// Copyright (c) 2015, 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.

/// Analysis to determine how to generate code for typed JavaScript interop.
library compiler.src.js_backend.js_interop_analysis;

import '../elements/types.dart';
import '../js/js.dart' as jsAst;
import '../js/js.dart' show js;
import '../universe/selector.dart' show Selector;
import '../universe/world_builder.dart' show SelectorConstraints;
import 'js_backend.dart' show JavaScriptBackend;

class JsInteropAnalysis {
  final JavaScriptBackend backend;

  JsInteropAnalysis(this.backend);

  jsAst.Statement buildJsInteropBootstrap() {
    if (!backend.compiler.frontendStrategy.nativeBasicData.isJsInteropUsed)
      return null;
    List<jsAst.Statement> statements = <jsAst.Statement>[];
    backend.compiler.codegenWorldBuilder.forEachInvokedName(
        (String name, Map<Selector, SelectorConstraints> selectors) {
      selectors.forEach((Selector selector, SelectorConstraints constraints) {
        if (selector.isClosureCall) {
          // TODO(jacobr): support named arguments.
          if (selector.namedArgumentCount > 0) return;
          int argumentCount = selector.argumentCount;
          var candidateParameterNames =
              'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
          var parameters = new List<String>.generate(
              argumentCount, (i) => candidateParameterNames[i]);

          var name = backend.namer.invocationName(selector);
          statements.add(js.statement(
              'Function.prototype.# = function(#) { return this(#) }',
              [name, parameters, parameters]));
        }
      });
    });
    return new jsAst.Block(statements);
  }

  FunctionType buildJsFunctionType() {
    // TODO(jacobr): consider using codegenWorldBuilder.isChecks to determine the
    // range of positional arguments that need to be supported by JavaScript
    // function types.
    return new FunctionType(
        const DynamicType(),
        const <DartType>[],
        new List<DartType>.filled(16, const DynamicType()),
        const <String>[],
        const <DartType>[],
        const <FunctionTypeVariable>[]);
  }
}