package envoy.client.data.commands;

import java.util.*;
import java.util.function.Consumer;

/**
 * This class acts as a builder for {@link SystemCommand}s.
 *
 * @author Leon Hofmeister
 * @since Envoy Client v0.2-beta
 */
public final class SystemCommandBuilder {

	private int						numberOfArguments;
	private Consumer<List<String>>	action;
	private List<String>			defaults;
	private String					description;
	private int						relevance;

	private final SystemCommandMap commandsMap;

	/**
	 * Creates a new {@code SystemCommandsBuilder} without underlying {@link SystemCommandMap}.
	 *
	 * @since Envoy Client v0.2-beta
	 */
	public SystemCommandBuilder() {
		this(null);
	}

	/**
	 * @param commandsMap the map to use when calling build (optional)
	 * @since Envoy Client v0.2-beta
	 */
	public SystemCommandBuilder(SystemCommandMap commandsMap) {
		this.commandsMap = commandsMap;
	}

	/**
	 * @param numberOfArguments the numberOfArguments to set
	 * @return this {@code SystemCommandBuilder}
	 * @since Envoy Client v0.2-beta
	 */
	public SystemCommandBuilder setNumberOfArguments(int numberOfArguments) {
		this.numberOfArguments = numberOfArguments;
		return this;
	}

	/**
	 * @param action the action to set
	 * @return this {@code SystemCommandBuilder}
	 * @since Envoy Client v0.2-beta
	 */
	public SystemCommandBuilder setAction(Consumer<List<String>> action) {
		this.action = action;
		return this;
	}

	/**
	 * @param description the description to set
	 * @return this {@code SystemCommandBuilder}
	 * @since Envoy Client v0.2-beta
	 */
	public SystemCommandBuilder setDescription(String description) {
		this.description = description;
		return this;
	}

	/**
	 * @param relevance the relevance to set
	 * @return this {@code SystemCommandBuilder}
	 * @since Envoy Client v0.2-beta
	 */
	public SystemCommandBuilder setRelevance(int relevance) {
		this.relevance = relevance;
		return this;
	}

	/**
	 * @param defaults the defaults to set
	 * @return this {@code SystemCommandBuilder}
	 * @since Envoy Client v0.2-beta
	 */
	public SystemCommandBuilder setDefaults(String... defaults) {
		this.defaults = List.of(defaults);
		return this;
	}

	/**
	 * Resets all values stored.
	 *
	 * @return this {@code SystemCommandBuilder}
	 * @since Envoy Client v0.2-beta
	 */
	public SystemCommandBuilder reset() {
		numberOfArguments	= 0;
		action				= null;
		defaults			= new ArrayList<>();
		description			= "";
		relevance			= 0;
		return this;
	}

	/**
	 * Builds a {@code SystemCommand} based upon the previously entered data.
	 *
	 * @return the built {@code SystemCommand}
	 * @since Envoy Client v0.2-beta
	 */
	public SystemCommand build() {
		return build(true);
	}

	/**
	 * Builds a {@code SystemCommand} based upon the previously entered data.<br>
	 * {@code SystemCommand#numberOfArguments} will be set to 0, regardless of the previous
	 * value.<br>
	 * At the end, this {@code SystemCommandBuilder} will be reset.
	 *
	 * @return the built {@code SystemCommand}
	 * @since Envoy Client v0.2-beta
	 */
	public SystemCommand buildNoArg() {
		numberOfArguments = 0;
		return build(true);
	}

	/**
	 * Builds a {@code SystemCommand} based upon the previously entered data.<br>
	 * {@code SystemCommand#numberOfArguments} will be set to use the rest of the string as
	 * argument, regardless of the previous value.<br>
	 * At the end, this {@code SystemCommandBuilder} will be reset.
	 *
	 * @return the built {@code SystemCommand}
	 * @since Envoy Client v0.2-beta
	 */
	public SystemCommand buildRemainingArg() {
		numberOfArguments = -1;
		return build(true);
	}

	/**
	 * Builds a {@code SystemCommand} based upon the previously entered data.<br>
	 * Automatically adds the built object to the given map. At the end, this
	 * {@code SystemCommandBuilder} <b>can</b> be reset but must not be.
	 *
	 * @param reset whether this {@code SystemCommandBuilder} should be reset afterwards.<br>
	 *              This can be useful if another command wants to execute something similar
	 * @return the built {@code SystemCommand}
	 * @since Envoy Client v0.2-beta
	 */
	public SystemCommand build(boolean reset) {
		final var sc = new SystemCommand(action, numberOfArguments, defaults, description);
		sc.setRelevance(relevance);
		if (reset)
			reset();
		return sc;
	}

	/**
	 * Builds a {@code SystemCommand} based upon the previously entered data. Automatically adds the
	 * built object to the given map.
	 *
	 * @param command the command under which to store the SystemCommand in the
	 *                {@link SystemCommandMap}
	 * @return the built {@code SystemCommand}
	 * @throws NullPointerException if no map has been assigned to this builder
	 * @since Envoy Client v0.2-beta
	 */
	public SystemCommand build(String command) {
		return build(command, true);
	}

	/**
	 * Builds a {@code SystemCommand} based upon the previously entered data.<br>
	 * Automatically adds the built object to the given map. {@code SystemCommand#numberOfArguments}
	 * will be set to 0, regardless of the previous value.<br>
	 * At the end, this {@code SystemCommandBuilder} will be reset.
	 *
	 * @param command the command under which to store the SystemCommand in the
	 *                {@link SystemCommandMap}
	 * @return the built {@code SystemCommand}
	 * @throws NullPointerException if no map has been assigned to this builder
	 * @since Envoy Client v0.2-beta
	 */
	public SystemCommand buildNoArg(String command) {
		numberOfArguments = 0;
		return build(command, true);
	}

	/**
	 * Builds a {@code SystemCommand} based upon the previously entered data.<br>
	 * Automatically adds the built object to the given map. {@code SystemCommand#numberOfArguments}
	 * will be set to use the rest of the string as argument, regardless of the previous value.<br>
	 * At the end, this {@code SystemCommandBuilder} will be reset.
	 *
	 * @param command the command under which to store the SystemCommand in the
	 *                {@link SystemCommandMap}
	 * @return the built {@code SystemCommand}
	 * @throws NullPointerException if no map has been assigned to this builder
	 * @since Envoy Client v0.2-beta
	 */
	public SystemCommand buildRemainingArg(String command) {
		numberOfArguments = -1;
		return build(command, true);
	}

	/**
	 * Builds a {@code SystemCommand} based upon the previously entered data.<br>
	 * Automatically adds the built object to the given map. At the end, this
	 * {@code SystemCommandBuilder} <b>can</b> be reset but must not be.
	 *
	 * @param command the command under which to store the SystemCommand in the
	 *                {@link SystemCommandMap}
	 * @param reset   whether this {@code SystemCommandBuilder} should be reset afterwards.<br>
	 *                This can be useful if another command wants to execute something similar
	 * @return the built {@code SystemCommand}
	 * @throws NullPointerException if no map has been assigned to this builder
	 * @since Envoy Client v0.2-beta
	 */
	public SystemCommand build(String command, boolean reset) {
		final var sc = new SystemCommand(action, numberOfArguments, defaults, description);
		sc.setRelevance(relevance);
		if (commandsMap != null)
			commandsMap.add(command, sc);
		else
			throw new NullPointerException("No map in SystemCommandsBuilder present");
		if (reset)
			reset();
		return sc;
	}
}