package org.springframework.cloud.localconfig;

import static org.junit.Assert.assertEquals;

import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.nio.charset.Charset;

/**
 * Provides an easy way to stub the {@code openFile} method on the local connector.
 *
 * @author Christopher Smith
 */
class StubbedOpenFileLocalConfigConnector extends LocalConfigConnector {

	static final Charset UTF_8 = Charset.forName("UTF-8");

	private InputStreamProvider fileProvider;

	@Override
	InputStream openFile(File file) throws IOException {
		return fileProvider.openFile(file);
	}

	@Override
	boolean fileExists(File file) {
		return true;
	}

	public void setFileProvider(InputStreamProvider provider) {
		this.fileProvider = provider;
	}

	interface InputStreamProvider {
		InputStream openFile(File file) throws IOException;
	}

	/**
	 * Returns the supplied input stream. Used for reading out of the classpath for testing.
	 *
	 * @param expectedFilename the filename we expect the connector to open
	 * @param stream the contents to return
	 */
	static InputStreamProvider fileContentsFromStream(final String expectedFilename, final InputStream stream) {
		return new InputStreamProvider() {
			@Override
			public InputStream openFile(File file) throws IOException {
				assertEquals(expectedFilename, file.getPath());
				return stream;
			}
		};
	}

	/**
	 * Returns a stream view of the provided string.
	 *
	 * @param expectedFilename the filename we expect the connector to open
	 * @param contents the contents to return
	 */
	static InputStreamProvider fileContentsFromString(final String expectedFilename, final String contents) {
		return fileContentsFromStream(expectedFilename, new ByteArrayInputStream(contents.getBytes(UTF_8)));
	}
}