module Bob

open System

let containsLowercase = Seq.fold (fun a x -> if x >= 'a' && x <= 'z' then true else a) false

let containsUppercase = Seq.fold (fun a x -> if x >= 'A' && x <= 'Z' then true else a) false

let containsLetters input = containsLowercase input || containsUppercase input

let lastLetter = Seq.last

let question (input: string) = String.length input > 0 && lastLetter input = '?'

let upperCase (input: string) = 
    not (containsLowercase input) && containsUppercase input

let emptyOrBlank (input: string) =
    String.length input = 0 

let response (rawInput: string): string =
    let strip = ['\t';' ';'\n';'\r']
    let input = rawInput |> Seq.filter (fun c -> not (List.contains c strip)) |> String.Concat
    let uc = upperCase input
    let q = question input
    let empty = emptyOrBlank input
    if q && uc then "Calm down, I know what I'm doing!" else
    if q then "Sure." else 
    if empty then "Fine. Be that way!" else
    if uc then "Whoa, chill out!" else
    "Whatever."