/*
    * 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.myfaces.tobago.internal.util;
  
  import org.apache.myfaces.tobago.component.Attributes;
  import org.apache.myfaces.tobago.component.Visual;
  import org.apache.myfaces.tobago.context.Markup;
  import org.apache.myfaces.tobago.util.ComponentUtils;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import javax.el.ValueExpression;
  import javax.faces.component.UIComponent;
  import javax.faces.component.UISelectItem;
  import javax.faces.component.UISelectItems;
  import javax.faces.context.FacesContext;
  import javax.faces.model.SelectItem;
  import java.lang.invoke.MethodHandles;
  import java.lang.reflect.Array;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Map;
  import java.util.NoSuchElementException;
  
  /**
   * Based on code from MyFaces core.
   */
  public class SelectItemUtils {
  
    private static final Logger LOG = LoggerFactory.getLogger(MethodHandles.lookup().lookupClass());
  
    /**
     * Creates a list of SelectItems to use for rendering.
     */
    public static Iterable<SelectItem> getItemIterator(final FacesContext facesContext, final UIComponent selector) {
      if (selector.getChildCount() == 0) {
        return Collections.emptyList();
      } else {
        return new Iterable<SelectItem>() {
  
          private SelectItemsIterator iterator;
  
          @Override
          public Iterator<SelectItem> iterator() {
            if (iterator == null) {
              iterator = new SelectItemsIterator(facesContext, selector);
            }
            return iterator;
          }
        };
      }
    }
  
    /**
     * Creates a list of SelectItems to use for rendering.
     * You should only use this method (which returns a list), when you need a list.
     * Otherwise please use {@link #getItemIterator(javax.faces.context.FacesContext, javax.faces.component.UIComponent)}
     */
    public static List<SelectItem> getItemList(final FacesContext facesContext, final UIComponent selector) {
      if (selector.getChildCount() == 0) {
        return Collections.emptyList();
      } else {
        final Iterable<SelectItem> iterator = getItemIterator(facesContext, selector);
        final List<SelectItem> result = new ArrayList<>();
        for (final SelectItem selectItem : iterator) {
          result.add(selectItem);
        }
        return result;
      }
    }
  
    private static class SelectItemsIterator implements Iterator<SelectItem> {
  
      private final FacesContext facesContext;
      private final Iterator<UIComponent> children;
      private Iterator<?> nestedItems;
      private SelectItem nextItem;
      private UISelectItems currentUISelectItems;
  
     private SelectItemsIterator(final FacesContext facesContext, final UIComponent selector) {
       this.children = selector.getChildren().iterator();
       this.facesContext = facesContext;
     }
 
     @Override
     @SuppressWarnings("unchecked")
     public boolean hasNext() {
       if (nextItem != null) {
         return true;
       }
       if (nestedItems != null) {
         if (nestedItems.hasNext()) {
           return true;
         }
         nestedItems = null;
       }
 
       UIComponent child = null;
       while (children.hasNext()) {
         final UIComponent c = children.next();
         // When there is other components nested that does
         // not extends from UISelectItem or UISelectItems
         // the behavior for this iterator is just skip this
         // element(s) until an element that extends from these
         // classes are found. If there is no more elements
         // that conform this condition, just return false.
         if (c instanceof UISelectItem || c instanceof UISelectItems) {
           child = c;
           break;
         }
       }
       if (child == null) {
         return false;
       }
 
       if (child instanceof UISelectItem) {
         final UISelectItem uiSelectItem = (UISelectItem) child;
         Object item = uiSelectItem.getValue();
         if (item == null) {
           // no value attribute --> create the SelectItem out of the other attributes
           final Object itemValue = uiSelectItem.getItemValue();
           String label = uiSelectItem.getItemLabel();
           final String description = uiSelectItem.getItemDescription();
           final boolean disabled = uiSelectItem.isItemDisabled();
 //          boolean escape = uiSelectItem.isItemEscaped();
 //          boolean noSelectionOption = uiSelectItem.isNoSelectionOption();
           if (label == null && itemValue != null) {
             label = itemValue.toString();
           }
           String image = null;
           Markup markup = null;
           if (uiSelectItem instanceof org.apache.myfaces.tobago.component.UISelectItem) {
             final org.apache.myfaces.tobago.component.UISelectItem tobagoSelectItem
                 = (org.apache.myfaces.tobago.component.UISelectItem) uiSelectItem;
             image = tobagoSelectItem.getItemImage();
             markup = tobagoSelectItem.getMarkup();
           }
           item = new org.apache.myfaces.tobago.model.SelectItem(itemValue, label, description, disabled, image, markup);
         } else if (!(item instanceof SelectItem)) {
           final ValueExpression expression = uiSelectItem.getValueExpression("value");
           throw new IllegalArgumentException("ValueExpression '"
               + (expression == null ? null : expression.getExpressionString()) + "' of UISelectItem : "
               + child + " does not reference an Object of type SelectItem");
         }
         nextItem = (SelectItem) item;
         return true;
       } else { // UISelectItems
         currentUISelectItems = (UISelectItems) child;
         final Object value = currentUISelectItems.getValue();
 
         if (value instanceof SelectItem) {
           nextItem = (SelectItem) value;
           return true;
         } else if (value != null && value.getClass().isArray()) {
           // value is any kind of array (primitive or non-primitive)
           // --> we have to use class Array to get the values
           final int length = Array.getLength(value);
           final Collection<Object> items = new ArrayList<>(length);
           for (int i = 0; i < length; i++) {
             items.add(Array.get(value, i));
           }
           nestedItems = items.iterator();
           return hasNext();
         } else if (value instanceof Iterable) {
           // value is Iterable --> Collection, DataModel,...
           nestedItems = ((Iterable<?>) value).iterator();
           return hasNext();
         } else if (value instanceof Map) {
           final Map<Object, Object> map = (Map<Object, Object>) value;
           final Collection<SelectItem> items = new ArrayList<>(map.size());
           for (final Map.Entry<Object, Object> entry : map.entrySet()) {
             items.add(new org.apache.myfaces.tobago.model.SelectItem(entry.getValue(), entry.getKey().toString()));
           }
           nestedItems = items.iterator();
           return hasNext();
         }
       }
       return false;
     }
 
     @Override
     public SelectItem next() {
       if (!hasNext()) {
         throw new NoSuchElementException();
       }
       if (nextItem != null) {
         final SelectItem value = nextItem;
         nextItem = null;
         return value;
       }
       if (nestedItems != null) {
         Object item = nestedItems.next();
 
         if (!(item instanceof SelectItem)) {
           // check new params of SelectItems (since 2.0): itemValue, itemLabel, itemDescription,...
           // Note that according to the spec UISelectItems does not provide Getter and Setter
           // methods for this values, so we have to use the attribute map
           final Map<String, Object> attributeMap = currentUISelectItems.getAttributes();
 
           // write the current item into the request map under the key listed in var, if available
           boolean wroteRequestMapVarValue = false;
           Object oldRequestMapVarValue = null;
           final String var = ComponentUtils.getStringAttribute(currentUISelectItems, Attributes.var);
           if (var != null && !"".equals(var)) {
             // save the current value of the key listed in var from the request map
             oldRequestMapVarValue = facesContext.getExternalContext().getRequestMap().put(var, item);
             wroteRequestMapVarValue = true;
           }
 
           // check the itemValue attribute
           Object itemValue = ComponentUtils.getAttribute(currentUISelectItems, Attributes.itemValue);
           if (itemValue == null) {
             // the itemValue attribute was not provided
             // --> use the current item as the itemValue
             itemValue = item;
           }
 
           // Spec: When iterating over the select items, toString()
           // must be called on the string rendered attribute values
           final Object itemLabelObject = ComponentUtils.getAttribute(currentUISelectItems, Attributes.itemLabel);
           final String itemLabel;
           if (itemLabelObject != null) {
             itemLabel = itemLabelObject.toString();
           } else if (itemValue != null) {
             itemLabel = itemValue.toString();
           } else {
             LOG.warn("Label string can't be created!");
             itemLabel = "???";
           }
           Object itemDescription = ComponentUtils.getAttribute(currentUISelectItems, Attributes.itemDescription);
           if (itemDescription != null) {
             itemDescription = itemDescription.toString();
           }
           final boolean itemDisabled
               = ComponentUtils.getBooleanAttribute(currentUISelectItems, Attributes.itemDisabled, false);
           final String itemImage = ComponentUtils.getStringAttribute(currentUISelectItems, Attributes.itemImage);
           final Markup markup;
           if (currentUISelectItems instanceof Visual) {
             markup = ((Visual) currentUISelectItems).getMarkup();
           } else {
             markup = Markup.NULL;
           }
 // TBD: should this be possible?
 //        Boolean itemLabelEscaped = getBooleanAttribute(currentUISelectItems, ITEM_LABEL_ESCAPED_PROP, true);
 // TBD ?
 //        Object noSelectionValue = attributeMap.get(NO_SELECTION_VALUE_PROP);
           item = new org.apache.myfaces.tobago.model.SelectItem(
               itemValue, itemLabel, (String) itemDescription, itemDisabled, itemImage, markup);
 
           // remove the value with the key from var from the request map, if previously written
           if (wroteRequestMapVarValue) {
             // If there was a previous value stored with the key from var in the request map, restore it
             if (oldRequestMapVarValue != null) {
               facesContext.getExternalContext().getRequestMap().put(var, oldRequestMapVarValue);
             } else {
               facesContext.getExternalContext().getRequestMap().remove(var);
             }
           }
         }
         return (SelectItem) item;
       }
       throw new NoSuchElementException();
     }
 
     @Override
     public void remove() {
       throw new UnsupportedOperationException();
     }
   }
 
 }