package net.minecraft.util.filefix.virtualfilesystem;

import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.Objects;
import net.minecraft.util.filefix.virtualfilesystem.exception.CowFSNoSuchFileException;
import net.minecraft.util.filefix.virtualfilesystem.exception.CowFSNotDirectoryException;
import org.jspecify.annotations.Nullable;

final class DirectoryNode extends Node {
	private final Map<String, Node> childNodes = new HashMap();

	public DirectoryNode(final CopyOnWriteFSPath path) {
		super(path);
	}

	public Collection<Node> children() {
		return Collections.unmodifiableCollection(this.childNodes.values());
	}

	public void addChild(final Node child) {
		String name = (String)Objects.requireNonNull(child.name());
		this.childNodes.put(name, child);
		child.setParent(this);
	}

	void removeChild(final String name) {
		this.childNodes.remove(name);
	}

	@Nullable
	public Node getChild(final String name) {
		return (Node)this.childNodes.get(name);
	}

	public DirectoryNode directoryByPath(final CopyOnWriteFSPath path) throws CowFSNoSuchFileException, CowFSNotDirectoryException {
		if (this.byPath(path) instanceof DirectoryNode result) {
			return result;
		} else {
			throw new CowFSNotDirectoryException(path + " was a file, expected directory");
		}
	}

	public FileNode fileByPath(final CopyOnWriteFSPath path) throws CowFSNoSuchFileException {
		if (this.byPathOrNull(path) instanceof FileNode result) {
			return result;
		} else {
			throw new CowFSNoSuchFileException(path.toString());
		}
	}

	public Node byPath(final CopyOnWriteFSPath path) throws CowFSNoSuchFileException {
		Node node = this.byPathOrNull(path);
		if (node != null) {
			return node;
		} else {
			throw new CowFSNoSuchFileException(path.toString());
		}
	}

	@Nullable
	public Node byPathOrNull(final CopyOnWriteFSPath path) {
		int nameCount = path.getNameCount();
		DirectoryNode directory = this;

		for (int i = 0; i < nameCount; i++) {
			String name = path.getName(i).toString();
			if (!name.equals(".")) {
				if (name.equals("..")) {
					DirectoryNode parent = directory.parent;
					if (parent != null) {
						directory = parent;
					}
				} else {
					Node nextNode = directory.getChild(name);
					if (!(nextNode instanceof DirectoryNode nextDirectory)) {
						return i == nameCount - 1 ? nextNode : null;
					}

					directory = nextDirectory;
				}
			}
		}

		return directory;
	}
}