let ( let* ) = Result.bind

module Error = Error
module Expr = Expr
module Interpreter = Interpreter
module Lexer = Lexer
module Parser = Parser
module Stmt = Stmt

type lox_error = Error.lox_error

let run ?(env : Environment.environment option) ?(debug = false) (source : string) :
    (unit, lox_error) result =
  let env = Option.value env ~default:(Environment.Env.make ()) in
  let* tokens = Error.of_lexer_error (Lexer.tokenize source) in
  let () =
    if debug then
      let print_tokens () =
        prerr_endline "--- Tokens ---";
        let f token = Printf.eprintf "%s %!" (Lexer.show_token token) in
        Printf.eprintf "Got %d tokens\n%!" (List.length tokens);
        List.iter f tokens;
        prerr_newline ();
        prerr_endline "--------------";
        prerr_newline ()
      in
      print_tokens ()
    else ()
  in
  let* stmts = Parser.parse tokens |> Error.of_parser_error in
  let () =
    if debug then
      let print_statements () =
        prerr_endline "--- Statements ---";
        let f (stmt : Stmt.stmt_node) = prerr_endline (Stmt.show_stmt stmt.stmt) in
        List.iter f stmts;
        prerr_endline "------------------";
        prerr_newline ()
      in
      print_statements ()
    else ()
  in
  let rec interpret_stmts (stmts : Stmt.stmt_node list) =
    match stmts with
    | [] -> Ok ()
    | stmt :: tail ->
        let* () = Interpreter.interpret_stmt env stmt in
        interpret_stmts tail
  in
  interpret_stmts stmts |> Error.of_runtimer_error

let runRepl ?(debug = false) () : unit =
  let env = Environment.Env.make () in
  try
    while true do
      print_string "> ";
      let line = read_line () in
      let result = run ~env ~debug line in
      Result.iter_error Error.print_error result
    done
  with End_of_file -> ()