(*
 * Copyright (c) 2017 - present Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the BSD style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 *)
open! IStd

module CLOpt = CommandLineOption
module L = Logging

let infer_profile_name = "infer-capture"

let infer_profile = lazy
  (* indented so that users may copy it into their projects if they want to *)
  (Printf.sprintf "\
\n    <profile>\
\n      <id>%s</id>\
\n      <build>\
\n        <plugins>\
\n          <plugin>\
\n            <groupId>org.apache.maven.plugins</groupId>\
\n            <artifactId>maven-compiler-plugin</artifactId>\
\n            <configuration>\
\n              <compilerId>javac</compilerId>\
\n              <forceJavacCompilerUse>true</forceJavacCompilerUse>\
\n              <fork>true</fork>\
\n              <executable>%s</executable>\
\n            </configuration>\
\n          </plugin>\
\n        </plugins>\
\n      </build>\
\n    </profile>\
  " infer_profile_name (Config.(bin_dir ^/ string_of_analyzer Infer)))

let pom_worklist = ref [Config.init_work_dir]

let add_infer_profile_to_xml maven_xml infer_xml =
  let copy xml_in xml_out = Xmlm.output xml_out (Xmlm.input xml_in) in
  (* whether we ever found a <profiles> tag *)
  let found_profiles_tag = ref false in
  (* whether there already is an infer profile --this will always be true at the end *)
  let found_infer_profile = ref false in
  (* Process an xml document from the root. Assume the Dtd has already been handled. *)
  let rec process_root xml_in xml_out =
    process xml_in xml_out []
  and insert_infer_profile xml_out =
    let infer_xml = Xmlm.make_input ~strip:false (`String (0, Lazy.force infer_profile)) in
    Xmlm.input infer_xml |> ignore; (* skip dummy DTD *)
    process_root infer_xml xml_out
  and process xml_in xml_out tag_stack =
    let elt_in = Xmlm.input xml_in in
    match elt_in with
    | `El_start tag ->
        Xmlm.output xml_out elt_in;
        let tag_name = snd (fst tag) in
        if tag_name = "profiles" then (
          found_profiles_tag := true
        );
        process xml_in xml_out (tag_name::tag_stack)
    | `El_end ->
        (match tag_stack with
         | "profiles"::_ when not !found_infer_profile ->
             (* found the </profiles> tag but no infer profile found, add one *)
             insert_infer_profile xml_out
         | _::[] when not !found_profiles_tag->
             (* closing the root tag but no <profiles> tag found, add
                <profiles>[infer profile]</profiles> *)
             Xmlm.output xml_out (`El_start (("", "profiles"), []));
             found_profiles_tag := true; (* do not add <profiles> again *)
             insert_infer_profile xml_out;
             Xmlm.output xml_out `El_end
         | _ -> ()
        );
        Xmlm.output xml_out elt_in;
        (match tag_stack with
         | _::parent::tl ->
             process xml_in xml_out (parent::tl)
         | _::[] ->
             (* closing the first tag, we're done *)
             ()
         | [] ->
             invalid_arg "ill-formed xml")
    | `Data data ->
        Xmlm.output xml_out elt_in;
        (match tag_stack with
         | "id"::"profile"::"profiles"::_ when data = infer_profile_name ->
             L.do_out "Found infer profile, not adding one@.";
             found_infer_profile := true
         | "module"::"modules"::_ ->
             let abs_data = Config.init_work_dir ^/ data in
             L.do_out "Adding maven module %s@." abs_data;
             pom_worklist := abs_data::!pom_worklist
         | _ -> ()
        );
        process xml_in xml_out tag_stack
    | `Dtd _ ->
        (* already processed the Dtd node *)
        assert false in
  let process_document () =
    (* process `Dtd; if present, it is always the first node *)
    (match Xmlm.peek maven_xml with
     | `Dtd _ ->
         copy maven_xml infer_xml
     | _ ->
         Xmlm.output infer_xml (`Dtd None)
    );
    process_root maven_xml infer_xml;
    Xmlm.eoi maven_xml |> ignore;
    if not (Xmlm.eoi maven_xml) then invalid_arg "More than one document" in
  process_document ()

let add_infer_profile mvn_pom infer_pom =
  let ic = In_channel.create mvn_pom in
  let with_oc out_chan =
    let with_ic () =
      let xml_in = Xmlm.make_input ~strip:false (`Channel ic) in
      let xml_out = Xmlm.make_output ~nl:true (`Channel out_chan) in
      add_infer_profile_to_xml xml_in xml_out in
    protect ~f:with_ic ~finally:(fun () -> In_channel.close ic) in
  Utils.with_file infer_pom ~f:with_oc

let add_profile_to_pom_in_directory dir =
  (* Even though there is a "-f" command-line arguments to change the config file Maven reads from,
     this is unreliable and Maven pretty much always reads from "pom.xml" anyway. So, we replace
     "pom.xml" with a version holding a special profile for infer capture, then put the original
     back in place. *)
  let maven_pom_path = dir ^/ "pom.xml" in
  let saved_pom_path = dir ^/ "pom.xml.infer-orig" in
  let infer_pom_path = dir ^/ "pom.xml.infer" in
  add_infer_profile maven_pom_path infer_pom_path;
  Unix.rename ~src:maven_pom_path ~dst:saved_pom_path;
  Utils.register_epilogue (fun () -> Unix.rename ~src:saved_pom_path ~dst:maven_pom_path);
  Unix.rename ~src:infer_pom_path ~dst:maven_pom_path;
  if Config.debug_mode || Config.stats_mode then
    Utils.register_epilogue (fun () -> Unix.rename ~src:maven_pom_path ~dst:infer_pom_path)

let capture ~prog ~args =
  while not (List.is_empty !pom_worklist); do
    let pom = List.hd_exn !pom_worklist in
    pom_worklist := List.tl_exn !pom_worklist;
    add_profile_to_pom_in_directory pom
  done;
  let extra_args = "-P"::infer_profile_name::[] in
  let capture_args = args @ extra_args in
  L.do_out "Running maven capture:@\n%s %s@." prog
    (String.concat ~sep:" " (List.map ~f:(Printf.sprintf "'%s'") capture_args));
  (* let children infer processes know that they are spawned by Maven *)
  Unix.fork_exec ~prog ~args:(prog::capture_args) ~env:Config.env_inside_maven ()
  |> Unix.waitpid
  |> function
  | Ok () -> ()
  | Error _ as status ->
      failwithf "*** ERROR: Maven command failed:@\n*** %s@\n*** %s@\n"
        (String.concat ~sep:" " (prog::capture_args))
        (Unix.Exit_or_signal.to_string_hum status)