//
//  AuthService.swift
//  SwApp
//
//  Created by Juan Alvarez on 11/24/21.
//

// Use to Authenticate users in Firebase
//Use to handle User accounts in Firebase

import Foundation
import FirebaseAuth
import FirebaseFirestore // Database

let DB_BASE = Firestore.firestore() // NOTE: Global variable, check if we want to actually use it across files.

class AuthService {
    
    //MARK: PROPERTIES
    
    static let instance = AuthService()
    
    private var REF_USERS = DB_BASE.collection("users") // NOTE:  Title of the folders, its private to be accessible only in this Auth Service file
    
    
    //MARK: AUTH USER FUNCTIONS
    
    func logInUserToFirebase(credential: AuthCredential, handler: @escaping (_ providerID: String?, _ isError: Bool) -> ())  {
        
        Auth.auth().signIn(with: credential) { (result, error) in
            
            // Check for errors
            if error != nil {
                print("Error logging into Firebase")
                handler(nil, true)
                return
            }
            
            // Check for provider ID
            guard let providerID = result?.user.uid else {
                print("Error getting provider ID")
                handler(nil, true)
                return
            }
            
            // Success connection to Firebase
            handler(providerID, false) // Handler used to be called whenever we want, unlike the return function that gets called immediately. Used because we are going to have wait time during the auth process and don't need to return results immediately.
            
        }
        
    }
    
    func logInUserToApp(userID: String, handler: @escaping (_ success: Bool) -> ()) {
        
        // Get the users info
        getUserInfo(forUserID: userID) { returnedName, returnedBio in
            if let name = returnedName, let bio = returnedBio {
                // Success
                print("Success getting user info while loggin in")
                handler(true)
                
                DispatchQueue.main.asyncAfter(deadline: .now() + 1.0) { // Set userDefaults one second after loggin them in
                    // Set the users info into our app
                    UserDefaults.standard.set(userID, forKey: CurrentUserDefaults.userID)
                    UserDefaults.standard.set(bio, forKey: CurrentUserDefaults.bio)
                    UserDefaults.standard.set(name, forKey: CurrentUserDefaults.displayName)
                }
            } else {
                // Error
                print("Error getting user info while loggin in")
                handler(false)
            }
        }
    }
    
    func createNewUserInDatabase(name: String, email: String, providerID: String, provider: String, profileImage: UIImage, handler: @escaping (_ userID: String?) -> ()) {
        
        // Set up a user Document with the user Collection, for Firestore Database
        let document = REF_USERS.document()
        let userID = document.documentID
        
        //Upload profile image to Storage
        ImageManager.instance.uploadProfileImage(userID: userID, image: profileImage)
        
        
        // Upload profile data to Firestore
        let userData: [String: Any] = [
            DatabaseUserField.displayName : name,
            DatabaseUserField.email : email,
            DatabaseUserField.providerID : providerID,
            DatabaseUserField.provider : provider,
            DatabaseUserField.userID : userID,
            DatabaseUserField.bio : "",
            DatabaseUserField.dateCreated : FieldValue.serverTimestamp(),
            
        ]
        
        // Put data in the document
        document.setData(userData) { (error) in
            
            if let error = error {
                // Error
                print("Error uploading data to user document. \(error)")
                handler(nil)
            } else {
                // Success
                handler(userID)
            }
            
        }
        
    }
    
    // MARK: GET USER FUNCTIONS
    
    // forUserID is the global name, and userID is the local name.
    func getUserInfo(forUserID userID: String, handler: @escaping (_ name: String?, _ bio: String?) -> ()) {
        
        REF_USERS.document(userID).getDocument { (documentSnapshot, error) in
            if let document = documentSnapshot,
                let name = document.get(DatabaseUserField.displayName) as? String,
                let bio = document.get(DatabaseUserField.bio) as? String {
                    print("Success getting user info")
                    handler(name, bio)
                    return
                } else {
                    print("Error getting user info")
                    handler(nil,nil)
                    return
            }
        }
    }
    
}