/*
 * Copyright (c) 2015 - 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;

open! PVariant;

let module Hashtbl = Caml.Hashtbl;

let module F = Format;

let module L = Logging;

type attr_kind =
  | ProcDefined
  | ProcObjCAccessor
  | ProcUndefined
[@@deriving compare];


/** Module to manage the table of attributes. */
let serializer: Serialization.serializer ProcAttributes.t = Serialization.create_serializer Serialization.Key.attributes;

let attributes_filename proc_kind::proc_kind pname_file => {
  let file_suffix =
    switch proc_kind {
    | ProcDefined => ".attr"
    | ProcObjCAccessor => ".objc_acc.attr"
    | ProcUndefined => ".decl.attr"
    };
  pname_file ^ file_suffix
};


/** path to the .attr file for the given procedure in the current results directory */
let res_dir_attr_filename proc_kind::proc_kind pname => {
  let pname_file = Typ.Procname.to_filename pname;
  let attr_fname = attributes_filename proc_kind::proc_kind pname_file;
  let bucket_dir = {
    let base = pname_file;
    let len = String.length base;
    if (len < 2) {
      Filename.current_dir_name
    } else {
      String.sub base pos::(len - 2) len::2
    }
  };
  let filename =
    DB.Results_dir.path_to_filename
      DB.Results_dir.Abs_root [Config.attributes_dir_name, bucket_dir, attr_fname];
  DB.filename_create_dir filename;
  filename
};

/* Load the proc attribute for the defined filename if it exists,
   otherwise try to load the declared filename. */
let load_attr defined_only::defined_only proc_name => {
  let attributes_file proc_kind::proc_kind proc_name => Multilinks.resolve (
    res_dir_attr_filename proc_kind::proc_kind proc_name
  );
  let attr =
    Serialization.read_from_file serializer (attributes_file proc_kind::ProcDefined proc_name);
  if (is_none attr && not defined_only) {
    /* We try to load the objc accesor one if they exist, if not then we load the undefined one */
    let attr =
      Serialization.read_from_file
        serializer (attributes_file proc_kind::ProcObjCAccessor proc_name);
    switch attr {
    | Some attr => Some attr
    | None =>
      Serialization.read_from_file serializer (attributes_file proc_kind::ProcUndefined proc_name)
    }
  } else {
    attr
  }
};

let create_proc_kind (proc_attributes: ProcAttributes.t) =>
  if proc_attributes.is_defined {
    ProcDefined
  } else if (
    Option.is_some proc_attributes.objc_accessor
  ) {
    ProcObjCAccessor
  } else {
    ProcUndefined
  };

let less_relevant_proc_kinds proc_kind =>
  switch proc_kind {
  | ProcDefined => [ProcObjCAccessor, ProcUndefined]
  | ProcObjCAccessor => [ProcUndefined]
  | ProcUndefined => []
  };

/* Write a proc attributes to file.
   If defined, delete the declared file if it exists. */
let write_and_delete proc_name (proc_attributes: ProcAttributes.t) => {
  let proc_kind = create_proc_kind proc_attributes;
  let attributes_file proc_kind => res_dir_attr_filename proc_kind::proc_kind proc_name;
  Serialization.write_to_file serializer (attributes_file proc_kind) data::proc_attributes;
  let upgrade_relevance less_relevant_proc_kind => {
    let fname_declared = DB.filename_to_string (attributes_file less_relevant_proc_kind);
    if (Sys.file_exists fname_declared == `Yes) {
      try (Unix.unlink fname_declared) {
      | Unix.Unix_error _ => ()
      }
    }
  };
  List.iter f::upgrade_relevance (less_relevant_proc_kinds proc_kind)
};

/* This creates an ordering in the attribute files: 1.defined, 2.objc accessor, 3.else.
   To be used to figure out if we should override an existing attribute file with a new
   one, if relevant information will be updated, or lost.
   If the relevance is not upgraded, choose based on whether its associated file has higher
   rank (alphabetically) than the other. */
let should_override_attr (new_attr: ProcAttributes.t) (old_attr: ProcAttributes.t) =>
  if new_attr.is_defined {
    if old_attr.is_defined {
      SourceFile.compare new_attr.loc.file old_attr.loc.file > 0
    } else {
      true /* new becomes defined, override  */
    }
  } else if
    old_attr.is_defined {
    false /* old was defined, new isn't, don't override */
  } else if (
    Option.is_some new_attr.objc_accessor
  ) {
    if (Option.is_some old_attr.objc_accessor) {
      SourceFile.compare new_attr.loc.file old_attr.loc.file > 0
    } else {
      true /* new becomes objc accessor, override */
    }
  } else {
    false /* new isn't defined or objc accessor, don't overide */
  };

let store_attributes (proc_attributes: ProcAttributes.t) => {
  let proc_name = proc_attributes.proc_name;
  let should_write =
    switch (load_attr defined_only::false proc_name) {
    | None => true
    | Some proc_attributes_on_disk => should_override_attr proc_attributes proc_attributes_on_disk
    };
  if should_write {
    write_and_delete proc_name proc_attributes
  }
};

let attr_tbl = Typ.Procname.Hash.create 16;

let defined_attr_tbl = Typ.Procname.Hash.create 16;

let load_attributes proc_name =>
  try (Typ.Procname.Hash.find attr_tbl proc_name) {
  | Not_found =>
    let proc_attributes = load_attr defined_only::false proc_name;
    switch proc_attributes {
    | Some attrs =>
      Typ.Procname.Hash.add attr_tbl proc_name proc_attributes;
      if attrs.is_defined {
        Typ.Procname.Hash.add defined_attr_tbl proc_name proc_attributes
      }
    | None => ()
    };
    proc_attributes
  };

let load_defined_attributes cache_none::cache_none proc_name =>
  try (Typ.Procname.Hash.find defined_attr_tbl proc_name) {
  | Not_found =>
    let proc_attributes = load_attr defined_only::true proc_name;
    if (proc_attributes != None) {
      /* procedure just got defined, replace attribute in attr_tbl with defined version */
      Typ.Procname.Hash.replace attr_tbl proc_name proc_attributes;
      Typ.Procname.Hash.add defined_attr_tbl proc_name proc_attributes
    } else if cache_none {
      Typ.Procname.Hash.add defined_attr_tbl proc_name proc_attributes
    };
    proc_attributes
  };


/** Given the name of an ObjC class, extract the type from the tenv where the class was defined. We
    do this by adding a method that is unique to each class, and then finding the tenv that
    corresponds to the class definition. */
let get_correct_type_from_objc_class_name type_name =>
  /* ToDo: this function should return a type that includes a reference to the tenv computed by:
     let class_method = Typ.Procname.get_default_objc_class_method (Typename.name type_name);
     switch (find_tenv_from_class_of_proc class_method) {
     | Some tenv =>
      */
  Some (Typ.Tstruct type_name);

type t = {
  num_bindings: int,
  num_buckets: int,
  max_bucket_length: int,
  serialized_size_kb: option int
};

let to_json at => {
  let extra_field =
    switch at.serialized_size_kb {
    | Some v => [("serialized_size_kb", `Int v)]
    | None => []
    };
  `Assoc (
    [
      ("num_bindings", `Int at.num_bindings),
      ("num_buckets", `Int at.num_buckets),
      ("max_bucket_length", `Int at.max_bucket_length)
    ] @ extra_field
  )
};

let from_json json => {
  open! Yojson.Basic.Util;
  {
    num_bindings: json |> member "num_bindings" |> to_int,
    num_buckets: json |> member "num_buckets" |> to_int,
    max_bucket_length: json |> member "max_bucket_length" |> to_int,
    serialized_size_kb: json |> member "serialized_size_kb" |> to_option to_int
  }
};

let aggregate s => {
  let all_num_bindings = List.map f::(fun stats => float_of_int stats.num_bindings) s;
  let all_num_buckets = List.map f::(fun stats => float_of_int stats.num_buckets) s;
  let all_max_bucket_length = List.map f::(fun stats => float_of_int stats.max_bucket_length) s;
  let aggr_num_bindings = StatisticsToolbox.compute_statistics all_num_bindings;
  let aggr_num_buckets = StatisticsToolbox.compute_statistics all_num_buckets;
  let aggr_max_bucket_length = StatisticsToolbox.compute_statistics all_max_bucket_length;
  `Assoc [
    ("num_bindings", StatisticsToolbox.to_json aggr_num_bindings),
    ("num_buckets", StatisticsToolbox.to_json aggr_num_buckets),
    ("max_bucket_length", StatisticsToolbox.to_json aggr_max_bucket_length)
  ]
};

let stats () => {
  let stats = Typ.Procname.Hash.stats attr_tbl;
  let {Hashtbl.num_bindings: num_bindings, num_buckets, max_bucket_length} = stats;
  let serialized_size_kb =
    Config.developer_mode ?
      Some (Marshal.data_size (Marshal.to_bytes attr_tbl []) 0 / 1024) : None;
  {num_bindings, num_buckets, max_bucket_length, serialized_size_kb}
};

/* Find the file where the procedure was captured, if a cfg for that file exists.
   Return also a boolean indicating whether the procedure is defined in an
   include file. */
let find_file_capturing_procedure pname =>
  switch (load_attributes pname) {
  | None => None
  | Some proc_attributes =>
    let source_file = proc_attributes.ProcAttributes.source_file_captured;
    let source_dir = DB.source_dir_from_source_file source_file;
    let origin =
      /* Procedure coming from include files if it has different location
         than the file where it was captured. */
      SourceFile.compare source_file proc_attributes.ProcAttributes.loc.file != 0 ?
        `Include : `Source;
    let cfg_fname = DB.source_dir_get_internal_file source_dir ".cfg";
    let cfg_fname_exists = Sys.file_exists (DB.filename_to_string cfg_fname) == `Yes;
    if cfg_fname_exists {
      Some (source_file, origin)
    } else {
      None
    }
  };