open System
open System.Diagnostics
open System.Reflection
open System.Text.RegularExpressions

let pwd = System.Environment.CurrentDirectory
let getCurrentSourceFile =
    let _base = String.concat "/" [pwd; "Testlib"]
    in (_base+".cs", _base+".dll")

let getFileAsString filepath =
    String.concat "\n" <| System.IO.File.ReadLines(filepath)

let writeToFile filepath contents =
    if not <| System.IO.File.Exists filepath
    then System.IO.File.WriteAllLines (filepath, contents)
    else System.IO.File.WriteAllLines (filepath, contents)

let compileFile source target =
  let process = Process.Start("mcs", "-t:library -o:"+target+" "+source)
  process.WaitForExit()
  printfn "%d" process.ExitCode
  0

[<EntryPoint>]
let main argv =
    let (source, target) = getCurrentSourceFile
    let current_source = getFileAsString source
    let tmp_path = target + ".tmp"
    let tmp_out = target + ".dll"
    writeToFile tmp_path [|current_source|]

    compileFile tmp_path tmp_out

    let DLL = Assembly.LoadFile(tmp_out)
    let Test = DLL.GetType("Test")
    let Test' = Activator.CreateInstance(Test)
    let Method = Test.GetMethod("add5")
    let x = downcast (Method.Invoke (Test', [|5|])) : int

    printfn "%d" <| x // prints 10
    0 // return an integer exit code
~