(*
 * Copyright (c) 2016 - 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 F = Format
module L = Logging

(** enable debug mode (to get more data saved to disk for future inspections) *)
let debug_mode = Config.debug_mode || Config.frontend_stats

(** This function reads the json file in fname, validates it, and encodes in the AST data structure
    defined in Clang_ast_t.  *)
let validate_decl_from_file fname =
  Ag_util.Biniou.from_file ~len:CFrontend_config.biniou_buffer_size Clang_ast_b.read_decl fname


let validate_decl_from_channel chan =
  Ag_util.Biniou.from_channel ~len:CFrontend_config.biniou_buffer_size Clang_ast_b.read_decl chan


let register_perf_stats_report source_file =
  let stats_type =
    match (Config.capture, Config.linters) with
    | true, true ->
        PerfStats.ClangFrontendLinters source_file
    | true, false ->
        PerfStats.ClangFrontend source_file
    | false, true ->
        PerfStats.ClangLinters source_file
    | false, false ->
        Logging.(die UserError) "Clang frontend should be run in capture and/or linters mode."
  in
  PerfStats.register_report_at_exit stats_type


let init_global_state_for_capture_and_linters source_file =
  L.(debug Capture Medium) "Processing %s" (Filename.basename (SourceFile.to_abs_path source_file)) ;
  Language.curr_language := Language.Clang ;
  register_perf_stats_report source_file ;
  if Config.capture then DB.Results_dir.init source_file ;
  CFrontend_config.reset_global_state ()


let run_clang_frontend ast_source =
  let init_time = Mtime_clock.counter () in
  let print_elapsed () =
    L.(debug Capture Quiet) "Elapsed: %a.@\n" Mtime.Span.pp (Mtime_clock.count init_time)
  in
  let ast_decl =
    match ast_source with
    | `File path ->
        validate_decl_from_file path
    | `Pipe chan ->
        validate_decl_from_channel chan
  in
  let trans_unit_ctx =
    match ast_decl with
    | Clang_ast_t.TranslationUnitDecl (_, _, _, info) ->
        Config.arc_mode := info.Clang_ast_t.tudi_arc_enabled ;
        let source_file = SourceFile.from_abs_path info.Clang_ast_t.tudi_input_path in
        init_global_state_for_capture_and_linters source_file ;
        let lang =
          match info.Clang_ast_t.tudi_input_kind with
          | `IK_C ->
              CFrontend_config.C
          | `IK_CXX ->
              CFrontend_config.CPP
          | `IK_ObjC ->
              CFrontend_config.ObjC
          | `IK_ObjCXX ->
              CFrontend_config.ObjCPP
          | _ ->
              assert false
        in
        {CFrontend_config.source_file; lang}
    | _ ->
        assert false
  in
  let pp_ast_filename fmt ast_source =
    match ast_source with
    | `File path ->
        Format.fprintf fmt "%s" path
    | `Pipe _ ->
        Format.fprintf fmt "stdin of %a" SourceFile.pp trans_unit_ctx.CFrontend_config.source_file
  in
  ClangPointers.populate_all_tables ast_decl ;
  L.(debug Capture Quiet) "Clang frontend action is %s@\n" Config.clang_frontend_action_string ;
  L.(debug Capture Medium)
    "Start %s of AST from %a@\n" Config.clang_frontend_action_string pp_ast_filename ast_source ;
  if Config.linters then CFrontend_checkers_main.do_frontend_checks trans_unit_ctx ast_decl ;
  if Config.capture then CFrontend.do_source_file trans_unit_ctx ast_decl ;
  L.(debug Capture Medium)
    "End %s of AST file %a... OK!@\n" Config.clang_frontend_action_string pp_ast_filename
    ast_source ;
  print_elapsed ()


let run_and_validate_clang_frontend ast_source =
  try run_clang_frontend ast_source with exc ->
    IExn.reraise_if exc ~f:(fun () -> not Config.keep_going) ;
    L.internal_error "ERROR RUNNING CAPTURE: %a@\n%s@\n" Exn.pp exc (Printexc.get_backtrace ())


let run_clang clang_command read =
  let exit_with_error exit_code =
    L.external_error "Error: the following clang command did not run successfully:@\n  %a@."
      ClangCommand.pp clang_command ;
    L.exit exit_code
  in
  (* NOTE: exceptions will propagate through without exiting here *)
  match Utils.with_process_in (ClangCommand.command_to_run clang_command) read with
  | res, Ok () ->
      res
  | _, Error `Exit_non_zero n ->
      (* exit with the same error code as clang in case of compilation failure *)
      exit_with_error n
  | _ ->
      exit_with_error 1


let run_plugin_and_frontend source_path frontend clang_cmd =
  let clang_plugin_cmd = ClangCommand.with_plugin_args clang_cmd in
  if debug_mode then (
    (* -cc1 clang commands always set -o explicitly *)
    let basename = source_path ^ ".ast" in
    (* Emit the clang command with the extra args piped to infer-as-clang *)
    let frontend_script_fname = Printf.sprintf "%s.sh" basename in
    let debug_script_out = Out_channel.create frontend_script_fname in
    let debug_script_fmt = Format.formatter_of_out_channel debug_script_out in
    let biniou_fname = Printf.sprintf "%s.biniou" basename in
    Format.fprintf debug_script_fmt "%s \\@\n  > %s@\n"
      (ClangCommand.command_to_run clang_plugin_cmd)
      biniou_fname ;
    Format.fprintf debug_script_fmt
      "bdump -x -d \"%s/clang_ast.dict\" -w '!!DUMMY!!' %s \\@\n  > %s.bdump" Config.etc_dir
      biniou_fname basename ;
    Out_channel.close debug_script_out ) ;
  run_clang clang_plugin_cmd frontend


let cc1_capture clang_cmd =
  let source_path =
    let root = Unix.getcwd () in
    let orig_argv = ClangCommand.get_orig_argv clang_cmd in
    (* the source file is always the last argument of the original -cc1 clang command *)
    Utils.filename_to_absolute ~root (List.last_exn orig_argv)
  in
  L.(debug Capture Quiet) "@\n*** Beginning capture of file %s ***@\n" source_path ;
  if Config.equal_analyzer Config.analyzer Config.CompileOnly
     || not Config.skip_analysis_in_path_skips_compilation
        && CLocation.is_file_blacklisted source_path
  then (
    L.(debug Capture Quiet) "@\n Skip the analysis of source file %s@\n@\n" source_path ;
    (* We still need to run clang, but we don't have to attach the plugin. *)
    run_clang clang_cmd Utils.consume_in )
  else if Config.skip_analysis_in_path_skips_compilation
          && CLocation.is_file_blacklisted source_path
  then (
    L.(debug Capture Quiet) "@\n Skip compilation and analysis of source file %s@\n@\n" source_path ;
    () )
  else
    match Config.clang_biniou_file with
    | Some fname ->
        run_and_validate_clang_frontend (`File fname)
    | None ->
        run_plugin_and_frontend source_path
          (fun chan_in -> run_and_validate_clang_frontend (`Pipe chan_in))
          clang_cmd


let capture clang_cmd =
  if ClangCommand.can_attach_ast_exporter clang_cmd then
    (* this command compiles some code; replace the invocation of clang with our own clang and
       plugin *)
    cc1_capture clang_cmd
  else if Option.is_some Config.buck_compilation_database then
    (* when running with buck's compilation-database, skip commands where frontend cannot be
       attached, as they may cause unnecessary compilation errors *)
    ()
  else (
    (* Non-compilation (eg, linking) command. Run the command as-is. It will not get captured
       further since `clang -### ...` will only output commands that invoke binaries using their
       absolute paths. *)
    L.(debug Capture Medium)
      "Running non-cc command without capture: %a@\n" ClangCommand.pp clang_cmd ;
    run_clang clang_cmd Utils.echo_in )