/*
 * 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.juneau.bean.openapi3.ui;

import static java.util.Collections.*;
import static org.apache.juneau.bean.html5.HtmlBuilder.*;
import static org.apache.juneau.bean.html5.HtmlBuilder.a;
import static org.apache.juneau.common.utils.Utils.*;

import java.util.*;

import org.apache.juneau.*;
import org.apache.juneau.bean.html5.*;
import org.apache.juneau.bean.openapi3.*;
import org.apache.juneau.collections.*;
import org.apache.juneau.common.utils.*;
import org.apache.juneau.cp.*;
import org.apache.juneau.swap.*;

/**
 * Generates an OpenAPI-UI interface from an OpenAPI document.
 *
 * <h5 class='section'>See Also:</h5><ul>
 *    <li class='link'><a class="doclink" href="https://juneau.apache.org/docs/topics/JuneauBeanOpenApi3">juneau-bean-openapi-v3</a>
 * </ul>
 */
public class OpenApiUI extends ObjectSwap<OpenApi,Div> {

   static final FileFinder RESOURCES = FileFinder
      .create(BeanStore.INSTANCE)
      .cp(OpenApiUI.class, null, true)
      .dir(",")
      .caching(Boolean.getBoolean("RestContext.disableClasspathResourceCaching.b") ? -1 : 1_000_000)
      .build();

   private static final Set<String> STANDARD_METHODS = set("get", "put", "post", "delete", "options", "head", "patch", "trace");

   /**
    * This UI applies to HTML requests only.
    */
   @Override
   public org.apache.juneau.MediaType[] forMediaTypes() {
      return new org.apache.juneau.MediaType[] {org.apache.juneau.MediaType.HTML};
   }

   private static class Session {
      final int resolveRefsMaxDepth;
      final OpenApi openApi;

      Session(OpenApi openApi) {
         this.openApi = openApi.copy();
         this.resolveRefsMaxDepth = 1;
      }
   }

   @Override
   public Div swap(BeanSession beanSession, OpenApi openApi) throws Exception {

      var s = new Session(openApi);

      var css = RESOURCES.getString("files/htdocs/styles/OpenApiUI.css", null).orElse(null);
      if (css == null)
         css = RESOURCES.getString("OpenApiUI.css", null).orElse(null);

      var outer = div(
         style(css),
         script("text/javascript", RESOURCES.getString("OpenApiUI.js", null).orElse(null)),
         header(s)
      )._class("openapi-ui");

      // Operations without tags are rendered first.
      outer.child(div()._class("tag-block tag-block-open").children(tagBlockContents(s, null)));

      if (s.openApi.getTags() != null) {
         s.openApi.getTags().forEach(x -> {
            var tagBlock = div()._class("tag-block tag-block-open").children(
               tagBlockSummary(x),
               tagBlockContents(s, x)
            );
            outer.child(tagBlock);
         });
      }

      if (s.openApi.getComponents() != null && s.openApi.getComponents().getSchemas() != null) {
         var modelBlock = div()._class("tag-block").children(
            modelsBlockSummary(),
            modelsBlockContents(s)
         );
         outer.child(modelBlock);
      }

      return outer;
   }

   // Creates the informational summary before the ops.
   private Table header(Session s) {
      var table = table()._class("header");

      var info = s.openApi.getInfo();
      if (info != null) {

         if (info.getDescription() != null)
            table.child(tr(th("Description:"),td(toBRL(info.getDescription()))));

         if (info.getVersion() != null)
            table.child(tr(th("Version:"),td(info.getVersion())));

         var c = info.getContact();
         if (c != null) {
            var t2 = table();

            if (c.getName() != null)
               t2.child(tr(th("Name:"),td(c.getName())));
            if (c.getUrl() != null)
               t2.child(tr(th("URL:"),td(a(c.getUrl(), c.getUrl()))));
            if (c.getEmail() != null)
               t2.child(tr(th("Email:"),td(a("mailto:"+ c.getEmail(), c.getEmail()))));

            table.child(tr(th("Contact:"),td(t2)));
         }

         var l = info.getLicense();
         if (l != null) {
            var content = l.getName() != null ? l.getName() : l.getUrl();
            var child = l.getUrl() != null ? a(l.getUrl(), content) : l.getName();
            table.child(tr(th("License:"),td(child)));
         }

         ExternalDocumentation ed = s.openApi.getExternalDocs();
         if (ed != null) {
            var content = ed.getDescription() != null ? ed.getDescription() : ed.getUrl();
            var child = ed.getUrl() != null ? a(ed.getUrl(), content) : ed.getDescription();
            table.child(tr(th("Docs:"),td(child)));
         }

         if (info.getTermsOfService() != null) {
            var tos = info.getTermsOfService();
            var child = StringUtils.isUri(tos) ? a(tos, tos) : tos;
            table.child(tr(th("Terms of Service:"),td(child)));
         }
      }

      return table;
   }

   // Creates the "pet  Everything about your Pets  ext-link" header.
   private HtmlElement tagBlockSummary(Tag t) {
      var ed = t.getExternalDocs();

      var content = ed != null && ed.getDescription() != null ? ed.getDescription() : (ed != null ? ed.getUrl() : null);
      return div()._class("tag-block-summary").children(
         span(t.getName())._class("name"),
         span(toBRL(t.getDescription()))._class("description"),
         ed != null && ed.getUrl() != null ? span(a(ed.getUrl(), content))._class("extdocs") : null
      ).onclick("toggleTagBlock(this)");
   }

   // Creates the contents under the "pet  Everything about your Pets  ext-link" header.
   private Div tagBlockContents(Session s, Tag t) {
      var tagBlockContents = div()._class("tag-block-contents");

      if (s.openApi.getPaths() != null) {
         s.openApi.getPaths().forEach((path, pathItem) -> {
            // Check each HTTP method in the path item
            if (pathItem.getGet() != null)
               addOperationIfTagMatches(tagBlockContents, s, path, "get", pathItem.getGet(), t);
            if (pathItem.getPut() != null)
               addOperationIfTagMatches(tagBlockContents, s, path, "put", pathItem.getPut(), t);
            if (pathItem.getPost() != null)
               addOperationIfTagMatches(tagBlockContents, s, path, "post", pathItem.getPost(), t);
            if (pathItem.getDelete() != null)
               addOperationIfTagMatches(tagBlockContents, s, path, "delete", pathItem.getDelete(), t);
            if (pathItem.getOptions() != null)
               addOperationIfTagMatches(tagBlockContents, s, path, "options", pathItem.getOptions(), t);
            if (pathItem.getHead() != null)
               addOperationIfTagMatches(tagBlockContents, s, path, "head", pathItem.getHead(), t);
            if (pathItem.getPatch() != null)
               addOperationIfTagMatches(tagBlockContents, s, path, "patch", pathItem.getPatch(), t);
            if (pathItem.getTrace() != null)
               addOperationIfTagMatches(tagBlockContents, s, path, "trace", pathItem.getTrace(), t);
         });
      }

      return tagBlockContents;
   }

   private void addOperationIfTagMatches(Div tagBlockContents, Session s, String path, String method, Operation op, Tag t) {
      if ((t == null && (op.getTags() == null || op.getTags().isEmpty())) ||
         (t != null && op.getTags() != null && op.getTags().contains(t.getName()))) {
         tagBlockContents.child(opBlock(s, path, method, op));
      }
   }

   private Div opBlock(Session s, String path, String opName, Operation op) {

      var opClass = op.getDeprecated() != null && op.getDeprecated() ? "deprecated" : opName.toLowerCase();
      if (!(op.getDeprecated() != null && op.getDeprecated()) && !STANDARD_METHODS.contains(opClass))
         opClass = "other";

      return div()._class("op-block op-block-closed " + opClass).children(
         opBlockSummary(path, opName, op),
         div(tableContainer(s, op))._class("op-block-contents")
      );
   }

   private HtmlElement opBlockSummary(String path, String opName, Operation op) {
      return div()._class("op-block-summary").children(
         span(opName.toUpperCase())._class("method-button"),
         span(path)._class("path"),
         op.getSummary() != null ? span(op.getSummary())._class("summary") : null
      ).onclick("toggleOpBlock(this)");
   }

   private Div tableContainer(Session s, Operation op) {
      var tableContainer = div()._class("table-container");

      if (op.getDescription() != null)
         tableContainer.child(div(toBRL(op.getDescription()))._class("op-block-description"));

      if (op.getParameters() != null) {
         tableContainer.child(div(h4("Parameters")._class("title"))._class("op-block-section-header"));

         var parameters = table(tr(th("Name")._class("parameter-key"), th("Description")._class("parameter-key")))._class("parameters");

         op.getParameters().forEach(x -> {
            var piName = x.getName();
            var required = x.getRequired() != null && x.getRequired();

            var parameterKey = td(
               div(piName)._class("name" + (required ? " required" : "")),
               required ? div("required")._class("requiredlabel") : null,
               x.getSchema() != null ? div(x.getSchema().getType())._class("type") : null,
               div('(' + x.getIn() + ')')._class("in")
            )._class("parameter-key");

            var parameterValue = td(
               div(toBRL(x.getDescription()))._class("description"),
               examples(s, x)
            )._class("parameter-value");

            parameters.child(tr(parameterKey, parameterValue));
         });

         tableContainer.child(parameters);
      }

      if (op.getResponses() != null) {
         tableContainer.child(div(h4("Responses")._class("title"))._class("op-block-section-header"));

         var responses = table(tr(th("Code")._class("response-key"), th("Description")._class("response-key")))._class("responses");
         tableContainer.child(responses);

         op.getResponses().forEach((k,v) -> {
            var code = td(k)._class("response-key");

            var codeValue = td(
               div(toBRL(v.getDescription()))._class("description"),
               examples(s, v),
               headers(v)
            )._class("response-value");

            responses.child(tr(code, codeValue));
         });
      }

      return tableContainer;
   }

   private Div headers(Response ri) {
      if (ri.getHeaders() == null)
         return null;

      var sectionTable = table(tr(th("Name"),th("Description"),th("Schema")))._class("section-table");

      var headers = div(
         div("Headers:")._class("section-name"),
         sectionTable
      )._class("headers");

      ri.getHeaders().forEach((k,v) ->
         sectionTable.child(
            tr(
               td(k)._class("name"),
               td(toBRL(v.getDescription()))._class("description"),
               td(v.asMap().keepAll("type","format","items","collectionFormat","default","maximum","exclusiveMaximum","minimum","exclusiveMinimum","maxLength","minLength","pattern","maxItems","minItems","uniqueItems","enum","multipleOf"))
            )
         )
      );

      return headers;
   }

   private Div examples(Session s, Parameter pi) {
      var m = new JsonMap();

      try {
         var si = pi.getSchema();
         if (si != null)
            m.put("model", si.copy().resolveRefs(s.openApi, new ArrayDeque<>(), s.resolveRefsMaxDepth));
      } catch (Exception e) {
         e.printStackTrace();
      }

      if (m.isEmpty())
         return null;

      return examplesDiv(m);
   }

   private Div examples(Session s, Response ri) {
      var m = new JsonMap();
      try {
         var content = ri.getContent();
         if (content != null) {
            // For OpenAPI 3.0, content is a map of media types to MediaType objects
            content.forEach((mediaType, mediaTypeObj) -> {
               if (mediaTypeObj.getSchema() != null) {
                  try {
                     var schema = mediaTypeObj.getSchema().copy().resolveRefs(s.openApi, new ArrayDeque<>(), s.resolveRefsMaxDepth);
                     m.put(mediaType, schema);
                  } catch (Exception e) {
                     e.printStackTrace();
                  }
               }
            });
         }
      } catch (Exception e) {
         e.printStackTrace();
      }

      if (m.isEmpty())
         return null;

      return examplesDiv(m);
   }

   private Div examplesDiv(JsonMap m) {
      if (m.isEmpty())
         return null;

      Select select = null;
      if (m.size() > 1) {
         select = select().onchange("selectExample(this)")._class("example-select");
      }

      var div = div(select)._class("examples");

      if (select != null)
         select.child(option("model","model"));
      div.child(div(m.remove("model"))._class("model active").attr("data-name", "model"));

      var select2 = select;
      m.forEach((k,v) -> {
         if (select2 != null)
            select2.child(option(k, k));
         div.child(div(v.toString().replace("\\n", "\n"))._class("example").attr("data-name", k));
      });

      return div;
   }

   // Creates the "Model" header.
   private HtmlElement modelsBlockSummary() {
      return div()._class("tag-block-summary").children(span("Models")._class("name")).onclick("toggleTagBlock(this)");
   }

   // Creates the contents under the "Model" header.
   private Div modelsBlockContents(Session s) {
      var modelBlockContents = div()._class("tag-block-contents");
      if (s.openApi.getComponents() != null && s.openApi.getComponents().getSchemas() != null) {
         s.openApi.getComponents().getSchemas().forEach((k,v) -> modelBlockContents.child(modelBlock(k,v)));
      }
      return modelBlockContents;
   }

   private Div modelBlock(String modelName, SchemaInfo model) {
      return div()._class("op-block op-block-closed model").children(
         modelBlockSummary(modelName, model),
         div(model)._class("op-block-contents")
      );
   }

   private HtmlElement modelBlockSummary(String modelName, SchemaInfo model) {
      return div()._class("op-block-summary").children(
         span(modelName)._class("method-button"),
         model.getDescription() != null ? span(toBRL(model.getDescription()))._class("summary") : null
      ).onclick("toggleOpBlock(this)");
   }

   /**
    * Replaces newlines with <br> elements.
    */
   private static List<Object> toBRL(String s) {
      if (s == null)
         return null;  // NOSONAR - Intentionally returning null.
      if (s.indexOf(',') == -1)
         return singletonList(s);
      var l = Utils.list();
      var sa = s.split("\n");
      for (var i = 0; i < sa.length; i++) {
         if (i > 0)
            l.add(br());
         l.add(sa[i]);
      }
      return l;
   }
}