/*
 * Copyright 2002-2019 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
 *
 *      https://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.springframework.web.servlet.view;

import javax.servlet.http.HttpServletRequest;

import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.StringUtils;
import org.springframework.web.servlet.HandlerMapping;
import org.springframework.web.servlet.RequestToViewNameTranslator;
import org.springframework.web.util.UrlPathHelper;

/**
 * {@link RequestToViewNameTranslator} that simply transforms the URI of
 * the incoming request into a view name.
 *
 * <p>Can be explicitly defined as the {@code viewNameTranslator} bean in a
 * {@link org.springframework.web.servlet.DispatcherServlet} context.
 * Otherwise, a plain default instance will be used.
 *
 * <p>The default transformation simply strips leading and trailing slashes
 * as well as the file extension of the URI, and returns the result as the
 * view name with the configured {@link #setPrefix prefix} and a
 * {@link #setSuffix suffix} added as appropriate.
 *
 * <p>The stripping of the leading slash and file extension can be disabled
 * using the {@link #setStripLeadingSlash stripLeadingSlash} and
 * {@link #setStripExtension stripExtension} properties, respectively.
 *
 * <p>Find below some examples of request to view name translation.
 * <ul>
 * <li>{@code http://localhost:8080/gamecast/display.html} &raquo; {@code display}</li>
 * <li>{@code http://localhost:8080/gamecast/displayShoppingCart.html} &raquo; {@code displayShoppingCart}</li>
 * <li>{@code http://localhost:8080/gamecast/admin/index.html} &raquo; {@code admin/index}</li>
 * </ul>
 *
 * @author Rob Harrop
 * @author Juergen Hoeller
 * @since 2.0
 * @see org.springframework.web.servlet.RequestToViewNameTranslator
 * @see org.springframework.web.servlet.ViewResolver
 */
public class DefaultRequestToViewNameTranslator implements RequestToViewNameTranslator {

        private static final String SLASH = "/";


        private String prefix = "";

        private String suffix = "";

        private String separator = SLASH;

        private boolean stripLeadingSlash = true;

        private boolean stripTrailingSlash = true;

        private boolean stripExtension = true;

        private UrlPathHelper urlPathHelper = new UrlPathHelper();


        /**
         * Set the prefix to prepend to generated view names.
         * @param prefix the prefix to prepend to generated view names
         */
        public void setPrefix(@Nullable String prefix) {
                this.prefix = (prefix != null ? prefix : "");
        }

        /**
         * Set the suffix to append to generated view names.
         * @param suffix the suffix to append to generated view names
         */
        public void setSuffix(@Nullable String suffix) {
                this.suffix = (suffix != null ? suffix : "");
        }

        /**
         * Set the value that will replace '{@code /}' as the separator
         * in the view name. The default behavior simply leaves '{@code /}'
         * as the separator.
         */
        public void setSeparator(String separator) {
                this.separator = separator;
        }

        /**
         * Set whether or not leading slashes should be stripped from the URI when
         * generating the view name. Default is "true".
         */
        public void setStripLeadingSlash(boolean stripLeadingSlash) {
                this.stripLeadingSlash = stripLeadingSlash;
        }

        /**
         * Set whether or not trailing slashes should be stripped from the URI when
         * generating the view name. Default is "true".
         */
        public void setStripTrailingSlash(boolean stripTrailingSlash) {
                this.stripTrailingSlash = stripTrailingSlash;
        }

        /**
         * Set whether or not file extensions should be stripped from the URI when
         * generating the view name. Default is "true".
         */
        public void setStripExtension(boolean stripExtension) {
                this.stripExtension = stripExtension;
        }

        /**
         * Shortcut to same property on underlying {@link #setUrlPathHelper UrlPathHelper}.
         * @see org.springframework.web.util.UrlPathHelper#setAlwaysUseFullPath
         */
        public void setAlwaysUseFullPath(boolean alwaysUseFullPath) {
                this.urlPathHelper.setAlwaysUseFullPath(alwaysUseFullPath);
        }

        /**
         * Shortcut to same property on underlying {@link #setUrlPathHelper UrlPathHelper}.
         * @see org.springframework.web.util.UrlPathHelper#setUrlDecode
         */
        public void setUrlDecode(boolean urlDecode) {
                this.urlPathHelper.setUrlDecode(urlDecode);
        }

        /**
         * Set if ";" (semicolon) content should be stripped from the request URI.
         * @see org.springframework.web.util.UrlPathHelper#setRemoveSemicolonContent(boolean)
         */
        public void setRemoveSemicolonContent(boolean removeSemicolonContent) {
                this.urlPathHelper.setRemoveSemicolonContent(removeSemicolonContent);
        }

        /**
         * Set the {@link org.springframework.web.util.UrlPathHelper} to use for
         * the resolution of lookup paths.
         * <p>Use this to override the default UrlPathHelper with a custom subclass,
         * or to share common UrlPathHelper settings across multiple web components.
         */
        public void setUrlPathHelper(UrlPathHelper urlPathHelper) {
                Assert.notNull(urlPathHelper, "UrlPathHelper must not be null");
                this.urlPathHelper = urlPathHelper;
        }


        /**
         * Translates the request URI of the incoming {@link HttpServletRequest}
         * into the view name based on the configured parameters.
         * @see org.springframework.web.util.UrlPathHelper#getLookupPathForRequest
         * @see #transformPath
         */
        @Override
        public String getViewName(HttpServletRequest request) {
                String lookupPath = this.urlPathHelper.getLookupPathForRequest(request, HandlerMapping.LOOKUP_PATH);
                return (this.prefix + transformPath(lookupPath) + this.suffix);
        }

        /**
         * Transform the request URI (in the context of the webapp) stripping
         * slashes and extensions, and replacing the separator as required.
         * @param lookupPath the lookup path for the current request,
         * as determined by the UrlPathHelper
         * @return the transformed path, with slashes and extensions stripped
         * if desired
         */
        @Nullable
        protected String transformPath(String lookupPath) {
                String path = lookupPath;
                if (this.stripLeadingSlash && path.startsWith(SLASH)) {
                        path = path.substring(1);
                }
                if (this.stripTrailingSlash && path.endsWith(SLASH)) {
                        path = path.substring(0, path.length() - 1);
                }
                if (this.stripExtension) {
                        path = StringUtils.stripFilenameExtension(path);
                }
                if (!SLASH.equals(this.separator)) {
                        path = StringUtils.replace(path, SLASH, this.separator);
                }
                return path;
        }

}