// SPDX-License-Identifier: Apache-2.0

// This file contains macros for adding source locators at the point of invocation.
//
// This is not part of coreMacros to disallow this macro from being implicitly invoked in Chisel
// frontend (and generating source locators in Chisel core), which is almost certainly a bug.
//
// Note: While these functions and definitions are not private (macros can't be
// private), these are NOT meant to be part of the public API (yet) and no
// forward compatibility guarantees are made.
// A future revision may stabilize the source locator API to allow library
// writers to append source locator information at the point of a library
// function invocation.

package chisel3.internal.sourceinfo

import scala.language.experimental.macros
import scala.reflect.macros.blackbox.Context

/** Abstract base class for generalized source information.
  */
sealed trait SourceInfo {

  /** A prettier toString
    *
    * Make a useful message if SourceInfo is available, nothing otherwise
    */
  def makeMessage(f: String => String): String
}

sealed trait NoSourceInfo extends SourceInfo {
  def makeMessage(f: String => String): String = ""
}

/** For when source info can't be generated because of a technical limitation, like for Reg because
  * Scala macros don't support named or default arguments.
  */
case object UnlocatableSourceInfo extends NoSourceInfo

/** For when source info isn't generated because the function is deprecated and we're lazy.
  */
case object DeprecatedSourceInfo extends NoSourceInfo

/** For FIRRTL lines from a Scala source line.
  */
case class SourceLine(filename: String, line: Int, col: Int) extends SourceInfo {
  def makeMessage(f: String => String): String = f(s"@[$filename $line:$col]")
}

/** Provides a macro that returns the source information at the invocation point.
  */
object SourceInfoMacro {
  def generate_source_info(c: Context): c.Tree = {
    import c.universe._
    val p = c.enclosingPosition

    val userDir = sys.props.get("user.dir") // Figure out what to do if not provided
    val projectRoot = sys.props.get("chisel.project.root")
    val root = projectRoot.orElse(userDir)

    val path = root.map(r => p.source.file.canonicalPath.stripPrefix(r)).getOrElse(p.source.file.name)
    val pathNoStartingSlash = if (path(0) == '/') path.tail else path

    q"_root_.chisel3.internal.sourceinfo.SourceLine($pathNoStartingSlash, ${p.line}, ${p.column})"
  }
}

object SourceInfo {
  implicit def materialize: SourceInfo = macro SourceInfoMacro.generate_source_info
}
