(*
 * 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 ProcnameSet = PrettyPrintable.MakePPSet(struct
    type t = Procname.t
    let compare = Procname.compare
    let pp_element = Procname.pp
  end)

module Domain = AbstractDomain.FiniteSet(ProcnameSet)

(* 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 summary = Stacktree_j.stacktree option

    let update_payload frame payload =
      { payload with Specs.crashcontext_frame = frame }

    let read_from_payload payload =
      Some payload.Specs.crashcontext_frame
  end)

type extras_t = {
  get_proc_desc : 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 = Procname.to_unique_id procname;
    location = frame_loc;
    callees = callees }

let stacktree_stub_of_procname procname =
  { Stacktree_j.method_name = 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 = IList.map
        (fun pn ->
           match SpecSummary.read_summary pdesc pn with
           | None | Some 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 (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"
        (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
            | Procname.Java java_proc ->
                String.equal
                  frame.Stacktrace.class_str
                  (Procname.java_get_class_name java_proc)
            | Procname.ObjC_Cpp objc_cpp_prod ->
                String.equal
                  frame.Stacktrace.class_str
                  (Procname.objc_cpp_get_class_name objc_cpp_prod)
            | Procname.C _ -> true (* Needed for test code. *)
            | Procname.Block _ | Procname.Linters_dummy_method ->
                failwith "Proc type not supported by crashcontext: block" in
          frame.Stacktrace.method_str = (Procname.get_method caller) &&
          matches_class caller in
        let all_frames = IList.flatten
            (IList.map (fun trace -> trace.Stacktrace.frames) traces) in
        begin
          try
            let frame = IList.find matches_proc all_frames in
            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
          with
            Not_found -> 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)
    (Scheduler.ReversePostorder)
    (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 (IList.map Stacktrace.of_json_file files)

let checker { Callbacks.proc_desc; tenv; get_proc_desc; } =
  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
      SpecSummary.write_summary
        (Procdesc.get_proc_name proc_desc)
        (Some (stacktree_of_pdesc proc_desc "proc_start"));
      ignore(Analyzer.exec_pdesc (ProcData.make proc_desc tenv extras) ~initial:Domain.empty)
    end