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// *  http://www.apache.org/licenses/LICENSE-2.0                                                                             *
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package org.apache.juneau.rest;

import static org.apache.juneau.internal.ClassUtils.*;
import static org.apache.juneau.internal.StringUtils.*;
import static org.apache.juneau.rest.util.RestUtils.*;

import java.lang.reflect.Method;
import java.util.*;
import java.util.concurrent.*;

import org.apache.juneau.dto.swagger.*;
import org.apache.juneau.internal.*;
import org.apache.juneau.reflect.*;
import org.apache.juneau.rest.annotation.*;
import org.apache.juneau.svl.*;

/**
 * Default implementation of {@link RestInfoProvider}.
 *
 * <p>
 * Subclasses can override these methods to tailor how HTTP REST resources are documented.
 *
 * <ul class='seealso'>
 *    <li class='jf'>{@link RestContext#REST_infoProvider}
 *    <li class='link'>{@doc juneau-rest-server.Swagger}
 * </ul>
 */
public class BasicRestInfoProvider implements RestInfoProvider {

   private final RestContext context;
   private final String
      siteName,
      title,
      description;
   private final ConcurrentHashMap<Locale,ConcurrentHashMap<Integer,Swagger>> swaggers = new ConcurrentHashMap<>();

   /**
    * Constructor.
    *
    * @param context The resource context.
    */
   public BasicRestInfoProvider(RestContext context) {
      this.context = context;

      Builder b = new Builder(context);
      this.siteName = b.siteName;
      this.title = b.title;
      this.description = b.description;
   }

   private static final class Builder {
      String
         siteName,
         title,
         description;

      Builder(RestContext context) {
         ClassInfo ci = getClassInfo(context.getResource().getClass());
         for (RestResource r : ci.getAnnotationsParentFirst(RestResource.class)) {
            if (! r.siteName().isEmpty())
               siteName = r.siteName();
            if (r.title().length > 0)
               title = joinnl(r.title());
            if (r.description().length > 0)
               description = joinnl(r.description());
         }
      }
   }

   /**
    * Returns the localized swagger for this REST resource.
    *
    * <p>
    * Subclasses can override this method to customize the Swagger.
    *
    * @param req The incoming HTTP request.
    * @return
    *    A new Swagger instance.
    *    <br>Never <jk>null</jk>.
    * @throws Exception Error occurred.
    */
   @Override /* RestInfoProvider */
   public Swagger getSwagger(RestRequest req) throws Exception {

      Locale locale = req.getLocale();

      // Find it in the cache.
      // Swaggers are cached by user locale and an int hash of the @RestMethods they have access to.
      HashCode userHash = HashCode.create();
      for (RestMethodContext sm : context.getCallMethods().values())
         if (sm.isRequestAllowed(req))
            userHash.add(sm.hashCode());
      int hashCode = userHash.get();

      if (! swaggers.containsKey(locale))
         swaggers.putIfAbsent(locale, new ConcurrentHashMap<Integer,Swagger>());

      Swagger swagger = swaggers.get(locale).get(hashCode);
      if (swagger != null)
         return swagger;

      // Wasn't cached...need to create one.
      swagger = new SwaggerGenerator(req).getSwagger();

      swaggers.get(locale).put(hashCode, swagger);

      return swagger;
   }

   /**
    * Returns the localized summary of the specified java method on this servlet.
    *
    * <p>
    * Subclasses can override this method to provide their own summary.
    *
    * <p>
    * The default implementation returns the value from the following locations (whichever matches first):
    * <ol class='spaced-list'>
    *    <li>{@link RestMethod#summary() @RestMethod(summary)} annotation.
    *       <h5 class='figure'>Examples:</h5>
    *       <p class='bcode w800'>
    *    <cc>// Direct value</cc>
    *    <ja>@RestMethod</ja>(summary=<js>"Summary of my method"</js>)
    *    <jk>public</jk> Object myMethod() {...}
    *
    *    <cc>// Pulled from some other location</cc>
    *    <ja>@RestMethod</ja>(summary=<js>"$L{myLocalizedSummary}"</js>)
    *    <jk>public</jk> Object myMethod() {...}
    *       </p>
    *    <li>Localized string from resource bundle identified by {@link RestResource#messages() @RestResource(messages)}
    *       on the resource class, then any parent classes.
    *       <ol>
    *          <li><ck>[ClassName].[javaMethodName].summary</ck>
    *          <li><ck>[javaMethodName].summary</ck>
    *       </ol>
    *       <br>Value can contain any SVL variables defined on the {@link RestMethod#summary() @RestMethod(summary)} annotation.
    *       <h5 class='figure'>Examples:</h5>
    *       <p class='bcode w800'>
    *    <cc>// Direct value</cc>
    *    <ck>MyClass.myMethod.summary</ck> = <cv>Summary of my method.</cv>
    *
    *    <cc>// Pulled from some other location</cc>
    *    <ck>MyClass.myMethod.summary</ck> = <cv>$C{MyStrings/MyClass.myMethod.summary}</cv>
    *       </p>
    * </ol>
    *
    * @param method The Java method annotated with {@link RestMethod @RestMethod}.
    * @param req The current request.
    * @return The localized summary of the method, or <jk>null</jk> if none was found.
    * @throws Exception Error occurred.
    */
   @Override /* RestInfoProvider */
   public String getMethodSummary(Method method, RestRequest req) throws Exception {
      VarResolverSession vr = req.getVarResolverSession();

      String s = getMethodInfo(method).getAnnotation(RestMethod.class).summary();
      if (s.isEmpty()) {
         Operation o = getSwaggerOperation(method, req);
         if (o != null)
            s = o.getSummary();
      }

      return isEmpty(s) ? null : vr.resolve(s);
   }

   /**
    * Returns the localized description of the specified java method on this servlet.
    *
    * <p>
    * Subclasses can override this method to provide their own description.
    *
    * <p>
    * The default implementation returns the value from the following locations (whichever matches first):
    * <ol class='spaced-list'>
    *    <li>{@link RestMethod#description() @RestMethod(description)} annotation.
    *       <h5 class='figure'>Examples:</h5>
    *       <p class='bcode w800'>
    *    <cc>// Direct value</cc>
    *    <ja>@RestMethod</ja>(description=<js>"Description of my method"</js>)
    *    <jk>public</jk> Object myMethod() {...}
    *
    *    <cc>// Pulled from some other location</cc>
    *    <ja>@RestMethod</ja>(description=<js>"$L{myLocalizedDescription}"</js>)
    *    <jk>public</jk> Object myMethod() {...}
    *       </p>
    *    <li>Localized string from resource bundle identified by {@link RestResource#messages() @RestResource(messages)}
    *       on the resource class, then any parent classes.
    *       <ol>
    *          <li><ck>[ClassName].[javaMethodName].description</ck>
    *          <li><ck>[javaMethodName].description</ck>
    *       </ol>
    *       <br>Value can contain any SVL variables defined on the {@link RestMethod#description() @RestMethod(description)} annotation.
    *       <h5 class='figure'>Examples:</h5>
    *       <p class='bcode w800'>
    *    <cc>// Direct value</cc>
    *    <ck>MyClass.myMethod.description</ck> = <cv>Description of my method.</cv>
    *
    *    <cc>// Pulled from some other location</cc>
    *    <ck>MyClass.myMethod.description</ck> = <cv>$C{MyStrings/MyClass.myMethod.description}</cv>
    *       </p>
    * </ol>
    *
    * @param method The Java method annotated with {@link RestMethod @RestMethod}.
    * @param req The current request.
    * @return The localized description of the method, or <jk>null</jk> if none was found.
    * @throws Exception Error occurred.
    */
   @Override /* RestInfoProvider */
   public String getMethodDescription(Method method, RestRequest req) throws Exception {
      VarResolverSession vr = req.getVarResolverSession();

      String s = joinnl(getMethodInfo(method).getAnnotation(RestMethod.class).description());
      if (s.isEmpty()) {
         Operation o = getSwaggerOperation(method, req);
         if (o != null)
            s = o.getDescription();
      }

      return isEmpty(s) ? null : vr.resolve(s);
   }

   /**
    * Returns the localized site name of this REST resource.
    *
    * <p>
    * Subclasses can override this method to provide their own site name.
    *
    * <p>
    * The default implementation returns the value from the following locations (whichever matches first):
    * <ol class='spaced-list'>
    *    <li>{@link RestResource#siteName() @RestResource(siteName)} annotation on this class, and then any parent classes.
    *       <h5 class='figure'>Examples:</h5>
    *       <p class='bcode w800'>
    *    <jc>// Direct value</jc>
    *    <ja>@RestResource</ja>(siteName=<js>"My Site"</js>)
    *    <jk>public class</jk> MyResource {...}
    *
    *    <jc>// Pulled from some other location</jc>
    *    <ja>@RestResource</ja>(siteName=<js>"$L{myLocalizedSiteName}"</js>)
    *    <jk>public class</jk> MyResource {...}
    *       </p>
    *    <li>Localized strings from resource bundle identified by {@link RestResource#messages() @RestResource(messages)}
    *       on the resource class, then any parent classes.
    *       <ol>
    *          <li><ck>[ClassName].siteName</ck>
    *          <li><ck>siteName</ck>
    *       </ol>
    *       <br>Value can contain any SVL variables defined on the {@link RestResource#siteName() @RestResource(siteName)} annotation.
    *       <h5 class='figure'>Examples:</h5>
    *       <p class='bcode w800'>
    *    <cc>// Direct value</cc>
    *    <ck>MyClass.siteName</ck> = <cv>My Site</cv>
    *
    *    <cc>// Pulled from some other location</cc>
    *    <ck>MyClass.siteName</ck> = <cv>$C{MyStrings/MyClass.siteName}</cv>
    *       </p>
    * </ol>
    *
    * @param req The current request.
    * @return The localized site name of this REST resource, or <jk>null</jk> if none was found.
    * @throws Exception Error occurred.
    */
   @Override /* RestInfoProvider */
   public String getSiteName(RestRequest req) throws Exception {
      VarResolverSession vr = req.getVarResolverSession();
      if (siteName != null)
         return vr.resolve(siteName);
      String siteName = context.getMessages().findFirstString(req.getLocale(), "siteName");
      if (siteName != null)
         return vr.resolve(siteName);
      return null;
   }

   /**
    * Returns the localized title of this REST resource.
    *
    * <p>
    * Subclasses can override this method to provide their own title.
    *
    * <p>
    * The default implementation returns the value from the following locations (whichever matches first):
    * <ol class='spaced-list'>
    *    <li>{@link RestResource#title() @RestResource(siteName)} annotation on this class, and then any parent classes.
    *       <h5 class='figure'>Examples:</h5>
    *       <p class='bcode w800'>
    *    <jc>// Direct value</jc>
    *    <ja>@RestResource</ja>(title=<js>"My Resource"</js>)
    *    <jk>public class</jk> MyResource {...}
    *
    *    <jc>// Pulled from some other location</jc>
    *    <ja>@RestResource</ja>(title=<js>"$L{myLocalizedTitle}"</js>)
    *    <jk>public class</jk> MyResource {...}
    *       </p>
    *    <li>Localized strings from resource bundle identified by {@link RestResource#messages() @RestResource(messages)}
    *       on the resource class, then any parent classes.
    *       <ol>
    *          <li><ck>[ClassName].title</ck>
    *          <li><ck>title</ck>
    *       </ol>
    *       <br>Value can contain any SVL variables defined on the {@link RestResource#title() @RestResource(title)} annotation.
    *       <h5 class='figure'>Examples:</h5>
    *       <p class='bcode w800'>
    *    <cc>// Direct value</cc>
    *    <ck>MyClass.title</ck> = <cv>My Resource</cv>
    *
    *    <cc>// Pulled from some other location</cc>
    *    <ck>MyClass.title</ck> = <cv>$C{MyStrings/MyClass.title}</cv>
    *       </p>
    *    <li><ck>/info/title</ck> entry in swagger file.
    * </ol>
    *
    * @param req The current request.
    * @return The localized title of this REST resource, or <jk>null</jk> if none was found.
    * @throws Exception Error occurred.
    */
   @Override /* RestInfoProvider */
   public String getTitle(RestRequest req) throws Exception {
      VarResolverSession vr = req.getVarResolverSession();
      if (title != null)
         return vr.resolve(title);
      String title = context.getMessages().findFirstString(req.getLocale(), "title");
      if (title != null)
         return vr.resolve(title);
      return null;
   }

   /**
    * Returns the localized description of this REST resource.
    *
    * <p>
    * Subclasses can override this method to provide their own description.
    *
    * <p>
    * The default implementation returns the value from the following locations (whichever matches first):
    * <ol class='spaced-list'>
    *    <li>{@link RestResource#description() @RestResource(description)} annotation on this class, and then any parent classes.
    *       <h5 class='figure'>Examples:</h5>
    *       <p class='bcode w800'>
    *    <jc>// Direct value</jc>
    *    <ja>@RestResource</ja>(description=<js>"My Resource"</js>)
    *    <jk>public class</jk> MyResource {...}
    *
    *    <jc>// Pulled from some other location</jc>
    *    <ja>@RestResource</ja>(description=<js>"$L{myLocalizedDescription}"</js>)
    *    <jk>public class</jk> MyResource {...}
    *       </p>
    *    <li>Localized strings from resource bundle identified by {@link RestResource#messages() @RestResource(messages)}
    *       on the resource class, then any parent classes.
    *       <ol>
    *          <li><ck>[ClassName].description</ck>
    *          <li><ck>description</ck>
    *       </ol>
    *       <br>Value can contain any SVL variables defined on the {@link RestResource#description() @RestResource(description)} annotation.
    *       <h5 class='figure'>Examples:</h5>
    *       <p class='bcode w800'>
    *    <cc>// Direct value</cc>
    *    <ck>MyClass.description</ck> = <cv>My Resource</cv>
    *
    *    <cc>// Pulled from some other location</cc>
    *    <ck>MyClass.description</ck> = <cv>$C{MyStrings/MyClass.description}</cv>
    *       </p>
    *    <li><ck>/info/description</ck> entry in swagger file.
    * </ol>
    *
    * @param req The current request.
    * @return The localized description of this REST resource, or <jk>null</jk> if none was was found.
    * @throws Exception Error occurred.
    */
   @Override /* RestInfoProvider */
   public String getDescription(RestRequest req) throws Exception {
      VarResolverSession vr = req.getVarResolverSession();
      if (description != null)
         return vr.resolve(description);
      String description = context.getMessages().findFirstString(req.getLocale(), "description");
      if (description != null)
         return vr.resolve(description);
      return null;
   }

   //-----------------------------------------------------------------------------------------------------------------
   // Utility methods
   //-----------------------------------------------------------------------------------------------------------------

   private Operation getSwaggerOperation(Method method, RestRequest req) throws Exception {

      Swagger s = getSwagger(req);
      if (s != null) {
         Map<String,OperationMap> sp = s.getPaths();
         if (sp != null) {
            Map<String,Operation> spp = sp.get(fixMethodPath(getMethodInfo(method).getAnnotation(RestMethod.class).path()));
            if (spp != null)
               return spp.get(req.getMethod());
         }
      }
      return null;
   }

   static String joinnl(String[] ss) {
      if (ss.length == 0)
         return "";
      return StringUtils.joinnl(ss).trim();
   }
}