package scala.reflect
package runtime

import internal.Flags
import java.lang.{Class => jClass, Package => jPackage}
import collection.mutable

trait Loaders { self: SymbolTable =>

  /** The lazy type for root.
   */
  override val rootLoader = new LazyType {
    override def complete(sym: Symbol) = sym setInfo new LazyPackageType
  }

  /** The standard completer for top-level classes
   *  @param clazz   The top-level class
   *  @param module  The companion object of `clazz`
   *  Calling `complete` on this type will assign the infos of `clazz` and `module`
   *  by unpickling information from the corresponding Java class. If no Java class
   *  is found, a package is created instead.
   */
  class TopClassCompleter(clazz: Symbol, module: Symbol) extends SymLoader {
//    def makePackage() {
//      println("wrong guess; making package "+clazz)
//      val ptpe = newPackageType(module.moduleClass)
//      for (sym <- List(clazz, module, module.moduleClass)) {
//        sym setFlag Flags.PACKAGE
//        sym setInfo ptpe
//      }
//    }

    override def complete(sym: Symbol) = {
      debugInfo("completing "+sym+"/"+clazz.fullName)
      assert(sym == clazz || sym == module || sym == module.moduleClass)
//      try {
      atPhaseNotLaterThan(picklerPhase) {
        unpickleClass(clazz, module, javaClass(clazz.javaClassName))
//      } catch {
//        case ex: ClassNotFoundException => makePackage()
//        case ex: NoClassDefFoundError => makePackage()
          // Note: We catch NoClassDefFoundError because there are situations
          // where a package and a class have the same name except for capitalization.
          // It seems in this case the class is loaded even if capitalization differs
          // but then a NoClassDefFound error is issued with a ("wrong name: ...")
          // reason. (I guess this is a concession to Windows).
          // The present behavior is a bit too forgiving, in that it masks
          // all class load errors, not just wrong name errors. We should try
          // to be more discriminating. To get on the right track simply delete
          // the clause above and load a collection class such as collection.Iterable.
          // You'll see an error that class `parallel` has the wrong name.
//      }
      }
    }
    override def load(sym: Symbol) = complete(sym)
  }

  /** Create a class and a companion object, enter in enclosing scope,
   *  and initialize with a lazy type completer.
   *  @param owner   The owner of the newly created class and object
   *  @param name    The simple name of the newly created class
   *  @param completer  The completer to be used to set the info of the class and the module
   */
  protected def createClassModule(owner: Symbol, name: TypeName, completer: (Symbol, Symbol) => LazyType) = {
    assert(!(name.ToString EndsWith "[]"), name)
    val clazz = owner.newClass(name)
    val module = owner.newModule(name.toTermName)
    owner.info.decls enter clazz
    owner.info.decls enter module
    initClassModule(clazz, module, completer(clazz, module))
    (clazz, module)
  }

  protected def setAllInfos(clazz: Symbol, module: Symbol, info: Type) = {
    List(clazz, module, module.moduleClass) foreach (_ setInfo info)
  }

  protected def initClassModule(clazz: Symbol, module: Symbol, completer: LazyType) =
    setAllInfos(clazz, module, completer)

  /** The type completer for packages.
   */
  class LazyPackageType extends LazyType {
    override def complete(sym: Symbol) {
      assert(sym.isPackageClass)
      sym setInfo new ClassInfoType(List(), new PackageScope(sym), sym)
        // override def safeToString = pkgClass.toString
      openPackageModule(sym)
    }
  }

  /** Is the given name valid for a top-level class? We exclude names with embedded $-signs, because
   *  these are nested classes or anonymous classes,
   */
  def invalidClassName(name: Name) = {
    val dp = name pos '$'
    0 < dp && dp < (name.length - 1)
  }

  class PackageScope(pkgClass: Symbol) extends Scope() with SynchronizedScope {
    assert(pkgClass.isType)
    private val negatives = mutable.Set[Name]() // Syncnote: Performance only, so need not be protected.
    override def lookupEntry(name: Name): ScopeEntry = {
      val e = super.lookupEntry(name)
      if (e != null)
        e
      else if (invalidClassName(name) || (negatives contains name))
        null
      else {
        val path =
          if (pkgClass.isEmptyPackageClass) name.ToString
          else pkgClass.fullName + "." + name
        if (isJavaClass(path)) {
          val (clazz, module) = createClassModule(pkgClass, name.toTypeName, new TopClassCompleter(_, _))
          debugInfo("created "+module+"/"+module.moduleClass+" in "+pkgClass)
          lookupEntry(name)
        } else {
          debugInfo("*** not found : "+path)
          negatives += name
          null
        }
      }
    }
  }

  override def newPackageScope(pkgClass: Symbol) = new PackageScope(pkgClass)

  override def scopeTransform(owner: Symbol)(op: => Scope): Scope =
    if (owner.isPackageClass) owner.info.decls else op
}
