/*
 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.
 */

import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

import org.codehaus.jackson.JsonNode;

public class Attributes {
  private final String patternId;
  private final String parentId;
  private final Map<String, String> attributes;
  private final Map<String, AttributeTransformer> attributeTransformers;

  public Attributes(JsonNode json) throws Exception {

    //PARSE ATTRIBUTE JSON

    if(JsonFile.empty(json, "patternId")) {
      throw new Exception("Bad attribute patternId found");
    }

    patternId = json.get("patternId").asText();
    parentId = (JsonFile.empty(json, "parentId") ? null : json.get("parentId").asText());
    attributeTransformers = new HashMap<>();

    //ATTRIBUTE MAP

    Map<String, String> attributeMap = new HashMap<>();

    if(JsonFile.get(json, "attributes").isObject()) {
      for(Iterator<String> j = json.get("attributes").getFieldNames(); j.hasNext();) {
        String key = j.next();
        String value = json.get("attributes").get(key).asText();

        if(key.isEmpty()) {
          throw new Exception("Empty attribute name not allowed for " + patternId);
        }

        if(key.equals("patternId")) {
          throw new Exception("patternId is a reserved attribute name");
        }

        if(key.endsWith("_error")) {
          String ekey = key.substring(0, key.length() - 6);
          if(attributeMap.containsKey(ekey)) {
            throw new Exception("This attribute is reserved: " + key);
          }
        } else if(attributeMap.containsKey(key + "_error")) {
          throw new Exception("This attribute is reserved: " + key + "_error");
        }

        attributeMap.put(key, value);
      }
    }

    attributeMap.put("patternId", patternId);

    //ATTRIBUTE TRANFORMERS

    if(JsonFile.get(json, "attributeTransformers").isObject()) {
      for(Iterator<String> j = json.get("attributeTransformers").getFieldNames(); j.hasNext();) {
        String key = j.next();
        JsonNode attributeTransformerNode = json.get("attributeTransformers").get(key);

        AttributeTransformer attributeTransformer = new AttributeTransformer(attributeTransformerNode);

        attributeTransformers.put(key, attributeTransformer);
      }

      if(attributeTransformers.isEmpty()) {
        throw new Exception("No attribute transformers found for " + patternId);
      }
    }

    attributes = Collections.unmodifiableMap(attributeMap);
  }

  public Map<String, String> getAttributes(String input) {

    //RETURN MAP
    
    if(attributeTransformers.isEmpty()) {
      return attributes;
    }

    //ADD TRANSFORMED ATTRIBUTES
    
    Map<String, String> custom = new HashMap<>(attributes);

    for(String key : attributeTransformers.keySet()) {
      AttributeTransformer attributeTransformer = attributeTransformers.get(key);

      try {
        String value = attributeTransformer.getValue(input);

        custom.put(key, value);
      } catch(Exception e) {
        custom.put(key, attributeTransformer.getDefaultValue());
        custom.put(key + "_error", e.toString());
      }
    }

    return Collections.unmodifiableMap(custom);
  }

  @Override
  public String toString() {
    return "Attribute patternId: " + patternId + ", attribute(s): " + attributes +
        (attributeTransformers.size() > 0 ? " attributeTransformer(s): " + attributeTransformers : "");
  }

  public String getPatternId() {
    return patternId;
  }

  public String getParentId() {
    return parentId;
  }
}