Hyperz

(* ====================================================================
 * Basic F# Multi-Core Random Password Generator
 * ====================================================================
 *
 * Usage examples:
 * - let mySafePasswrd = PasswordGen.Generate true true true 12
 * - let another5Passwrds = PasswordGen.GenerateMultiple true true true 12 5
 *
 * Benchmark - create 10.000 12-char passwords
 * - let benchResult = PasswordGen.Benchmark 12 10000
 *
 * That's all folks!
 *
 * ==================================================================== *)

open System


module PasswordGen =

    (* List of numbers *)
    let mutable DigitChars   = ['0'..'9']
    (* List of letters *)
    let mutable LetterChars  = ['a'..'z'] @ ['A'..'Z']
    (* List of special characters *)
    let mutable SpecialChars = "_()[]{}<>!?;:=*-+/\\%.,$£&#@"
                               |> fun s -> s.ToCharArray()
                               |> List.ofArray

    (* Creates an async computation that generates a random (based on the seed value) password *)
    let private Gen seed allowedChars length = async {
        let random = new Random(seed)
        let count = (allowedChars:char[]).Length
        return
            Array.zeroCreate<char> length
            |> Array.map (fun char -> allowedChars.[random.Next(count)])
            |> fun passwrd -> new String(passwrd) }

    (*  Generate a single random password *)
    let Generate allowDigits allowLetters allowSpecial length =
        [| if allowDigits then yield! DigitChars
           if allowLetters then yield! LetterChars
           if allowSpecial then yield! SpecialChars |]
        |> fun chars -> Gen (Environment.TickCount) chars length
        |> Async.RunSynchronously

    (* Generate multiple passwords in parallel *)
    let GenerateMultiple allowDigits allowLetters allowSpecial length amount =
        let seedGen = new Random()
        [| if allowDigits then yield! DigitChars
           if allowLetters then yield! LetterChars
           if allowSpecial then yield! SpecialChars |]
        |> fun chars -> [| for _ in 1 .. amount -> Gen (seedGen.Next()) chars length |]
        |> Async.Parallel
        |> Async.RunSynchronously

    (* Basic benchmark :) *)
    let Benchmark passLength passAmount =
        let str = "Seconds: {0:n4}"
        if passAmount = 1 then
            let sw = System.Diagnostics.Stopwatch.StartNew()
            let pw = Generate true true true passLength
            sw.Stop()
            String.Format(str, sw.Elapsed.TotalSeconds)
        elif passAmount > 1 then
            let sw = System.Diagnostics.Stopwatch.StartNew()
            let pw = GenerateMultiple true true true passLength passAmount
            sw.Stop()
            String.Format(str, sw.Elapsed.TotalSeconds)
        else
            "Seconds: N/A"