import 'package:flutter/material.dart';
import 'package:flutter/services.dart';

import 'common.dart';
import 'network.dart';
import 'consts.dart';

abstract class BaseState<T> extends State<T> {

  bool loading = false;
  String error = null;
  String textFieldValue = '';

  TextEditingController controller = new TextEditingController();

  @override Widget build(BuildContext context) {
    return new Scaffold(appBar: getAppBar(context), body: getBody(context));
  }

  AppBar getAppBar(BuildContext context) {
    return new AppBar(title: new Text(getTitle(), style: new TextStyle(fontSize: 18.0)),
        backgroundColor: primaryColor,  actions: getMenuButtons(context));
  }

  @overide getMenuButtons(BuildContext context) {
    return <Widget>[getFaqButton()];
  }

  getFaqButton() {
    return new IconButton(icon: new Icon(Icons.help_outline), onPressed: () => faq(context, false));
  }

  getLogoutButton() {
    return new IconButton(icon: new Image.asset(logout_png, height: iconHeight, width: iconHeight), onPressed: () => logout(context));
  }

  Widget getBody(BuildContext context) {
    return new Stack(children: <Widget>[getScreenContent(), getProgressIndicator()]);
  }

  Widget getScreenContent(BuildContext context);

  String getTitle();

  String getHint();

  /// Метод возвращает контейнер с отступами, который содержит картинку с логотипом.
  getLogo() {
    double containerHeight = 92.0;
    double imageWidth = 156.0;
    return new Container(height: containerHeight, child: new Image.asset(logo_png, width: imageWidth));
  }

  getHintLabel() {
    double horizontalMargin = 8.0;
    return new Container(margin: new EdgeInsets.only(top: horizontalMargin, bottom: horizontalMargin, left: verticalMargin, right: verticalMargin),
      child: new Row(crossAxisAlignment: CrossAxisAlignment.start, 
        children: <Widget>[new Text(getHintText(), textAlign: TextAlign.left,
         style: new TextStyle(fontWeight: FontWeight.w300, color: error == null ? greyTextColor : primaryColor, fontSize: 14.0))]));
  }

  getHintText() {
    if (textFieldValue.length == 0 && error == null) {
      return ' ';
    } else if (error != null) {
      return error; 
    } else {
      return getHint();
    }
  }

  /// Смена состояния экрана при изменении текста в поле ввода.
  handleUserInput(String text) {
    setState(() {
      textFieldValue = text;
    });
  }

  /// Метод возвращает контейнер с установленными отступами, в котором размещен TextField обернутый в BoxDecoration.
  getDecoratedTextWidget() {
    return new Container(margin: new EdgeInsets.only(left: verticalMargin, right: verticalMargin),
      padding: getPaddingForTextWidget(),
      decoration: getDecoraionForTextWidget(),
      child: getTextWidget());
  }

  getPaddingForTextWidget() {
  	const double verticalPadding = 12.0;
    const double horizontalPadding = 16.0;
  	return new EdgeInsets.only(top: verticalPadding, 
  		bottom: verticalPadding, 
  		left: horizontalPadding, 
  		right: horizontalPadding);
  }

  /// Метод возвращает BoxDecoration для _getDecoratedInputField
  getDecoraionForTextWidget() {
    return new BoxDecoration(color: getTextFilledBackground(),
      border: new Border.all(color: textBorderColor, width: 1.0),
      borderRadius: new BorderRadius.all(new Radius.circular(4.0)));
  }

  Color getTextFilledBackground() {
    return const Color(0xffefefef);
  }

  Widget getTextWidget() {
  	return new TextField(keyboardType: TextInputType.number,
  	 decoration: new InputDecoration.collapsed(hintText: getHint(),
      hintStyle: new TextStyle(color: greyTextColor, fontSize: 16.0)),
      controller: controller,
      onChanged: (text) => handleUserInput(text));
  }

  Widget getProgressIndicator() {
    return new Center(child: loading ? new CircularProgressIndicator() : null);
  }

   Widget getValueWithTitle(String title, String value) {
    return new Container(padding: new EdgeInsets.only(left: verticalMargin, right: verticalMargin, top: 18.0),
     child: new Column(children: <Widget>[
      new Row(crossAxisAlignment: CrossAxisAlignment.start, children: <Widget>[new Text(title, textAlign: TextAlign.left, style: new TextStyle(color: greyTextColor, fontSize: 14.0))]),
      new Row(crossAxisAlignment: CrossAxisAlignment.start, children: <Widget>[new Expanded(child: new Text(value, textAlign: TextAlign.left, style: new TextStyle(color: Colors.black, fontSize: 20.0)))])
    ]));
  }

  Widget buildButton(EdgeInsets margin, Widget widget) {
    return new Container(margin: margin, height: buttonHeight, child: new Row(children: <Widget>[new Expanded(child: widget)]));
  }
 
  Widget buildRaisedButton(BuildContext context, String text, VoidCallback onPressed) {
    return new RaisedButton(child: new Text(text,
                style: new TextStyle(color: Colors.white)),
                onPressed: onPressed,
                color: primaryColor);
  }

  Widget buildFlatButton(BuildContext context, String title, Color textColor) {
    return new Container(height: buttonHeight, child: new FlatButton(child: new Text(title,
        style: new TextStyle(color: textColor)),
        onPressed: () => startScanner(context)),
        decoration: _getDecoraionForScanButton());
  }

  _getDecoraionForScanButton() {
    return new BoxDecoration(
      border: new Border.all(color: primaryColor, width: 1.0),
      borderRadius: new BorderRadius.all(new Radius.circular(4.0)));
  }
}