/*
 * 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.solr.client.solrj.io.stream;


import java.io.IOException;
import java.util.HashMap;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.stream.Collectors;

import org.apache.solr.client.solrj.io.stream.expr.Explanation;
import org.apache.solr.client.solrj.io.stream.expr.Expressible;
import org.apache.solr.client.solrj.io.stream.expr.StreamExplanation;
import org.apache.solr.client.solrj.io.stream.expr.StreamExpression;
import org.apache.solr.client.solrj.io.stream.expr.StreamExpressionNamedParameter;
import org.apache.solr.client.solrj.io.stream.expr.StreamExpressionValue;
import org.apache.solr.client.solrj.io.stream.expr.StreamFactory;
import org.apache.solr.common.params.CommonParams;
import org.apache.solr.common.params.ModifiableSolrParams;


/**
 * @since 6.6.0
 */
public class ShuffleStream extends CloudSolrStream implements Expressible {

  public ShuffleStream(StreamExpression expression, StreamFactory factory) throws IOException {
    // grab all parameters out
    String collectionName = factory.getValueOperand(expression, 0);
    List<StreamExpressionNamedParameter> namedParams = factory.getNamedOperands(expression);
    StreamExpressionNamedParameter aliasExpression = factory.getNamedOperand(expression, "aliases");
    StreamExpressionNamedParameter zkHostExpression = factory.getNamedOperand(expression, "zkHost");

    // Collection Name
    if(null == collectionName){
      throw new IOException(String.format(Locale.ROOT,"invalid expression %s - collectionName expected as first operand",expression));
    }

    // Validate there are no unknown parameters - zkHost and alias are namedParameter so we don't need to count it twice
    if(expression.getParameters().size() != 1 + namedParams.size()){
      throw new IOException(String.format(Locale.ROOT,"invalid expression %s - unknown operands found",expression));
    }

    // Named parameters - passed directly to solr as solrparams
    if(0 == namedParams.size()){
      throw new IOException(String.format(Locale.ROOT,"invalid expression %s - at least one named parameter expected. eg. 'q=*:*'",expression));
    }

    ModifiableSolrParams mParams = new ModifiableSolrParams();
    for(StreamExpressionNamedParameter namedParam : namedParams){
      if(!namedParam.getName().equals("zkHost") && !namedParam.getName().equals("aliases")){
        mParams.add(namedParam.getName(), namedParam.getParameter().toString().trim());
      }
    }

    // Aliases, optional, if provided then need to split
    if(null != aliasExpression && aliasExpression.getParameter() instanceof StreamExpressionValue){
      fieldMappings = new HashMap<>();
      for(String mapping : ((StreamExpressionValue)aliasExpression.getParameter()).getValue().split(",")){
        String[] parts = mapping.trim().split("=");
        if(2 == parts.length){
          fieldMappings.put(parts[0], parts[1]);
        }
        else{
          throw new IOException(String.format(Locale.ROOT,"invalid expression %s - alias expected of the format origName=newName",expression));
        }
      }
    }

    // zkHost, optional - if not provided then will look into factory list to get
    String zkHost = null;
    if(null == zkHostExpression){
      zkHost = factory.getCollectionZkHost(collectionName);
      if(zkHost == null) {
        zkHost = factory.getDefaultZkHost();
      }
    }
    else if(zkHostExpression.getParameter() instanceof StreamExpressionValue){
      zkHost = ((StreamExpressionValue)zkHostExpression.getParameter()).getValue();
    }
    if(null == zkHost){
      throw new IOException(String.format(Locale.ROOT,"invalid expression %s - zkHost not found for collection '%s'",expression,collectionName));
    }

    // We've got all the required items
    init(collectionName, zkHost, mParams);
  }

  @Override
  public StreamExpression toExpression(StreamFactory factory) throws IOException {
    // functionName(collectionName, param1, param2, ..., paramN, sort="comp", [aliases="field=alias,..."])

    // function name
    StreamExpression expression = new StreamExpression(factory.getFunctionName(this.getClass()));

    // collection
    expression.addParameter(collection);

    for (Map.Entry<String, String[]> param : params.getMap().entrySet()) {
      for (String val : param.getValue()) {
        // SOLR-8409: Escaping the " is a special case.
        // Do note that in any other BASE streams with parameters where a " might come into play
        // that this same replacement needs to take place.
        expression.addParameter(new StreamExpressionNamedParameter(param.getKey(),
            val.replace("\"", "\\\"")));
      }
    }

    // zkHost
    expression.addParameter(new StreamExpressionNamedParameter("zkHost", zkHost));

    // aliases
    if(null != fieldMappings && 0 != fieldMappings.size()){
      StringBuilder sb = new StringBuilder();
      for(Map.Entry<String,String> mapping : fieldMappings.entrySet()){
        if(sb.length() > 0){ sb.append(","); }
        sb.append(mapping.getKey());
        sb.append("=");
        sb.append(mapping.getValue());
      }

      expression.addParameter(new StreamExpressionNamedParameter("aliases", sb.toString()));
    }

    return expression;
  }

  @Override
  public Explanation toExplanation(StreamFactory factory) throws IOException {

    StreamExplanation explanation = new StreamExplanation(getStreamNodeId().toString());

    explanation.setFunctionName(factory.getFunctionName(this.getClass()));
    explanation.setImplementingClass(this.getClass().getName());
    explanation.setExpressionType(Explanation.ExpressionType.STREAM_SOURCE);
    explanation.setExpression(toExpression(factory).toString());

    // child is a datastore so add it at this point
    StreamExplanation child = new StreamExplanation(getStreamNodeId() + "-datastore");
    child.setFunctionName(String.format(Locale.ROOT, "solr (%s)", collection));
    child.setImplementingClass("Solr/Lucene");
    child.setExpressionType(Explanation.ExpressionType.DATASTORE);

    if(null != params){
      ModifiableSolrParams mParams = new ModifiableSolrParams(params);
      child.setExpression(mParams.getMap().entrySet().stream().map(e -> String.format(Locale.ROOT, "%s=%s", e.getKey(), e.getValue())).collect(Collectors.joining(",")));
    }
    explanation.addChild(child);

    return explanation;
  }


  public ModifiableSolrParams adjustParams(ModifiableSolrParams mParams) {
    mParams.set(CommonParams.QT, "/export");
    return mParams;
  }

}