import React from 'react';
import { Subscription } from '@unimodules/core';
import * as AppleAuthentication from 'expo-apple-authentication';
import { Alert, AsyncStorage, ScrollView, StyleSheet, View, Text, Button, Slider } from 'react-native';

import MonoText from '../components/MonoText';

const {
  AppleAuthenticationButtonStyle,
  AppleAuthenticationButtonType,
  AppleAuthenticationCredentialState,
  AppleAuthenticationScope,
} = AppleAuthentication;

type State = {
  isAvailable: boolean;
  buttonStyle: AppleAuthentication.AppleAuthenticationButtonStyle;
  buttonType: AppleAuthentication.AppleAuthenticationButtonType;
  cornerRadius: number;
  credentials?: AppleAuthentication.AppleAuthenticationCredential | null;
  credentialState?: AppleAuthentication.AppleAuthenticationCredentialState;
}

const USER_CREDENTIAL_KEY = 'ExpoNativeComponentList/AppleAuthentication';

const CREDENTIAL_MESSAGES = {
  [AppleAuthenticationCredentialState.REVOKED]: 'Your authorization has been revoked.',
  [AppleAuthenticationCredentialState.AUTHORIZED]: 'You\'re authorized.',
  [AppleAuthenticationCredentialState.NOT_FOUND]: 'You\'re not registered yet.',
  [AppleAuthenticationCredentialState.TRANSFERRED]: 'Credentials transferred.', // Whatever that means...
};

export default class AppleAuthenticationScreen extends React.Component<{}, State> {
  static navigationOptions = {
    title: 'Apple Authentication',
  };

  readonly state: State = {
    isAvailable: false,
    buttonStyle: AppleAuthenticationButtonStyle.WHITE,
    buttonType: AppleAuthenticationButtonType.SIGN_IN,
    cornerRadius: 5,
    credentials: null,
  };

  _subscription?: Subscription;

  componentDidMount() {
    this.checkAvailability();
    this.checkCredentials();
    this._subscription = AppleAuthentication.addRevokeListener(this.revokeListener);
  }

  componentWillUnmount() {
    if (this._subscription) {
      this._subscription.remove();
    }
  }

  revokeListener = () => {
    this.setState({ credentials: null });
    Alert.alert('Credentials revoked!');
  };

  checkAvailability = async () => {
    const isAvailable = await AppleAuthentication.isAvailableAsync();
    this.setState({ isAvailable });
  };

  signIn = async () => {
    try {
      const credentials = await AppleAuthentication.signInAsync({
        requestedScopes: [
          AppleAuthenticationScope.FULL_NAME,
          AppleAuthenticationScope.EMAIL,
        ],
        state: 'this-is-a-test',
      });
      this.setState({ credentials });
      if (credentials.user) {
        await AsyncStorage.setItem(USER_CREDENTIAL_KEY, credentials.user);
      }
      await this.checkCredentials();
    } catch (error) {
      alert(error);
    }
  }

  refresh = async () => {
    try {
      const credentials = await AppleAuthentication.refreshAsync({
        requestedScopes: [
          AppleAuthenticationScope.FULL_NAME,
          AppleAuthenticationScope.EMAIL,
        ],
        user: await this.getUserIdentifier(),
        state: 'this-is-a-test',
      });
      this.setState({ credentials });
      await this.checkCredentials();
    } catch (error) {
      alert(error);
    }
  }

  signOut = async () => {
    try {
      const credentials = await AppleAuthentication.signOutAsync({
        user: await this.getUserIdentifier(),
        state: 'this-is-a-test',
      });
      this.setState({ credentials: null, credentialState: null });
    } catch (error) {
      alert(error);
    }
  }

  async checkCredentials() {
    try {
      const user = await this.getUserIdentifier();
      const credentialState = await AppleAuthentication.getCredentialStateAsync(user);
      this.setState({ credentialState });
    } catch (e) {
      // Obtaining a user or the credentials failed - fallback to not found.
      this.setState({ credentialState: AppleAuthenticationCredentialState.NOT_FOUND });
    }
  };

  async getUserIdentifier(): Promise<string> {
    return this.state.credentials && this.state.credentials.user || await AsyncStorage.getItem(USER_CREDENTIAL_KEY);
  }

  isAuthorized(): boolean {
    return this.state.credentialState === AppleAuthenticationCredentialState.AUTHORIZED;
  }

  render() {
    if (this.state.isAvailable === undefined) {
      return (
        <View style={styles.container}>
          <Text>Checking availability ...</Text>
        </View>
      );
    }

    if (!this.state.isAvailable) {
      return (
        <View style={styles.container}>
          <Text>SignIn with Apple is not available</Text>
        </View>
      )
    }

    return (
      <ScrollView style={styles.container} contentContainerStyle={styles.scrollViewContainer}>
        <View style={styles.credentialStateContainer}>
          <Text style={styles.credentialStateText}>
            {CREDENTIAL_MESSAGES[this.state.credentialState]}
          </Text>
        </View>
        <View style={styles.buttonContainer}>
          <AppleAuthentication.AppleAuthenticationButton
            buttonStyle={this.state.buttonStyle}
            buttonType={this.state.buttonType}
            cornerRadius={this.state.cornerRadius}
            onPress={this.signIn}
            style={{ width: 250, height: 44, margin: 15 }}
          />
        </View>
        <View style={styles.controlsContainer}>
          <Text style={styles.controlsText}>
            Button Style:
          </Text>
          <View style={styles.controlsButtonsContainer}>
            <Button
              title={`${AppleAuthenticationButtonStyle[AppleAuthenticationButtonStyle.WHITE]}`}
              onPress={() => this.setState({ buttonStyle: AppleAuthenticationButtonStyle.WHITE })}
            />
            <Button
              title={`${AppleAuthenticationButtonStyle[AppleAuthenticationButtonStyle.WHITE_OUTLINE]}`}
              onPress={() => this.setState({ buttonStyle: AppleAuthenticationButtonStyle.WHITE_OUTLINE })}
            />
            <Button
              title={`${AppleAuthenticationButtonStyle[AppleAuthenticationButtonStyle.BLACK]}`}
              onPress={() => this.setState({ buttonStyle: AppleAuthenticationButtonStyle.BLACK })}
            />
          </View>
        </View>
        <View style={styles.controlsContainer}>
          <Text style={styles.controlsText}>
            Button Type:
          </Text>
          <View style={styles.controlsButtonsContainer}>
            <Button
              title={`${AppleAuthenticationButtonType[AppleAuthenticationButtonType.SIGN_IN]}`}
              onPress={() => this.setState({ buttonType: AppleAuthenticationButtonType.SIGN_IN })}
            />
            <Button
              title={`${AppleAuthenticationButtonType[AppleAuthenticationButtonType.CONTINUE]}`}
              onPress={() => this.setState({ buttonType: AppleAuthenticationButtonType.CONTINUE })}
            />
          </View>
        </View>
        <View style={styles.controlsContainer}>
          <Text style={styles.controlsText}>
            Button Corner Radius: {this.state.cornerRadius.toFixed(2)}
          </Text>
          <Slider minimumValue={0} maximumValue={20} value={this.state.cornerRadius} onValueChange={cornerRadius => this.setState({ cornerRadius })} />
        </View>
        { this.state.credentials &&
          <View>
            <Text>Credentials data:</Text>
            <MonoText>
              {JSON.stringify(this.state.credentials, null, 2)}
            </MonoText>
          </View>
        }
        { this.isAuthorized() &&
          <View style={styles.credentialsContainer}>
            <Button title="Sign out" onPress={this.signOut} />
            <Button title="Refresh" onPress={this.refresh} />
          </View>
        }
      </ScrollView>
    );
  }
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    padding: 10,
  },
  scrollViewContainer: {
    justifyContent: 'flex-start',
    alignItems: 'center',
    paddingBottom: 15,
  },
  credentialStateContainer: {
    padding: 10,
  },
  credentialStateText: {
    fontSize: 16,
    fontWeight: 'bold',
  },
  buttonContainer: {
    justifyContent: 'center',
    alignItems: 'center',
    marginBottom: 20,
  },
  controlsContainer: {
    marginBottom: 10,
    justifyContent: 'center',
    alignItems: 'stretch',
  },
  controlsButtonsContainer: {
    flexDirection: 'row',
    justifyContent: 'center',
  },
  controlsText: {
    fontSize: 16,
    textAlign: 'center',
  },
  credentialsContainer: {
    justifyContent: 'center',
    alignItems: 'center',
  },
});