module VersionOne.CommandLine

type OptionBag = {
  storedCredsFile : string
  secretsFile : string
  } with
  static member Default = {
    storedCredsFile = "stored_credentials.json"
    secretsFile = "client_secrets.json"
    }

let flagFuncs =
  Map [
    "-h", fun state -> failwith "Would display help here"
    ]

let valueFuncs =
  Map [
    "--creds",   fun state v -> {state with storedCredsFile = v}
    "--secrets", fun state v -> {state with secretsFile = v}
    ]

let rec parseArgs' state = function
  | flag :: tail when flagFuncs.ContainsKey flag  -> parseArgs' (flagFuncs.[flag] state) tail
  | flag :: v :: tail when valueFuncs.ContainsKey flag -> parseArgs'  (valueFuncs.[flag] state v) tail
  | item :: tail -> failwith "Unexpected argument \"%s\" in command line"
  | [] -> state

let parseArgs = parseArgs' OptionBag.Default