// Copyright 2013 The Flutter Authors. 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:typed_data';

import 'package:flutter/material.dart';

import 'src/common.dart';
import 'src/fife.dart' as fife;

/// Builds a CircleAvatar profile image of the appropriate resolution
class GoogleUserCircleAvatar extends StatelessWidget {
  /// Creates a new widget based on the specified [identity].
  ///
  /// If [identity] does not contain a `photoUrl` and [placeholderPhotoUrl] is
  /// specified, then the given URL will be used as the user's photo URL. The
  /// URL must be able to handle a [sizeDirective] path segment.
  ///
  /// If [identity] does not contain a `photoUrl` and [placeholderPhotoUrl] is
  /// *not* specified, then the widget will render the user's first initial
  /// in place of a profile photo, or a default profile photo if the user's
  /// identity does not specify a `displayName`.
  const GoogleUserCircleAvatar({
    Key? key,
    required this.identity,
    this.placeholderPhotoUrl,
    this.foregroundColor,
    this.backgroundColor,
  })  : assert(identity != null),
        super(key: key);

  /// A regular expression that matches against the "size directive" path
  /// segment of Google profile image URLs.
  ///
  /// The format is is "`/sNN-c/`", where `NN` is the max width/height of the
  /// image, and "`c`" indicates we want the image cropped.
  static final RegExp sizeDirective = fife.sizeDirective;

  /// The Google user's identity; guaranteed to be non-null.
  final GoogleIdentity identity;

  /// The color of the text to be displayed if photo is not available.
  ///
  /// If a foreground color is not specified, the theme's text color is used.
  final Color? foregroundColor;

  /// The color with which to fill the circle. Changing the background color
  /// will cause the avatar to animate to the new color.
  ///
  /// If a background color is not specified, the theme's primary color is used.
  final Color? backgroundColor;

  /// The URL of a photo to use if the user's [identity] does not specify a
  /// `photoUrl`.
  ///
  /// If this is `null` and the user's [identity] does not contain a photo URL,
  /// then this widget will attempt to display the user's first initial as
  /// determined from the identity's [displayName] field. If that is `null` a
  /// default (generic) Google profile photo will be displayed.
  final String? placeholderPhotoUrl;

  @override
  Widget build(BuildContext context) {
    return CircleAvatar(
      backgroundColor: backgroundColor,
      foregroundColor: foregroundColor,
      child: LayoutBuilder(builder: _buildClippedImage),
    );
  }

  Widget _buildClippedImage(BuildContext context, BoxConstraints constraints) {
    assert(constraints.maxWidth == constraints.maxHeight);

    // Placeholder to use when there is no photo URL, and while the photo is
    // loading. Uses the first character of the display name (if it has one),
    // or the first letter of the email address if it does not.
    final List<String?> placeholderCharSources = <String?>[
      identity.displayName,
      identity.email,
      '-',
    ];
    final String placeholderChar = placeholderCharSources
        .firstWhere((String? str) => str != null && str.trimLeft().isNotEmpty)!
        .trimLeft()[0]
        .toUpperCase();
    final Widget placeholder = Center(
      child: Text(placeholderChar, textAlign: TextAlign.center),
    );

    final String? photoUrl = identity.photoUrl ?? placeholderPhotoUrl;
    if (photoUrl == null) {
      return placeholder;
    }

    // Add a sizing directive to the profile photo URL.
    final double size =
        MediaQuery.of(context).devicePixelRatio * constraints.maxWidth;
    final String sizedPhotoUrl = fife.addSizeDirectiveToUrl(photoUrl, size);

    // Fade the photo in over the top of the placeholder.
    return SizedBox(
        width: size,
        height: size,
        child: ClipOval(
          child: Stack(fit: StackFit.expand, children: <Widget>[
            placeholder,
            FadeInImage.memoryNetwork(
              // This creates a transparent placeholder image, so that
              // [placeholder] shows through.
              placeholder: _transparentImage,
              image: sizedPhotoUrl,
            )
          ]),
        ));
  }
}

/// This is an transparent 1x1 gif image.
///
/// Those bytes come from `resources/transparentImage.gif`.
final Uint8List _transparentImage = Uint8List.fromList(
  <int>[
    0x47, 0x49, 0x46, 0x38, 0x39, 0x61, 0x01, 0x00, 0x01, 0x00, 0x80, 0x00, //
    0x00, 0x00, 0x00, 0x00, 0xFF, 0xFF, 0xFF, 0x21, 0xf9, 0x04, 0x01, 0x00, //
    0x00, 0x00, 0x00, 0x2C, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x01, 0x00, //
    0x00, 0x02, 0x01, 0x44, 0x00, 0x3B
  ],
);