//
//  KeyChain.swift
//  PaiAi
//
//  Created by FFIB on 16/5/3.
//  Copyright © 2016年 FFIB. All rights reserved.
//

import Foundation

protocol DataConvertable {
    init?(data: Data)
    func toData() -> Data?
}

extension String: DataConvertable {
    init?(data: Data) {
        self.init(data: data, encoding: String.Encoding.utf8)
    }

    func toData() -> Data? {
        return self.data(using: String.Encoding.utf8)
    }
}

func GetInfoFromKeyChain<T: DataConvertable>(_ intoType: T.Type, key: String) -> T? {
    let keyChainDic = NSMutableDictionary()
    keyChainDic.setObject(String(kSecClassGenericPassword), forKey: kSecClass as! NSCopying)
    keyChainDic.setObject(key, forKey: kSecAttrAccount as! NSCopying)
    keyChainDic.setObject(kCFBooleanTrue, forKey: kSecReturnAttributes  as! NSCopying)
    keyChainDic.setObject(kCFBooleanTrue, forKey: kSecReturnData as! NSCopying)

    var result: AnyObject?
    var resultObj: T? = nil
    SecItemCopyMatching(keyChainDic, &result)
    if let resultDic = result as? NSDictionary {
        if let data = resultDic.object(forKey: kSecValueData) as? Data {
            resultObj = T(data: data)
        }
    }
    return resultObj
}

enum KeyChainErrorCode: Int, Error {
    case alreadyExist = 10
    case dataConvertFail
    case keyChainWriteFail
}
func SaveInfoToKeyChain<T: DataConvertable>(_ info: T, key: String, override: Bool = true) throws {
    let existObj = GetInfoFromKeyChain(type(of: info), key: key)
    guard existObj == nil || override else {
        throw KeyChainErrorCode.alreadyExist
    }
    let keyChainDic = NSMutableDictionary()
    keyChainDic.setObject(String(kSecClassGenericPassword), forKey: kSecClass as! NSCopying)
    keyChainDic.setObject(key, forKey: kSecAttrAccount as! NSCopying)
    guard let data = info.toData() else {
        throw KeyChainErrorCode.dataConvertFail
    }
    let updateDic: NSDictionary = [String(kSecValueData): data]
    var success: OSStatus = 0
    if existObj == nil {
        keyChainDic.addEntries(from: updateDic as! [AnyHashable: Any])
        success = SecItemAdd(keyChainDic, nil)
    } else {
        success = SecItemUpdate(keyChainDic, updateDic)
    }
    guard success == errSecSuccess else {
        throw KeyChainErrorCode.keyChainWriteFail
    }
}