throw new IllegalArgumentException("min > max: " + min + " " + max);
			} else {
				return new Climate.Parameter(min.min(), max.max());
			}
		}

		public String toString() {
			return this.min == this.max ? String.format(Locale.ROOT, "%d", this.min) : String.format(Locale.ROOT, "[%d-%d]", this.min, this.max);
		}

		public long distance(long pointValue) {
			long l = pointValue - this.max;
			long m = this.min - pointValue;
			return l > 0L ? l : Math.max(m, 0L);
		}

		public long distance(Climate.Parameter parameter) {
			long l = parameter.min() - this.max;
			long m = this.min - parameter.max();
			return l > 0L ? l : Math.max(m, 0L);
		}

		public Climate.Parameter span(@Nullable Climate.Parameter param) {
			return param == null ? this : new Climate.Parameter(Math.min(this.min, param.min()), Math.max(this.max, param.max()));
		}
	}

	public static class ParameterList<T> {
		private final List<Pair<Climate.ParameterPoint, T>> values;
		private final Climate.RTree<T> index;

		public static <T> Codec<Climate.ParameterList<T>> codec(MapCodec<T> codec) {
			return ExtraCodecs.nonEmptyList(
					RecordCodecBuilder.<T>create(
							instance -> instance.group(Climate.ParameterPoint.CODEC.fieldOf("parameters").forGetter(Pair::getFirst), codec.forGetter(Pair::getSecond))
								.apply(instance, Pair::of)
						)
						.listOf()
				)
				.xmap(Climate.ParameterList::new, Climate.ParameterList::values);
		}

		public ParameterList(List<Pair<Climate.ParameterPoint, T>> values) {
			this.values = values;
			this.index = Climate.RTree.create(values);
		}

		public List<Pair<Climate.ParameterPoint, T>> values() {
			return this.values;
		}

		public T findValue(Climate.TargetPoint targetPoint) {
			return this.findValueIndex(targetPoint);
		}

		@VisibleForTesting
		public T findValueBruteForce(Climate.TargetPoint targetPoint) {
			Iterator<Pair<Climate.ParameterPoint, T>> iterator = this.values().iterator();
			Pair<Climate.ParameterPoint, T> pair = (Pair<Climate.ParameterPoint, T>)iterator.next();
			long l = pair.getFirst().fitness(targetPoint);
			T object = pair.getSecond();

			while (iterator.hasNext()) {
				Pair<Climate.ParameterPoint, T> pair2 = (Pair<Climate.ParameterPoint, T>)iterator.next();
				long m = pair2.getFirst().fitness(targetPoint);
				if (m < l) {
					l = m;
					object = pair2.getSecond();
				}
			}

			return object;
		}

		public T findValueIndex(Climate.TargetPoint targetPoint) {
			return this.findValueIndex(targetPoint, Node::distance);
		}

		protected T findValueIndex(Climate.TargetPoint targetPoint, Climate.DistanceMetric<T> distanceMetric) {
			return this.index.search(targetPoint, distanceMetric);
		}
	}

	public record ParameterPoint(
		Climate.Parameter temperature,
		Climate.Parameter humidity,
		Climate.Parameter continentalness,
		Climate.Parameter erosion,
		Climate.Parameter depth,
		Climate.Parameter weirdness,
		long offset
	) {
		public static final Codec<Climate.ParameterPoint> CODEC = RecordCodecBuilder.create(
			instance -> instance.group(
					Climate.Parameter.CODEC.fieldOf("temperature").forGetter(parameterPoint -> parameterPoint.temperature),
					Climate.Parameter.CODEC.fieldOf("humidity").forGetter(parameterPoint -> parameterPoint.humidity),
					Climate.Parameter.CODEC.fieldOf("continentalness").forGetter(parameterPoint -> parameterPoint.continentalness),
					Climate.Parameter.CODEC.fieldOf("erosion").forGetter(parameterPoint -> parameterPoint.erosion),
					Climate.Parameter.CODEC.fieldOf("depth").forGetter(parameterPoint -> parameterPoint.depth),
					Climate.Parameter.CODEC.fieldOf("weirdness").forGetter(parameterPoint -> parameterPoint.weirdness),
					Codec.floatRange(0.0F, 1.0F).fieldOf("offset").xmap(Climate::quantizeCoord, Climate::unquantizeCoord).forGetter(parameterPoint -> parameterPoint.offset)
				)
				.apply(instance, Climate.ParameterPoint::new)
		);

		long fitness(Climate.TargetPoint point) {
			return Mth.square(this.temperature.distance(point.temperature))
				+ Mth.square(this.humidity.distance(point.humidity))
				+ Mth.square(this.continentalness.distance(point.continentalness))
				+ Mth.square(this.erosion.distance(point.erosion))
				+ Mth.square(this.depth.distance(point.depth))
				+ Mth.square(this.weirdness.distance(point.weirdness))
				+ Mth.square(this.offset);
		}

		protected List<Climate.Parameter> parameterSpace() {
			return ImmutableList.of(
				this.temperature, this.humidity, this.continentalness, this.erosion, this.depth, this.weirdness, new Climate.Parameter(this.offset, this.offset)
			);
		}
	}

	protected static final class RTree<T> {
		private static final int CHILDREN_PER_NODE = 6;
		private final Node<T> root;
		private final ThreadLocal<Leaf<T>> lastResult = new ThreadLocal();

		private RTree(Node<T> root) {
			this.root = root;
		}

		public static <T> Climate.RTree<T> create(List<Pair<Climate.ParameterPoint, T>> nodes) {
			if (nodes.isEmpty()) {
				throw new IllegalArgumentException("Need at least one value to build the search tree.");
			} else {
				int i = ((Climate.ParameterPoint)((Pair)nodes.get(0)).getFirst()).parameterSpace().size();
				if (i != 7) {
					throw new IllegalStateException("Expecting parameter space to be 7, got " + i);
				} else {
					List<Leaf<T>> list = (List<Leaf<T>>)nodes.stream()
						.map(pair -> new Leaf((Climate.ParameterPoint)pair.getFirst(), pair.getSecond()))
						.collect(Collectors.toCollection(ArrayList::new));
					return new Climate.RTree<>(build(i, list));
				}
			}
		}

		private static <T> Node<T> build(int paramSpaceSize, List<? extends Node<T>> children) {
			if (children.isEmpty()) {
				throw new IllegalStateException("Need at least one child to build a node");
			} else if (children.size() == 1) {
				return (Node<T>)children.get(0);
			} else if (children.size() <= 6) {
				children.sort(Comparator.comparingLong(node -> {
					long lx = 0L;

					for (int jx = 0; jx < paramSpaceSize; jx++) {
						Climate.Parameter parameter = node.parameterSpace[jx];
						lx += Math.abs((parameter.min() + parameter.max()) / 2L);
					}

					return lx;
				}));
				return new SubTree(children);
			} else {
				long l = Long.MAX_VALUE;
				int i = -1;
				List<SubTree<T>> list = null;

				for (int j = 0; j < paramSpaceSize; j++) {
					sort(children, paramSpaceSize, j, false);
					List<SubTree<T>> list2 = bucketize(children);
					long m = 0L;

					for (SubTree<T> subTree : list2) {
						m += cost(subTree.parameterSpace);
					}

					if (l > m) {
						l = m;
						i = j;
						list = list2;
					}
				}

				sort(list, paramSpaceSize, i, true);
				return new SubTree((List)list.stream().map(subTreex -> build(paramSpaceSize, Arrays.asList(subTreex.children))).collect(Collectors.toList()));
			}
		}

		private static <T> void sort(List<? extends Node<T>> children, int paramSpaceSize, int size, boolean absolute) {
			Comparator<Node<T>> comparator = comparator(size, absolute);

			for (int i = 1; i < paramSpaceSize; i++) {
				comparator = comparator.thenComparing(comparator((size + i) % paramSpaceSize, absolute));
			}

			children.sort(comparator);
		}

		private static <T> Comparator<Node<T>> comparator(int size, boolean absolute) {
			return Comparator.comparingLong(node -> {
				Climate.Parameter parameter = node.parameterSpace[size];
				long l = (parameter.min() + parameter.max()) / 2L;
				return absolute ? Math.abs(l) : l;
			});
		}

		private static <T> List<SubTree<T>> bucketize(List<? extends Node<T>> nodes) {
			List<SubTree<T>> list = Lists.<SubTree<T>>newArrayList();
			List<Node<T>> list2 = Lists.<Node<T>>newArrayList();
			int i = (int)Math.pow(6.0, Math.floor(Math.log(nodes.size() - 0.01) / Math.log(6.0)));

			for (Node<T> node : nodes) {
				list2.add(node);
				if (list2.size() >= i) {
					list.add(new SubTree(list2));
					list2 = Lists.<Node<T>>newArrayList();
				}
			}

			if (!list2.isEmpty()) {
				list.add(new SubTree(list2));
			}

			return list;
		}

		private static long cost(Climate.Parameter[] parameters) {
			long l = 0L;

			for (Climate.Parameter parameter : parameters) {
				l += Math.abs(parameter.max() - parameter.min());
			}

			return l;
		}

		static <T> List<Climate.Parameter> buildParameterSpace(List<? extends Node<T>> children) {
			if (children.isEmpty()) {
				throw new IllegalArgumentException("SubTree needs at least one child");
			} else {
				int i = 7;
				List<Climate.Parameter> list = Lists.<Climate.Parameter>newArrayList();

				for (int j = 0; j < 7; j++) {
					list.add(null);
				}

				for (Node<T> node : children) {
					for (int k = 0; k < 7; k++) {
						list.set(k, node.parameterSpace[k].span((Climate.Parameter)list.get(k)));
					}
				}

				return list;
			}
		}

		public T search(Climate.TargetPoint targetPoint, Climate.DistanceMetric<T> distanceMetric) {
			long[] ls = targetPoint.toParameterArray();
			Leaf<T> leaf = this.root.search(ls, (Leaf)this.lastResult.get(), distanceMetric);
			this.lastResult.set(leaf);
			return (T)leaf.value;
		}
	}

	public record Sampler(
		DensityFunction temperature,
		DensityFunction humidity,
		DensityFunction continentalness,
		DensityFunction erosion,
		DensityFunction depth,
		DensityFunction weirdness,
		List<Climate.ParameterPoint> spawnTarget
	) {
		public Climate.TargetPoint sample(int x, int y, int z) {
			int i = QuartPos.toBlock(x);
			int j = QuartPos.toBlock(y);
			int k = QuartPos.toBlock(z);
			SinglePointContext singlePointContext = new SinglePointContext(i, j, k);
			return Climate.target(
				(float)this.temperature.compute(singlePointContext),
				(float)this.humidity.compute(singlePointContext),
				(float)this.continentalness.compute(singlePointContext),
				(float)this.erosion.compute(singlePointContext),
				(float)this.depth.compute(singlePointContext),
				(float)this.weirdness.compute(singlePointContext)
			);
		}

		public BlockPos findSpawnPosition() {
			return this.spawnTarget.isEmpty() ? BlockPos.ZERO : Climate.findSpawnPosition(this.spawnTarget, this);
		}
	}

	static class SpawnFinder {
		private static final long MAX_RADIUS = 2048L;
		Result result;

		SpawnFinder(List<Climate.ParameterPoint> points, Climate.Sampler sampler) {
			this.result = getSpawnPositionAndFitness(points, sampler, 0, 0);
			this.radialSearch(points, sampler, 2048.0F, 512.0F);
			this.radialSearch(points, sampler, 512.0F, 32.0F);
		}

		private void radialSearch(List<Climate.ParameterPoint> point, Climate.Sampler sampler, float max, float min) {
			float f = 0.0F;
			float g = min;
			BlockPos blockPos = this.result.location();

			while (g <= max) {
				int i = blockPos.getX() + (int)(Math.sin(f) * g);
				int j = blockPos.getZ() + (int)(Math.cos(f) * g);
				Result result = getSpawnPositionAndFitness(point, sampler, i, j);
				if (result.fitness() < this.result.fitness()) {
					this.result = result;
				}

				f += min / g;
				if (f > Math.PI * 2) {
					f = 0.0F;
					g += min;
				}
			}
		}

		private static Result getSpawnPositionAndFitness(List<Climate.ParameterPoint> points, Climate.Sampler sampler, int x, int z) {
			Climate.TargetPoint targetPoint = sampler.sample(QuartPos.fromBlock(x), 0, QuartPos.fromBlock(z));
			Climate.TargetPoint targetPoint2 = new Climate.TargetPoint(
				targetPoint.temperature(), targetPoint.humidity(), targetPoint.continentalness(), targetPoint.erosion(), 0L, targetPoint.weirdness()
			);
			long l = Long.MAX_VALUE;

			for (Climate.ParameterPoint parameterPoint : points) {
				l = Math.min(l, parameterPoint.fitness(targetPoint2));
			}

			long m = Mth.square((long)x) + Mth.square((long)z);
			long n = l * Mth.square(2048L) + m;
			return new Result(new BlockPos(x, 0, z), n);
		}
	}

	public record TargetPoint(long temperature, long humidity, long continentalness, long erosion, long depth, long weirdness) {

		@VisibleForTesting
		protected long[] toParameterArray() {
			return new long[]{this.temperature, this.humidity, this.continentalness, this.erosion, this.depth, this.weirdness, 0L};
		}
	}
}