(*
 * Copyright (c) 2009 - 2013 Monoidics ltd.
 * Copyright (c) 2013 - 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! Utils

(** Support for Execution environments *)

module L = Logging

(** per-file data: type environment and cfg *)
type file_data =
  { source: SourceFile.t;
    tenv_file: DB.filename;
    mutable tenv: Tenv.t option;
    cfg_file: DB.filename;
    mutable cfg: Cfg.cfg option;
  }

(** get the path to the tenv file, which either one tenv file per source file or a global tenv file *)
let tenv_filename file_base =
  let per_source_tenv_filename = DB.filename_add_suffix file_base ".tenv" in
  if Sys.file_exists (DB.filename_to_string per_source_tenv_filename) = `Yes then
    per_source_tenv_filename
  else
    DB.global_tenv_fname

module FilenameHash = Hashtbl.Make(
  struct
    type t = DB.filename
    let equal file1 file2 = DB.compare_filename file1 file2 = 0
    let hash = Hashtbl.hash
  end)

(** create a new file_data *)
let new_file_data source cg_fname =
  let file_base = DB.chop_extension cg_fname in
  let tenv_file = tenv_filename file_base in
  let cfg_file = DB.filename_add_suffix file_base ".cfg" in
  { source = source;
    tenv_file = tenv_file;
    tenv = None; (* Sil.load_tenv_from_file tenv_file *)
    cfg_file = cfg_file;
    cfg = None; (* Cfg.load_cfg_from_file cfg_file *)
  }

let create_file_data table source cg_fname =
  match FilenameHash.find table cg_fname with
  | file_data ->
      file_data
  | exception Not_found ->
      let file_data = new_file_data source cg_fname in
      FilenameHash.add table cg_fname file_data;
      file_data

(** execution environment *)
type t =
  { cg: Cg.t; (** global call graph *)
    proc_map: file_data Procname.Hash.t; (** map from procedure name to file data *)
    file_map: file_data FilenameHash.t; (** map from cg fname to file data *)
    mutable source_files : SourceFile.Set.t; (** Source files in the execution environment *)
  }

(** initial state, used to add cg's *)
type initial = t

(** freeze the execution environment, so it can be queried *)
let freeze exe_env = exe_env (* TODO: unclear what this function is used for *)

(** create a new execution environment *)
let create () =
  { cg = Cg.create None;
    proc_map = Procname.Hash.create 17;
    file_map = FilenameHash.create 1;
    source_files = SourceFile.Set.empty;
  }

(** add call graph from fname in the spec db,
    with relative tenv and cfg, to the execution environment *)
let add_cg (exe_env: t) (source_dir : DB.source_dir) =
  let cg_fname = DB.source_dir_get_internal_file source_dir ".cg" in
  match Cg.load_from_file cg_fname with
  | None ->
      L.stderr "cannot load %s@." (DB.filename_to_string cg_fname)
  | Some cg ->
      let source = Cg.get_source cg in
      exe_env.source_files <- SourceFile.Set.add source exe_env.source_files;
      let defined_procs = Cg.get_defined_nodes cg in

      IList.iter
        (fun pname ->
           (match AttributesTable.find_file_capturing_procedure pname with
            | None ->
                ()
            | Some (source_captured, origin) ->
                let multiply_defined = SourceFile.compare source source_captured <> 0 in
                if multiply_defined then Cg.remove_node_defined cg pname;
                if Config.check_duplicate_symbols &&
                   multiply_defined &&
                   origin <> `Include then
                  L.stderr "@.DUPLICATE_SYMBOLS source: %a source_captured:%a pname:%a@."
                    SourceFile.pp source
                    SourceFile.pp source_captured
                    Procname.pp pname
           ))
        defined_procs;
      Cg.extend exe_env.cg cg

(** get the global call graph *)
let get_cg exe_env =
  exe_env.cg

let get_file_data exe_env pname =
  try
    Some (Procname.Hash.find exe_env.proc_map pname)
  with Not_found ->
    begin
      match AttributesTable.load_attributes pname with
      | None ->
          L.err "can't find tenv_cfg_object for %a@." Procname.pp pname;
          None
      | Some proc_attributes ->
          let source_file = proc_attributes.ProcAttributes.source_file_captured in
          let source_dir = DB.source_dir_from_source_file source_file in
          let cg_fname = DB.source_dir_get_internal_file source_dir ".cg" in
          let file_data = create_file_data exe_env.file_map source_file cg_fname in
          Procname.Hash.replace exe_env.proc_map pname file_data;
          Some file_data
    end

(** return the source file associated to the procedure *)
let get_source exe_env pname =
  Option.map
    ~f:(fun file_data -> file_data.source)
    (get_file_data exe_env pname)

let file_data_to_tenv file_data =
  if file_data.tenv == None
  then file_data.tenv <- Tenv.load_from_file file_data.tenv_file;
  file_data.tenv

let file_data_to_cfg file_data =
  if file_data.cfg = None
  then file_data.cfg <- Cfg.load_cfg_from_file file_data.cfg_file;
  file_data.cfg

(** return the type environment associated to the procedure *)
let get_tenv ?(create=false) exe_env proc_name : Tenv.t =
  let not_found () =
    (* ToDo: a tenv should always be found, it should not be necessary to create one here *)
    if create then
      Tenv.create ()
    else
      failwith ("get_tenv: file_data not found for" ^ Procname.to_string proc_name) in
  match get_file_data exe_env proc_name with
  | Some file_data ->
      begin
        match file_data_to_tenv file_data with
        | Some tenv ->
            tenv
        | None ->
            not_found ()
      end
  | None ->
      not_found ()

(** return the cfg associated to the procedure *)
let get_cfg exe_env pname =
  match get_file_data exe_env pname with
  | None ->
      None
  | Some file_data ->
      file_data_to_cfg file_data

(** return the proc desc associated to the procedure *)
let get_proc_desc exe_env pname =
  match get_cfg exe_env pname with
  | Some cfg ->
      Cfg.find_proc_desc_from_name cfg pname
  | None ->
      None

(** [iter_files f exe_env] applies [f] to the filename and tenv and cfg for each file in [exe_env] *)
let iter_files f exe_env =
  let do_file _ file_data seen_files_acc =
    let fname = file_data.source in
    if SourceFile.Set.mem fname seen_files_acc ||
       (* only files added with add_cg* functions *)
       not (SourceFile.Set.mem fname exe_env.source_files)
    then seen_files_acc
    else
      begin
        Option.iter ~f:(fun cfg -> f fname cfg) (file_data_to_cfg file_data);
        SourceFile.Set.add fname seen_files_acc
      end in
  ignore (Procname.Hash.fold do_file exe_env.proc_map SourceFile.Set.empty)