// 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.

library dart2js.js_emitter.code_emitter_task;

import 'package:js_runtime/shared/embedded_names.dart' show JsBuiltin;

import '../common.dart';
import '../common/tasks.dart' show CompilerTask;
import '../compiler.dart' show Compiler;
import '../constants/values.dart';
import '../deferred_load.dart' show OutputUnit;
import '../elements/entities.dart';
import '../js/js.dart' as jsAst;
import '../js_backend/js_backend.dart' show JavaScriptBackend, Namer;
import '../js_backend/inferred_data.dart';
import '../universe/codegen_world_builder.dart';
import '../world.dart' show JClosedWorld;
import 'program_builder/program_builder.dart';
import 'startup_emitter/emitter.dart' as startup_js_emitter;

import 'metadata_collector.dart' show MetadataCollector;
import 'model.dart';
import 'native_emitter.dart' show NativeEmitter;
import 'type_test_registry.dart' show TypeTestRegistry;
import 'sorter.dart';

/// Generates the code for all used classes in the program. Static fields (even
/// in classes) are ignored, since they can be treated as non-class elements.
///
/// The code for the containing (used) methods must exist in the `universe`.
class CodeEmitterTask extends CompilerTask {
  TypeTestRegistry typeTestRegistry;
  NativeEmitter _nativeEmitter;
  MetadataCollector metadataCollector;
  final EmitterFactory _emitterFactory;
  Emitter _emitter;
  final Compiler compiler;

  JavaScriptBackend get backend => compiler.backend;

  @deprecated
  // This field should be removed. It's currently only needed for dump-info and
  // tests.
  // The field is set after the program has been emitted.
  /// Contains a list of all classes that are emitted.
  Set<ClassEntity> neededClasses;

  CodeEmitterTask(Compiler compiler, bool generateSourceMap)
      : compiler = compiler,
        _emitterFactory = startup_js_emitter.EmitterFactory(
            generateSourceMap: generateSourceMap),
        super(compiler.measurer);

  NativeEmitter get nativeEmitter {
    assert(
        _nativeEmitter != null,
        failedAt(
            NO_LOCATION_SPANNABLE, "NativeEmitter has not been created yet."));
    return _nativeEmitter;
  }

  Emitter get emitter {
    assert(_emitter != null,
        failedAt(NO_LOCATION_SPANNABLE, "Emitter has not been created yet."));
    return _emitter;
  }

  @override
  String get name => 'Code emitter';

  /// Returns true, if the emitter supports reflection.
  bool get supportsReflection => _emitterFactory.supportsReflection;

  /// Returns the closure expression of a static function.
  jsAst.Expression isolateStaticClosureAccess(FunctionEntity element) {
    return emitter.isolateStaticClosureAccess(element);
  }

  /// Returns the JS function that must be invoked to get the value of the
  /// lazily initialized static.
  jsAst.Expression isolateLazyInitializerAccess(FieldEntity element) {
    return emitter.isolateLazyInitializerAccess(element);
  }

  /// Returns the JS code for accessing the embedded [global].
  jsAst.Expression generateEmbeddedGlobalAccess(String global) {
    return emitter.generateEmbeddedGlobalAccess(global);
  }

  /// Returns the JS code for accessing the given [constant].
  jsAst.Expression constantReference(ConstantValue constant) {
    return emitter.constantReference(constant);
  }

  jsAst.Expression staticFieldAccess(FieldEntity e) {
    return emitter.staticFieldAccess(e);
  }

  /// Returns the JS function representing the given function.
  ///
  /// The function must be invoked and can not be used as closure.
  jsAst.Expression staticFunctionAccess(FunctionEntity e) {
    return emitter.staticFunctionAccess(e);
  }

  /// Returns the JS constructor of the given element.
  ///
  /// The returned expression must only be used in a JS `new` expression.
  jsAst.Expression constructorAccess(ClassEntity e) {
    return emitter.constructorAccess(e);
  }

  /// Returns the JS prototype of the given class [e].
  jsAst.Expression prototypeAccess(ClassEntity e,
      {bool hasBeenInstantiated: false}) {
    return emitter.prototypeAccess(e, hasBeenInstantiated);
  }

  /// Returns the JS prototype of the given interceptor class [e].
  jsAst.Expression interceptorPrototypeAccess(ClassEntity e) {
    return jsAst.js('#.prototype', interceptorClassAccess(e));
  }

  /// Returns the JS constructor of the given interceptor class [e].
  jsAst.Expression interceptorClassAccess(ClassEntity e) {
    return emitter.interceptorClassAccess(e);
  }

  /// Returns the JS expression representing the type [e].
  ///
  /// The given type [e] might be a Typedef.
  jsAst.Expression typeAccess(Entity e) {
    return emitter.typeAccess(e);
  }

  /// Returns the JS template for the given [builtin].
  jsAst.Template builtinTemplateFor(JsBuiltin builtin) {
    return emitter.templateForBuiltin(builtin);
  }

  void _finalizeRti() {
    // Compute the required type checks to know which classes need a
    // 'is$' method.
    typeTestRegistry.computeRequiredTypeChecks(backend.rtiChecksBuilder);
    // Compute the classes needed by RTI.
    typeTestRegistry.computeRtiNeededClasses(
        backend.rtiSubstitutions, backend.generatedCode.keys);
  }

  /// Creates the [Emitter] for this task.
  void createEmitter(Namer namer, JClosedWorld closedWorld,
      CodegenWorldBuilder codegenWorldBuilder, Sorter sorter) {
    measure(() {
      _nativeEmitter = new NativeEmitter(this, closedWorld, codegenWorldBuilder,
          backend.nativeCodegenEnqueuer);
      _emitter =
          _emitterFactory.createEmitter(this, namer, closedWorld, sorter);
      metadataCollector = new MetadataCollector(compiler.options,
          compiler.reporter, _emitter, backend.rtiEncoder, codegenWorldBuilder);
      typeTestRegistry = new TypeTestRegistry(compiler.options,
          codegenWorldBuilder, closedWorld.elementEnvironment);
    });
  }

  int assembleProgram(
      Namer namer, JClosedWorld closedWorld, InferredData inferredData) {
    return measure(() {
      _finalizeRti();
      ProgramBuilder programBuilder = new ProgramBuilder(
          compiler.options,
          compiler.reporter,
          closedWorld.elementEnvironment,
          closedWorld.commonElements,
          closedWorld.outputUnitData,
          compiler.codegenWorldBuilder,
          backend.nativeCodegenEnqueuer,
          closedWorld.backendUsage,
          backend.constants,
          closedWorld.nativeData,
          closedWorld.rtiNeed,
          closedWorld.interceptorData,
          backend.superMemberData,
          typeTestRegistry.rtiChecks,
          backend.rtiEncoder,
          backend.oneShotInterceptorData,
          backend.customElementsCodegenAnalysis,
          backend.generatedCode,
          namer,
          this,
          closedWorld,
          closedWorld.fieldAnalysis,
          inferredData,
          backend.sourceInformationStrategy,
          closedWorld.sorter,
          typeTestRegistry.rtiNeededClasses,
          closedWorld.elementEnvironment.mainFunction);
      int size = emitter.emitProgram(programBuilder);
      // TODO(floitsch): we shouldn't need the `neededClasses` anymore.
      neededClasses = programBuilder.collector.neededClasses;
      return size;
    });
  }
}

abstract class EmitterFactory {
  /// Returns true, if the emitter supports reflection.
  bool get supportsReflection;

  /// Create the [Emitter] for the emitter [task] that uses the given [namer].
  Emitter createEmitter(CodeEmitterTask task, Namer namer,
      JClosedWorld closedWorld, Sorter sorter);
}

abstract class Emitter {
  Program get programForTesting;

  /// Uses the [programBuilder] to generate a model of the program, emits
  /// the program, and returns the size of the generated output.
  int emitProgram(ProgramBuilder programBuilder);

  /// Returns the JS function that must be invoked to get the value of the
  /// lazily initialized static.
  jsAst.Expression isolateLazyInitializerAccess(covariant FieldEntity element);

  /// Returns the closure expression of a static function.
  jsAst.Expression isolateStaticClosureAccess(covariant FunctionEntity element);

  /// Returns the JS code for accessing the embedded [global].
  jsAst.Expression generateEmbeddedGlobalAccess(String global);

  /// Returns the JS function representing the given function.
  ///
  /// The function must be invoked and can not be used as closure.
  jsAst.Expression staticFunctionAccess(FunctionEntity element);

  jsAst.Expression staticFieldAccess(FieldEntity element);

  /// Returns the JS constructor of the given element.
  ///
  /// The returned expression must only be used in a JS `new` expression.
  jsAst.Expression constructorAccess(ClassEntity e);

  /// Returns the JS prototype of the given class [e].
  jsAst.Expression prototypeAccess(
      covariant ClassEntity e, bool hasBeenInstantiated);

  /// Returns the JS constructor of the given interceptor class [e].
  jsAst.Expression interceptorClassAccess(ClassEntity e);

  /// Returns the JS expression representing the type [e].
  jsAst.Expression typeAccess(Entity e);

  /// Returns the JS expression representing a function that returns 'null'
  jsAst.Expression generateFunctionThatReturnsNull();

  int compareConstants(ConstantValue a, ConstantValue b);
  bool isConstantInlinedOrAlreadyEmitted(ConstantValue constant);

  /// Returns the JS code for accessing the given [constant].
  jsAst.Expression constantReference(ConstantValue constant);

  /// Returns the JS template for the given [builtin].
  jsAst.Template templateForBuiltin(JsBuiltin builtin);

  /// Returns the size of the code generated for a given output [unit].
  int generatedSize(OutputUnit unit);
}

abstract class EmitterBase implements Emitter {
  @override
  Program programForTesting;
  Namer get namer;

  jsAst.PropertyAccess globalPropertyAccessForMember(MemberEntity element) {
    jsAst.Name name = namer.globalPropertyNameForMember(element);
    jsAst.PropertyAccess pa = new jsAst.PropertyAccess(
        new jsAst.VariableUse(namer.globalObjectForMember(element)), name);
    return pa;
  }

  jsAst.PropertyAccess globalPropertyAccessForClass(ClassEntity element) {
    jsAst.Name name = namer.globalPropertyNameForClass(element);
    jsAst.PropertyAccess pa = new jsAst.PropertyAccess(
        new jsAst.VariableUse(namer.globalObjectForClass(element)), name);
    return pa;
  }

  jsAst.PropertyAccess globalPropertyAccessForType(Entity element) {
    jsAst.Name name = namer.globalPropertyNameForType(element);
    jsAst.PropertyAccess pa = new jsAst.PropertyAccess(
        new jsAst.VariableUse(namer.globalObjectForType(element)), name);
    return pa;
  }

  @override
  jsAst.PropertyAccess staticFieldAccess(FieldEntity element) {
    return globalPropertyAccessForMember(element);
  }

  @override
  jsAst.PropertyAccess staticFunctionAccess(FunctionEntity element) {
    return globalPropertyAccessForMember(element);
  }

  @override
  jsAst.PropertyAccess constructorAccess(ClassEntity element) {
    return globalPropertyAccessForClass(element);
  }

  @override
  jsAst.Expression interceptorClassAccess(ClassEntity element) {
    return globalPropertyAccessForClass(element);
  }

  @override
  jsAst.Expression typeAccess(Entity element) {
    return globalPropertyAccessForType(element);
  }
}