/// Copyright (c) 2021 Razeware LLC
///
/// Permission is hereby granted, free of charge, to any person obtaining a copy
/// of this software and associated documentation files (the "Software"), to deal
/// in the Software without restriction, including without limitation the rights
/// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
/// copies of the Software, and to permit persons to whom the Software is
/// furnished to do so, subject to the following conditions:
///
/// The above copyright notice and this permission notice shall be included in
/// all copies or substantial portions of the Software.
///
/// Notwithstanding the foregoing, you may not use, copy, modify, merge, publish,
/// distribute, sublicense, create a derivative work, and/or sell copies of the
/// Software in any work that is designed, intended, or marketed for pedagogical or
/// instructional purposes related to programming, coding, application development,
/// or information technology.  Permission for such use, copying, modification,
/// merger, publication, distribution, sublicensing, creation of derivative works,
/// or sale is expressly withheld.
///
/// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
/// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
/// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
/// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
/// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
/// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
/// THE SOFTWARE.

import Foundation
import UIKit

enum AuthResult {
  case success
  case failure
}

class Auth {
  static let keychainKey = "TIL-API-KEY"

  var token: String? {
    get {
      Keychain.load(key: Auth.keychainKey)
    }
    set {
      if let newToken = newValue {
        Keychain.save(key: Auth.keychainKey, data: newToken)
      } else {
        Keychain.delete(key: Auth.keychainKey)
      }
    }
  }

  func logout() {
    token = nil
    DispatchQueue.main.async {
      guard let applicationDelegate =
        UIApplication.shared.delegate as? AppDelegate else {
          return
      }
      let rootController =
        UIStoryboard(name: "Login", bundle: Bundle.main).instantiateViewController(withIdentifier: "LoginNavigation")
      applicationDelegate.window?.rootViewController = rootController
    }
  }

  func login(username: String, password: String, completion: @escaping (AuthResult) -> Void) {
    let path = "\(apiHostname)/api/users/login"
    guard let url = URL(string: path) else {
      fatalError("Failed to convert URL")
    }
    guard
      let loginString = "\(username):\(password)"
        .data(using: .utf8)?
        .base64EncodedString()
    else {
      fatalError("Failed to encode credentials")
    }

    var loginRequest = URLRequest(url: url)
    loginRequest.addValue("Basic \(loginString)", forHTTPHeaderField: "Authorization")
    loginRequest.httpMethod = "POST"

    let dataTask = URLSession.shared.dataTask(with: loginRequest) { data, response, _ in
      guard
        let httpResponse = response as? HTTPURLResponse,
        httpResponse.statusCode == 200,
        let jsonData = data
      else {
        completion(.failure)
        return
      }

      do {
        let token = try JSONDecoder().decode(Token.self, from: jsonData)
        self.token = token.value
        completion(.success)
      } catch {
        completion(.failure)
      }
    }
    dataTask.resume()
  }

  func login(signInWithAppleInformation: SignInWithAppleToken, completion: @escaping (AuthResult) -> Void) throws {
    let path = "\(apiHostname)/api/users/siwa"
    guard let url = URL(string: path) else {
      fatalError("Failed to convert URL")
    }
    var loginRequest = URLRequest(url: url)
    loginRequest.httpMethod = "POST"
    loginRequest.addValue("application/json", forHTTPHeaderField: "Content-Type")
    loginRequest.httpBody = try JSONEncoder().encode(signInWithAppleInformation)

    let dataTask = URLSession.shared.dataTask(with: loginRequest) { data, response, _ in
      guard
        let httpResponse = response as? HTTPURLResponse,
        httpResponse.statusCode == 200,
        let jsonData = data
      else {
        completion(.failure)
        return
      }

      do {
        let token = try JSONDecoder().decode(Token.self, from: jsonData)
        self.token = token.value
        completion(.success)
      } catch {
        completion(.failure)
      }
    }
    dataTask.resume()
  }
}

struct SignInWithAppleToken: Codable {
  let token: String
  let name: String?
}
