/*
 * Copyright 2014 Attila Szegedi, Daniel Dekany, Jonathan Revusky
 * 
 * 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.
 */

package freemarker.core;

import java.util.List;

import freemarker.ext.beans.BeansWrapper;
import freemarker.template.ObjectWrapper;
import freemarker.template.TemplateException;
import freemarker.template.TemplateMethodModelEx;
import freemarker.template.TemplateModel;
import freemarker.template.TemplateModelException;

/**
 * A built-in that allows us to instantiate an instance of a java class.
 * Usage is something like: <tt><#assign foobar = "foo.bar.MyClass"?new()></tt>;
 */
class NewBI extends BuiltIn {
    
    static final Class BEAN_MODEL_CLASS = freemarker.ext.beans.BeanModel.class;
    static Class JYTHON_MODEL_CLASS;
    static {
        try {
            JYTHON_MODEL_CLASS = Class.forName("freemarker.ext.jython.JythonModel");
        } catch (Throwable e) {
            JYTHON_MODEL_CLASS = null;
        }
    }
    
    @Override
    TemplateModel _eval(Environment env)
            throws TemplateException {
        return new ConstructorFunction(target.evalAndCoerceToString(env), env);
    }

    class ConstructorFunction implements TemplateMethodModelEx {

        private final Class cl;
        private final Environment env;
        
        public ConstructorFunction(String classname, Environment env) throws TemplateException {
            this.env = env;
            cl = env.getNewBuiltinClassResolver().resolve(classname, env, env.getCurrentTemplate());
            if (!TemplateModel.class.isAssignableFrom(cl)) {
                throw new _MiscTemplateException(NewBI.this, env,
                        "Class ", cl.getName(), " does not implement freemarker.template.TemplateModel");
            }
            if (BEAN_MODEL_CLASS.isAssignableFrom(cl)) {
                throw new _MiscTemplateException(NewBI.this, env,
                        "Bean Models cannot be instantiated using the ?", key, " built-in");
            }
            if (JYTHON_MODEL_CLASS != null && JYTHON_MODEL_CLASS.isAssignableFrom(cl)) {
                throw new _MiscTemplateException(NewBI.this, env,
                        "Jython Models cannot be instantiated using the ?", key, " built-in");
            }
        }

        public Object exec(List arguments) throws TemplateModelException {
            ObjectWrapper ow = env.getObjectWrapper();
            BeansWrapper bw = 
                ow instanceof BeansWrapper 
                ? (BeansWrapper) ow
                : BeansWrapper.getDefaultInstance();
            return bw.newInstance(cl, arguments);
        }
    }
}