EnergonRelics/src/main/java/com/thebrokenrail/energonrelics/block/portal/EnergyTeleporter.java

package com.thebrokenrail.energonrelics.block.portal;

import com.mojang.brigadier.exceptions.CommandSyntaxException;
import com.thebrokenrail.energonrelics.config.HardcodedConfig;
import com.thebrokenrail.energonrelics.mixin.ServerPlayerEntityAccessor;
import net.minecraft.block.Block;
import net.minecraft.block.BlockState;
import net.minecraft.block.Blocks;
import net.minecraft.entity.Entity;
import net.minecraft.network.packet.s2c.play.PlayerPositionLookS2CPacket;
import net.minecraft.server.command.TeleportCommand;
import net.minecraft.server.network.ServerPlayerEntity;
import net.minecraft.server.world.ServerWorld;
import net.minecraft.sound.SoundCategory;
import net.minecraft.sound.SoundEvents;
import net.minecraft.util.math.BlockPos;
import net.minecraft.util.math.Vec3d;
import net.minecraft.util.registry.RegistryKey;
import net.minecraft.world.Heightmap;
import net.minecraft.world.World;

import java.util.EnumSet;

class EnergyTeleporter {
    private static void teleport(Entity entity, ServerWorld to, Vec3d pos) {
        if (entity instanceof ServerPlayerEntity) {
            ((ServerPlayerEntityAccessor) entity).setInTeleportationState(true);
        }
        try {
            TeleportCommand.teleport(null, entity, to, pos.getX(), pos.getY(), pos.getZ(), EnumSet.noneOf(PlayerPositionLookS2CPacket.Flag.class), entity.yaw, entity.pitch, null);
        } catch (CommandSyntaxException e) {
            throw new RuntimeException(e);
        }
        if (entity instanceof ServerPlayerEntity) {
            ((ServerPlayerEntity) entity).networkHandler.syncWithPlayerPosition();
        }
    }

    static void teleport(ServerWorld world, Vec3d pos, BlockPos blockPos, Entity entity) {
        BlockPos center = EnergyPortalBlock.getCenterPos(world, blockPos);
        Vec3d offset = pos.subtract(Vec3d.ofBottomCenter(center));

        RegistryKey<World> worldKey = world.getRegistryKey();
        if (worldKey == World.OVERWORLD) {
            teleportWithMultiplier(world, entity, center, offset, World.NETHER, 1d / HardcodedConfig.ENERGY_PORTAL_MULTIPLIER);
        } else if (worldKey == World.NETHER) {
            teleportWithMultiplier(world, entity, center, offset, World.OVERWORLD, HardcodedConfig.ENERGY_PORTAL_MULTIPLIER);
        } else {
            teleportToWorldSpawn(world, entity);
        }

        if (entity instanceof ServerPlayerEntity) {
            ((ServerPlayerEntity) entity).playSound(SoundEvents.BLOCK_PORTAL_TRAVEL, SoundCategory.PLAYERS, 0.25f, world.random.nextFloat() * 0.4f + 0.8f);
        }
    }

    private static int convertY(int y, int oldHeight, int newHeight) {
        int newY = (int) (((float) newHeight / (float) oldHeight) * (float) y);

        int bottomY = HardcodedConfig.ENERGY_PORTAL_Y_PADDING;
        int topY = newHeight - (bottomY + HardcodedConfig.ENERGY_PORTAL_Y_PADDING_EXTRA_TOP);
        newY = Math.max(bottomY, Math.min(topY, newY));

        return newY;
    }

    private static void teleportWithMultiplier(ServerWorld world, Entity entity, BlockPos center, Vec3d offset, RegistryKey<World> toKey, double multiplier) {
        ServerWorld to = world.getServer().getWorld(toKey);
        assert to != null;

        int y = convertY(center.getY(), world.getDimensionHeight(), to.getDimensionHeight());
        int x = (int) (center.getX() * multiplier);
        int z = (int) (center.getZ() * multiplier);

        BlockPos targetBlock = new BlockPos(x, y, z);

        BlockPos start = targetBlock.add(-1, -1, -1);
        for (int xPos = 0; xPos < 3; xPos++) {
            for (int yPos = 0; yPos < 4; yPos++) {
                for (int zPos = 0; zPos < 3; zPos++) {
                    BlockPos pos = start.add(xPos, yPos, zPos);
                    BlockState oldState = to.getBlockState(pos);
                    if (oldState.getHardness(world, pos) >= 0) {
                        Block block = yPos == 0 ? Blocks.OBSIDIAN : Blocks.AIR;
                        BlockState state = block.getDefaultState();
                        to.setBlockState(pos, state);
                    }
                }
            }
        }

        offset = new Vec3d(offset.getX(), Math.max(0, offset.getY()), offset.getZ());
        Vec3d target = Vec3d.ofBottomCenter(targetBlock).add(offset);

        teleport(entity, to, target);
    }

    private static void teleportToWorldSpawn(ServerWorld world, Entity entity) {
        ServerWorld to = world.getServer().getWorld(World.OVERWORLD);
        assert to != null;
        BlockPos dest = to.getTopPosition(Heightmap.Type.MOTION_BLOCKING_NO_LEAVES, to.getSpawnPos());
        teleport(entity, to, Vec3d.ofBottomCenter(dest));
    }
}