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package com.blitline.image.functions;

import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;

import org.apache.commons.lang3.Validate;

import com.blitline.image.Function;
import com.blitline.image.SavedImage;

/**
 * Abstract base class extended by all of the Blitline functions included in this library. Uses a plain {@code HashMap} as the store
 * for parameters and includes a few convenience methods for adding parameters that need validation.
 *
 * @author Christopher Smith
 *
 */
public abstract class AbstractFunction implements Function {

	private static final long serialVersionUID = 1L;

	protected Map params = new HashMap();

	private SavedImage saveLocation;

	private List childFunctions = new LinkedList();

	public Map getParams() {
		return Collections.unmodifiableMap(params);
	}

	protected void putOpacity(double opacity) {
		Validate.inclusiveBetween(0.0, 1.0, opacity);
		params.put("opacity", opacity);
	}

	protected void putRadius(double radius) {
		Validate.isTrue(radius >= 0., "radius must be nonnegative");
		params.put("radius", radius);
	}

	public Function andSaveResultTo(SavedImage location) {
		Validate
			.validState(
				saveLocation == null,
				"only one save location is supported for each function; to save the output of a pipeline in multiple formats or locations, add a child NoOp function");
		saveLocation = location;
		return this;
	}

	/**
	 * Saves the output of the current function node to Blitline's S3 container.
	 *
	 * @param imageIdentifier
	 *            The image identifier Blitline will use to indicate the location of the saved file.
	 * @return this {@code Function} node
	 */
	public Function andSaveResult(String imageIdentifier) {
		return andSaveResultTo(SavedImage.withId(imageIdentifier).toBlitlineContainer());
	}

	/**
	 * Performs a "save to {@code /dev/null}"; returns information about the output of this function but does not actually persist
	 * the resulting file anywhere. Primarily useful to determine image metadata.
	 *
	 * @param imageIdentifier
	 *            The image identifier Blitline will use to indicate information about the output of this node.
	 * @return this {@code Function} node
	 */
	public Function andSkipSave(String imageIdentifier) {
		return andSaveResultTo(SavedImage.withId(imageIdentifier).butSkipSave());
	}

	public SavedImage getSave() {
		return saveLocation;
	}

	public Function thenApply(Function... functions) {
		childFunctions.addAll(Arrays.asList(functions));
		return this;
	}

	public List getFunctions() {
		return Collections.unmodifiableList(childFunctions);
	}
}