// 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.

library dart2js.source_information;

import '../common.dart';
import '../elements/elements.dart'
    show
        AstElement,
        CompilationUnitElement,
        LocalElement,
        ResolvedAst,
        ResolvedAstKind;
import '../js/js.dart' show JavaScriptNodeSourceInformation;
import '../script.dart';
import '../tree/tree.dart' show Node;
import 'source_file.dart';

/// Interface for passing source information, for instance for use in source
/// maps, through the backend.
abstract class SourceInformation extends JavaScriptNodeSourceInformation {
  const SourceInformation();

  SourceSpan get sourceSpan;

  /// The source location associated with the start of the JS node.
  SourceLocation get startPosition => null;

  /// The source location associated with the closing of the JS node.
  SourceLocation get closingPosition => null;

  /// The source location associated with the end of the JS node.
  SourceLocation get endPosition => null;

  /// All source locations associated with this source information.
  List<SourceLocation> get sourceLocations;

  /// Return a short textual representation of the source location.
  String get shortText;
}

/// Strategy for creating, processing and applying [SourceInformation].
class SourceInformationStrategy {
  const SourceInformationStrategy();

  /// Create a [SourceInformationBuilder] for [resolvedAst].
  SourceInformationBuilder createBuilderForContext(ResolvedAst resolvedAst) {
    return const SourceInformationBuilder();
  }

  /// Generate [SourceInformation] marker for non-preamble code.
  SourceInformation buildSourceMappedMarker() => null;

  /// Called when compilation has completed.
  void onComplete() {}
}

/// Interface for generating [SourceInformation].
class SourceInformationBuilder {
  const SourceInformationBuilder();

  /// Create a [SourceInformationBuilder] for [resolvedAst].
  SourceInformationBuilder forContext(ResolvedAst resolvedAst) => this;

  /// Generate [SourceInformation] the declaration of the element in
  /// [resolvedAst].
  SourceInformation buildDeclaration(ResolvedAst resolvedAst) => null;

  /// Generate [SourceInformation] for the generic [node].
  @deprecated
  SourceInformation buildGeneric(Node node) => null;

  /// Generate [SourceInformation] for an instantiation of a class using [node]
  /// for the source position.
  SourceInformation buildCreate(Node node) => null;

  /// Generate [SourceInformation] for the return [node].
  SourceInformation buildReturn(Node node) => null;

  /// Generate [SourceInformation] for an implicit return in [element].
  SourceInformation buildImplicitReturn(AstElement element) => null;

  /// Generate [SourceInformation] for the loop [node].
  SourceInformation buildLoop(Node node) => null;

  /// Generate [SourceInformation] for a read access like `a.b` where in
  /// [receiver] points to the left-most part of the access, `a` in the example,
  /// and [property] points to the 'name' of accessed property, `b` in the
  /// example.
  SourceInformation buildGet(Node node) => null;

  /// Generate [SourceInformation] for the read access in [node].
  SourceInformation buildCall(Node receiver, Node call) => null;

  /// Generate [SourceInformation] for the if statement in [node].
  SourceInformation buildIf(Node node) => null;

  /// Generate [SourceInformation] for the constructor invocation in [node].
  SourceInformation buildNew(Node node) => null;

  /// Generate [SourceInformation] for the throw in [node].
  SourceInformation buildThrow(Node node) => null;

  /// Generate [SourceInformation] for the assignment in [node].
  SourceInformation buildAssignment(Node node) => null;

  /// Generate [SourceInformation] for the variable declaration inserted as
  /// first statement of a function.
  SourceInformation buildVariableDeclaration() => null;

  /// Generate [SourceInformation] for an invocation of a foreign method.
  SourceInformation buildForeignCode(Node node) => null;

  /// Generate [SourceInformation] for a string interpolation of [node].
  SourceInformation buildStringInterpolation(Node node) => null;

  /// Generate [SourceInformation] for the for-in `iterator` access in [node].
  SourceInformation buildForInIterator(Node node) => null;

  /// Generate [SourceInformation] for the for-in `moveNext` call in [node].
  SourceInformation buildForInMoveNext(Node node) => null;

  /// Generate [SourceInformation] for the for-in `current` access in [node].
  SourceInformation buildForInCurrent(Node node) => null;

  /// Generate [SourceInformation] for the for-in variable assignment in [node].
  SourceInformation buildForInSet(Node node) => null;

  /// Generate [SourceInformation] for the operator `[]` access in [node].
  SourceInformation buildIndex(Node node) => null;

  /// Generate [SourceInformation] for the operator `[]=` assignment in [node].
  SourceInformation buildIndexSet(Node node) => null;

  /// Generate [SourceInformation] for the binary operation in [node].
  SourceInformation buildBinary(Node node) => null;

  /// Generate [SourceInformation] for the unary operator in [node].
  SourceInformation buildCatch(Node node) => null;

  /// Generate [SourceInformation] for the is-test in [node].
  SourceInformation buildIs(Node node) => null;

  /// Generate [SourceInformation] for the as-cast in [node].
  SourceInformation buildAs(Node node) => null;

  /// Generate [SourceInformation] for the switch statement [node].
  SourceInformation buildSwitch(Node node) => null;

  /// Generate [SourceInformation] for the switch case in [node].
  SourceInformation buildSwitchCase(Node node) => null;
}

/// A location in a source file.
abstract class SourceLocation {
  final SourceFile _sourceFile;
  int _line;

  SourceLocation(this._sourceFile) {
    assert(invariant(new SourceSpan(sourceUri, 0, 0), isValid,
        message: "Invalid source location in ${sourceUri}: "
            "offset=$offset, length=${_sourceFile.length}."));
  }

  /// The absolute URI of the source file of this source location.
  Uri get sourceUri => _sourceFile.uri;

  /// The character offset of the this source location into the source file.
  int get offset;

  /// The 0-based line number of the [offset].
  int get line {
    if (_line == null) _line = _sourceFile.getLine(offset);
    return _line;
  }

  /// The 0-base column number of the [offset] with its line.
  int get column => _sourceFile.getColumn(line, offset);

  /// The name associated with this source location, if any.
  String get sourceName;

  /// `true` if the offset within the length of the source file.
  bool get isValid => offset < _sourceFile.length;

  int get hashCode {
    return sourceUri.hashCode * 17 +
        offset.hashCode * 17 +
        sourceName.hashCode * 23;
  }

  bool operator ==(other) {
    if (identical(this, other)) return true;
    if (other is! SourceLocation) return false;
    return sourceUri == other.sourceUri &&
        offset == other.offset &&
        sourceName == other.sourceName;
  }

  String get shortText {
    // Use 1-based line/column info to match usual dart tool output.
    return '${sourceUri.pathSegments.last}:[${line + 1},${column + 1}]';
  }

  String toString() {
    // Use 1-based line/column info to match usual dart tool output.
    return '${sourceUri}:[${line + 1},${column + 1}]';
  }
}

class OffsetSourceLocation extends SourceLocation {
  final int offset;
  final String sourceName;

  OffsetSourceLocation(SourceFile sourceFile, this.offset, this.sourceName)
      : super(sourceFile);

  String get shortText {
    return '${super.shortText}:$sourceName';
  }

  String toString() {
    return '${super.toString()}:$sourceName';
  }
}

/// Compute the source map name for [element].
String computeElementNameForSourceMaps(AstElement element) {
  if (element.isClosure) {
    return computeElementNameForSourceMaps(element.enclosingElement);
  } else if (element.isClass) {
    return element.name;
  } else if (element.isConstructor || element.isGenerativeConstructorBody) {
    String className = element.enclosingClass.name;
    if (element.name == '') {
      return className;
    }
    return '$className.${element.name}';
  } else if (element.isLocal) {
    LocalElement local = element;
    String name = local.name;
    if (name == '') {
      name = '<anonymous function>';
    }
    return '${computeElementNameForSourceMaps(local.executableContext)}.$name';
  } else if (element.enclosingClass != null) {
    if (element.enclosingClass.isClosure) {
      return computeElementNameForSourceMaps(element.enclosingClass);
    }
    return '${element.enclosingClass.name}.${element.name}';
  } else {
    return element.name;
  }
}

/// Computes the [SourceFile] for the source code of [resolvedAst].
SourceFile computeSourceFile(ResolvedAst resolvedAst) {
  SourceFile sourceFile;
  if (resolvedAst.kind != ResolvedAstKind.PARSED) {
    // Synthesized node. Use the enclosing element for the location.
    sourceFile = resolvedAst.element.compilationUnit.script.file;
  } else {
    Uri uri = resolvedAst.sourceUri;
    AstElement implementation = resolvedAst.element.implementation;
    Script script = implementation.compilationUnit.script;
    if (uri == script.resourceUri) {
      sourceFile = script.file;
    } else {
      // Slow path, happens only for deserialized elements.
      // TODO(johnniwinther): Support a way to get a [SourceFile] from a
      // [Uri].
      for (CompilationUnitElement compilationUnit
          in implementation.library.compilationUnits) {
        Script script = compilationUnit.script;
        if (uri == script.resourceUri) {
          sourceFile = script.file;
          break;
        }
      }
    }
  }
  return sourceFile;
}