FilteringCOGLayerReader.scala

/*
 * Copyright 2017 Azavea
 *
 * 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 geotrellis.spark.io.cog

import geotrellis.raster.{CellGrid, RasterExtent}
import geotrellis.raster.merge.TileMergeMethods
import geotrellis.spark._
import geotrellis.spark.io._
import geotrellis.spark.io.index.Index
import geotrellis.util._

import org.apache.spark.rdd._
import spray.json._
import org.apache.spark.SparkContext

import java.net.URI

import scala.reflect._

abstract class FilteringCOGLayerReader[ID] extends COGLayerReader[ID] {

  val attributeStore: AttributeStore

  /** read
    *
    * This function will read an RDD layer based on a query.
    *
    * @param id              The ID of the layer to be read
    * @param rasterQuery     The query that will specify the filter for this read.
    * @param numPartitions   The desired number of partitions in the resulting RDD.
    * @param indexFilterOnly If true, the reader should only filter out elements who's KeyIndex entries
    *                        do not match the indexes of the query key bounds. This can include keys that
    *                        are not inside the query key bounds.
    * @tparam K              Type of RDD Key (ex: SpatialKey)
    * @tparam V              Type of RDD Value (ex: Tile or MultibandTile )
    */
  def read[
    K: SpatialComponent: Boundable: JsonFormat: ClassTag,
    V <: CellGrid: TiffMethods: (? => TileMergeMethods[V]): ClassTag
  ](id: ID, rasterQuery: LayerQuery[K, TileLayerMetadata[K]], numPartitions: Int, indexFilterOnly: Boolean): RDD[(K, V)] with Metadata[TileLayerMetadata[K]]

  def baseRead[
    K: SpatialComponent: Boundable: JsonFormat: ClassTag,
    V <: CellGrid: TiffMethods: (? => TileMergeMethods[V]): ClassTag
  ](
    id: LayerId,
    tileQuery: LayerQuery[K, TileLayerMetadata[K]],
    numPartitions: Int,
    filterIndexOnly: Boolean,
    getKeyPath: (ZoomRange, Int) => BigInt => String,
    pathExists: String => Boolean, // check the path above exists
    fullPath: String => URI, // add an fs prefix
    defaultThreads: Int
  )(implicit sc: SparkContext,
             getByteReader: URI => ByteReader,
             idToLayerId: ID => LayerId
  ): RDD[(K, V)] with Metadata[TileLayerMetadata[K]] = {

    val COGLayerStorageMetadata(cogLayerMetadata, keyIndexes) =
      try {
        attributeStore.read[COGLayerStorageMetadata[K]](LayerId(id.name, 0), "cog_metadata")
      } catch {
        // to follow GeoTrellis Layer Readers logic
        case e: AttributeNotFoundError => throw new LayerNotFoundError(id).initCause(e)
      }

    val metadata = cogLayerMetadata.tileLayerMetadata(id.zoom)

    val queryKeyBounds: Seq[KeyBounds[K]] = tileQuery(metadata)

    val readDefinitions: Seq[(ZoomRange, Seq[(SpatialKey, Int, TileBounds, Seq[(TileBounds, SpatialKey)])])] =
      queryKeyBounds.map { case KeyBounds(minKey, maxKey) =>
        cogLayerMetadata.getReadDefinitions(
          KeyBounds(minKey.getComponent[SpatialKey], maxKey.getComponent[SpatialKey]),
          id.zoom
        )
      }

    val zoomRange = readDefinitions.head._1
    val baseKeyIndex = keyIndexes(zoomRange)

    val maxWidth = Index.digits(baseKeyIndex.toIndex(baseKeyIndex.keyBounds.maxKey))
    val keyPath: BigInt => String = getKeyPath(zoomRange, maxWidth)
    val decompose = (bounds: KeyBounds[K]) => baseKeyIndex.indexRanges(bounds)

    val baseLayout = cogLayerMetadata.layoutForZoom(zoomRange.minZoom)
    val layout = cogLayerMetadata.layoutForZoom(id.zoom)

    val baseKeyBounds = cogLayerMetadata.zoomRangeInfoFor(zoomRange.minZoom)._2

    def transformKeyBounds(keyBounds: KeyBounds[K]): KeyBounds[K] = {
      val KeyBounds(minKey, maxKey) = keyBounds
      val extent = layout.extent
      val sourceRe = RasterExtent(extent, layout.layoutCols, layout.layoutRows)
      val targetRe = RasterExtent(extent, baseLayout.layoutCols, baseLayout.layoutRows)

      val minSpatialKey = minKey.getComponent[SpatialKey]
      val (minCol, minRow) = {
        val (x, y) = sourceRe.gridToMap(minSpatialKey.col, minSpatialKey.row)
        targetRe.mapToGrid(x, y)
      }

      val maxSpatialKey = maxKey.getComponent[SpatialKey]
      val (maxCol, maxRow) = {
        val (x, y) = sourceRe.gridToMap(maxSpatialKey.col, maxSpatialKey.row)
        targetRe.mapToGrid(x, y)
      }

      KeyBounds(
        minKey.setComponent(SpatialKey(minCol, minRow)),
        maxKey.setComponent(SpatialKey(maxCol, maxRow))
      )
    }

    val baseQueryKeyBounds: Seq[KeyBounds[K]] =
      queryKeyBounds
        .flatMap { qkb =>
          transformKeyBounds(qkb).intersect(baseKeyBounds) match {
            case EmptyBounds => None
            case kb: KeyBounds[K] => Some(kb)
          }
        }
        .distinct

    val rdd =
      COGRDDReader
        .read[K, V](
          keyPath            = keyPath,
          pathExists         = pathExists,
          fullPath           = fullPath,
          baseQueryKeyBounds = baseQueryKeyBounds,
          decomposeBounds    = decompose,
          readDefinitions    = readDefinitions.flatMap(_._2).groupBy(_._1),
          threads            = defaultThreads,
          numPartitions      = Some(numPartitions)
        )

    new ContextRDD(rdd, metadata)
  }

  def read[
    K: SpatialComponent: Boundable: JsonFormat: ClassTag,
    V <: CellGrid: TiffMethods: (? => TileMergeMethods[V]): ClassTag
  ](id: ID, rasterQuery: LayerQuery[K, TileLayerMetadata[K]], numPartitions: Int): RDD[(K, V)] with Metadata[TileLayerMetadata[K]] =
    read(id, rasterQuery, numPartitions, false)

  def read[
    K: SpatialComponent: Boundable: JsonFormat: ClassTag,
    V <: CellGrid: TiffMethods: (? => TileMergeMethods[V]): ClassTag
  ](id: ID, rasterQuery: LayerQuery[K, TileLayerMetadata[K]]): RDD[(K, V)] with Metadata[TileLayerMetadata[K]] =
    read(id, rasterQuery, defaultNumPartitions)

  def read[
    K: SpatialComponent: Boundable: JsonFormat: ClassTag,
    V <: CellGrid: TiffMethods: (? => TileMergeMethods[V]): ClassTag
  ](id: ID, numPartitions: Int): RDD[(K, V)] with Metadata[TileLayerMetadata[K]] =
    read(id, new LayerQuery[K, TileLayerMetadata[K]], numPartitions)

  def query[
    K: SpatialComponent: Boundable: JsonFormat: ClassTag,
    V <: CellGrid: TiffMethods: (? => TileMergeMethods[V]): ClassTag
  ](layerId: ID): BoundLayerQuery[K, TileLayerMetadata[K], RDD[(K, V)] with Metadata[TileLayerMetadata[K]]] =
    new BoundLayerQuery(new LayerQuery, read(layerId, _))

  def query[
    K: SpatialComponent: Boundable: JsonFormat: ClassTag,
    V <: CellGrid: TiffMethods: (? => TileMergeMethods[V]): ClassTag
  ](layerId: ID, numPartitions: Int): BoundLayerQuery[K, TileLayerMetadata[K], RDD[(K, V)] with Metadata[TileLayerMetadata[K]]] =
    new BoundLayerQuery(new LayerQuery, read(layerId, _, numPartitions))
}