//
//  ChangeVerificatorHash.swift
//  Befund
//
//  Created by Artur Savitskiy on 02.08.22.
//  Copyright © 2022 MVZ Dr. Stein und Kollegen. All rights reserved.
//
import Foundation

extension Core.Models.Request
{
    public class ChangeVerificatorHash : Encodable, Decodable
    {
        public var udid: String? = nil
        public var old_verificator_hash: String? = nil
        public var new_verificator_hash: String? = nil
        public var pin: String? = nil
    }
    
    public class ChangeVerificatorHashProvider
    {
        private static let password_policy = "^(?=.*?[A-Z])(?=.*?[a-z])(?=.*?[0-9])(?=.*?[#?!+@$%^&<>*~:`-]).{8,}$"
        
        public static func IsPasswordStrong(password: String) -> Bool
        {
            return NSPredicate(format: "SELF MATCHES %@", password_policy).evaluate(with: password)
        }
        
        public static func GetDecryptedOldPasswordByPassword(settings: Core.Models.Settings, oldPassword: String) -> String?
        {
            let oldPassAESKey=Core.Security.AES.GetKey(password: oldPassword)
            let oldPwdDecryptedKey = Core.Security.AES.Decrypt(value: (settings.hashed_private_key ?? ""), password: String( decoding: oldPassAESKey, as: UTF8.self))
            return oldPwdDecryptedKey
        }
        
        public static func GetDecryptedOldPasswordByPin(settings: Core.Models.Settings, pin: String) -> String?
        {
            let oldPassAESKey=Core.Security.AES.GetKey(password: (settings.password_reset_hash ?? "") + pin)
            let oldPwdDecryptedKey = Core.Security.AES.Decrypt(value: (settings.password_hash ?? ""), password: String(decoding: oldPassAESKey, as: UTF8.self))
            return oldPwdDecryptedKey
        }
        
        public static func PrepareChangeVerificatorHash(settings: Core.Models.Settings, oldPassword: String, newPassword: String, newPin: String) -> Core.Models.Request.ChangeVerificatorHash
        {
            
            let oldPassAESKey=Core.Security.AES.GetKey(password: oldPassword)
            let newPassAESkey = Core.Security.AES.GetKey(password: newPassword)
                    
            let changeVerificatorHash = Core.Models.Request.ChangeVerificatorHash()
                    
            changeVerificatorHash.old_verificator_hash = settings.verificator_hash
                    
            changeVerificatorHash.new_verificator_hash = Core.Security.SHA512.HMAC(message: Core.Security.SHA512.VerificatorHashingValue.data(using: .utf8)!, key: String(decoding: newPassAESkey, as: UTF8.self))
                        
            changeVerificatorHash.udid = settings.udid
                    
            changeVerificatorHash.pin = newPin // String(Int.random(in: 10000..<99999))
                    
            let results = Core.Database.Results.GetResults()
                    
            if(results != nil && results!.count>0)
            {
                for res in results!
                {

                    let file = Core.System.GetPathForStorageEncryptedFile(filename: res.pgs!)
                        
                    if(file != nil && Core.System.FileExists(atPath: file!))
                    {
                        let encrypted_content = Core.System.ReadFromEncryptedStorage(filename: res.pgs!)
                                
                        if(!encrypted_content!.isEmpty)
                        {
                            let decrypted_content = Core.Security.AES.Decrypt(
                                value: String (decoding: encrypted_content!, as: UTF8.self),
                                password: String(decoding: oldPassAESKey, as: UTF8.self))

                            if(decrypted_content != nil)
                            {
                                let local_encrypted = Core.Security.AES.Encrypt(
                                    value: decrypted_content!,
                                    password: String(decoding: newPassAESkey, as: UTF8.self))
                                    
                                if(local_encrypted != nil)
                                {
                                    Core.System.WriteToEncryptedStorage(filename: res.pgs!, data: local_encrypted!.data(using: .utf8)!)
                                }
                            }
                        }
                    }
                }
            }
            
            return changeVerificatorHash
        }
        
        public static func SaveChangedVerificatorBySuccess(settings: Core.Models.Settings, oldPassword: String, newPassword: String, pin: String, errorMsg: inout String?) -> Core.Models.Settings?
        {
            let oldPassAESKey=Core.Security.AES.GetKey(password: oldPassword)
            let newPassAESkey = Core.Security.AES.GetKey(password: newPassword)
            let decrypted_private_key = Core.Security.AES.Decrypt(value: (settings.hashed_private_key ?? ""), password: String( decoding: oldPassAESKey, as: UTF8.self))

            settings.password_reset_hash = NSUUID().uuidString

            let pwdPlus = (settings.password_reset_hash ?? "") + pin
            
            let passwordHashKey = Core.Security.AES.GetKey(password: pwdPlus)
            
            settings.password_hash = Core.Security.AES.Encrypt(value: newPassword, password: String(decoding: passwordHashKey, as: UTF8.self))
            
            settings.verificator_hash = Core.Security.SHA512.HMAC(
                message: Core.Security.SHA512.VerificatorHashingValue.data(using: .utf8)!,
                key: String(decoding: newPassAESkey, as: UTF8.self))
            
            settings.hashed_private_key = Core.Security.AES.Encrypt(value: decrypted_private_key!, password: String(decoding: newPassAESkey, as: UTF8.self))
            
            if(!settings.save(atPath: Core.System.SettingsPath()))
            {
                errorMsg = Core.Lang.Get(key: "ERROR_COULD_NOT_SAVE")
                return settings
            }
            else
            {
                errorMsg = nil
                return Core.Models.Settings.loadFromFile(atPath: Core.System.SettingsPath())
            }
        }
    }
}