/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * License: GNU Lesser General Public License (LGPL), version 2.1 or later.
 * See the lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>.
 */
package org.hibernate.tool.schema.internal.exec;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Reader;

import org.hibernate.tool.schema.spi.SchemaManagementException;
import org.hibernate.tool.schema.spi.ScriptSourceInput;

import org.jboss.logging.Logger;

/**
 * ScriptSourceInput implementation for File references.  A reader is opened here and then explicitly closed on
 * {@link #release}.
 *
 * @author Steve Ebersole
 */
public class ScriptSourceInputFromFile extends AbstractScriptSourceInput implements ScriptSourceInput {
	private static final Logger log = Logger.getLogger( ScriptSourceInputFromFile.class );

	private final File file;
	private final String charsetName;

	private Reader reader;

	/**
	 * Constructs a ScriptSourceInputFromFile
	 *
	 * @param file The file to read from
	 * @param charsetName The charset name
	 */
	public ScriptSourceInputFromFile(File file, String charsetName) {
		this.file = file;
		this.charsetName = charsetName;
	}

	@Override
	protected Reader reader() {
		if ( reader == null ) {
			throw new SchemaManagementException( "Illegal state - reader is null - not prepared" );
		}
		return reader;
	}

	@Override
	public void prepare() {
		super.prepare();
		this.reader = toReader( file, charsetName );
	}

	@SuppressWarnings("ResultOfMethodCallIgnored")
	private static Reader toReader(File file, String charsetName) {
		if ( ! file.exists() ) {
			log.warnf( "Specified schema generation script file [%s] did not exist for reading", file );
			return new Reader() {
				@Override
				public int read(char[] cbuf, int off, int len) throws IOException {
					return -1;
				}

				@Override
				public void close() throws IOException {
				}
			};
		}

		try {
			return charsetName != null ?
				new InputStreamReader( new FileInputStream(file), charsetName ) :
				new InputStreamReader( new FileInputStream(file) );
		}
		catch (IOException e) {
			throw new SchemaManagementException(
					"Unable to open specified script target file [" + file + "] for reading",
					e
			);
		}
	}

	@Override
	public void release() {
		try {
			reader.close();
		}
		catch (IOException e) {
			log.warn( "Unable to close file reader for generation script source" );
		}
	}

	@Override
	public String toString() {
		return "ScriptSourceInputFromFile(" + file.getAbsolutePath() + ")";
	}
}