// SPDX-License-Identifier: Apache-2.0

package chisel3.stage.phases

import firrtl.{AnnotationSeq, EmittedFirrtlCircuit, EmittedFirrtlCircuitAnnotation}
import firrtl.annotations.DeletedAnnotation
import firrtl.options.{Dependency, Phase, StageOptions}
import firrtl.options.Viewer.view

import chisel3.internal.firrtl.{Emitter => OldEmitter}
import chisel3.stage.{ChiselCircuitAnnotation, ChiselOptions}

import java.io.{File, FileWriter}

/** Emit a [[chisel3.stage.ChiselCircuitAnnotation]] to a file if a [[chisel3.stage.ChiselOutputFileAnnotation]] is
  * present. A deleted [[firrtl.EmittedFirrtlCircuitAnnotation]] is added.
  *
  * @todo This should be switched to support correct emission of multiple circuits to multiple files. The API should
  * likely mirror how the [[firrtl.stage.phases.Compiler]] parses annotations into "global" annotations and
  * left-associative per-circuit annotations.
  * @todo The use of the deleted [[firrtl.EmittedFirrtlCircuitAnnotation]] is a kludge to provide some breadcrumbs such
  * that the emitted CHIRRTL can be provided back to the old Driver. This should be removed or a better solution
  * developed.
  */
class Emitter extends Phase {

  override def prerequisites =
    Seq(
      Dependency[Elaborate],
      Dependency[AddImplicitOutputFile],
      Dependency[AddImplicitOutputAnnotationFile],
      Dependency[MaybeAspectPhase]
    )
  override def optionalPrerequisites = Seq.empty
  override def optionalPrerequisiteOf = Seq(Dependency[Convert])
  override def invalidates(a: Phase) = false

  def transform(annotations: AnnotationSeq): AnnotationSeq = {
    val copts = view[ChiselOptions](annotations)
    val sopts = view[StageOptions](annotations)

    annotations.flatMap {
      case a: ChiselCircuitAnnotation if copts.outputFile.isDefined =>
        val file = new File(sopts.getBuildFileName(copts.outputFile.get, Some(".fir")))
        val emitted = OldEmitter.emit(a.circuit)
        val w = new FileWriter(file)
        w.write(emitted)
        w.close()
        val anno = EmittedFirrtlCircuitAnnotation(EmittedFirrtlCircuit(a.circuit.name, emitted, ".fir"))
        Seq(DeletedAnnotation(name, anno), a)
      case a => Some(a)
    }
  }

}
