/*
 * Copyright 2016 Google LLC
 *
 * Licensed 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 com.google.cloud.bigquery;

import com.google.api.services.bigquery.model.ErrorProto;
import com.google.common.base.Function;
import com.google.common.base.MoreObjects;

import java.io.Serializable;
import java.util.Objects;

/**
 * Google Cloud BigQuery Error. Objects of this class represent errors encountered by the BigQuery
 * service while executing a request. A BigQuery Job that terminated with an error has a non-null
 * {@link JobStatus#getError()}. A job can also encounter errors during its execution that do not
 * cause the whole job to fail (see {@link JobStatus#getExecutionErrors()}). Similarly, queries and
 * insert all requests can cause BigQuery errors that do not mean the whole operation failed (see
 * {@link JobStatus#getExecutionErrors()} and {@link InsertAllResponse#getInsertErrors()}).
 * When a {@link BigQueryException} is thrown the BigQuery Error that caused it, if any, can be
 * accessed with {@link BigQueryException#getError()}.
 */
public final class BigQueryError implements Serializable {

  static final Function<ErrorProto, BigQueryError> FROM_PB_FUNCTION =
      new Function<ErrorProto, BigQueryError>() {
        @Override
        public BigQueryError apply(ErrorProto pb) {
          return BigQueryError.fromPb(pb);
        }
      };
  static final Function<BigQueryError, ErrorProto> TO_PB_FUNCTION =
      new Function<BigQueryError, ErrorProto>() {
        @Override
        public ErrorProto apply(BigQueryError error) {
          return error.toPb();
        }
      };
  private static final long serialVersionUID = -6566785320629096688L;

  private final String reason;
  private final String location;
  private final String debugInfo;
  private final String message;

  public BigQueryError(String reason, String location, String message, String debugInfo) {
    this.reason = reason;
    this.location = location;
    this.debugInfo = debugInfo;
    this.message = message;
  }

  public BigQueryError(String reason, String location, String message) {
    this.reason = reason;
    this.location = location;
    this.message = message;
    this.debugInfo = null;
  }


  /**
   * Returns short error code that summarizes the error.
   *
   * @see <a href="https://cloud.google.com/bigquery/troubleshooting-errors">Troubleshooting
   *     Errors</a>
   */
  public String getReason() {
    return reason;
  }


  /**
   * Returns where the error occurred, if present.
   */
  public String getLocation() {
    return location;
  }

  String getDebugInfo() {
    return debugInfo;
  }


  /**
   * Returns a human-readable description of the error.
   */
  public String getMessage() {
    return message;
  }

  @Override
  public int hashCode() {
    return Objects.hash(reason, location, message);
  }

  @Override
  public String toString() {
    return MoreObjects.toStringHelper(this)
        .add("reason", reason)
        .add("location", location)
        .add("message", message)
        .toString();
  }

  @Override
  public boolean equals(Object obj) {
    return obj == this
        || obj instanceof BigQueryError
        && Objects.equals(toPb(), ((BigQueryError) obj).toPb());
  }

  ErrorProto toPb() {
    ErrorProto errorPb = new ErrorProto();
    if (reason != null) {
      errorPb.setReason(reason);
    }
    if (location != null) {
      errorPb.setLocation(location);
    }
    if (message != null) {
      errorPb.setMessage(message);
    }
    if (debugInfo != null) {
      errorPb.setDebugInfo(debugInfo);
    }
    return errorPb;
  }

  static BigQueryError fromPb(ErrorProto errorPb) {
    return new BigQueryError(errorPb.getReason(), errorPb.getLocation(), errorPb.getMessage(),
        errorPb.getDebugInfo());
  }
}
