/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you 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.apache.cxf.jaxrs.swagger;

import java.net.URL;
import java.net.URLClassLoader;
import java.util.Enumeration;

public class SwaggerUiResolver {
    static final String UI_RESOURCES_ROOT_START = "META-INF/resources/webjars/swagger-ui/";
    
    static final SwaggerUiResolver HELPER;
    static {
        SwaggerUiResolver theHelper = null;
        try {
            theHelper = new OsgiSwaggerUiResolver();
        } catch (Throwable ex) {
            theHelper = new SwaggerUiResolver();
        }
        HELPER = theHelper;
    }
    
    
    protected SwaggerUiResolver() {
    }

    protected String findSwaggerUiRootInternal(String swaggerUiMavenGroupAndArtifact,
                                               String swaggerUiVersion) {
        try {
            ClassLoader cl = AbstractSwaggerFeature.class.getClassLoader();
            if (cl instanceof URLClassLoader) {
                for (URL url : ((URLClassLoader)cl).getURLs()) {
                    String root = 
                        checkUiRoot(url.toString(), swaggerUiVersion);
                    if (root != null) {
                        return root;
                    }
                }
            } 
            Enumeration<URL> urls = cl.getResources(UI_RESOURCES_ROOT_START);
            while (urls.hasMoreElements()) {
                String urlStr = urls.nextElement().toString().replace(UI_RESOURCES_ROOT_START, "");     
                String root = checkUiRoot(urlStr, swaggerUiVersion);
                if (root != null) {
                    return root;
                }
            }
        } catch (Throwable ex) {
            // ignore
        }   
        return null;
    }

    protected static String checkUiRoot(String urlStr, String swaggerUiVersion) {
        int swaggerUiIndex = urlStr.lastIndexOf("/swagger-ui-");
        if (swaggerUiIndex != -1) {
            boolean urlEndsWithJarSep = urlStr.endsWith(".jar!/");
            if (urlEndsWithJarSep || urlStr.endsWith(".jar")) {
                int offset = urlEndsWithJarSep ? 6 : 4;
                String version = urlStr.substring(swaggerUiIndex + 12, urlStr.length() - offset);
                if (swaggerUiVersion != null && !swaggerUiVersion.equals(version)) {
                    return null;
                }
                if (!urlEndsWithJarSep) {
                    urlStr = "jar:" + urlStr + "!/";
                }
                return urlStr + UI_RESOURCES_ROOT_START + version + "/";
            }
        }
        return null;
    }

    public static String findSwaggerUiRoot(String swaggerUiMavenGroupAndArtifact, 
                                           String swaggerUiVersion) {
        String root = HELPER.findSwaggerUiRootInternal(swaggerUiMavenGroupAndArtifact, 
                                                       swaggerUiVersion);
        if (root == null && HELPER.getClass() != SwaggerUiResolver.class) {
            root = new SwaggerUiResolver().findSwaggerUiRootInternal(swaggerUiMavenGroupAndArtifact, 
                                                                     swaggerUiVersion);
        }
        return root;
    }
}
