// 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.

import 'dart:async';

import 'package:path/path.dart' as path;

import '../entrypoint.dart';
import '../utils.dart';
import '../validator.dart';

/// A validator that validates the name of the package and its libraries.
class NameValidator extends Validator {
  NameValidator(Entrypoint entrypoint) : super(entrypoint);

  Future validate() {
    return new Future.sync(() {
      _checkName(entrypoint.root.name, 'Package name "${entrypoint.root.name}"',
          isPackage: true);

      var libraries = _libraries;
      for (var library in libraries) {
        var libName = path.basenameWithoutExtension(library);
        _checkName(libName, 'The name of "$library", "$libName",',
            isPackage: false);
      }

      if (libraries.length == 1) {
        var libName = path.basenameWithoutExtension(libraries[0]);
        if (libName == entrypoint.root.name) return;
        warnings.add('The name of "${libraries[0]}", "$libName", should match '
            'the name of the package, "${entrypoint.root.name}".\n'
            'This helps users know what library to import.');
      }
    });
  }

  /// Returns a list of all libraries in the current package as paths relative
  /// to the package's root directory.
  List<String> get _libraries {
    var libDir = entrypoint.root.path("lib");
    return entrypoint.root
        .listFiles(beneath: "lib")
        .map((file) => path.relative(file, from: path.dirname(libDir)))
        .where((file) =>
            !path.split(file).contains("src") &&
            path.extension(file) == '.dart')
        .toList();
  }

  void _checkName(String name, String description, {bool isPackage}) {
    // Packages names are more stringent than libraries.
    var messages = isPackage ? errors : warnings;

    if (name == "") {
      errors.add("$description may not be empty.");
    } else if (!new RegExp(r"^[a-zA-Z0-9_]*$").hasMatch(name)) {
      messages.add("$description may only contain letters, numbers, and "
          "underscores.\n"
          "Using a valid Dart identifier makes the name usable in Dart code.");
    } else if (!new RegExp(r"^[a-zA-Z_]").hasMatch(name)) {
      messages.add("$description must begin with a letter or underscore.\n"
          "Using a valid Dart identifier makes the name usable in Dart code.");
    } else if (reservedWords.contains(name.toLowerCase())) {
      messages.add("$description may not be a reserved word in Dart.\n"
          "Using a valid Dart identifier makes the name usable in Dart code.");
    } else if (new RegExp(r"[A-Z]").hasMatch(name)) {
      warnings.add('$description should be lower-case. Maybe use '
          '"${_unCamelCase(name)}"?');
    }
  }

  String _unCamelCase(String source) {
    var builder = new StringBuffer();
    var lastMatchEnd = 0;
    for (var match in new RegExp(r"[a-z]([A-Z])").allMatches(source)) {
      builder
        ..write(source.substring(lastMatchEnd, match.start + 1))
        ..write("_")
        ..write(match.group(1).toLowerCase());
      lastMatchEnd = match.end;
    }
    builder.write(source.substring(lastMatchEnd));
    return builder.toString().toLowerCase();
  }
}