// Copyright (c) 2015 Alex Sanderson (bitcalc)
//
// 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.
//
// 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

let ApplicationName = "YourApp"

/** Will fetch the password associated with username. */
func fetchPasswordForUsername(username: String) -> String? {
    var item: AnyObject? = nil
    let attributes = [
        String(kSecClass)      : kSecClassGenericPassword,
        String(kSecAttrAccount): username,
        String(kSecAttrService): ApplicationName,
        String(kSecMatchLimit) : kSecMatchLimitOne,
        String(kSecReturnData) : true
    ]

    if SecItemCopyMatching(attributes, &item) == errSecSuccess && item != nil {
        if let encodedPassword = item as? NSData {
            return String(data: encodedPassword, encoding: NSUTF8StringEncoding) // decode the string and return!
        }
    }

    return nil // nothing found...
}

/** Will store password against username, updating if it already exists. */
func storePassword(password: String, forUsername username: String) {
    if fetchPasswordForUsername(username) != nil {
        let newAttributes = [
            String(kSecValueData): password.dataUsingEncoding(NSUTF8StringEncoding)!
        ]
        let searchVector = [
            String(kSecClass)      : kSecClassGenericPassword,
            String(kSecAttrAccount): username,
            String(kSecAttrService): ApplicationName
        ]

        let result = SecItemUpdate(searchVector, newAttributes)

        if result != errSecSuccess {
            fatalError("[\(__FILE__):\(__LINE__)] Keychain Services Responded: \(result)")
        }
    } else {
        let attributes = [
            String(kSecClass)      : kSecClassGenericPassword,
            String(kSecAttrAccount): username,
            String(kSecAttrService): ApplicationName,
            String(kSecValueData)  : password.dataUsingEncoding(NSUTF8StringEncoding)!
        ]

        // New Storage Request...
        let result = SecItemAdd(attributes, nil)

        if result != errSecSuccess {
            fatalError("[\(__FILE__):\(__LINE__)] Keychain Services Responded: \(result)")
        }
    }
}

func deletePasswordForUsername(username: String) {
    let attributes = [
        String(kSecClass)      : kSecClassGenericPassword,
        String(kSecAttrAccount): username,
        String(kSecAttrService): ApplicationName
    ]

    // Delete the Keychain...
    let result = SecItemDelete(attributes)

    if result != errSecSuccess {
        fatalError("[\(__FILE__):\(__LINE__)] Keychain Services Responded: \(result)")
    }
}

print(fetchPasswordForUsername("alex"))
storePassword("password", forUsername: "alex")
print(fetchPasswordForUsername("alex"))
storePassword("NEW_password", forUsername: "alex")
print(fetchPasswordForUsername("alex"))
deletePasswordForUsername("alex")
print(fetchPasswordForUsername("alex"))