(* Unison file synchronizer: src/main.ml *)
(* Copyright 1999-2020, Benjamin C. Pierce

    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/>.
*)


(* ---------------------------------------------------------------------- *)

(* This is the main program -- the thing that gets executed first when
   unison is run.

   The Main module is actually a functor that takes the user interface
   (e.g., Uitext or Uigtk) as a parameter.  This allows us to build with
   just one user interface at a time, which avoids having to always link
   in all the libraries needed by all the user interfaces.

   A non-functor interface is provided to allow the Mac GUI to reuse the
   startup code for non-GUI options.
 *)

(* ---------------------------------------------------------------------- *)

(* Some command-line arguments are handled specially during startup, e.g.,
   -doc
   -help
   -version
   -server
   -socket
   -ui
   They are expected to appear on the command-line only, not in a
   profile. In particular, -version and -doc will print to the
   standard output, so they only make sense if invoked from the
   command-line (and not a click-launched gui that has no standard
   output).

   Furthermore, the actions associated with these command-line
   arguments are executed without loading a profile or doing the usual
   command-line parsing. This is because we want to run the actions
   without loading a profile; and then we can't do command-line
   parsing because it is intertwined with profile loading.

   NB: the Mac GUI handles these options itself and needs to change
   if any more are added.
*)

let versionPrefName = "version"
let printVersionAndExit =
  Prefs.createBool versionPrefName false
    ~category:(`Basic `General)
    ~cli_only:true
    "print version and exit"
    ("Print the current version number and exit.  "
     ^ "(This option only makes sense on the command line.)")

let docsPrefName = "doc"
let docs =
  Prefs.createString docsPrefName ""
    ~category:(`Basic `General)
    ~cli_only:true
    "show documentation ('-doc topics' lists topics)"
    (  "The command-line argument \\texttt{-doc \\ARG{secname}} causes unison to "
       ^ "display section  \\ARG{secname} of the manual on the standard output "
       ^ "and then exit.   Use \\verb|-doc all| to display the whole manual, "
       ^ "which includes exactly the same information as the printed and HTML "
       ^ "manuals, modulo "
       ^ "formatting.  Use \\verb|-doc topics| to obtain a list of the "
       ^ "names of the various sections that can be printed.")

let prefsdocsPrefName = "prefsdocs"
let prefsdocs =
  Prefs.createBool prefsdocsPrefName false
    ~category:(`Internal `Devel)
    ~cli_only:true
    "*show full documentation for all preferences (and then exit)"
    ""

let prefsmanPrefName = "prefsman"
let prefsman =
  Prefs.createString prefsmanPrefName ""
    ~category:(`Internal `Devel)
    ~cli_only:true
    "*show manpage documentation for all preferences (and then exit)"
    ""

let serverPrefName = "server"
let server =
  Prefs.createBool serverPrefName false
    ~category:(`Internal `Other)
    ~cli_only:true
    "*normal or server mode" ""

let socketPrefName = "socket"
let socket =
  Prefs.createString socketPrefName ""
    ~category:(`Advanced `Remote)
    ~cli_only:true
    "act as a server on a socket"
    ("Start " ^ Uutil.myName ^ " as a server listening on a TCP socket "
     ^ "(with TCP port number as argument) or a local socket (aka Unix "
     ^ "domain socket) (with socket path as argument).")

let serverHostNameAlias = "host"
let serverHostName = "listen"
let serverHost =
  Prefs.createString serverHostName ""
    ~category:(`Advanced `Remote)
    ~cli_only:true
    "listen on this name or addr in server socket mode (can repeat)"
    ("When acting as a server on a TCP socket, Unison will by default listen "
     ^ "on \"any\" address (0.0.0.0 and [::]).  This command-line argument "
     ^ "allows to specify a different listening address and can be repeated "
     ^ "to listen on multiple addresses.  Listening address can be specified "
     ^ "as a host name or an IP address.")
let () = Prefs.alias serverHost serverHostNameAlias

(* User preference for which UI to use if there is a choice *)
let uiPrefName = "ui"
let interface =
  Prefs.create uiPrefName Uicommon.Graphic
    ~category:(`Advanced `General)
    ~cli_only:true
    "select UI ('text' or 'graphic'); command-line only"
    ("This preference selects either the graphical or the textual user "
     ^ "interface.  Legal values are \\verb|graphic| or \\verb|text|.  "
     ^ "\n\nBecause this option is processed specially during Unison's "
     ^ "start-up sequence, it can {\\em only} be used on the command line.  "
     ^ "In preference files it has no effect."
     ^ "\n\nIf "
     ^ "the Unison executable was compiled with only a textual interface, "
     ^ "this option has "
     ^ "no effect.  (The pre-compiled binaries are all compiled with both "
     ^ "interfaces available.)")
    (fun _ -> function
        "text" -> Uicommon.Text
      | "graphic" -> Uicommon.Graphic
      | other ->
          raise (Prefs.IllegalValue ("option ui :\n\
                                      text -> textual user interface\n\
                                      graphic -> graphic user interface\n"
                                      ^other^ " is not a legal value")))
    (function Uicommon.Text -> ["text"]
      | Uicommon.Graphic -> ["graphic"])
    Uicommon.minterface

let catch_all f =
  try
    try
      (* Util.msg "Starting catch_all...\n"; *)
      f ();
      (* Util.msg "Done catch_all...\n"; *)
    with Prefs.IllegalValue str -> raise (Util.Fatal str)
  with e ->
    Util.msg "Unison server failed: %s\n" (Uicommon.exn2string e);
    (* A final desperate attempt to print out some debug information.
       If we are really-really out of memory then this may fail but
       then it's unlikely we reach this point anyway. *)
    if e = Out_of_memory then Gc.print_stat stderr;
    exit 1

let gui_safe_printf fmt =
  Printf.ksprintf (fun s ->
    if System.has_stdout ~info:s then Printf.printf "%s" s) fmt

let verify_stdout () =
  if not (System.has_stdout ~info:"") then exit 37

let init () = begin
  ignore (Gc.set {(Gc.get ()) with Gc.max_overhead = 150});
  (* Make sure exception descriptions include backtraces *)
  Printexc.record_backtrace true;

  let argv = Prefs.scanCmdLine Uicommon.usageMsg in

  (* Print version if requested *)
  if Util.StringMap.mem versionPrefName argv then begin
    gui_safe_printf "%s version %s\n" Uutil.myName Uutil.myVersion;
    exit 0
  end;

  (* Print docs for all preferences if requested (this is used when building
     the manual) *)
  if Util.StringMap.mem prefsdocsPrefName argv then begin
    Prefs.printFullDocs `TeX;
    exit 0
  end;

  if Util.StringMap.mem prefsmanPrefName argv then begin
    begin match Util.StringMap.find prefsmanPrefName argv with
      | "short" :: _ -> Prefs.printUsageForMan ()
      | "full" :: _ -> Prefs.printFullDocs `man
      | _ -> ()
    end;
    exit 0
  end;

  (* Display documentation if requested *)
  begin try
    let docv = Util.StringMap.find docsPrefName argv in
    verify_stdout ();
    begin match docv with
      [] ->
        assert false
    | "topics"::_ ->
        Printf.printf "Documentation topics:\n";
        Safelist.iter
          (fun (sn,(n,doc)) ->
            if sn<>"" then Printf.printf "   %12s %s\n" sn n)
          Strings.docs;
        Printf.printf
          "\nType \"%s -doc <topic>\" for detailed information about <topic>\n"
          Uutil.myName;
        Printf.printf
          "or \"%s -doc all\" for the whole manual\n\n"
          Uutil.myName
    | "all"::_ ->
        Printf.printf "\n";
        Safelist.iter
          (fun (sn,(n,doc)) -> if n<>"Junk" then Printf.printf "%s\n" doc)
          Strings.docs
    | topic::_ ->
        (try
          let (_,d) = Safelist.assoc topic Strings.docs in
          Printf.printf "\n%s\n" d
        with
          Not_found ->
            Printf.printf "Documentation topic %s not recognized:"
              topic;
            Printf.printf "\nType \"%s -doc topics\" for a list\n"
              Uutil.myName)
    end;
    exit 0
  with
  | Not_found -> ()
  | Sys_error _ (* Broken pipe *) ->
      (* A broken pipe (when stdout is piped to pager, for example) will cause
         all output functions, including flush, to raise an exception. Catching
         the exception here is not sufficient because stdout is implicitly
         flushed on exit, which will again raise a broken pipe exception. The
         only way to avoid [exit] raising a broken pipe exception is to close
         [stdout] beforehand. *)
      close_out_noerr stdout;
      exit 0
  end;

  (* Start a server if requested *)
  if Util.StringMap.mem serverPrefName argv then begin
    catch_all (fun () ->
      Os.createUnisonDir();
      Remote.beAServer();
      exit 0)
  end;

  (* Start a socket server if requested *)
  begin try
    let i = List.hd (Util.StringMap.find socketPrefName argv) in
    catch_all (fun () ->
     Os.createUnisonDir();
      Remote.waitOnPort
        ((try Util.StringMap.find serverHostName argv with Not_found -> []) @
         (try Util.StringMap.find serverHostNameAlias argv with Not_found -> []))
        i);
    exit 0
  with Not_found -> () end;
  argv
end

(* non-GUI startup for Mac GUI version *)
let nonGuiStartup () = begin
  let argv = init() in (* might not return *)
  (* if it returns start a UI *)
  (try
    (match Util.StringMap.find uiPrefName argv with
      "text"::_    -> (Uitext.Body.start Uicommon.Text; exit 0)
    | "graphic"::_ -> () (* fallthru *)
    | _            -> Prefs.printUsage Uicommon.usageMsg; exit 1)
  with Not_found -> ());
  ()
end

module Body = functor (Ui : Uicommon.UI) -> struct
  let argv = init() in (* might not return *)
  (* if it returns start a UI *)
  Ui.start
    (try
      (match Util.StringMap.find uiPrefName argv with
      | "text"::_    -> verify_stdout (); Uicommon.Text
      | "graphic"::_ -> Uicommon.Graphic
      | _ -> verify_stdout (); Prefs.printUsage Uicommon.usageMsg; exit 1)
    with Not_found -> Ui.defaultUi)
end
