/*
 * 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.console.freemarker;

import static org.apache.juneau.commons.utils.Shorts.*;

import java.util.*;
import java.util.function.*;
import java.util.regex.*;

import org.apache.juneau.console.*;

/**
 * Builder for a {@code switcher} card: one card slot that shows one of several named views, each holding one card or a
 * strip of sections that each hold a card.
 *
 * <p>
 * A view with a single section that has the default id and no model block serializes as a plain {@code card}; any
 * other view serializes as {@code sections}.  A switcher cannot hold another switcher.  Validation runs in
 * {@link #toCardSpec()} and is shared with {@link SwitcherCardType} through {@link #validate(String, Map)}, so both
 * paths report the same messages.
 *
 * <h2 class='section'>Example:</h2>
 * <p class='bjava'>
 *    CardSpec <jv>c</jv> = SwitcherDef.<jsm>create</jsm>(<js>"revenue-sw"</js>).title(<js>"Revenue"</js>)
 *       .view(<js>"chart"</js>, <js>"Chart"</js>, <jv>v</jv> -&gt; <jv>v</jv>.section(ChartDef.<jsm>line</jsm>(<js>"revenue-chart"</js>).src(<js>"/console/store/stats/revenue"</js>).toCardSpec()))
 *       .view(<js>"data"</js>, <js>"Data"</js>, <jv>v</jv> -&gt; <jv>v</jv>.section(<js>"all"</js>, <js>"All"</js>, CardSpec.<jsm>of</jsm>(<js>"html"</js>, <js>"d1"</js>)).section(<js>"open"</js>, <js>"Open"</js>, CardSpec.<jsm>of</jsm>(<js>"html"</js>, <js>"d2"</js>)))
 *       .initialView(<js>"chart"</js>)
 *       .toCardSpec();
 * </p>
 *
 * @since 10.0.0
 */
@SuppressWarnings({
   "java:S1192" // Map keys read more clearly inline than as constants.
})
public final class SwitcherDef {

   /** The grammar of a view or section id. */
   static final Pattern ID_GRAMMAR = Pattern.compile("^[A-Za-z][A-Za-z0-9_-]{0,63}$");

   /** The default switcher style: a folder-tab strip joined to the display. */
   public static final String STYLE_TABS = "tabs";

   /** The segmented-control style: a pill track with a sliding thumb. */
   public static final String STYLE_SLIDER = "slider";

   private static final String DEFAULT_SECTION = "main";

   private final String id;
   private String title;
   private String initialView;
   private String style;
   private final List<View> views = new ArrayList<>();

   private SwitcherDef(String id) {
      if (ib(id))
         throw iaex("SwitcherDef requires a non-blank id.");
      this.id = id;
   }

   /** @param id The card id. @return A new switcher. */
   public static SwitcherDef create(String id) { return new SwitcherDef(id); }

   /** @param v The card title. @return This object. */
   public SwitcherDef title(String v) { title = v; return this; }

   /** @param v The switcher style, {@link #STYLE_TABS} (default) or {@link #STYLE_SLIDER}. @return This object. */
   public SwitcherDef style(String v) { style = v; return this; }

   /**
    * Validates a switcher style token.
    *
    * @param id The switcher id, used in the message.
    * @param v The style, or <jk>null</jk> for the default.
    * @throws IllegalArgumentException If the value is neither {@link #STYLE_TABS} nor {@link #STYLE_SLIDER}.
    */
   public static void validateStyle(String id, Object v) {
      if (nn(v) && ! STYLE_TABS.equals(v) && ! STYLE_SLIDER.equals(v))
         throw iaex("SwitcherDef '%s' style '%s' must be one of tabs, slider.", id, v);
   }

   /** @param viewId The id of the view shown first when nothing else decides. @return This object. */
   public SwitcherDef initialView(String viewId) { initialView = viewId; return this; }

   /**
    * Adds a view.
    *
    * @param viewId The view id, matching {@code [A-Za-z][A-Za-z0-9_-]{0,63}}.
    * @param label The tab label.
    * @param config Fills in the view's sections and model block.
    * @return This object.
    */
   public SwitcherDef view(String viewId, String label, Consumer<View> config) {
      var v = new View(viewId, label);
      config.accept(v);
      views.add(v);
      return this;
   }

   /**
    * One view of a switcher.
    *
    * <h2 class='section'>Example:</h2>
    * <p class='bjava'>
    *    <jv>v</jv>.section(<js>"all"</js>, <js>"All"</js>, <jv>card</jv>).initialSection(<js>"all"</js>).on(<js>"activated"</js>, <js>"orders.shown"</js>);
    * </p>
    */
   public static final class View implements Handled<View> {
      private final String id;
      private final String label;
      private String initialSection;
      private final List<Section> sections = new ArrayList<>();
      private final List<CardSpec> stack = new ArrayList<>();
      private final ModelBlock model;

      private View(String id, String label) {
         this.id = id;
         this.label = label;
         this.model = new ModelBlock("view", id);
      }

      @Override /* Handled */
      public ModelBlock modelBlock() { return model; }

      @Override /* Handled */
      public View self() { return this; }

      /** @param card The only card of the view, in the default section. @return This object. */
      public View section(CardSpec card) {
         sections.add(new Section(DEFAULT_SECTION, label, card, true));
         return this;
      }

      /** @param sectionId The section id. @param sectionLabel The section tab label. @param card The section's card. @return This object. */
      public View section(String sectionId, String sectionLabel, CardSpec card) {
         sections.add(new Section(sectionId, sectionLabel, card, false));
         return this;
      }

      /** @param sectionId The section id. @param sectionLabel The section tab label. @param card The section's card. @param config Fills in the section's model block. @return This object. */
      public View section(String sectionId, String sectionLabel, CardSpec card, Consumer<Section> config) {
         var s = new Section(sectionId, sectionLabel, card, false);
         config.accept(s);
         sections.add(s);
         return this;
      }

      /**
       * Stacks the cards vertically in this view, with the card gap between them.
       *
       * @param cards The cards, two or more.
       * @return This object.
       */
      public View cards(CardSpec...cards) {
         stack.addAll(Arrays.asList(cards));
         return this;
      }

      /** @param sectionId The section shown first when nothing else decides. @return This object. */
      public View initialSection(String sectionId) { initialSection = sectionId; return this; }

      private Map<String,Object> toMap() {
         var m = new LinkedHashMap<String,Object>();
         m.put("id", id);
         m.put("label", label);
         if (nn(initialSection)) m.put("initialSection", initialSection);
         // A mix is emitted as authored; validate() rejects it with the switcher's id in the message.
         if (! stack.isEmpty())
            m.put("cards", stack.stream().map(CardSpec::toMap).toList());
         if (sections.size() == 1 && sections.get(0).implicit && sections.get(0).model.isEmpty()) {
            m.put("card", sections.get(0).card.toMap());
         } else if (! sections.isEmpty()) {
            m.put("sections", sections.stream().map(Section::toMap).toList());
         }
         var mm = model.toMap();
         if (mm != null) m.put("model", mm);
         return m;
      }
   }

   /**
    * One section of a switcher view.
    *
    * <h2 class='section'>Example:</h2>
    * <p class='bjava'>
    *    <jv>v</jv>.section(<js>"all"</js>, <js>"All"</js>, <jv>card</jv>, <jv>s</jv> -&gt; <jv>s</jv>.on(<js>"activated"</js>, <js>"orders.sectionShown"</js>));
    * </p>
    */
   public static final class Section implements Handled<Section> {
      private final String id;
      private final String label;
      private final CardSpec card;
      private final boolean implicit;
      private final ModelBlock model;

      private Section(String id, String label, CardSpec card, boolean implicit) {
         this.id = id;
         this.label = label;
         this.card = card;
         this.implicit = implicit;
         this.model = new ModelBlock("detailtab", id);
      }

      @Override /* Handled */
      public ModelBlock modelBlock() { return model; }

      @Override /* Handled */
      public Section self() { return this; }

      private Map<String,Object> toMap() {
         var m = new LinkedHashMap<String,Object>();
         m.put("id", id);
         m.put("label", label);
         m.put("card", card.toMap());
         var mm = model.toMap();
         if (mm != null) m.put("model", mm);
         return m;
      }
   }

   /**
    * Builds the {@code switcher} card entry.
    *
    * @return The card.
    * @throws IllegalArgumentException If the switcher is invalid.
    */
   public CardSpec toCardSpec() {
      var vs = views.stream().map(View::toMap).toList();
      var body = new LinkedHashMap<String,Object>();
      if (nn(initialView)) body.put("initialView", initialView);
      if (nn(style)) body.put("style", style);
      body.put("views", vs);
      validate(id, body);
      var c = CardSpec.of("switcher", id);
      if (nn(title)) c.title(title);
      if (nn(initialView)) c.body("initialView", initialView);
      if (nn(style)) c.body("style", style);
      c.body("views", vs);
      return c;
   }

   /**
    * Validates a switcher body: the shape the builder emits and the page-contract JSON carries.
    *
    * @param id The switcher id, used in messages.
    * @param body The body holding {@code views} and optionally {@code initialView}.
    * @throws IllegalArgumentException On the first problem found.
    */
   @SuppressWarnings({
      "java:S3776" // Branching is inherent to validate(), which checks many view/section combinations.
   })
   public static void validate(String id, Map<String,?> body) {
      var who = "SwitcherDef '" + id + "'";
      validateStyle(id, body.get("style"));
      if (! (body.get("views") instanceof List<?> views) || views.isEmpty())
         throw iaex("%s requires at least one view.", who);
      var viewIds = new HashSet<String>();
      var cardIds = new HashSet<String>();
      for (var o : views) {
         if (! (o instanceof Map<?,?> v))
            throw iaex("%s views must be objects.", who);
         var vid = String.valueOf(v.get("id"));
         if (! (v.get("id") instanceof String) || ! ID_GRAMMAR.matcher(vid).matches())
            throw iaex("%s view id '%s' must match %s.", who, vid, ID_GRAMMAR.pattern());
         if (! viewIds.add(vid))
            throw iaex("%s view id '%s' is declared more than once.", who, vid);
         if (! (v.get("label") instanceof String))
            throw iaex("%s view '%s' requires a string label.", who, vid);
         var hasCard = v.get("card") != null;
         var hasSections = v.get("sections") != null;
         var hasCards = v.get("cards") != null;
         if ((hasCard ? 1 : 0) + (hasSections ? 1 : 0) + (hasCards ? 1 : 0) > 1)
            throw iaex("%s view '%s' takes exactly one of card, sections or cards.", who, vid);
         if (! hasCard && ! hasCards && (! (v.get("sections") instanceof List<?> l) || l.isEmpty()))
            throw iaex("%s view '%s' requires a card, sections or cards.", who, vid);
         var sectionIds = new HashSet<String>();
         if (hasCard) {
            checkCard(who, vid, v.get("card"), cardIds);
         } else if (hasCards) {
            if (! (v.get("cards") instanceof List<?> stacked) || stacked.size() < 2)
               throw iaex("%s view '%s' cards needs at least two cards.", who, vid);
            for (var co : stacked)
               checkCard(who, vid, co, cardIds);
         } else {
            for (var so : (List<?>)v.get("sections")) {
               if (! (so instanceof Map<?,?> s))
                  throw iaex("%s view '%s' sections must be objects.", who, vid);
               var sid = String.valueOf(s.get("id"));
               if (! (s.get("id") instanceof String) || ! ID_GRAMMAR.matcher(sid).matches())
                  throw iaex("%s view '%s' section id '%s' must match %s.", who, vid, sid, ID_GRAMMAR.pattern());
               if (! sectionIds.add(sid))
                  throw iaex("%s view '%s' section id '%s' is declared more than once.", who, vid, sid);
               if (! (s.get("label") instanceof String))
                  throw iaex("%s view '%s' section '%s' requires a string label.", who, vid, sid);
               checkCard(who, vid, s.get("card"), cardIds);
            }
         }
         var is = v.get("initialSection");
         if (is != null && ! sectionIds.contains(is))
            throw iaex("%s view '%s' initialSection '%s' names no section.", who, vid, is);
      }
      var iv = body.get("initialView");
      if (iv != null && ! viewIds.contains(iv))
         throw iaex("%s initialView '%s' names no view.", who, iv);
   }

   private static void checkCard(String who, String vid, Object card, Set<String> cardIds) {
      if (! (card instanceof Map<?,?> c) || ! (c.get("id") instanceof String cid) || ! (c.get("type") instanceof String type))
         throw iaex("%s view '%s' cards must be objects with a string id and type.", who, vid);
      if ("switcher".equals(type))
         throw iaex("%s view '%s' cannot hold a switcher card ('%s').", who, vid, cid);
      if (! cardIds.add(cid))
         throw iaex("%s card id '%s' is declared more than once.", who, cid);
   }
}