open Printf
open Ast

let input_all ic =
    let n = in_channel_length ic in
    let buf = String.create n in
    really_input ic buf 0 n;
    close_in ic;
    buf

let phase ir =
    prerr_endline "- Load input file";
    match ir with
    | Args args ->
        let display_name = match args.filename with
            | Some filename -> filename
            | None -> "<stdin>"
        in

        if args.cpp then
            let _ = prerr_endline "- Run C preprocessor" in

            let cpp_out = match args.filename with
                | Some filename ->
                    Unix.open_process_in ("cpp " ^ filename)
                | None ->
                    let content = input_all stdin in
                    let (cpp_out, cpp_in) = Unix.open_process "cpp" in
                    output_string cpp_in content;
                    close_out cpp_in;
                    cpp_out
            in

            (* Read preprocessed code from cpp's stdout *)
            let bufsize = 1024 in
            let newbuf () = String.create bufsize in
            let rec read_all buf pos =
                let nread = input cpp_out buf pos bufsize in
                if nread = 0
                    then (close_in cpp_out; buf)
                    else read_all (String.concat "" [buf; newbuf ()]) nread
            in
            let preprocessed = read_all (newbuf ()) 0 in
            FileContent (display_name, preprocessed, args)
        else
            let infile = match args.filename with
                | Some filename -> open_in filename
                | None -> stdin
            in
            FileContent (display_name, input_all infile, args)
    | _ -> raise (InvalidInput "load")