/*
 * Copyright 2005-2010 LAMP/EPFL
 */

package scala.tools.refactoring
package implementations

import common.Change
import scala.tools.nsc.ast.parser.Tokens
import scala.tools.nsc.symtab.Flags

abstract class ExplicitGettersSetters extends MultiStageRefactoring with common.InteractiveScalaCompiler {
  
  import global._
  
  type PreparationResult = ValDef

  class RefactoringParameters
  
  def prepare(s: Selection) = {
    s.findSelectedOfType[ValDef] match {
      case Some(valdef) => Right(valdef)
      case None => Left(new PreparationError("no valdef selected"))
    }
  }
    
  override def perform(selection: Selection, selectedValue: PreparationResult, params: RefactoringParameters): Either[RefactoringError, List[Change]] = {
        
    val template = selection.findSelectedOfType[Template].getOrElse {
      return Left(RefactoringError("no template found"))
    }
    
    val createSetter = selectedValue.symbol.isMutable
    
    val publicName = selectedValue.name.toString.trim
    
    val privateName = "_"+ publicName
    
    val privateFieldMods = if(createSetter)
      Modifiers(Flags.PARAMACCESSOR).
        withPosition (Flags.PRIVATE, NoPosition).
        withPosition (Tokens.VAR, NoPosition)
    else
      Modifiers(Flags.PARAMACCESSOR)
      
    val privateField = selectedValue copy (mods = privateFieldMods, name = privateName)
    
    val getter = DefDef(
        mods = Modifiers(Flags.METHOD) withPosition (Flags.METHOD, NoPosition), 
        name = publicName, 
        tparams = Nil, 
        vparamss = Nil, 
        tpt = EmptyTree, 
        rhs = Block(
            Ident(privateName) :: Nil, EmptyTree))
    
    val setter = DefDef(
        mods = Modifiers(Flags.METHOD) withPosition (Flags.METHOD, NoPosition), 
        name = publicName +"_=",
        tparams = Nil,
        vparamss = List(List(ValDef(Modifiers(Flags.PARAM), publicName, TypeTree(selectedValue.tpt.tpe), EmptyTree))), 
        tpt = EmptyTree,
        rhs = Block(
            Assign(
                Ident(privateName),
                Ident(publicName)) :: Nil, EmptyTree))
    
    val insertGetterSettersTransformation = transform {
        
      case tpl: Template if tpl == template =>
      
        val classParameters = tpl.body.map {
          case t: ValDef if t == selectedValue => privateField setPos t.pos
          case t => t 
        }
        
        val body = if(createSetter) 
          getter :: setter :: classParameters
        else
          getter :: classParameters
        
        tpl.copy(body = body) setPos tpl.pos
    }
    
    Right(transformFile(selection.file, topdown(matchingChildren(insertGetterSettersTransformation))))
  }
}