space-ios/iOSClient/Extensions/String+Extensions.swift

//
//  String+Extensions.swift
//  Nextcloud
//
//  Created by Marino Faggiana on 22/12/20.
//  Copyright © 2020 Marino Faggiana. All rights reserved.
//
//  Author Marino Faggiana <marino.faggiana@nextcloud.com>
//
//  This program is free software: you can redistribute it and/or modify
//  it under the terms of the GNU General Public License as published by
//  the Free Software Foundation, either version 3 of the License, or
//  (at your option) any later version.
//
//  This program is distributed in the hope that it will be useful,
//  but WITHOUT ANY WARRANTY; without even the implied warranty of
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//  GNU General Public License for more details.
//
//  You should have received a copy of the GNU General Public License
//  along with this program.  If not, see <http://www.gnu.org/licenses/>.
//

import Foundation
import UIKit
import CommonCrypto

extension String {

    func urlSafeBase64Decoded() -> String? {
        var st = self
            .replacingOccurrences(of: "_", with: "/")
            .replacingOccurrences(of: "-", with: "+")
        let remainder = self.count % 4
        if remainder > 0 {
            st = self.padding(toLength: self.count + 4 - remainder,
                              withPad: "=",
                              startingAt: 0)
        }
        guard let d = Data(base64Encoded: st, options: .ignoreUnknownCharacters) else {
            return nil
        }
        return String(data: d, encoding: .utf8)
    }

    var alphanumeric: String {
        return self.components(separatedBy: CharacterSet.alphanumerics.inverted).joined().lowercased()
    }

    public var uppercaseInitials: String? {
        let initials = self.components(separatedBy: .whitespaces)
            .reduce("", {
                guard $0.count < 2, let nextLetter = $1.first else { return $0 }
                return $0 + nextLetter.uppercased()
            })
        return initials.isEmpty ? nil : initials
    }

    func formatSecondsToString(_ seconds: TimeInterval) -> String {
        if seconds.isNaN {
            return "00:00:00"
        }
        let sec = Int(seconds.truncatingRemainder(dividingBy: 60))
        let min = Int(seconds.truncatingRemainder(dividingBy: 3600) / 60)
        let hour = Int(seconds / 3600)
        return String(format: "%02d:%02d:%02d", hour, min, sec)
    }

    func md5() -> String {
        //https://stackoverflow.com/a/32166735/9506784

        let length = Int(CC_MD5_DIGEST_LENGTH)
        let messageData = self.data(using: .utf8)!
        var digestData = Data(count: length)

        _ = digestData.withUnsafeMutableBytes { digestBytes -> UInt8 in
            messageData.withUnsafeBytes { messageBytes -> UInt8 in
                if let messageBytesBaseAddress = messageBytes.baseAddress, let digestBytesBlindMemory = digestBytes.bindMemory(to: UInt8.self).baseAddress {
                    let messageLength = CC_LONG(messageData.count)
                    CC_MD5(messageBytesBaseAddress, messageLength, digestBytesBlindMemory)
                }
                return 0
            }
        }

        return digestData.map { String(format: "%02hhx", $0) }.joined()
    }
}