// SPDX-License-Identifier: Apache-2.0

package firrtl.options.phases

import firrtl.AnnotationSeq
import firrtl.annotations.{AnnotationFileNotFoundException, JsonProtocol}
import firrtl.options.{InputAnnotationFileAnnotation, Phase, StageUtils}
import firrtl.FileUtils

import java.io.File

import scala.collection.mutable
import scala.util.{Failure, Try}

/** Recursively expand all [[InputAnnotationFileAnnotation]]s in an [[AnnotationSeq]] */
class GetIncludes extends Phase {

  override def prerequisites = Seq.empty

  override def optionalPrerequisiteOf = Seq.empty

  override def invalidates(a: Phase) = false

  /** Read all [[annotations.Annotation]] from a file in JSON or YAML format
    * @param filename a JSON or YAML file of [[annotations.Annotation]]
    * @throws annotations.AnnotationFileNotFoundException if the file does not exist
    */
  private def readAnnotationsFromFile(filename: String): AnnotationSeq = {
    val file = new File(filename).getCanonicalFile
    if (!file.exists) { throw new AnnotationFileNotFoundException(file) }
    JsonProtocol.deserialize(file)
  }

  /** Recursively read all [[Annotation]]s from any [[InputAnnotationFileAnnotation]]s while making sure that each file is
    * only read once
    * @param includeGuard filenames that have already been read
    * @param annos a sequence of annotations
    * @return the original annotation sequence with any discovered annotations added
    */
  private def getIncludes(includeGuard: mutable.Set[String] = mutable.Set())(annos: AnnotationSeq): AnnotationSeq = {
    annos.flatMap {
      case a @ InputAnnotationFileAnnotation(value) =>
        if (includeGuard.contains(value)) {
          StageUtils.dramaticWarning(s"Annotation file ($value) already included! (Did you include it more than once?)")
          None
        } else {
          includeGuard += value
          getIncludes(includeGuard)(readAnnotationsFromFile(value))
        }
      case x => Seq(x)
    }
  }

  def transform(annotations: AnnotationSeq): AnnotationSeq = getIncludes()(annotations)

}
