// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

import '../compiler.dart' show Compiler;
import '../core_types.dart' show CoreClasses;
import '../elements/elements.dart';
import '../js_backend/js_backend.dart';
import '../native/native.dart' as native;
import '../tree/tree.dart' as ast;
import '../types/types.dart';
import '../universe/selector.dart' show Selector;
import '../world.dart' show ClassWorld, World;

class TypeMaskFactory {
  static TypeMask fromInferredType(TypeMask mask, Compiler compiler) {
    JavaScriptBackend backend = compiler.backend;
    if (mask == null) return backend.dynamicType;
    return mask;
  }

  static TypeMask inferredReturnTypeForElement(
      Element element, Compiler compiler) {
    return fromInferredType(
        compiler.typesTask.getGuaranteedReturnTypeOfElement(element), compiler);
  }

  static TypeMask inferredTypeForElement(Element element, Compiler compiler) {
    return fromInferredType(
        compiler.typesTask.getGuaranteedTypeOfElement(element), compiler);
  }

  static TypeMask inferredTypeForSelector(
      Selector selector, TypeMask mask, Compiler compiler) {
    return fromInferredType(
        compiler.typesTask.getGuaranteedTypeOfSelector(selector, mask),
        compiler);
  }

  static TypeMask inferredForNode(
      Element owner, ast.Node node, Compiler compiler) {
    return fromInferredType(
        compiler.typesTask.getGuaranteedTypeOfNode(owner, node), compiler);
  }

  static TypeMask fromNativeBehavior(
      native.NativeBehavior nativeBehavior, Compiler compiler) {
    ClassWorld classWorld = compiler.world;
    JavaScriptBackend backend = compiler.backend;
    if (nativeBehavior.typesReturned.isEmpty) return backend.dynamicType;

    TypeMask result = nativeBehavior.typesReturned
        .map((type) => fromNativeType(type, compiler))
        .reduce((t1, t2) => t1.union(t2, classWorld));
    assert(!result.isEmpty);
    return result;
  }

  // [type] is either an instance of [DartType] or special objects
  // like [native.SpecialType.JsObject].
  static TypeMask fromNativeType(type, Compiler compiler) {
    ClassWorld classWorld = compiler.world;
    JavaScriptBackend backend = compiler.backend;
    CoreClasses coreClasses = compiler.coreClasses;
    if (type == native.SpecialType.JsObject) {
      return new TypeMask.nonNullExact(coreClasses.objectClass, classWorld);
    } else if (type.isVoid) {
      return backend.nullType;
    } else if (type.element == coreClasses.nullClass) {
      return backend.nullType;
    } else if (type.treatAsDynamic) {
      return backend.dynamicType;
    } else {
      return new TypeMask.nonNullSubtype(type.element, classWorld);
    }
  }
}