import 'dart:convert';

import 'package:flutter/cupertino.dart';
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:flutter_platform_widgets/flutter_platform_widgets.dart' as fpw;
import 'package:intl/intl.dart';
import 'package:mobile_nebula/components/FormPage.dart';
import 'package:mobile_nebula/components/PlatformTextFormField.dart';
import 'package:mobile_nebula/components/config/ConfigPageItem.dart';
import 'package:mobile_nebula/components/config/ConfigItem.dart';
import 'package:mobile_nebula/components/config/ConfigSection.dart';
import 'package:mobile_nebula/models/Site.dart';
import 'package:mobile_nebula/screens/siteConfig/AdvancedScreen.dart';
import 'package:mobile_nebula/screens/siteConfig/CAListScreen.dart';
import 'package:mobile_nebula/screens/siteConfig/AddCertificateScreen.dart';
import 'package:mobile_nebula/screens/siteConfig/CertificateDetailsScreen.dart';
import 'package:mobile_nebula/screens/siteConfig/StaticHostsScreen.dart';
import 'package:mobile_nebula/services/utils.dart';

//TODO: Add a config test mechanism
//TODO: Enforce a name

class SiteConfigScreen extends StatefulWidget {
  const SiteConfigScreen({
    Key? key,
    this.site,
    required this.onSave,
    required this.supportsQRScanning,
  }) : super(key: key);

  final Site? site;

  // This is called after the target OS has saved the configuration
  final ValueChanged<Site> onSave;

  final bool supportsQRScanning;

  @override
  _SiteConfigScreenState createState() => _SiteConfigScreenState();
}

class _SiteConfigScreenState extends State<SiteConfigScreen> {
  bool changed = false;
  bool newSite = false;
  bool debug = false;
  late Site site;
  String? pubKey;
  String? privKey;

  static const platform = MethodChannel('net.defined.mobileNebula/NebulaVpnService');
  final nameController = TextEditingController();

  @override
  void initState() {
    //NOTE: this is slightly wasteful since a keypair will be generated every time this page is opened
    _generateKeys();
    if (widget.site == null) {
      newSite = true;
      site = Site();
    } else {
      site = widget.site!;
      nameController.text = site.name;
    }

    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    if (pubKey == null || privKey == null) {
      return Center(
        child: fpw.PlatformCircularProgressIndicator(cupertino: (_, __) {
          return fpw.CupertinoProgressIndicatorData(radius: 50);
        }),
      );
    }

    return FormPage(
        title: newSite ? 'New Site' : 'Edit Site',
        changed: changed,
        onSave: () async {
          site.name = nameController.text;
          try {
            await site.save();
          } catch (error) {
            return Utils.popError(context, 'Failed to save the site configuration', error.toString());
          }

          Navigator.pop(context);
          widget.onSave(site);
        },
        child: Column(
          children: <Widget>[
            _main(),
            _keys(),
            _hosts(),
            _advanced(),
            _managed(),
            kDebugMode ? _debugConfig() : Container(height: 0),
          ],
        ));
  }

  Widget _debugConfig() {
    var data = "";
    try {
      final encoder = new JsonEncoder.withIndent('  ');
      data = encoder.convert(site);
    } catch (err) {
      data = err.toString();
    }

    return ConfigSection(label: 'DEBUG', children: [ConfigItem(labelWidth: 0, content: SelectableText(data))]);
  }

  Widget _main() {
    return ConfigSection(children: <Widget>[
      ConfigItem(
          label: Text("Name"),
          content: PlatformTextFormField(
            placeholder: 'Required',
            controller: nameController,
            validator: (name) {
              if (name == null || name == "") {
                return "A name is required";
              }
              return null;
            },
          ))
    ]);
  }

  Widget _managed() {
    final formatter = DateFormat.yMMMMd('en_US').add_jm();
    var lastUpdate = "Unknown";
    if (site.lastManagedUpdate != null) {
      lastUpdate = formatter.format(site.lastManagedUpdate!.toLocal());
    }

    return site.managed ? ConfigSection(
      label: "MANAGED CONFIG",
      children: <Widget>[
        ConfigItem(
          label: Text("Last Update"),
          content: Wrap(alignment: WrapAlignment.end, crossAxisAlignment: WrapCrossAlignment.center, children: <Widget>[
            Text(lastUpdate),
          ]),
        )
      ]
    ) : Container();
  }

  Widget _keys() {
    final certError = site.certInfo == null || site.certInfo!.validity == null || !site.certInfo!.validity!.valid;
    var caError = false;
    if (!site.managed) {
      var caError = site.ca.length == 0;
      if (!caError) {
        site.ca.forEach((ca) {
          if (ca.validity == null || !ca.validity!.valid) {
            caError = true;
          }
        });
      }
    }

    return ConfigSection(
      label: "IDENTITY",
      children: [
        ConfigPageItem(
          label: Text('Certificate'),
          content: Wrap(alignment: WrapAlignment.end, crossAxisAlignment: WrapCrossAlignment.center, children: <Widget>[
            certError
                ? Padding(
                    child: Icon(Icons.error, color: CupertinoColors.systemRed.resolveFrom(context), size: 20),
                    padding: EdgeInsets.only(right: 5))
                : Container(),
            certError ? Text('Needs attention') : Text(site.certInfo?.cert.details.name ?? 'Unknown certificate')
          ]),
          onPressed: () {
            Utils.openPage(context, (context) {
              if (site.certInfo != null) {
                return CertificateDetailsScreen(
                    certInfo: site.certInfo!,
                    pubKey: pubKey,
                    privKey: privKey,
                    onReplace: site.managed ? null : (result) {
                      setState(() {
                        changed = true;
                        site.certInfo = result.certInfo;
                        site.key = result.key;
                      });
                    },
                    supportsQRScanning: widget.supportsQRScanning,
                );
              }

              return AddCertificateScreen(
                  pubKey: pubKey!,
                  privKey: privKey!,
                  onSave: (result) {
                    setState(() {
                      changed = true;
                      site.certInfo = result.certInfo;
                      site.key = result.key;
                    });
                  },
                supportsQRScanning: widget.supportsQRScanning,
              );
            });
          },
        ),
        ConfigPageItem(
            label: Text("CA"),
            content:
                Wrap(alignment: WrapAlignment.end, crossAxisAlignment: WrapCrossAlignment.center, children: <Widget>[
              caError
                  ? Padding(
                      child: Icon(Icons.error, color: CupertinoColors.systemRed.resolveFrom(context), size: 20),
                      padding: EdgeInsets.only(right: 5))
                  : Container(),
              caError ? Text('Needs attention') : Text(Utils.itemCountFormat(site.ca.length))
            ]),
            onPressed: () {
              Utils.openPage(context, (context) {
                return CAListScreen(
                    cas: site.ca,
                    onSave: site.managed ? null : (ca) {
                      setState(() {
                        changed = true;
                        site.ca = ca;
                      });
                    },
                    supportsQRScanning: widget.supportsQRScanning,
                );
              });
            })
      ],
    );
  }

  Widget _hosts() {
    return ConfigSection(
      label: "LIGHTHOUSES / STATIC HOSTS",
      children: <Widget>[
        ConfigPageItem(
          label: Text('Hosts'),
          content: Wrap(alignment: WrapAlignment.end, crossAxisAlignment: WrapCrossAlignment.center, children: <Widget>[
            site.staticHostmap.length == 0
                ? Padding(
                    child: Icon(Icons.error, color: CupertinoColors.systemRed.resolveFrom(context), size: 20),
                    padding: EdgeInsets.only(right: 5))
                : Container(),
            site.staticHostmap.length == 0
                ? Text('Needs attention')
                : Text(Utils.itemCountFormat(site.staticHostmap.length))
          ]),
          onPressed: () {
            Utils.openPage(context, (context) {
              return StaticHostsScreen(
                  hostmap: site.staticHostmap,
                  onSave: site.managed ? null : (map) {
                    setState(() {
                      changed = true;
                      site.staticHostmap = map;
                    });
                  });
            });
          },
        ),
      ],
    );
  }

  Widget _advanced() {
    return ConfigSection(
      label: "ADVANCED",
      children: <Widget>[
        ConfigPageItem(
            label: Text('Advanced'),
            onPressed: () {
              Utils.openPage(context, (context) {
                return AdvancedScreen(
                    site: site,
                    onSave: (settings) {
                      setState(() {
                        changed = true;
                        site.cipher = settings.cipher;
                        site.lhDuration = settings.lhDuration;
                        site.port = settings.port;
                        site.logVerbosity = settings.verbosity;
                        site.unsafeRoutes = settings.unsafeRoutes;
                        site.dnsResolvers = settings.dnsResolvers;
                        site.mtu = settings.mtu;
                      });
                    });
              });
            })
      ],
    );
  }

  _generateKeys() async {
    try {
      var kp = await platform.invokeMethod("nebula.generateKeyPair");
      Map<String, dynamic> keyPair = jsonDecode(kp);

      setState(() {
        pubKey = keyPair['PublicKey'];
        privKey = keyPair['PrivateKey'];
      });
    } on PlatformException catch (err) {
      Utils.popError(context, 'Failed to generate key pair', err.details ?? err.message);
    }
  }
}