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 input =
    print_endline "- Parse input";
    match input with
    | Args args ->
        let infile = match args.filename with
            | Some value -> open_in value
            | None -> stdin
        in
        let display_name = match args.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 -> Ast (ast, args))
    | _ -> raise (InvalidInput "parse")