// Copyright (c) 2013, 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 'package:path/path.dart' as path;

import 'trace.dart';
import 'unparsed_frame.dart';

// #1      Foo._bar (file:///home/nweiz/code/stuff.dart:42:21)
// #1      Foo._bar (file:///home/nweiz/code/stuff.dart:42)
// #1      Foo._bar (file:///home/nweiz/code/stuff.dart)
final _vmFrame = RegExp(r'^#\d+\s+(\S.*) \((.+?)((?::\d+){0,2})\)$');

//     at Object.stringify (native)
//     at VW.call$0 (https://example.com/stuff.dart.js:560:28)
//     at VW.call$0 (eval as fn
//         (https://example.com/stuff.dart.js:560:28), efn:3:28)
//     at https://example.com/stuff.dart.js:560:28
final _v8Frame =
    RegExp(r'^\s*at (?:(\S.*?)(?: \[as [^\]]+\])? \((.*)\)|(.*))$');

// https://example.com/stuff.dart.js:560:28
// https://example.com/stuff.dart.js:560
final _v8UrlLocation = RegExp(r'^(.*?):(\d+)(?::(\d+))?$|native$');

// eval as function (https://example.com/stuff.dart.js:560:28), efn:3:28
// eval as function (https://example.com/stuff.dart.js:560:28)
// eval as function (eval as otherFunction
//     (https://example.com/stuff.dart.js:560:28))
final _v8EvalLocation =
    RegExp(r'^eval at (?:\S.*?) \((.*)\)(?:, .*?:\d+:\d+)?$');

// anonymous/<@https://example.com/stuff.js line 693 > Function:3:40
// anonymous/<@https://example.com/stuff.js line 693 > eval:3:40
final _firefoxEvalLocation =
    RegExp(r'(\S+)@(\S+) line (\d+) >.* (Function|eval):\d+:\d+');

// .VW.call$0@https://example.com/stuff.dart.js:560
// .VW.call$0("arg")@https://example.com/stuff.dart.js:560
// .VW.call$0/name<@https://example.com/stuff.dart.js:560
// .VW.call$0@https://example.com/stuff.dart.js:560:36
// https://example.com/stuff.dart.js:560
final _firefoxSafariFrame = RegExp(r'^'
    r'(?:' // Member description. Not present in some Safari frames.
    r'([^@(/]*)' // The actual name of the member.
    r'(?:\(.*\))?' // Arguments to the member, sometimes captured by Firefox.
    r'((?:/[^/]*)*)' // Extra characters indicating a nested closure.
    r'(?:\(.*\))?' // Arguments to the closure.
    r'@'
    r')?'
    r'(.*?)' // The frame's URL.
    r':'
    r'(\d*)' // The line number. Empty in Safari if it's unknown.
    r'(?::(\d*))?' // The column number. Not present in older browsers and
    // empty in Safari if it's unknown.
    r'$');

// foo/bar.dart 10:11 Foo._bar
// foo/bar.dart 10:11 (anonymous function).dart.fn
// https://dart.dev/foo/bar.dart Foo._bar
// data:... 10:11 Foo._bar
final _friendlyFrame = RegExp(r'^(\S+)(?: (\d+)(?::(\d+))?)?\s+([^\d].*)$');

/// A regular expression that matches asynchronous member names generated by the
/// VM.
final _asyncBody = RegExp(r'<(<anonymous closure>|[^>]+)_async_body>');

final _initialDot = RegExp(r'^\.');

/// A single stack frame. Each frame points to a precise location in Dart code.
class Frame {
  /// The URI of the file in which the code is located.
  ///
  /// This URI will usually have the scheme `dart`, `file`, `http`, or `https`.
  final Uri uri;

  /// The line number on which the code location is located.
  ///
  /// This can be null, indicating that the line number is unknown or
  /// unimportant.
  final int line;

  /// The column number of the code location.
  ///
  /// This can be null, indicating that the column number is unknown or
  /// unimportant.
  final int column;

  /// The name of the member in which the code location occurs.
  ///
  /// Anonymous closures are represented as `<fn>` in this member string.
  final String member;

  /// Whether this stack frame comes from the Dart core libraries.
  bool get isCore => uri.scheme == 'dart';

  /// Returns a human-friendly description of the library that this stack frame
  /// comes from.
  ///
  /// This will usually be the string form of [uri], but a relative URI will be
  /// used if possible. Data URIs will be truncated.
  String get library {
    if (uri.scheme == 'data') return 'data:...';
    return path.prettyUri(uri);
  }

  /// Returns the name of the package this stack frame comes from, or `null` if
  /// this stack frame doesn't come from a `package:` URL.
  String get package {
    if (uri.scheme != 'package') return null;
    return uri.path.split('/').first;
  }

  /// A human-friendly description of the code location.
  String get location {
    if (line == null) return library;
    if (column == null) return '$library $line';
    return '$library $line:$column';
  }

  /// Returns a single frame of the current stack.
  ///
  /// By default, this will return the frame above the current method. If
  /// [level] is `0`, it will return the current method's frame; if [level] is
  /// higher than `1`, it will return higher frames.
  factory Frame.caller([int level = 1]) {
    if (level < 0) {
      throw ArgumentError('Argument [level] must be greater than or equal '
          'to 0.');
    }

    return Trace.current(level + 1).frames.first;
  }

  /// Parses a string representation of a Dart VM stack frame.
  factory Frame.parseVM(String frame) => _catchFormatException(frame, () {
        // The VM sometimes folds multiple stack frames together and replaces
        // them with "...".
        if (frame == '...') {
          return Frame(Uri(), null, null, '...');
        }

        var match = _vmFrame.firstMatch(frame);
        if (match == null) return UnparsedFrame(frame);

        // Get the pieces out of the regexp match. Function, URI and line should
        // always be found. The column is optional.
        var member = match[1]
            .replaceAll(_asyncBody, '<async>')
            .replaceAll('<anonymous closure>', '<fn>');
        var uri = match[2].startsWith('<data:')
            ? Uri.dataFromString('')
            : Uri.parse(match[2]);

        var lineAndColumn = match[3].split(':');
        var line =
            lineAndColumn.length > 1 ? int.parse(lineAndColumn[1]) : null;
        var column =
            lineAndColumn.length > 2 ? int.parse(lineAndColumn[2]) : null;
        return Frame(uri, line, column, member);
      });

  /// Parses a string representation of a Chrome/V8 stack frame.
  factory Frame.parseV8(String frame) => _catchFormatException(frame, () {
        var match = _v8Frame.firstMatch(frame);
        if (match == null) return UnparsedFrame(frame);

        // v8 location strings can be arbitrarily-nested, since it adds a layer
        // of nesting for each eval performed on that line.
        Frame parseLocation(String location, String member) {
          var evalMatch = _v8EvalLocation.firstMatch(location);
          while (evalMatch != null) {
            location = evalMatch[1];
            evalMatch = _v8EvalLocation.firstMatch(location);
          }

          if (location == 'native') {
            return Frame(Uri.parse('native'), null, null, member);
          }

          var urlMatch = _v8UrlLocation.firstMatch(location);
          if (urlMatch == null) return UnparsedFrame(frame);

          final uri = _uriOrPathToUri(urlMatch[1]);
          final line = int.parse(urlMatch[2]);
          final column = urlMatch[3] != null ? int.parse(urlMatch[3]) : null;
          return Frame(uri, line, column, member);
        }

        // V8 stack frames can be in two forms.
        if (match[2] != null) {
          // The first form looks like " at FUNCTION (LOCATION)". V8 proper
          // lists anonymous functions within eval as "<anonymous>", while IE10
          // lists them as "Anonymous function".
          return parseLocation(
              match[2],
              match[1]
                  .replaceAll('<anonymous>', '<fn>')
                  .replaceAll('Anonymous function', '<fn>')
                  .replaceAll('(anonymous function)', '<fn>'));
        } else {
          // The second form looks like " at LOCATION", and is used for
          // anonymous functions.
          return parseLocation(match[3], '<fn>');
        }
      });

  /// Parses a string representation of a JavaScriptCore stack trace.
  factory Frame.parseJSCore(String frame) => Frame.parseV8(frame);

  /// Parses a string representation of an IE stack frame.
  ///
  /// IE10+ frames look just like V8 frames. Prior to IE10, stack traces can't
  /// be retrieved.
  factory Frame.parseIE(String frame) => Frame.parseV8(frame);

  /// Parses a Firefox 'eval' or 'function' stack frame.
  ///
  /// for example:
  /// anonymous/<@https://example.com/stuff.js line 693 > Function:3:40
  /// anonymous/<@https://example.com/stuff.js line 693 > eval:3:40
  factory Frame._parseFirefoxEval(String frame) =>
      _catchFormatException(frame, () {
        final match = _firefoxEvalLocation.firstMatch(frame);
        if (match == null) return UnparsedFrame(frame);
        var member = match[1].replaceAll('/<', '');
        final uri = _uriOrPathToUri(match[2]);
        final line = int.parse(match[3]);
        if (member.isEmpty || member == 'anonymous') {
          member = '<fn>';
        }
        return Frame(uri, line, null, member);
      });

  /// Parses a string representation of a Firefox stack frame.
  factory Frame.parseFirefox(String frame) => _catchFormatException(frame, () {
        var match = _firefoxSafariFrame.firstMatch(frame);
        if (match == null) return UnparsedFrame(frame);

        if (match[3].contains(' line ')) {
          return Frame._parseFirefoxEval(frame);
        }

        // Normally this is a URI, but in a jsshell trace it can be a path.
        var uri = _uriOrPathToUri(match[3]);

        String member;
        if (match[1] != null) {
          member = match[1];
          member +=
              List.filled('/'.allMatches(match[2]).length, '.<fn>').join();
          if (member == '') member = '<fn>';

          // Some Firefox members have initial dots. We remove them for
          // consistency with other platforms.
          member = member.replaceFirst(_initialDot, '');
        } else {
          member = '<fn>';
        }

        var line = match[4] == '' ? null : int.parse(match[4]);
        var column =
            match[5] == null || match[5] == '' ? null : int.parse(match[5]);
        return Frame(uri, line, column, member);
      });

  /// Parses a string representation of a Safari 6.0 stack frame.
  @Deprecated('Use Frame.parseSafari instead.')
  factory Frame.parseSafari6_0(String frame) => Frame.parseFirefox(frame);

  /// Parses a string representation of a Safari 6.1+ stack frame.
  @Deprecated('Use Frame.parseSafari instead.')
  factory Frame.parseSafari6_1(String frame) => Frame.parseFirefox(frame);

  /// Parses a string representation of a Safari stack frame.
  factory Frame.parseSafari(String frame) => Frame.parseFirefox(frame);

  /// Parses this package's string representation of a stack frame.
  factory Frame.parseFriendly(String frame) => _catchFormatException(frame, () {
        var match = _friendlyFrame.firstMatch(frame);
        if (match == null) {
          throw FormatException(
              "Couldn't parse package:stack_trace stack trace line '$frame'.");
        }
        // Fake truncated data urls generated by the friendly stack trace format
        // cause Uri.parse to throw an exception so we have to special case
        // them.
        var uri = match[1] == 'data:...'
            ? Uri.dataFromString('')
            : Uri.parse(match[1]);
        // If there's no scheme, this is a relative URI. We should interpret it
        // as relative to the current working directory.
        if (uri.scheme == '') {
          uri = path.toUri(path.absolute(path.fromUri(uri)));
        }

        var line = match[2] == null ? null : int.parse(match[2]);
        var column = match[3] == null ? null : int.parse(match[3]);
        return Frame(uri, line, column, match[4]);
      });

  /// A regular expression matching an absolute URI.
  static final _uriRegExp = RegExp(r'^[a-zA-Z][-+.a-zA-Z\d]*://');

  /// A regular expression matching a Windows path.
  static final _windowsRegExp = RegExp(r'^([a-zA-Z]:[\\/]|\\\\)');

  /// Converts [uriOrPath], which can be a URI, a Windows path, or a Posix path,
  /// to a URI (absolute if possible).
  static Uri _uriOrPathToUri(String uriOrPath) {
    if (uriOrPath.contains(_uriRegExp)) {
      return Uri.parse(uriOrPath);
    } else if (uriOrPath.contains(_windowsRegExp)) {
      return Uri.file(uriOrPath, windows: true);
    } else if (uriOrPath.startsWith('/')) {
      return Uri.file(uriOrPath, windows: false);
    }

    // As far as I've seen, Firefox and V8 both always report absolute paths in
    // their stack frames. However, if we do get a relative path, we should
    // handle it gracefully.
    if (uriOrPath.contains('\\')) return path.windows.toUri(uriOrPath);
    return Uri.parse(uriOrPath);
  }

  /// Runs [body] and returns its result.
  ///
  /// If [body] throws a [FormatException], returns an [UnparsedFrame] with
  /// [text] instead.
  static Frame _catchFormatException(String text, Frame Function() body) {
    try {
      return body();
    } on FormatException catch (_) {
      return UnparsedFrame(text);
    }
  }

  Frame(this.uri, this.line, this.column, this.member);

  @override
  String toString() => '$location in $member';
}