/*
 * 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.io.IOException;
import java.io.Writer;

import freemarker.template.TemplateModelException;

/**
 * Common superclass for implementing {@link MarkupOutputFormat}-s that use a {@link CommonTemplateMarkupOutputModel}
 * subclass.
 * 
 * @since 2.3.24
 */
public abstract class CommonMarkupOutputFormat<MO extends CommonTemplateMarkupOutputModel>
        extends MarkupOutputFormat<MO> {

    protected CommonMarkupOutputFormat() {
        // Only to decrease visibility
    }
    
    @Override
    public final MO fromPlainTextByEscaping(String textToEsc) throws TemplateModelException {
        return newTemplateMarkupOutputModel(textToEsc, null);
    }

    @Override
    public final MO fromMarkup(String markupText) throws TemplateModelException {
        return newTemplateMarkupOutputModel(null, markupText);
    }

    @Override
    public final void output(MO mo, Writer out) throws IOException, TemplateModelException {
        String mc = mo.getMarkupContent();
        if (mc != null) {
            out.write(mc);
        } else {
            output(mo.getPlainTextContent(), out);
        }
    }

    @Override
    public abstract void output(String textToEsc, Writer out) throws IOException, TemplateModelException;
    
    @Override
    public final String getSourcePlainText(MO mo) throws TemplateModelException {
        return mo.getPlainTextContent();
    }

    @Override
    public final String getMarkupString(MO mo) throws TemplateModelException {
        String mc = mo.getMarkupContent();
        if (mc != null) {
            return mc;
        }
        
        mc = escapePlainText(mo.getPlainTextContent());
        mo.setMarkupContet(mc);
        return mc;
    }
    
    @Override
    public final MO concat(MO mo1, MO mo2) throws TemplateModelException {
        String pc1 = mo1.getPlainTextContent();
        String mc1 = mo1.getMarkupContent();
        String pc2 = mo2.getPlainTextContent();
        String mc2 = mo2.getMarkupContent();
        
        String pc3 = pc1 != null && pc2 != null ? pc1 + pc2 : null;
        String mc3 = mc1 != null && mc2 != null ? mc1 + mc2 : null;
        if (pc3 != null || mc3 != null) {
            return newTemplateMarkupOutputModel(pc3, mc3);
        }
        
        if (pc1 != null) {
            return newTemplateMarkupOutputModel(null, getMarkupString(mo1) + mc2);
        } else {
            return newTemplateMarkupOutputModel(null, mc1 + getMarkupString(mo2));
        }
    }
    
    @Override
    public boolean isEmpty(MO mo) throws TemplateModelException {
        String s = mo.getPlainTextContent();
        if (s != null) {
            return s.length() == 0;
        }
        return mo.getMarkupContent().length() == 0;
    }
    
    @Override
    public boolean isOutputFormatMixingAllowed() {
        return false;
    }
    
    @Override
    public boolean isAutoEscapedByDefault() {
        return true;
    }

    /**
     * Creates a new {@link CommonTemplateMarkupOutputModel} that's bound to this {@link OutputFormat} instance.
     */
    protected abstract MO newTemplateMarkupOutputModel(String plainTextContent, String markupContent)
            throws TemplateModelException;
    
}