(*
 *    _  _   ____                         _  
 *  _| || |_/ ___|  ___ _ __  _ __   ___ | | 
 * |_  ..  _\___ \ / _ \ '_ \| '_ \ / _ \| | 
 * |_      _|___) |  __/ |_) | |_) | (_) |_| 
 *   |_||_| |____/ \___| .__/| .__/ \___/(_) 
 *                     |_|   |_|             
 *
 * Personal Social Web.
 *
 * Copyright (C) The #Seppo contributors. All rights reserved.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *)


module C = Cgi
open Seppo_lib
open Astring

(*
 * Being a CGI[1] means #Seppo is a binary executable reading from stdin
 * writing to stdout in the first place. The Webserver puts incoming HTTP Header
 * variables into the environment.
 *
 * Serving dynamic content via CGI can be as simple as putting the executable
 * into the web directory of e.g. an Apache webserver and entering the according
 * http url into your browser.
 *
 * Besides that, seppo.cgi has housekeeping commands for the commandline.
 *
 * [1] RFC3875 The Common Gateway Interface https://www.rfc-editor.org/rfc/rfc3875.html
*)
let () =
  Mirage_crypto_rng_unix.use_default ();
  let uuid = () |> (() |> Random.State.make_self_init |> Uuidm.v4_gen) in
  let resp_err ec ?(hdrs = [Http.H.ct_plain]) status msg =
    (try Logr.err (fun m -> m "%a %s %s" Uuidm.pp uuid  ec msg);
     with _ -> ());
    Cgi.Response.flush uuid stdout (status, hdrs, fun oc ->
        let s = status |> Cohttp.Code.string_of_status in
        Printf.eprintf "FATAL: %s\r\nsee %s\r\n%s\r\n" s ec msg;
        Printf.fprintf oc "Status: %s\r\n\r\n%s\r\n%s" s ec msg ) in
  (try match Cgi.Request.(from_env () |> consolidate |> proxy) with
     | Error "Not Found." ->
       (* some CLI commands are fine without logging. At least -h and -V have to. *)
       Sys.argv
       |> Array.to_list
       |> Shell.exec
     | Error msg ->
       resp_err E.e1036 `Internal_server_error msg
     | Ok req ->
       req.script_name
       |> Cgi.cd_cgi_bin_twin_path
       |> Unix.chdir;
       match "app/var/log/" |> File.mkdir_p 0o770 with
       | Error msg -> resp_err E.e1035 `Internal_server_error msg
       | Ok log_dir ->
         let tnow = Ptime_clock.now () in
         assert (log_dir |> St.is_suffix ~affix:"/");
         Logr.open_out (log_dir ^ "seppo.log");
         let r = req
                 |> C.handle uuid tnow stdin
                 |> Cgi.Response.flush uuid stdout in
         close_in stdin;
         (* closing kills the cgi: close_out stdout; *)
         flush stderr;
         (* L.close_out (); *)
         r
   with
   | Unix.(Unix_error(ENOENT, "chdir", dir)) -> resp_err E.e1037 `Internal_server_error ("cd: The directory '" ^ dir ^ "' does not exist")
   | Sys_error msg -> resp_err E.e1034 `Internal_server_error msg
   | e -> resp_err E.e1005 `Internal_server_error (Printexc.to_string e) )
  |> exit
