// This file handles the authentication state.

import { Session as KratosSession } from '@oryd/kratos-client'
import * as SecureStore from 'expo-secure-store'
import AsyncStore from '@react-native-community/async-storage'
import { Platform } from 'react-native'

// The key under which the session is being stored
const userSessionName = 'user_session'

// The session type
export type SessionContext = {
  // The session token
  session_token: string

  // The session itself
  session: KratosSession
} | null

// getAuthenticatedSession returns a promise with the session of the authenticated user, if the
// user is authenticated or null is the user is not authenticated.
//
// If an error (e.g. network error) occurs, the promise rejects with an error.
export const getAuthenticatedSession = (): Promise<SessionContext> => {
  const parse = (sessionRaw: string | null): SessionContext => {
    if (!sessionRaw) {
      return null
    }

    // sessionRaw is a JSON String that needs to be parsed.
    return JSON.parse(sessionRaw)
  }

  let p = AsyncStore.getItem(userSessionName)
  if (Platform.OS !== 'web') {
    // We can use SecureStore if not on web instead!
    p = SecureStore.getItemAsync(userSessionName)
  }

  return p.then(parse)
}

// Sets the session.
export const setAuthenticatedSession = (
  session: SessionContext
): Promise<void> => {
  if (!session) {
    return killAuthenticatedSession()
  }

  if (Platform.OS === 'web') {
    // SecureStore is not available on the web platform. We need to use AsyncStore
    // instead.
    return AsyncStore.setItem(userSessionName, JSON.stringify(session))
  }

  return (
    SecureStore
      // The SecureStore only supports strings so we encode the session.
      .setItemAsync(userSessionName, JSON.stringify(session))
  )
}

// Removes the session from the store.
export const killAuthenticatedSession = () => {
  if (Platform.OS === 'web') {
    // SecureStore is not available on the web platform. We need to use AsyncStore
    // instead.
    return AsyncStore.removeItem(userSessionName)
  }

  return SecureStore.deleteItemAsync(userSessionName)
}