(*
 * 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 F = Format
module L = Logging

(** find transitive procedure calls for each procedure *)

module Domain = AbstractDomain.FiniteSet(Typ.Procname)

(* Store a single stacktree frame per method. That is, callees is
   always []. Instead, the expanded per-method summaries are directly stored
   in the output directory as JSON files and *only* for those methods that
   will be part of the final crashcontext.json. *)
module SpecSummary = Summary.Make (struct
    type payload = Stacktree_j.stacktree

    let update_payload frame (summary : Specs.summary) =
      let payload =
        { summary.payload with Specs.crashcontext_frame = Some frame } in
      { summary with payload = payload }

    let read_payload (summary : Specs.summary) =
      summary.payload.crashcontext_frame

  end)

type extras_t = {
  get_proc_desc : Typ.Procname.t -> Procdesc.t option;
  stacktraces : Stacktrace.t list;
}

let line_range_of_pdesc pdesc =
  let ploc = Procdesc.get_loc pdesc in
  let start_line = ploc.Location.line in
  let end_line = Procdesc.fold_instrs
      (fun acc _ instr ->
         let new_loc = Sil.instr_get_loc instr in
         max acc new_loc.Location.line)
      start_line
      pdesc in
  { Stacktree_j.start_line; end_line }

let stacktree_of_pdesc
    pdesc
    ?(loc=Procdesc.get_loc pdesc)
    ?(callees=[])
    location_type =
  let procname = Procdesc.get_proc_name pdesc in
  let frame_loc =
    Some { Stacktree_j.location_type = location_type;
           file = SourceFile.to_string loc.Location.file;
           line = Some loc.Location.line;
           blame_range = [line_range_of_pdesc pdesc] } in
  { Stacktree_j.method_name = Typ.Procname.to_unique_id procname;
    location = frame_loc;
    callees = callees }

let stacktree_stub_of_procname procname =
  { Stacktree_j.method_name = Typ.Procname.to_unique_id procname;
    location = None;
    callees = [] }

module TransferFunctions (CFG : ProcCfg.S) = struct
  module CFG = CFG
  module Domain = Domain
  type extras = extras_t

  let stacktree_of_astate pdesc astate loc location_type get_proc_desc =
    let procs = Domain.elements astate in
    let callees = List.map
        ~f:(fun pn ->
            match SpecSummary.read_summary pdesc pn with
            | None ->
                (match get_proc_desc pn with
                 | None -> stacktree_stub_of_procname pn
                 (* This can happen when the callee is in the same cluster/ buck
                    target, but it hasn't been checked yet. So we need both the
                    inter-target lookup (SpecSummary) and the intra-target
                    lookup (using get_proc_desc). *)
                 | Some callee_pdesc ->
                     stacktree_of_pdesc callee_pdesc "proc_start")
            | Some stracktree -> stracktree )
        procs in
    stacktree_of_pdesc pdesc ~loc ~callees location_type

  let output_json_summary pdesc astate loc location_type get_proc_desc =
    let caller = Procdesc.get_proc_name pdesc in
    let stacktree = stacktree_of_astate pdesc astate loc location_type get_proc_desc in
    let dir = Filename.concat Config.results_dir "crashcontext" in
    let suffix = F.sprintf "%s_%d" location_type loc.Location.line in
    let fname = F.sprintf "%s.%s.json"
        (Typ.Procname.to_filename caller)
        suffix in
    let fpath = Filename.concat dir fname in
    Utils.create_dir dir;
    Ag_util.Json.to_file Stacktree_j.write_stacktree fpath stacktree

  let exec_instr astate proc_data _ = function
    | Sil.Call (_, Const (Const.Cfun pn), _, loc, _) ->
        let get_proc_desc = proc_data.ProcData.extras.get_proc_desc in
        let traces = proc_data.ProcData.extras.stacktraces in
        let caller = Procdesc.get_proc_name proc_data.ProcData.pdesc in
        let matches_proc frame =
          let matches_class pname = match pname with
            | Typ.Procname.Java java_proc ->
                String.equal
                  frame.Stacktrace.class_str
                  (Typ.Procname.java_get_class_name java_proc)
            | Typ.Procname.ObjC_Cpp objc_cpp_prod ->
                String.equal
                  frame.Stacktrace.class_str
                  (Typ.Procname.objc_cpp_get_class_name objc_cpp_prod)
            | Typ.Procname.C _ -> true (* Needed for test code. *)
            | Typ.Procname.Block _ | Typ.Procname.Linters_dummy_method ->
                failwith "Proc type not supported by crashcontext: block" in
          String.equal frame.Stacktrace.method_str (Typ.Procname.get_method caller) &&
          matches_class caller in
        let all_frames = List.concat
            (List.map ~f:(fun trace -> trace.Stacktrace.frames) traces) in
        begin
          match List.find ~f:matches_proc all_frames with
          | Some frame ->
              let new_astate = Domain.add pn astate in
              if Stacktrace.frame_matches_location frame loc then begin
                let pdesc = proc_data.ProcData.pdesc in
                output_json_summary pdesc new_astate loc "call_site" get_proc_desc
              end;
              new_astate
          | None ->
              astate
        end
    | Sil.Call _ ->
        (* We currently ignore calls through function pointers in C and
           other potential special kinds of procedure calls to be added later,
           e.g. Java reflection. *)
        astate
    | Sil.Load _ | Store _ | Prune _ | Declare_locals _ | Remove_temps _ | Abstract _ | Nullify _ ->
        astate
end

module Analyzer = AbstractInterpreter.Make (ProcCfg.Exceptional) (TransferFunctions)

let loaded_stacktraces =
  (* Load all stacktraces defined in either Config.stacktrace or
     Config.stacktraces_dir.  *)
  let json_files_in_dir dir =
    let stacktrace_path_regexp = Str.regexp ".*\\.json" in
    let path_matcher path =  Str.string_match stacktrace_path_regexp path 0 in
    DB.paths_matching dir path_matcher in
  let filenames = match Config.stacktrace, Config.stacktraces_dir  with
    | None, None -> None
    | Some fname, None -> Some [fname]
    | None, Some dir -> Some (json_files_in_dir dir)
    | Some fname, Some dir -> Some (fname :: (json_files_in_dir dir)) in
  match filenames with
  | None -> None
  | Some files -> Some (List.map ~f:Stacktrace.of_json_file files)

let checker { Callbacks.proc_desc; tenv; get_proc_desc; summary } : Specs.summary =
  begin
    match loaded_stacktraces with
    | None -> failwith "Missing command line option. Either \
                        '--stacktrace stack.json' or '--stacktrace-dir ./dir' \
                        must be used when running '-a crashcontext'. This \
                        options expects a JSON formated stack trace or a \
                        directory containing multiple such traces, \
                        respectively. See \
                        tests/codetoanalyze/java/crashcontext/*.json for \
                        examples of the expected format."
    | Some stacktraces -> begin
        let extras = { get_proc_desc; stacktraces; } in
        ignore (Analyzer.exec_pdesc (ProcData.make proc_desc tenv extras) ~initial:Domain.empty)
      end
  end;
  summary