package com.twitter.search.common.schema;

import java.util.Collection;
import java.util.Map;
import java.util.concurrent.atomic.AtomicReference;

import javax.annotation.Nullable;

import com.google.common.base.Preconditions;
import com.google.common.base.Predicate;
import com.google.common.collect.ImmutableCollection;
import com.google.common.collect.ImmutableMap;

import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.facet.FacetsConfig;
import org.apache.lucene.index.FieldInfos;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.twitter.search.common.features.thrift.ThriftSearchFeatureSchema;
import com.twitter.search.common.schema.base.FeatureConfiguration;
import com.twitter.search.common.schema.base.FieldWeightDefault;
import com.twitter.search.common.schema.base.ImmutableSchemaInterface;
import com.twitter.search.common.schema.base.Schema;
import com.twitter.search.common.schema.thriftjava.ThriftAnalyzer;
import com.twitter.search.common.schema.thriftjava.ThriftCSFType;
import com.twitter.search.common.schema.thriftjava.ThriftFieldConfiguration;

/**
 * A schema implementation that allow minor version increments at run time.
 */
public class DynamicSchema implements Schema {
  private static final Logger LOG = LoggerFactory.getLogger(DynamicSchema.class);

  private final AtomicReference<ImmutableSchema> schema;

  public DynamicSchema(ImmutableSchema schema) {
    this.schema = new AtomicReference<>(schema);
  }

  public ImmutableSchemaInterface getSchemaSnapshot() {
    return schema.get();
  }

  /**
   * Update the schema reference inside this DynamicSchema.
   */
  public synchronized void updateSchema(ImmutableSchema newSchema) throws SchemaUpdateException {
    ImmutableSchema oldSchema = schema.get();
    if (newSchema.getMajorVersionNumber() != oldSchema.getMajorVersionNumber()) {
      throw new SchemaUpdateException("Dynamic major version update is not supported.");
    } else {
      if (newSchema.getMinorVersionNumber() <= oldSchema.getMinorVersionNumber()) {
        throw new SchemaUpdateException("Dynamic backward minor version update is not supported.");
      } else {
        LOG.info("DynamicSchema accepted update. Old version is {}.{}; new version is {}.{}",
            oldSchema.getMajorVersionNumber(),
            oldSchema.getMinorVersionNumber(),
            newSchema.getMajorVersionNumber(),
            newSchema.getMinorVersionNumber());
        schema.set(newSchema);
      }
    }
  }

  public static class SchemaUpdateException extends Exception {
    public SchemaUpdateException(String message) {
      super(message);
    }
  }

  // The below are all methods in the Schema interface delegated to the underlying ImmutableSchema.
  // The below is generated by IntelliJ, and reviewers can stop reviewing this file here.
  // If you are adding logic into this class, please do so above this line.
  @Override
  public FieldInfos getLuceneFieldInfos(
      Predicate<String> acceptedFields) {
    return schema.get().getLuceneFieldInfos(acceptedFields);
  }

  @Override
  public FacetsConfig getFacetsConfig() {
    return schema.get().getFacetsConfig();
  }

  @Override
  public Analyzer getDefaultAnalyzer(
      ThriftAnalyzer override) {
    return schema.get().getDefaultAnalyzer(override);
  }

  @Override
  public ImmutableCollection<FieldInfo> getFieldInfos() {
    return schema.get().getFieldInfos();
  }

  @Override
  public boolean hasField(int fieldConfigId) {
    return schema.get().hasField(fieldConfigId);
  }

  @Override
  public boolean hasField(String fieldName) {
    return schema.get().hasField(fieldName);
  }

  @Override
  @Nullable
  public FieldInfo getFieldInfo(int fieldConfigId) {
    return schema.get().getFieldInfo(fieldConfigId);
  }

  @Override
  @Nullable
  public FieldInfo getFieldInfo(String fieldName) {
    return schema.get().getFieldInfo(fieldName);
  }

  @Override
  public String getFieldName(int fieldConfigId) {
    return schema.get().getFieldName(fieldConfigId);
  }

  @Override
  public FieldInfo getFieldInfo(int fieldConfigId,
                                ThriftFieldConfiguration override) {
    return schema.get().getFieldInfo(fieldConfigId, override);
  }

  @Override
  public int getNumFacetFields() {
    return schema.get().getNumFacetFields();
  }

  @Override
  public FieldInfo getFacetFieldByFacetName(
      String facetName) {
    return schema.get().getFacetFieldByFacetName(facetName);
  }

  @Override
  public FieldInfo getFacetFieldByFieldName(
      String fieldName) {
    return schema.get().getFacetFieldByFieldName(fieldName);
  }

  @Override
  public Collection<FieldInfo> getFacetFields() {
    return schema.get().getFacetFields();
  }

  @Override
  public Collection<FieldInfo> getCsfFacetFields() {
    return schema.get().getCsfFacetFields();
  }

  @Override
  public String getVersionDescription() {
    return schema.get().getVersionDescription();
  }

  @Override
  public int getMajorVersionNumber() {
    return schema.get().getMajorVersionNumber();
  }

  @Override
  public int getMinorVersionNumber() {
    return schema.get().getMinorVersionNumber();
  }

  @Override
  public boolean isVersionOfficial() {
    return schema.get().isVersionOfficial();
  }

  @Override
  public Map<String, FieldWeightDefault> getFieldWeightMap() {
    return schema.get().getFieldWeightMap();
  }

  @Override
  public FeatureConfiguration getFeatureConfigurationByName(
      String featureName) {
    return schema.get().getFeatureConfigurationByName(featureName);
  }

  @Override
  public FeatureConfiguration getFeatureConfigurationById(int featureFieldId) {
    return Preconditions.checkNotNull(schema.get().getFeatureConfigurationById(featureFieldId));
  }

  @Override
  @Nullable
  public ThriftCSFType getCSFFieldType(
      String fieldName) {
    return schema.get().getCSFFieldType(fieldName);
  }

  @Override
  public ThriftSearchFeatureSchema getSearchFeatureSchema() {
    return schema.get().getSearchFeatureSchema();
  }

  @Override
  public ImmutableMap<Integer, FeatureConfiguration> getFeatureIdToFeatureConfig() {
    return schema.get().getFeatureIdToFeatureConfig();
  }

  @Override
  public ImmutableMap<String, FeatureConfiguration> getFeatureNameToFeatureConfig() {
    return schema.get().getFeatureNameToFeatureConfig();
  }
}