first basic i18n support for webpage

server/pom.xml

@@ -14,6 +14,16 @@
     <name>moth-server</name>
     <url>http://maven.apache.org</url>
     <dependencies>
+        <dependency>
+            <groupId>org.thymeleaf</groupId>
+            <artifactId>thymeleaf</artifactId>
+            <version>3.1.1.RELEASE</version>
+        </dependency>
+        <dependency>
+            <groupId>org.thymeleaf</groupId>
+            <artifactId>thymeleaf-spring5</artifactId>
+            <version>3.1.1.RELEASE</version>
+        </dependency>
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-data-mongodb-reactive</artifactId>

server/src/main/java/edu/sjsu/moth/server/controller/AppController.java

@@ -11,6 +11,7 @@
 import edu.sjsu.moth.server.util.Util.TTLHashMap;
 import lombok.extern.apachecommons.CommonsLog;
 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.context.i18n.LocaleContextHolder;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.ResponseEntity;
 import org.springframework.web.bind.annotation.GetMapping;
@@ -19,9 +20,10 @@
 import org.springframework.web.bind.annotation.RequestHeader;
 import org.springframework.web.bind.annotation.RequestParam;
 import org.springframework.web.bind.annotation.RestController;
+import org.thymeleaf.context.Context;
+import org.thymeleaf.spring5.SpringTemplateEngine;
 import reactor.core.publisher.Mono;
 
-import java.io.IOException;
 import java.security.Principal;
 import java.security.SecureRandom;
 import java.time.LocalDateTime;
@@ -33,6 +35,8 @@
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.logging.Logger;
 
+import static edu.sjsu.moth.server.controller.i18nController.getExceptionMessage;
+
 /**
  * This code handles first contact and oauth outh with the client.
  * The flow seems to be:
@@ -76,6 +80,9 @@ public class AppController {
     TTLHashMap<String, AppRegistrationEntry> registrations = new TTLHashMap<>(10, TimeUnit.MINUTES);
     @Autowired
     TokenRepository tokenRepository;
+    // required for i18n
+    @Autowired
+    private SpringTemplateEngine templateEngine;
 
     /**
      * base64 URL encode a nonce of byteCount random bytes.
@@ -155,16 +162,10 @@ private CredentialAccount convertAccount2CredentialAccount(Account a) {
     }
 
     @GetMapping("/oauth/authorize")
-    String getOauthAuthorize(@RequestParam String client_id, @RequestParam String redirect_uri,
-                             @RequestParam(required = false, defaultValue = "") String error) throws IOException {
-        try (var is = AppController.class.getResourceAsStream("/static/oauth/authorize.html")) {
-            var authorizePage = new String(is.readAllBytes());
-            authorizePage = authorizePage.replace("client_id_value", client_id);
-            authorizePage = authorizePage.replace("redirect_uri_value", redirect_uri);
-            authorizePage = authorizePage.replace("authorize_error", error);
-            //noinspection ReassignedVariable
-            return authorizePage;
-        }
+    public String getOauthAuthorize() {
+        // resolves locale to user locale; resolves the locale based on the "Accept-Language" header in the
+        // request packet. resolved via the WebFilterChain.
+        return templateEngine.process("authorize", new Context(LocaleContextHolder.getLocale()));
     }
 
     @GetMapping("/oauth/login")
@@ -193,7 +194,8 @@ Mono<ResponseEntity<Object>> postOauthToken(@RequestBody TokenRequest req) {
             scopes = req.scope;
         } else {
             if (!registration.registration.client_secret.equals(req.client_secret)) {
-                throw new RuntimeException("bad client_secret");
+                throw new RuntimeException(
+                        getExceptionMessage("clientSecretException", LocaleContextHolder.getLocale()));
             }
             scopes = registration.scopes;
             name = registration.registration.name;

server/src/main/java/edu/sjsu/moth/server/controller/i18nController.java

@@ -0,0 +1,55 @@
+package edu.sjsu.moth.server.controller;
+
+import org.springframework.context.MessageSource;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.context.support.ResourceBundleMessageSource;
+import org.thymeleaf.spring5.SpringTemplateEngine;
+import org.thymeleaf.templateresolver.ClassLoaderTemplateResolver;
+
+import java.util.Locale;
+import java.util.ResourceBundle;
+
+@Configuration
+public class i18nController {
+    //from baeldung https://www.baeldung.com/java-localize-exception-messages
+    public static String getExceptionMessage(String key, Locale locale) {
+        return ResourceBundle.getBundle("messages", locale).getString(key);
+    }
+
+    @Bean
+    // message source is responsible for retrieving messages based on current locale. it loads different message sets
+    // and
+    // applies as necessary. message sets r based off of 'basename'. (e.g, spanish is messages_es now since basename is
+    // messages
+    public MessageSource messageSource() {
+        ResourceBundleMessageSource messageSource = new ResourceBundleMessageSource();
+        messageSource.setBasename("messages");
+        messageSource.setDefaultEncoding("UTF-8");
+        return messageSource;
+    }
+
+    // this method searches for the template to dynamically load based on prefix (filepath) and suffix. required for
+    // template engine.
+    public ClassLoaderTemplateResolver templateResolver() {
+        ClassLoaderTemplateResolver templateSettings = new ClassLoaderTemplateResolver();
+        templateSettings.setPrefix(
+                "static/oauth/"); // classpath for the template, if/when we need more pages in the future we
+        //should probably rename this folder for readability
+        templateSettings.setSuffix(".html"); // suffix for templates so it knows what to load
+        templateSettings.setTemplateMode("HTML"); // can switch between HTML, XML, and text
+        templateSettings.setCharacterEncoding("UTF-8"); //only involves reading, doesn't overlap messageSource encoding
+        return templateSettings;
+    }
+
+    @Bean
+    // CORE component of Thymeleaf -- it takes and parses a template, requires context for various details e.g locale,
+    // and renders page, outputting HTML
+    // all current and future autowires will refer to this one
+    public SpringTemplateEngine springTemplateEngine() {
+        SpringTemplateEngine springTemplateEngine = new SpringTemplateEngine();
+        springTemplateEngine.setMessageSource(messageSource()); // message sets, defined above
+        springTemplateEngine.setTemplateResolver(templateResolver());
+        return springTemplateEngine;
+    }
+}

server/src/main/java/edu/sjsu/moth/server/util/ContentSecurityPolicyConfiguration.java

@@ -4,14 +4,21 @@
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.context.i18n.LocaleContextHolder;
+import org.springframework.http.HttpHeaders;
 import org.springframework.security.config.annotation.web.reactive.EnableWebFluxSecurity;
+import org.springframework.security.config.web.server.SecurityWebFiltersOrder;
 import org.springframework.security.config.web.server.ServerHttpSecurity;
 import org.springframework.security.oauth2.core.DefaultOAuth2AuthenticatedPrincipal;
 import org.springframework.security.oauth2.core.OAuth2AuthenticatedPrincipal;
 import org.springframework.security.oauth2.server.resource.introspection.BadOpaqueTokenException;
 import org.springframework.security.web.server.SecurityWebFilterChain;
+import org.springframework.web.server.ServerWebExchange;
+import org.springframework.web.server.WebFilter;
+import org.springframework.web.server.WebFilterChain;
 import reactor.core.publisher.Mono;
 
+import java.util.Locale;
 import java.util.Map;
 import java.util.Set;
 
@@ -32,6 +39,24 @@ public Mono<OAuth2AuthenticatedPrincipal> introspect(String token) {
     public SecurityWebFilterChain filterChain(ServerHttpSecurity http) {
         http.csrf().disable();
         http.oauth2ResourceServer().opaqueToken().introspector(this::introspect);
+        http.addFilterBefore(localeChangeFilter(), SecurityWebFiltersOrder.FIRST);
         return http.build();
     }
+
+    public LocaleChangeFilter localeChangeFilter() {
+        return new LocaleChangeFilter();
+    }
+
+    public static class LocaleChangeFilter implements WebFilter {
+        @Override
+        public Mono<Void> filter(ServerWebExchange exchange, WebFilterChain chain) {
+            String acceptLanguage = exchange.getRequest().getHeaders().getFirst(HttpHeaders.ACCEPT_LANGUAGE);
+            // to improve this code, i would say you could technically process the data grabbed above by "Q" value to
+            // switch to the most 'preferred' value by the User.
+            Locale resolvedLocale = (acceptLanguage != null) ? Locale.forLanguageTag(
+                    acceptLanguage) : Locale.getDefault();
+            LocaleContextHolder.setLocale(resolvedLocale);
+            return chain.filter(exchange);
+        }
+    }
 }

server/src/main/resources/application.properties

@@ -1,2 +1,3 @@
 spring.main.web-application-type=REACTIVE
-# NONE, SERVLET
+# NONE, SERVLET
+spring.thymeleaf.prefix=classpath:/oauth/

server/src/main/resources/messages.properties

@@ -0,0 +1,5 @@
+authorizeError=Authorize_Error
+email=Email
+password=Password
+signIn=Sign In
+clientSecretException=Bad Client Secret

server/src/main/resources/messages_es.properties

@@ -0,0 +1,5 @@
+authorizeError=Autorizar_Error
+email=Email
+password=Contrasena
+signIn=Acceso
+clientSecretException=Secreto de Cliente Incorrecto

server/src/main/resources/static/oauth/authorize.html

@@ -1,5 +1,5 @@
 <!DOCTYPE html>
-<html lang="en">
+<html lang="en" xmlns:th="http://www.thymeleaf.org">
 <head>
     <link rel="icon" type="image/png" sizes="32x32" href="/moth/favicon.png">
     <meta charset="UTF-8">
@@ -73,15 +73,18 @@
 <div class="spin">
     <img alt="Moth Logo" src="/moth/cyber-moth.png">
 </div>
-<h2>authorize_error</h2>
+<h2 th:text="#{authorizeError}">authError</h2>
 <form action="/oauth/login">
-    Email<br/>
-    <input name="user"/><br/>
-    Password<br/>
+    <span th:text="#{email}">Email</span>
+    <br/>
+    <input name="user"/>
+    <br/>
+    <span th:text="#{password}">Password</span>
+    <br/>
     <input name="password" type="password"/><br/>
     <input name="client_id" type="hidden" value="client_id_value"/>
     <input name="redirect_uri" type="hidden" value="redirect_uri_value"/>
-    <input type="submit" value="Sign In"/>
+    <input type="submit" value="#{signIn}" th:value="#{signIn}"/>
 </form>
 </body>
 </html>