package com.airhacks.enhydrator.transform;
/*
* #%L
* enhydrator
* %%
* Copyright (C) 2014 Adam Bien
* %%
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
* #L%
*/
import com.airhacks.enhydrator.in.Row;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.nio.file.Files;
import java.nio.file.Paths;
import javax.script.Bindings;
import javax.script.Invocable;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;
/**
* @author airhacks.com
*/
public class FunctionScriptLoader {
private final ScriptEngineManager manager;
private final ScriptEngine engine;
private String baseFolder;
public static final String COLUMN_SCRIPT_FOLDER = "column";
public static final String ROW_SCRIPT_FOLDER = "row";
public FunctionScriptLoader(String baseFolder) {
this();
this.baseFolder = baseFolder;
}
public FunctionScriptLoader() {
this.manager = new ScriptEngineManager();
this.engine = manager.getEngineByName("nashorn");
this.baseFolder = ".";
}
public ColumnTransformer getColumnTransformer(String scriptName) {
String content = load(COLUMN_SCRIPT_FOLDER, scriptName);
Invocable invocable = (Invocable) engine;
try {
engine.eval(content);
} catch (ScriptException ex) {
throw new IllegalStateException("Cannot evaluate script", ex);
}
return invocable.getInterface(ColumnTransformer.class);
}
public RowTransformer getRowTransformer(String scriptName) {
return (Row input) -> {
if (input == null) {
return null;
}
String content = load(ROW_SCRIPT_FOLDER, scriptName);
try {
Bindings bindings = ScriptingEnvironmentProvider.create(manager, input);
return (Row) engine.eval(content, bindings);
} catch (ScriptException ex) {
throw new IllegalStateException("Cannot evaluate script: " + scriptName, ex);
}
};
}
public String load(String scriptFolder, String name) {
String fileName = name + ".js";
try {
return new String(Files.readAllBytes(Paths.get(baseFolder, scriptFolder, fileName)), "UTF-8");
} catch (UnsupportedEncodingException ex) {
throw new IllegalStateException("Encoding is not supported");
} catch (IOException ex) {
throw new IllegalStateException("Cannot load script " + ex.getMessage());
}
}
}