53 lines
2.9 KiB
Forth
53 lines
2.9 KiB
Forth
open System
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open System.Text.RegularExpressions
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// A little utility to thread a negative test result (Option.None) through a
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// pipeline of tests
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let inline (|~>) valOption proc =
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match valOption with
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| Some(value) -> proc value
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| None -> None
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[<EntryPoint>]
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let main argv =
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let iban = if argv.Length = 0 then "" else argv.[0]
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iban
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|> (fun iban -> // Check for illegal characters
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if Regex.IsMatch(iban, @"[^0-9A-Za-z ]") then None else Some(iban.ToUpper().Replace(" ", "")))
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|~> (fun iban -> // Check length per country code
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let lengthPerCountry =
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dict [
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("AL", 28); ("AD", 24); ("AT", 20); ("AZ", 28); ("BE", 16); ("BH", 22); ("BA", 20); ("BR", 29);
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("BG", 22); ("CR", 21); ("HR", 21); ("CY", 28); ("CZ", 24); ("DK", 18); ("DO", 28); ("EE", 20);
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("FO", 18); ("FI", 18); ("FR", 27); ("GE", 22); ("DE", 22); ("GI", 23); ("GR", 27); ("GL", 18);
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("GT", 28); ("HU", 28); ("IS", 26); ("IE", 22); ("IL", 23); ("IT", 27); ("KZ", 20); ("KW", 30);
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("LV", 21); ("LB", 28); ("LI", 21); ("LT", 20); ("LU", 20); ("MK", 19); ("MT", 31); ("MR", 27);
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("MU", 30); ("MC", 27); ("MD", 24); ("ME", 22); ("NL", 18); ("NO", 15); ("PK", 24); ("PS", 29);
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("PL", 28); ("PT", 25); ("RO", 24); ("SM", 27); ("SA", 24); ("RS", 22); ("SK", 24); ("SI", 19);
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("ES", 24); ("SE", 24); ("CH", 21); ("TN", 24); ("TR", 26); ("AE", 23); ("GB", 22); ("VG", 24);
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]
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let country = iban.Substring(0, Math.Min(2, iban.Length))
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match lengthPerCountry.TryGetValue(country) with
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| true, length -> // country should have iban of this length
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if length = iban.Length then Some(iban) else None
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| _ -> None // country not known
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)
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|~> (fun iban -> Some(iban.Substring(4) + iban.Substring(0,4)))
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|~> (fun iban ->
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let replaceBase36LetterWithBase10String (s : string) (c :char) = s.Replace(c.ToString(), ((int)c - (int)'A' + 10).ToString())
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Some(List.fold replaceBase36LetterWithBase10String iban [ 'A' .. 'Z' ]))
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|~> (fun iban -> // iban mod 97
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// We could have used BigInteger, but with a loop by 7 char each
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// over the long digit string we get away with Int32 arithmetic
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// (as described in the Wikipedia article)
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let reduceOnce r n = Int32.Parse(r.ToString() + n) % 97
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let rest =
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Regex.Matches(iban.Substring(2), @"\d{1,7}") |> Seq.cast |> Seq.map (fun x -> x.ToString())
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|> Seq.fold reduceOnce (reduceOnce 0 (iban.Substring(0,2)))
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// an iban needs a rest of 1
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if rest = 1 then Some(1) else None
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)
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|> function | Some(_) -> "a valid IBAN" | None -> "an invalid IBAN"
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|> printfn "%s is %s" iban
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0
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