import gleam/list
import gleam/result
import gleam/string
import gleam/dynamic.{Dynamic}

/// Find and run all test functions for the current project using Erlang's EUnit
/// test framework.
///
/// Any Erlang or Gleam function in the `test` directory with a name editing in
/// `_test` is considered a test function and will be run.
///
pub fn main() -> Nil {
  let options = [Verbose, NoTty, Report(#(GleeunitProgress, [Colored(True)]))]

  let result =
    find_files(matching: "**/*.{erl,gleam}", in: "test")
    |> list.map(gleam_to_erlang_module_name)
    |> list.map(dangerously_convert_string_to_atom(_, Utf8))
    |> run_eunit(options)
    |> dynamic.result
    |> result.unwrap(Error(dynamic.from(Nil)))

  let code = case result {
    Ok(_) -> 0
    Error(_) -> 1
  }
  halt(code)
}

external fn halt(Int) -> Nil =
  "erlang" "halt"

fn gleam_to_erlang_module_name(path: String) -> String {
  path
  |> string.replace(".gleam", "")
  |> string.replace(".erl", "")
  |> string.replace("/", "@")
}

external fn find_files(matching: String, in: String) -> List(String) =
  "gleeunit_ffi" "find_files"

external type Atom

type Encoding {
  Utf8
}

external fn dangerously_convert_string_to_atom(String, Encoding) -> Atom =
  "erlang" "binary_to_atom"

type ReportModuleName {
  GleeunitProgress
}

type GleeunitProgressOption {
  Colored(Bool)
}

type EunitOption {
  Verbose
  NoTty
  Report(#(ReportModuleName, List(GleeunitProgressOption)))
}

external fn run_eunit(List(Atom), List(EunitOption)) -> Dynamic =
  "eunit" "test"