// Copyright (c) 2017, 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.

/// Defines the VM-specific translation of Dart source code to kernel binaries.
library vm.kernel_front_end;

import 'dart:async';

import 'package:front_end/src/api_prototype/compiler_options.dart'
    show CompilerOptions, ErrorHandler;
import 'package:front_end/src/api_prototype/kernel_generator.dart'
    show kernelForProgram;
import 'package:front_end/src/api_prototype/compilation_message.dart'
    show CompilationMessage, Severity;
import 'package:front_end/src/fasta/severity.dart' show Severity;
import 'package:kernel/ast.dart' show Program;
import 'package:kernel/core_types.dart' show CoreTypes;

import 'transformations/devirtualization.dart' as devirtualization
    show transformProgram;
import 'transformations/no_dynamic_invocations_annotator.dart'
    as no_dynamic_invocations_annotator show transformProgram;
import 'transformations/type_flow/transformer.dart' as globalTypeFlow
    show transformProgram;

// Flag to enable global type flow analysis and related transformations.
const kUseGlobalTypeFlow = const bool.fromEnvironment('use.global.type.flow');

/// Generates a kernel representation of the program whose main library is in
/// the given [source]. Intended for whole program (non-modular) compilation.
///
/// VM-specific replacement of [kernelForProgram].
///
Future<Program> compileToKernel(Uri source, CompilerOptions options,
    {bool aot: false}) async {
  // Replace error handler to detect if there are compilation errors.
  final errorDetector =
      new ErrorDetector(previousErrorHandler: options.onError);
  options.onError = errorDetector;

  final program = await kernelForProgram(source, options);

  // Restore error handler (in case 'options' are reused).
  options.onError = errorDetector.previousErrorHandler;

  // Run global transformations only if program is correct.
  if (aot && (program != null) && !errorDetector.hasCompilationErrors) {
    _runGlobalTransformations(program, options.strongMode);
  }

  return program;
}

_runGlobalTransformations(Program program, bool strongMode) {
  if (strongMode) {
    final coreTypes = new CoreTypes(program);

    if (kUseGlobalTypeFlow) {
      globalTypeFlow.transformProgram(coreTypes, program);
    } else {
      devirtualization.transformProgram(coreTypes, program);
    }

    no_dynamic_invocations_annotator.transformProgram(program);
  }
}

class ErrorDetector {
  final ErrorHandler previousErrorHandler;
  bool hasCompilationErrors = false;

  ErrorDetector({this.previousErrorHandler});

  void call(CompilationMessage message) {
    if ((message.severity != Severity.nit) &&
        (message.severity != Severity.warning)) {
      hasCompilationErrors = true;
    }

    previousErrorHandler?.call(message);
  }
}