package dotty.tools
package dotc
package core
package pickling

import ast.Trees._
import PickleFormat._
import core._
import Contexts._, Symbols._, Types._, Names._, Constants._, Decorators._, Annotations._, StdNames.tpnme, NameOps._
import collection.mutable
import NameOps._
import TastyBuffer._

class TreePickler(pickler: TastyPickler) {
  val buf = new TreeBuffer
  pickler.newSection("ASTs", buf)
  import buf._
  import pickler.nameBuffer.{nameIndex, fullNameIndex}
  import ast.tpd._

  private val symRefs = new mutable.HashMap[Symbol, Addr]
  private val forwardSymRefs = new mutable.HashMap[Symbol, List[Addr]]
  private val pickledTypes = new java.util.IdentityHashMap[Type, Any] // Value type is really Addr, but that's not compatible with null

  private def withLength(op: => Unit) = {
    val lengthAddr = reserveRef(relative = true)
    op
    fillRef(lengthAddr, currentAddr, relative = true)
  }

  def addrOfSym(sym: Symbol): Option[Addr] = {
    symRefs.get(sym)
  }

  def preRegister(tree: Tree)(implicit ctx: Context): Unit = tree match {
    case tree: MemberDef => 
      if (!symRefs.contains(tree.symbol)) symRefs(tree.symbol) = NoAddr
    case _ =>
  }

  def registerDef(sym: Symbol): Unit = {
    symRefs(sym) = currentAddr
    forwardSymRefs.get(sym) match {
      case Some(refs) =>
        refs.foreach(fillRef(_, currentAddr, relative = false))
        forwardSymRefs -= sym
      case None =>
    }
  }

  private def pickleName(name: Name): Unit = writeNat(nameIndex(name).index)
  private def pickleName(name: TastyName): Unit = writeNat(nameIndex(name).index)
  private def pickleNameAndSig(name: Name, sig: Signature) = {
    val Signature(params, result) = sig
    pickleName(TastyName.Signed(nameIndex(name), params.map(fullNameIndex), fullNameIndex(result)))
  }
  
  private def pickleName(sym: Symbol)(implicit ctx: Context): Unit =
    if (sym is Flags.ExpandedName) 
      pickleName(TastyName.Expanded(
        nameIndex(sym.name.expandedPrefix), nameIndex(sym.name.unexpandedName)))
    else pickleName(sym.name)
      
  private def pickleSymRef(sym: Symbol)(implicit ctx: Context) = symRefs.get(sym) match {
    case Some(label) =>
      if (label != NoAddr) writeRef(label) else pickleForwardSymRef(sym)
    case None =>
      ctx.log(i"pickling reference to as yet undefined $sym in ${sym.owner}", sym.pos)
      pickleForwardSymRef(sym)
  }
  
  private def pickleForwardSymRef(sym: Symbol)(implicit ctx: Context) = {
    val ref = reserveRef(relative = false)
    assert(!sym.is(Flags.Package), sym)
    forwardSymRefs(sym) = ref :: forwardSymRefs.getOrElse(sym, Nil)  
  }
  
  private def isLocallyDefined(sym: Symbol)(implicit ctx: Context) = symRefs.get(sym) match {
    case Some(label) => assert(sym.exists); label != NoAddr
    case None => false
  }

  def pickle(trees: List[Tree])(implicit ctx: Context) = {
    
    def qualifiedName(sym: Symbol): TastyName =
      if (sym.isRoot || sym.owner.isRoot) TastyName.Simple(sym.name.toTermName)
      else TastyName.Qualified(nameIndex(qualifiedName(sym.owner)), nameIndex(sym.name))

    def pickleConstant(c: Constant): Unit = c.tag match {
      case UnitTag =>
        writeByte(UNITconst)
      case BooleanTag =>
        writeByte(if (c.booleanValue) TRUEconst else FALSEconst)
      case ByteTag =>
        writeByte(BYTEconst)
        writeInt(c.byteValue)
      case ShortTag =>
        writeByte(SHORTconst)
        writeInt(c.shortValue)
      case CharTag =>
        writeByte(CHARconst)
        writeNat(c.charValue)
      case IntTag =>
        writeByte(INTconst)
        writeInt(c.intValue)
      case LongTag =>
        writeByte(LONGconst)
        writeLongInt(c.longValue)
      case FloatTag =>
        writeByte(FLOATconst)
        writeInt(java.lang.Float.floatToRawIntBits(c.floatValue))
      case DoubleTag =>
        writeByte(DOUBLEconst)
        writeLongInt(java.lang.Double.doubleToRawLongBits(c.doubleValue))
      case StringTag =>
        writeByte(STRINGconst)
        writeNat(nameIndex(c.stringValue).index)
      case NullTag =>
        writeByte(NULLconst)
      case ClazzTag =>
        writeByte(CLASSconst)
        pickleType(c.typeValue)
      case EnumTag =>
        writeByte(ENUMconst)
        pickleType(c.symbolValue.termRef)
    }

    def pickleType(tpe0: Type, richTypes: Boolean = false): Unit = try {
      val tpe = tpe0.stripTypeVar
      val prev = pickledTypes.get(tpe)
      if (prev == null) {
        pickledTypes.put(tpe, currentAddr)
        pickleNewType(tpe, richTypes)
      }
      else {
        writeByte(SHARED)
        writeRef(prev.asInstanceOf[Addr])
      }
    } catch {
      case ex: AssertionError =>
        println(i"error when pickling type $tpe0")
        throw ex
    }
      
    def pickleNewType(tpe: Type, richTypes: Boolean): Unit = try { tpe match {
      case ConstantType(value) => 
        pickleConstant(value)
      case tpe: TypeRef if tpe.info.isAlias && tpe.symbol.is(Flags.AliasPreferred) =>
        pickleType(tpe.info.bounds.hi)
      case tpe: WithFixedSym =>
        val sym = tpe.symbol
        if (sym.is(Flags.Package)) {
          writeByte(if (tpe.isType) TYPEREFpkg else TERMREFpkg)
          pickleName(qualifiedName(sym))
        } 
        else {
          assert(tpe.prefix == NoPrefix)
          def pickleRef() = {
            writeByte(if (tpe.isType) TYPEREFdirect else TERMREFdirect)
            pickleSymRef(sym)        
          }
          if (sym is Flags.BindDefinedType) {
            registerDef(sym)
            writeByte(BIND)
            withLength {
              pickleName(sym.name)
              pickleType(sym.info)
              pickleRef()
            }
          }
          else pickleRef()
        }
      case tpe: TermRefWithSignature =>
        writeByte(TERMREF)
        pickleNameAndSig(tpe.name, tpe.signature); pickleType(tpe.prefix)
      case tpe: NamedType =>
        if (tpe.name == tpnme.Apply && tpe.prefix.argInfos.nonEmpty && tpe.prefix.isInstantiatedLambda)
          // instantiated lambdas are pickled as APPLIEDTYPE; #Apply will 
          // be reconstituted when unpickling.
          pickleType(tpe.prefix)
        else if (isLocallyDefined(tpe.symbol)) {
          writeByte(if (tpe.isType) TYPEREFsymbol else TERMREFsymbol)
          pickleSymRef(tpe.symbol); pickleType(tpe.prefix)
        }
        else { 
          writeByte(if (tpe.isType) TYPEREF else TERMREF)
          pickleName(tpe.name); pickleType(tpe.prefix)
        }
      case tpe: ThisType =>
        writeByte(THIS)
        pickleType(tpe.tref)
      case tpe: SuperType =>
        writeByte(SUPERtype)
        withLength { pickleType(tpe.thistpe); pickleType(tpe.supertpe)}
      case tpe: SkolemType =>
        writeByte(SKOLEMtype)
        writeRef(pickledTypes.get(tpe.binder).asInstanceOf[Addr])
      case tpe: RefinedType =>
        val args = tpe.argInfos(interpolate = false)
        if (args.isEmpty) {
          writeByte(REFINEDtype)
          withLength { 
            pickleType(tpe.parent)
            pickleName(tpe.refinedName)
            pickleType(tpe.refinedInfo, richTypes = true) 
          }
        }
        else {
          writeByte(APPLIEDtype)
          withLength { pickleType(tpe.withoutArgs(args)); args.foreach(pickleType(_)) }
        }
      case tpe: TypeAlias =>
        writeByte(TYPEALIAS)
        withLength { 
          pickleType(tpe.alias, richTypes) 
          tpe.variance match {
            case 1 => writeByte(COVARIANT)
            case -1 => writeByte(CONTRAVARIANT)
            case 0 =>
          }
        }
      case tpe: TypeBounds =>
        writeByte(TYPEBOUNDS)
        withLength { pickleType(tpe.lo, richTypes); pickleType(tpe.hi, richTypes) }
      case tpe: AnnotatedType =>
        writeByte(ANNOTATED)
        withLength { pickleTree(tpe.annot.tree); pickleType(tpe.tpe, richTypes) }
      case tpe: AndOrType =>
        writeByte(if (tpe.isAnd) ANDtype else ORtype)
        withLength { pickleType(tpe.tp1, richTypes); pickleType(tpe.tp2, richTypes) }
      case tpe: ExprType =>
        writeByte(BYNAMEtype)
        pickleType(tpe.underlying)
      case tpe: MethodType if richTypes =>
        writeByte(METHODtype)
        pickleMethodic(tpe.resultType, tpe.paramNames, tpe.paramTypes)
      case tpe: PolyType if richTypes =>
        writeByte(POLYtype)
        pickleMethodic(tpe.resultType, tpe.paramNames, tpe.paramBounds)
      case tpe: PolyParam => 
        if (!pickleParamType(tpe))
          // TODO figure out why this case arises in e.g. pickling AbstractFileReader.
          ctx.typerState.constraint.entry(tpe) match {
            case TypeBounds(lo, hi) if lo eq hi => pickleNewType(lo, richTypes)
            case _ => assert(false, s"orphan poly parameter: $tpe")
          }
      case tpe: MethodParam =>
        assert(pickleParamType(tpe), s"orphan method parameter: $tpe")
      case tpe: LazyRef =>
        pickleType(tpe.ref)
    }} catch {
      case ex: AssertionError => 
        println(i"error while pickling type $tpe")
        throw ex
    }
    
    def pickleMethodic(result: Type, names: List[Name], types: List[Type]) = 
      withLength {
        pickleType(result, richTypes = true)
        (names, types).zipped.foreach { (name, tpe) =>
          pickleName(name); pickleType(tpe)       
        }
      }
    
    def pickleParamType(tpe: ParamType): Boolean = {
      val binder = pickledTypes.get(tpe.binder)
      val pickled = binder != null
      if (pickled) {
        writeByte(PARAMtype)
        withLength { writeRef(binder.asInstanceOf[Addr]); writeNat(tpe.paramNum) }
      }
      pickled
    }
    
    def pickleTpt(tpt: Tree): Unit = pickleType(tpt.tpe) // TODO correlate with original when generating positions
    
    def pickleTreeUnlessEmpty(tree: Tree): Unit = 
      if (!tree.isEmpty) pickleTree(tree)

    def pickleTree(tree: Tree): Unit = try {
      pickledTrees.put(tree, currentAddr)
      tree match {
      case Ident(name) =>
        tree.tpe match {
          case tp: TermRef => pickleType(tp)
          case _ => 
             writeByte(IDENT)
             pickleName(name)
             pickleType(tree.tpe)
        }
      case This(_) => 
        pickleType(tree.tpe)
      case Select(qual, name) => 
        writeByte(SELECT)
        val realName = tree.tpe match {
          case tp: NamedType if tp.name.isShadowedName => tp.name
          case _ => name
        }
        val sig = tree.tpe.signature
        if (sig == Signature.NotAMethod) pickleName(realName)
        else pickleNameAndSig(realName, sig)
        pickleTree(qual)
      case Apply(fun, args) =>
        writeByte(APPLY)
        withLength {
          pickleTree(fun)
          args.foreach(pickleTree)
        }
      case TypeApply(fun, args) =>
        writeByte(TYPEAPPLY)
        withLength {
          pickleTree(fun)
          args.foreach(pickleTpt)
        }
      case Literal(const1) =>
        pickleConstant {
          tree.tpe match {
            case ConstantType(const2) => const2
            case _ => const1
          }
        }
      case Super(qual, mix) =>
        writeByte(SUPER)
        withLength { 
          pickleTree(qual);
          if (!mix.isEmpty) {
            val SuperType(_, mixinType) = tree.tpe
            pickleType(mixinType)
          }
        }
      case New(tpt) =>
        writeByte(NEW)
        pickleTpt(tpt)
      case Pair(left, right) =>
        writeByte(PAIR)
        withLength { pickleTree(left); pickleTree(right) }
      case Typed(expr, tpt) =>
        writeByte(TYPED)
        withLength { pickleTree(expr); pickleTpt(tpt) }
      case NamedArg(name, arg) =>
        writeByte(NAMEDARG)
        withLength { pickleName(name); pickleTree(arg) }
      case Assign(lhs, rhs) =>
        writeByte(ASSIGN)
        withLength { pickleTree(lhs); pickleTree(rhs) }
      case Block(stats, expr) =>
        writeByte(BLOCK)
        stats.foreach(preRegister)
        withLength { pickleTree(expr); stats.foreach(pickleTree) }
      case If(cond, thenp, elsep) =>
        writeByte(IF)
        withLength{ pickleTree(cond); pickleTree(thenp); pickleTree(elsep) }
      case Closure(env, meth, tpt) => 
        writeByte(LAMBDA)
        assert(env.isEmpty)
        withLength{ 
          pickleTree(meth)
          if (tpt.tpe.exists) pickleTpt(tpt) 
        }
      case Match(selector, cases) =>
        writeByte(MATCH)
        withLength { pickleTree(selector); cases.foreach(pickleTree) }
      case CaseDef(pat, guard, rhs) =>
        writeByte(CASEDEF)
        withLength { pickleTree(pat); pickleTree(rhs); pickleTreeUnlessEmpty(guard) }
      case Return(expr, from) =>
        writeByte(RETURN)
        withLength { pickleSymRef(from.symbol); pickleTreeUnlessEmpty(expr) }
      case Try(block, cases, finalizer) =>
        writeByte(TRY)
        withLength { pickleTree(block); cases.foreach(pickleTree); pickleTreeUnlessEmpty(finalizer) }
      case SeqLiteral(elems) =>
        writeByte(REPEATED)
        withLength { elems.foreach(pickleTree) }
      case TypeTree(original) =>
        pickleTpt(tree)
      case Bind(name, body) =>
        registerDef(tree.symbol)
        writeByte(BIND)
        withLength { pickleName(name); pickleType(tree.symbol.info); pickleTree(body) }
      case Alternative(alts) =>
        writeByte(ALTERNATIVE)
        withLength { alts.foreach(pickleTree) }
      case UnApply(fun, implicits, patterns) =>
        writeByte(UNAPPLY)
        withLength { 
          pickleTree(fun)
          for (implicitArg <- implicits) {
            writeByte(IMPLICITarg)
            pickleTree(implicitArg)
          }
          pickleType(tree.tpe)
          patterns.foreach(pickleTree) 
        }
      case tree: ValDef =>
        pickleDef(VALDEF, tree.symbol, tree.tpt, tree.rhs)
      case tree: DefDef =>
        def pickleAllParams = {
          pickleParams(tree.tparams)
          for (vparams <- tree.vparamss) {
            writeByte(PARAMS)
            withLength { pickleParams(vparams) }
          }          
        }
        pickleDef(DEFDEF, tree.symbol, tree.tpt, tree.rhs, pickleAllParams)
      case tree: TypeDef =>
        pickleDef(TYPEDEF, tree.symbol, tree.rhs)
      case tree: Template =>
        registerDef(tree.symbol)
        writeByte(TEMPLATE)
        val (params, rest) = tree.body partition {
          case stat: TypeDef => stat.symbol is Flags.Param
          case stat: ValOrDefDef => 
            stat.symbol.is(Flags.ParamAccessor) && !stat.symbol.isSetter
          case _ => false
        }
        withLength {
          pickleParams(params)
          tree.parents.foreach(pickleTree)
          val cinfo @ ClassInfo(_, _, _, _, selfInfo) = tree.symbol.owner.info
          if ((selfInfo ne NoType) || !tree.self.isEmpty) {
            writeByte(SELFDEF)
            pickleName(tree.self.name)
            pickleType {
              cinfo.selfInfo match {
                case sym: Symbol => sym.info
                case tp: Type => tp
              }
            }
          }
          pickleStats(tree.constr :: rest)
        }
      case Import(expr, selectors) =>
        writeByte(IMPORT)
        withLength {
          pickleTree(expr)
          selectors foreach {
            case Pair(Ident(from), Ident(to)) => 
              writeByte(RENAMED)
              withLength { pickleName(from); pickleName(to) }
            case Ident(name) =>
              writeByte(IMPORTED)
              pickleName(name)
          }
        }
      case PackageDef(pid, stats) =>
        writeByte(PACKAGE)
        withLength { pickleType(pid.tpe); pickleStats(stats) }
    }}
    catch {
      case ex: AssertionError =>
        println(i"error when pickling tree $tree")
        throw ex
    }

    def pickleDef(tag: Int, sym: Symbol, tpt: Tree, rhs: Tree = EmptyTree, pickleParams: => Unit = ()) = {
      assert(symRefs(sym) == NoAddr)
      registerDef(sym)
      writeByte(tag)
      withLength {
        pickleName(sym)
        pickleParams
        tpt match {
          case tpt: TypeTree => pickleTpt(tpt)
          case _ => pickleTree(tpt)
        }
        pickleTreeUnlessEmpty(rhs)
        pickleModifiers(sym)
      }
    }
    
    def pickleParam(tree: Tree): Unit = tree match {
      case tree: ValDef => pickleDef(PARAM, tree.symbol, tree.tpt)
      case tree: DefDef => pickleDef(PARAM, tree.symbol, tree.tpt, tree.rhs)
      case tree: TypeDef => pickleDef(TYPEPARAM, tree.symbol, tree.rhs)      
    }
    
    def pickleParams(trees: List[Tree]): Unit = {
      trees.foreach(preRegister)
      trees.foreach(pickleParam)
    }

    def pickleStats(stats: List[Tree]) = {
      stats.foreach(preRegister)
      stats.foreach(stat => if (!stat.isEmpty) pickleTree(stat))
    }

    def pickleModifiers(sym: Symbol): Unit = {
      import Flags._
      val flags = sym.flags
      val privateWithin = sym.privateWithin
      if (privateWithin.exists) {
        writeByte(if (flags is Protected) PROTECTEDqualified else PRIVATEqualified)
        pickleType(privateWithin.typeRef)
      }
      if (flags is Private) writeByte(PRIVATE)
      if (flags is Protected) if (!privateWithin.exists) writeByte(PROTECTED)
      if ((flags is Final) && !(sym is Module)) writeByte(FINAL)
      if (flags is Case) writeByte(CASE)
      if (flags is Override) writeByte(OVERRIDE)
      if (flags is Inline) writeByte(INLINE)
      if (flags is JavaStatic) writeByte(STATIC)
      if (flags is Module) writeByte(OBJECT)
      if (flags is Local) writeByte(LOCAL)
      if (flags is Synthetic) writeByte(SYNTHETIC)
      if (flags is Artifact) writeByte(ARTIFACT)
      if (flags is Scala2x) writeByte(SCALA2X) 
      if (flags is InSuperCall) writeByte(INSUPERCALL)
      if (sym.isTerm) {
        if (flags is Implicit) writeByte(IMPLICIT)
        if ((flags is Lazy) && !(sym is Module)) writeByte(LAZY)
        if (flags is AbsOverride) writeByte(ABSOVERRIDE)
        if (flags is Mutable) writeByte(MUTABLE)
        if (flags is Accessor) writeByte(FIELDaccessor)
        if (flags is CaseAccessor) writeByte(CASEaccessor)  
        if (flags is DefaultParameterized) writeByte(DEFAULTparameterized)
      } else {
        if (flags is Sealed) writeByte(SEALED)
        if (flags is Abstract) writeByte(ABSTRACT)      
        if (flags is Trait) writeByte(TRAIT)
        if (flags is Covariant) writeByte(COVARIANT)
        if (flags is Contravariant) writeByte(CONTRAVARIANT)
      }
      sym.annotations.foreach(pickleAnnotation)
    }
    
    def pickleAnnotation(ann: Annotation) = {
      writeByte(ANNOTATION)
      withLength { pickleType(ann.symbol.typeRef); pickleTree(ann.tree) }
    }

    def updateMapWithDeltas[T](mp: collection.mutable.Map[T, Addr]) =
      for (key <- mp.keysIterator.toBuffer[T]) mp(key) = adjusted(mp(key))

    trees.foreach(tree => if (!tree.isEmpty) pickleTree(tree))
    assert(forwardSymRefs.isEmpty, i"unresolved symbols: ${forwardSymRefs.keySet.toList}%, %")
    compactify()
    updateMapWithDeltas(symRefs)
  }
}