/*
 * Copyright 2002-2005 the original author or authors.
 *
 * 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 org.springmodules.validation.valang.javascript.taglib;

import java.io.IOException;
import java.io.Reader;
import java.io.Writer;

import javax.servlet.ServletException;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspWriter;

import org.springframework.util.Assert;
import org.springframework.web.servlet.tags.RequestContextAwareTag;
import org.springmodules.validation.valang.javascript.ValangJavaScriptTranslator;

/**
 * Generates the JavaScript codebase that is necessary for the use of the JavaScript validation produced by
 * {@link ValangValidateTag}.
 * <p/>
 * <p>
 * The generated codebase is an exact copy of the code from the file "valang_codebase.js" located in
 * org.springmodules.validation.valang.javascript. You can therefor avoid having to use this tag by simply placing this
 * file on your web server and linking to it using a the following HTML:
 * 
 * <pre>
 * <script type="text/javascript" src="/somepath/valang_codebase.js"></script>
 * </pre>
 * <p/>
 * <p>
 * When using this tag or the HTML above you must make sure that the codebase is included before any
 * {@link ValangValidateTag}s in you JSP file.
 * 
 * @author Oliver Hutchison
 */
public class ValangCodebaseTag extends RequestContextAwareTag {

    private boolean includeScriptTags;

    private String logId;

    private String globalErrorsId;

    private String fieldErrorIdSuffix;

    /**
     * Sets the HTML ID of the log parent node.
     */
    public void setLogId(String logId) {
        this.logId = logId;
    }

    /**
     * Sets whether or not the generated code should be wrapped in HTML <script> tags. This is useful if you wont
     * to include the codebase directly in a HTML page.
     */
    public void setIncludeScriptTags(String includeScriptTags) {
        this.includeScriptTags = "true".equalsIgnoreCase(includeScriptTags);
    }

    /**
     * Sets the id of the element that will hold the global error. If not set, this tag will look for an element with id
     * "global_errors".
     * 
     * @param globalErrorsId
     *            The id of the element that should hold the global errors.
     */
    public void setGlobalErrorsId(String globalErrorsId) {
        this.globalErrorsId = globalErrorsId;
    }

    /**
     * Sets the id suffix of the element that should hold the error of a specific field. For example, if the validated
     * field is "firstName" and the suffix is set to "_err" then this tag will put the validation errors for the
     * firstName field in an element with id "firstName_err". If this suffix is not set, it is set by default to
     * "_error".
     * 
     * @param fieldErrorsIdSuffix
     *            The id suffix of the element that should hold the error of a specific field.
     */
    public void setFieldErrorsIdSuffix(String fieldErrorIdSuffix) {
        this.fieldErrorIdSuffix = fieldErrorIdSuffix;
    }

    protected int doStartTagInternal() throws ServletException, JspException {
        return SKIP_BODY;
    }

    public int doEndTag() throws JspException {
        try {
            JspWriter out = pageContext.getOut();
            if (includeScriptTags) {
                out.write("<script type=\"text/javascript\">\n");
            }
            copy(ValangJavaScriptTranslator.getCodebaseReader(), out);

            if (globalErrorsId != null) {
                out.write("ValangValidator.prototype.globalErrorsId = '" + globalErrorsId + "';\n");
            }
            if (fieldErrorIdSuffix != null) {
                out.write("ValangValidator.prototype.fieldErrorIdSuffix = '" + fieldErrorIdSuffix + "';\n");
            }
            if (logId != null) {
                out.write("ValangValidator.Logger.logId = '" + logId + "';\n");
            }
            if (includeScriptTags) {
                out.write("\n</script>");
            }
            return EVAL_PAGE;
        } catch (IOException e) {
            throw new JspException("Could not write validation codebase", e);
        }
    }

    /**
     * Copies the chars from in to out and then closes in but leaves out open.
     */
    private void copy(Reader in, Writer out) throws IOException {
        Assert.notNull(in, "No Reader specified");
        Assert.notNull(out, "No Writer specified");
        try {
            char[] buffer = new char[1024];
            int bytesRead;

            while ((bytesRead = in.read(buffer)) != -1) {
                out.write(buffer, 0, bytesRead);
            }
            out.flush();
        } finally {
            try {
                in.close();
            } catch (IOException ex) {
                logger.warn("Could not close Reader", ex);
            }
        }
    }

    public void doFinally() {
        super.doFinally();
        includeScriptTags = false;
    }
}