package com.twitter.search.common.schema;

import java.io.IOException;
import java.io.StringReader;
import java.util.Collections;
import java.util.List;
import java.util.Set;

import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Sets;

import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
import org.apache.lucene.analysis.tokenattributes.TermToBytesRefAttribute;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.facet.sortedset.SortedSetDocValuesFacetField;
import org.apache.lucene.util.BytesRef;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.twitter.common.text.token.TwitterTokenStream;
import com.twitter.search.common.schema.base.EarlybirdFieldType;
import com.twitter.search.common.schema.base.IndexedNumericFieldSettings;
import com.twitter.search.common.schema.base.Schema;
import com.twitter.search.common.schema.thriftjava.ThriftDocument;
import com.twitter.search.common.schema.thriftjava.ThriftField;
import com.twitter.search.common.schema.thriftjava.ThriftFieldData;
import com.twitter.search.common.schema.thriftjava.ThriftGeoCoordinate;
import com.twitter.search.common.util.analysis.IntTermAttribute;
import com.twitter.search.common.util.analysis.LongTermAttribute;
import com.twitter.search.common.util.analysis.SortableLongTermAttribute;
import com.twitter.search.common.util.spatial.GeoUtil;
import com.twitter.search.common.util.text.HighFrequencyTermPairs;
import com.twitter.search.common.util.text.OmitNormTextField;
import com.twitter.search.common.util.text.SingleTokenStream;

/**
 * A document factory that converts {@link ThriftDocument} into Lucene {@link Document}s
 * using the provided {@link com.twitter.search.common.schema.base.Schema}.
 */
public class SchemaDocumentFactory {
  private static final Logger LOG = LoggerFactory.getLogger(SchemaDocumentFactory.class);

  private final Schema schema;
  private final ImmutableList<TokenStreamRewriter> tokenStreamRewriters;

  /**
   * Creates a SchemaDocumentFactory with a schema and the tokenStreamRewriters.
   *
   * @param tokenStreamRewriters a list of token stream rewriters, which will be applied in order.
   */
  public SchemaDocumentFactory(
      Schema schema,
      List<TokenStreamRewriter> tokenStreamRewriters) {
    this.schema = schema;
    this.tokenStreamRewriters = ImmutableList.copyOf(tokenStreamRewriters);
  }

  /**
   * Creates a SchemaDocumentFactory with no tokenStreamRewriters.
   */
  public SchemaDocumentFactory(Schema schema) {
    this(schema, Collections.EMPTY_LIST);
  }

  public final Document newDocument(ThriftDocument document) throws IOException {
    return innerNewDocument(document);
  }

  /**
   * Create a Lucene document from the ThriftDocument.
   */
  @VisibleForTesting
  public Document innerNewDocument(ThriftDocument document) throws IOException {
    Document luceneDocument = new Document();
    Set<String> hfTerms = Sets.newHashSet();
    Set<String> hfPhrases = Sets.newHashSet();

    Analyzer defaultAnalyzer = schema.getDefaultAnalyzer(document.getDefaultAnalyzerOverride());

    for (ThriftField field : document.getFields()) {
      boolean successful = false;
      try {
        addLuceneFields(field, defaultAnalyzer, luceneDocument, hfTerms, hfPhrases);
        successful = true;
      } finally {
        if (!successful) {
          LOG.warn("Unexpected exception while trying to add field. Field ID: "
              + field.getFieldConfigId() + " Field Name: "
              + schema.getFieldName(field.getFieldConfigId()));
        }
      }
    }

    for (String token : hfTerms) {
      for (String token2 : hfTerms) {
        if (token.compareTo(token2) < 0) {
          luceneDocument.add(new Field(ImmutableSchema.HF_TERM_PAIRS_FIELD,
                                          HighFrequencyTermPairs.createPair(token, token2),
                                          OmitNormTextField.TYPE_NOT_STORED));
        }
      }
    }

    for (String phrase : hfPhrases) {
      // Tokens in the phrase set are not terms and have already been processed with
      // HighFrequencyTermPairs.createPhrasePair.
      luceneDocument.add(new Field(ImmutableSchema.HF_PHRASE_PAIRS_FIELD, phrase,
                                      OmitNormTextField.TYPE_NOT_STORED));
    }

    return schema.getFacetsConfig().build(luceneDocument);
  }

  private void addLuceneFields(ThriftField field, Analyzer analyzer, Document doc,
                               Set<String> hfTerms, Set<String> hfPhrases) throws IOException {
    Schema.FieldInfo fieldInfo =
        schema.getFieldInfo(field.getFieldConfigId(), field.getFieldConfigOverride());

    if (fieldInfo == null) {
      // field not defined in schema - skip it
      return;
    }

    ThriftFieldData fieldData = field.getFieldData();
    if (fieldInfo.getFieldType().getCsfType() !=  null) {
      addCSFField(doc, fieldInfo, fieldData);
      return;
    }

    // Checking which data type is set is not sufficient here. We also need to check schema to
    // see what the type the field is configured to be. See SEARCH-5173 for more details.
    // The problem is that Pig, while converting Tuples to Thrift, sets all primitive type
    // fields to 0. (i.e. the isSet calls will return true).
    IndexedNumericFieldSettings numericSettings =
        fieldInfo.getFieldType().getNumericFieldSettings();
    if (fieldData.isSetTokenStreamValue()) {
      addTokenField(doc, hfTerms, hfPhrases, fieldInfo, fieldData);
    } else if (fieldData.isSetStringValue()) {
      addStringField(analyzer, doc, hfTerms, hfPhrases, fieldInfo, fieldData);
    } else if (fieldData.isSetBytesValue()) {
      addBytesField(doc, fieldInfo, fieldData);
    } else if (fieldData.isSetGeoCoordinate()) {
      addGeoField(doc, fieldInfo, fieldData);
    } else if (numericSettings != null) {
      // handle numeric fields.
      switch (numericSettings.getNumericType()) {
        case INT:
          Preconditions.checkState(fieldData.isSetIntValue(),
              "Int field does not have int value set. Field name: %s", fieldInfo.getName());
          addIntField(doc, fieldInfo, fieldData);
          break;
        case LONG:
          Preconditions.checkState(fieldData.isSetLongValue(),
              "Long field does not have long value set. Field name: %s", fieldInfo.getName());
          addLongField(doc, fieldInfo, fieldData);
          break;
        case FLOAT:
          Preconditions.checkState(fieldData.isSetFloatValue(),
              "Float field does not have float value set. Field name: %s ", fieldInfo.getName());
          addFloatField();
          break;
        case DOUBLE:
          Preconditions.checkState(fieldData.isSetDoubleValue(),
              "Double field does not have double value set. Field name: %s", fieldInfo.getName());
          addDoubleFIeld();
          break;
        default:
          throw new UnsupportedOperationException("Earlybird does not know how to handle field "
              + field.getFieldConfigId() + " " + field);
      }
    } else {
      throw new UnsupportedOperationException("Earlybird does not know how to handle field "
          + field.getFieldConfigId() + " " + field);
    }
  }

  private void addCSFField(Document doc, Schema.FieldInfo fieldInfo, ThriftFieldData fieldData) {
    if (fieldInfo.getFieldType().getCsfFixedLengthNumValuesPerDoc() > 1) {

      // As an optimization, TBinaryProtocol stores a byte array field as a part of a larger byte
      // array field.  Must call fieldData.getBytesValue().  fieldData.bytesValue.array() will
      // return extraneous data. See: SEARCH-3996
      doc.add(new Field(fieldInfo.getName(), fieldData.getBytesValue(), fieldInfo.getFieldType()));
    } else {
      doc.add(new CSFField(fieldInfo.getName(), fieldInfo.getFieldType(), fieldData));
    }
  }

  private void addTokenField(
      Document doc,
      Set<String> hfTerms,
      Set<String> hfPhrases,
      Schema.FieldInfo fieldInfo,
      ThriftFieldData fieldData) throws IOException {
    TwitterTokenStream twitterTokenStream
        = fieldInfo.getFieldType().getTokenStreamSerializer().deserialize(
        fieldData.getTokenStreamValue(), fieldData.getStringValue());

    try {
      for (TokenStreamRewriter rewriter : tokenStreamRewriters) {
        twitterTokenStream = rewriter.rewrite(fieldInfo, twitterTokenStream);
      }

      expandStream(doc, fieldInfo, twitterTokenStream, hfTerms, hfPhrases);
      doc.add(new Field(fieldInfo.getName(), twitterTokenStream, fieldInfo.getFieldType()));
    } finally {
      twitterTokenStream.close();
    }
  }

  private void addStringField(Analyzer analyzer, Document doc, Set<String> hfTerms,
                              Set<String> hfPhrases, Schema.FieldInfo fieldInfo,
                              ThriftFieldData fieldData) {
    doc.add(new Field(fieldInfo.getName(), fieldData.getStringValue(), fieldInfo.getFieldType()));
    if (fieldInfo.getFieldType().tokenized()) {
      try {
        TokenStream tokenStream = analyzer.tokenStream(fieldInfo.getName(),
                new StringReader(fieldData.getStringValue()));
        try {
          expandStream(
              doc,
              fieldInfo,
              tokenStream,
              hfTerms,
              hfPhrases);
        } finally {
          tokenStream.close();
        }
      } catch (IOException e) {
        LOG.error("IOException expanding token stream", e);
      }
    } else {
      addFacetField(doc, fieldInfo, fieldData.getStringValue());
    }
  }

  private void addBytesField(Document doc, Schema.FieldInfo fieldInfo, ThriftFieldData fieldData) {
    doc.add(new Field(fieldInfo.getName(), fieldData.getBytesValue(), fieldInfo.getFieldType()));
  }

  private void addIntField(Document doc, Schema.FieldInfo fieldInfo,
                           ThriftFieldData fieldData) {
    int value = fieldData.getIntValue();
    addFacetField(doc, fieldInfo, String.valueOf(value));

    if (fieldInfo.getFieldType().getNumericFieldSettings() == null) {
      // No NumericFieldSettings. Even though the data is numeric, this field is not
      // really a numerical field. Just add as a string.
      doc.add(new Field(fieldInfo.getName(), String.valueOf(value), fieldInfo.getFieldType()));
    } else if (fieldInfo.getFieldType().getNumericFieldSettings().isUseTwitterFormat()) {
      addIntTermAttributeField(value, fieldInfo, doc);
    } else {
      // Use lucene style numerical fields
      doc.add(NumericField.newIntField(fieldInfo.getName(), value));
    }
  }

  private void addIntTermAttributeField(int value,
                                        Schema.FieldInfo fieldInfo,
                                        Document doc) {
    SingleTokenStream singleToken = new SingleTokenStream();
    IntTermAttribute termAtt = singleToken.addAttribute(IntTermAttribute.class);
    termAtt.setTerm(value);
    doc.add(new Field(fieldInfo.getName(), singleToken, fieldInfo.getFieldType()));
  }

  private void addLongField(Document doc, Schema.FieldInfo fieldInfo,
                            ThriftFieldData fieldData) {
    long value = fieldData.getLongValue();
    addFacetField(doc, fieldInfo, String.valueOf(value));

    if (fieldInfo.getFieldType().getNumericFieldSettings() == null) {
      // No NumericFieldSettings. Even though the data is numeric, this field is not
      // really a numerical field. Just add as a string.
      doc.add(new Field(fieldInfo.getName(), String.valueOf(value), fieldInfo.getFieldType()));
    } else if (fieldInfo.getFieldType().getNumericFieldSettings().isUseTwitterFormat()) {
      // Twitter style numerical field: use LongTermAttribute
      addLongTermAttributeField(value, fieldInfo, doc);
    } else {
      // Use lucene style numerical fields
      doc.add(NumericField.newLongField(fieldInfo.getName(), value));
    }
  }

  private void addLongTermAttributeField(long value,
                                         Schema.FieldInfo fieldInfo,
                                         Document doc) {
    SingleTokenStream singleToken = new SingleTokenStream();
    boolean useSortableEncoding =
        fieldInfo.getFieldType().getNumericFieldSettings().isUseSortableEncoding();

    if (useSortableEncoding) {
      SortableLongTermAttribute termAtt = singleToken.addAttribute(SortableLongTermAttribute.class);
      termAtt.setTerm(value);
    } else {
      LongTermAttribute termAtt = singleToken.addAttribute(LongTermAttribute.class);
      termAtt.setTerm(value);
    }
    doc.add(new Field(fieldInfo.getName(), singleToken, fieldInfo.getFieldType()));
  }

  private void addFloatField() {
    throw new UnsupportedOperationException("Earlybird does not support float values yet.");
  }

  private void addDoubleFIeld() {
    throw new UnsupportedOperationException("Earlybird does not support double values yet.");
  }

  private void addGeoField(Document doc, Schema.FieldInfo fieldInfo, ThriftFieldData fieldData) {
    ThriftGeoCoordinate coord = fieldData.getGeoCoordinate();
    if (GeoUtil.validateGeoCoordinates(coord.getLat(), coord.getLon())) {
      GeoUtil.fillGeoFields(doc, fieldInfo.getName(),
          coord.getLat(), coord.getLon(), coord.getAccuracy());
    }
  }

  private void addFacetField(Document doc, Schema.FieldInfo fieldInfo, String value) {
    Preconditions.checkArgument(doc != null);
    Preconditions.checkArgument(fieldInfo != null);
    Preconditions.checkArgument(value != null);

    if (fieldInfo.getFieldType().getFacetName() != null) {
      doc.add(new SortedSetDocValuesFacetField(fieldInfo.getFieldType().getFacetName(), value));
    }
  }

  private String getTerm(TermToBytesRefAttribute attr) {
    if (attr instanceof CharTermAttribute) {
      return ((CharTermAttribute) attr).toString();
    } else if (attr instanceof IntTermAttribute) {
      return String.valueOf(((IntTermAttribute) attr).getTerm());
    } else if (attr instanceof LongTermAttribute) {
      return String.valueOf(((LongTermAttribute) attr).getTerm());
    } else {
      return attr.getBytesRef().utf8ToString();
    }
  }

  /**
   * Expand the TwitterTokenStream and populate high-frequency terms, phrases and/or facet category paths.
   */
  private void expandStream(
      Document doc,
      Schema.FieldInfo fieldInfo,
      TokenStream stream,
      Set<String> hfTerms,
      Set<String> hfPhrases) throws IOException {
    // Checkstyle does not allow assignment to parameters.
    Set<String> facetHfTerms = hfTerms;
    Set<String> facetHfPhrases = hfPhrases;

    if (!(HighFrequencyTermPairs.INDEX_HF_TERM_PAIRS
        && fieldInfo.getFieldType().isIndexHFTermPairs())) {
      // high-frequency terms and phrases are not needed
      if (fieldInfo.getFieldType().getFacetName() == null) {
        // Facets are not needed either, simply return, would do nothing otherwise
        return;
      }
      facetHfTerms = null;
      facetHfPhrases = null;
    }

    final TermToBytesRefAttribute attr = stream.getAttribute(TermToBytesRefAttribute.class);
    stream.reset();

    String lastHFTerm = null;
    while (stream.incrementToken()) {
      String term = getTerm(attr);
      if (fieldInfo.getFieldType().getFacetName() != null) {
        addFacetField(doc, fieldInfo, term);
      }
      if (HighFrequencyTermPairs.HF_TERM_SET.contains(term)) {
        if (facetHfTerms != null) {
          facetHfTerms.add(term);
        }
        if (lastHFTerm != null) {
          if (facetHfPhrases != null) {
            facetHfPhrases.add(HighFrequencyTermPairs.createPhrasePair(lastHFTerm, term));
          }
        }
        lastHFTerm = term;
      } else {
        lastHFTerm = null;
      }
    }
  }

  public static final class CSFField extends Field {
    /**
     * Create a CSFField with the given fieldType, containing the given field data.
     */
    public CSFField(String name, EarlybirdFieldType fieldType, ThriftFieldData data) {
      super(name, fieldType);

      if (fieldType.isCsfVariableLength()) {
        fieldsData = new BytesRef(data.getBytesValue());
      } else {
        switch (fieldType.getCsfType()) {
          case BYTE:
            fieldsData = Long.valueOf(data.getByteValue());
            break;
          case INT:
            fieldsData = Long.valueOf(data.getIntValue());
            break;
          case LONG:
            fieldsData = Long.valueOf(data.getLongValue());
            break;
          case FLOAT:
            fieldsData = Long.valueOf(Float.floatToRawIntBits((float) data.getFloatValue()));
            break;
          case DOUBLE:
            fieldsData = Long.valueOf(Double.doubleToRawLongBits(data.getDoubleValue()));
            break;
          default:
            throw new IllegalArgumentException("Unknown csf type: " + fieldType.getCsfType());
        }
      }
    }
  }

  public interface TokenStreamRewriter {
    /**
     * Rewrite the token stream.
     */
    TwitterTokenStream rewrite(Schema.FieldInfo fieldInfo, TwitterTokenStream stream);
  }
}