open Lexing
open Printf
open Ast

let get_position lexbuf =
    let pos = lexbuf.lex_curr_p in
    sprintf "%s:%d:%d" pos.pos_fname pos.pos_lnum
                       (pos.pos_cnum - pos.pos_bol + 1)

let parse_with_error lexbuf =
    try Some (Parser.program Lexer.token lexbuf) with
    | Lexer.SyntaxError msg ->
        raise (CompileError (sprintf "%s: %s" (get_position lexbuf) msg))
    | Parser.Error ->
        raise (CompileError (sprintf "%s: syntax error" (get_position lexbuf)))

let phase repr =
    print_endline "- Parse input";
    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 -> failwith "error during parsing"
            | Some ast -> Node (ast, verbose))
    | _ -> failwith "invalid input for this phase"