open Lexing
open Printf
open Ast

let get_loc lexbuf =
    Util.loc_from_lexpos lexbuf.lex_curr_p lexbuf.lex_curr_p

let parse_with_error lexbuf =
    try Some (Parser.program Lexer.token lexbuf) with
    | Lexer.SyntaxError msg ->
        raise (LocError (get_loc lexbuf, msg))
    | Parser.Error ->
        raise (LocError (get_loc lexbuf, "syntax error"))

let phase repr =
    let _ = print_endline "- Parse input" in
    match repr with
    | Inputfile (filename, verbose) ->
        (* TODO: run preprocessor *)
        let infile = match filename with
            | Some value -> open_in value
            | None -> stdin
        in
        let display_name = match filename with
            | Some value -> value
            | None -> "stdin"
        in
        let lexbuf = Lexing.from_channel infile in
        lexbuf.lex_curr_p <- { lexbuf.lex_curr_p with pos_fname = display_name };
        let ast = parse_with_error lexbuf in
        close_in infile;
        (match ast with
            | None -> raise (CompileError "error during parsing")
            | Some ast -> Node (ast, verbose))
    | _ -> raise (CompileError "invalid input for this phase")