(*****************************************************************************)
(*                                                                           *)
(* Open Source License                                                       *)
(* Copyright (c) 2018 Dynamic Ledger Solutions, Inc. <contact@tezos.com>     *)
(* Copyright (c) 2019-2021 Nomadic Labs, <contact@nomadic-labs.com>          *)
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(* TODO: https://gitlab.com/tezos/tezos/-/issues/4656

   Test cancellation of a (pending) connection *)

(* TODO: https://gitlab.com/tezos/tezos/-/issues/4657

   Do not recompute list_known_points at each requests... but only
   once in a while, e.g. every minutes or when a point or the
   associated peer_id is blacklisted. *)

(* TODO: https://gitlab.com/tezos/tezos/-/issues/4658

   allow to track "requested peer_ids" when we reconnect to a point. *)

module Event = P2p_events.P2p_pool

type config = {
  identity : P2p_identity.t;
  trusted_points : (P2p_point.Id.t * P2p_peer.Id.t option) list;
  peers_file : string;
  private_mode : bool;
  max_known_points : (int * int) option;
  max_known_peer_ids : (int * int) option;
  peer_greylist_size : int;
  ip_greylist_size_in_kilobytes : int;
  ip_greylist_cleanup_delay : Time.System.Span.t;
}

module Point_LRU_set : Aches.Vache.SET with type elt = P2p_point.Id.t =
  Aches.Vache.Set (Aches.Vache.LRU_Precise) (Aches.Vache.Strong) (P2p_point.Id)

type ('msg, 'peer, 'conn) t = {
  config : config;
  peer_meta_config : 'peer P2p_params.peer_meta_config;
  (* Set of points corresponding to this peer *)
  my_id_points : Point_LRU_set.t;
  known_peer_ids :
    (('msg, 'peer, 'conn) P2p_conn.t, 'peer, 'conn) P2p_peer_state.Info.t
    P2p_peer.Table.t;
  connected_peer_ids :
    (('msg, 'peer, 'conn) P2p_conn.t, 'peer, 'conn) P2p_peer_state.Info.t
    P2p_peer.Table.t;
  known_points :
    ('msg, 'peer, 'conn) P2p_conn.t P2p_point_state.Info.t P2p_point.Table.t;
  connected_points :
    ('msg, 'peer, 'conn) P2p_conn.t P2p_point_state.Info.t P2p_point.Table.t;
  triggers : P2p_trigger.t;
  log : P2p_connection.P2p_event.t -> unit;
  acl : P2p_acl.t;
}

module Gc_point_set = Bounded_heap.Make (struct
  type t = Time.System.t * P2p_point.Id.t

  let compare (x, _) (y, _) = -Time.System.compare x y
end)

let gc_points {config = {max_known_points; _}; known_points; log; _} =
  match max_known_points with
  | None -> ()
  | Some (_, target) ->
      let current_size = P2p_point.Table.length known_points in
      if current_size > target then (
        let to_remove_target = current_size - target in
        (* TODO: https://gitlab.com/tezos/tezos/-/issues/4659

           Maybe use the time of discovery? *)
        let now = Time.System.now () in
        let table = Gc_point_set.create to_remove_target in
        P2p_point.Table.iter
          (fun p point_info ->
            if
              P2p_point_state.is_disconnected point_info
              && not (P2p_point_state.Info.trusted point_info)
            then
              let time =
                match P2p_point_state.Info.last_miss point_info with
                | None -> now
                | Some t -> t
              in
              Gc_point_set.insert (time, p) table)
          known_points ;
        let to_remove = Gc_point_set.get table in
        ListLabels.iter to_remove ~f:(fun (_, p) ->
            P2p_point.Table.remove known_points p) ;
        log Gc_points)

let greylist_addr pool addr = P2p_acl.IPGreylist.add pool.acl addr

let set_expected_peer_id :
    ('msg, 'peer, 'conn) t -> P2p_point.Id.t -> P2p_peer.Id.t -> unit Lwt.t =
 fun pool point peer_id ->
  match P2p_point.Table.find pool.known_points point with
  | None -> Lwt.return_unit
  | Some point_info -> (
      P2p_point_state.set_expected_peer_id point_info peer_id ;
      match P2p_point_state.get point_info with
      | Disconnected | Requested _ -> Lwt.return_unit
      (* If the expected_peer_id is not the same than the one given
         for the current connection, we greylist and disconnect if
         possible. *)
      | Running {current_peer_id; data} ->
          if not (P2p_peer.Id.equal peer_id current_peer_id) then (
            greylist_addr pool (fst point) ;
            P2p_conn.disconnect ~reason:Unexpected_peer_id data)
          else Lwt.return_unit
      | Accepted {current_peer_id; _} ->
          if not (P2p_peer.Id.equal peer_id current_peer_id) then (
            greylist_addr pool (fst point) ;
            Lwt.return_unit)
          else Lwt.return_unit)

let register_point ?trusted ?expected_peer_id pool ((addr, port) as point) =
  match P2p_point.Table.find pool.known_points point with
  | None ->
      let point_info =
        P2p_point_state.Info.create ?trusted ?expected_peer_id addr port
      in
      (* TODO: https://gitlab.com/tezos/tezos/-/issues/3175
         GC is off by one, it keeps one extra connection as it does not take
         into account the subsequent add.
      *)
      Option.iter
        (fun (max, _) ->
          if P2p_point.Table.length pool.known_points >= max then gc_points pool)
        pool.config.max_known_points ;
      P2p_point.Table.add pool.known_points point point_info ;
      P2p_trigger.broadcast_new_point pool.triggers ;
      pool.log (New_point point) ;
      point_info
  | Some point_info ->
      (match expected_peer_id with
      | Some peer_id ->
          Lwt.dont_wait
            (fun () -> set_expected_peer_id pool point peer_id)
            (fun _ -> ())
      | None -> ()) ;
      (match trusted with
      | Some true -> P2p_point_state.Info.set_trusted point_info
      | Some false -> P2p_point_state.Info.unset_trusted point_info
      | None -> ()) ;
      point_info

let unregister_point pool point = P2p_point.Table.remove pool.known_points point

let register_new_point ?trusted t point =
  if not (Point_LRU_set.mem t.my_id_points point) then
    Some (register_point ?trusted t point)
  else None

let register_list_of_new_points ?trusted ~medium ~source t point_list =
  let open Lwt_syntax in
  let* () = Event.(emit get_points) (medium, source, point_list) in
  let f point = register_new_point ?trusted t point |> ignore in
  Lwt.return (List.iter f point_list)

(* Bounded table used to garbage collect peer_id infos when needed. The
   strategy used is to remove the info of the peer_id with the lowest
   score first. In case of equality, the info of the most recent added
   peer_id is removed. The rationale behind this choice is that in the
   case of a flood attack, the newly added infos will probably belong
   to peer_ids with the same (low) score and removing the most recent ones
   ensure that older (and probably legit) peer_id infos are kept. *)
module Gc_peer_set = Bounded_heap.Make (struct
  type t = float * Time.System.t * P2p_peer.Id.t

  let compare (s, t, _) (s', t', _) =
    let score_cmp = Stdlib.compare s s' in
    if score_cmp = 0 then Time.System.compare t t' else -score_cmp
end)

let gc_peer_ids
    {
      peer_meta_config = {score; _};
      config = {max_known_peer_ids; _};
      known_peer_ids;
      log;
      _;
    } =
  match max_known_peer_ids with
  | None -> ()
  | Some (_, target) ->
      let current_size = P2p_peer.Table.length known_peer_ids in
      if current_size > target then (
        let to_remove_target = current_size - target in
        let table = Gc_peer_set.create to_remove_target in
        P2p_peer.Table.iter
          (fun peer_id peer_info ->
            let created = P2p_peer_state.Info.created peer_info in
            let score = score @@ P2p_peer_state.Info.peer_metadata peer_info in
            if
              P2p_peer_state.is_disconnected peer_info
              && not (P2p_peer_state.Info.trusted peer_info)
            then Gc_peer_set.insert (score, created, peer_id) table)
          known_peer_ids ;
        let to_remove = Gc_peer_set.get table in
        ListLabels.iter to_remove ~f:(fun (_, _, peer_id) ->
            P2p_peer.Table.remove known_peer_ids peer_id) ;
        log Gc_peer_ids)

let register_peer pool peer_id =
  match P2p_peer.Table.find pool.known_peer_ids peer_id with
  | None ->
      P2p_trigger.broadcast_new_peer pool.triggers ;
      let created = Time.System.now () in
      let peer =
        P2p_peer_state.Info.create
          ~created
          peer_id
          ~peer_metadata:(pool.peer_meta_config.peer_meta_initial ())
      in
      (* TODO: https://gitlab.com/tezos/tezos/-/issues/3175
         GC is off by one, it keeps one extra connection as it does not take
         into account the subsequent add.
      *)
      Option.iter
        (fun (max, _) ->
          if P2p_peer.Table.length pool.known_peer_ids >= max then
            gc_peer_ids pool)
        pool.config.max_known_peer_ids ;
      P2p_peer.Table.add pool.known_peer_ids peer_id peer ;
      pool.log (New_peer peer_id) ;
      peer
  | Some peer -> peer

(* this function duplicates bit of code from the modules below to avoid
   creating mutually recursive modules *)
let connection_of_peer_id pool peer_id =
  Option.bind (P2p_peer.Table.find pool.known_peer_ids peer_id) (fun p ->
      match P2p_peer_state.get p with
      | Running {data; _} -> Some data
      | _ -> None)

(* Every running connection matching the point's ip address is returned. *)
let connections_of_addr pool addr =
  P2p_point.Table.to_seq pool.connected_points
  |> Seq.filter_map (fun ((addr', _), p) ->
         if Ipaddr.V6.compare addr addr' = 0 then
           match P2p_point_state.get p with
           | P2p_point_state.Running {data; _} -> Some data
           | _ -> None
         else None)

let get_addr pool peer_id =
  Option.map
    (fun ci -> (P2p_conn.info ci).id_point)
    (connection_of_peer_id pool peer_id)

module Points = struct
  type ('msg, 'peer, 'conn) info =
    ('msg, 'peer, 'conn) P2p_conn.t P2p_point_state.Info.t

  let info {known_points; _} point = P2p_point.Table.find known_points point

  let get_trusted pool point =
    Option.fold
      ~none:false
      ~some:P2p_point_state.Info.trusted
      (P2p_point.Table.find pool.known_points point)

  let set_trusted pool point =
    ignore
    @@ register_point
         ~trusted:true
         ?expected_peer_id:(snd point)
         pool
         (fst point)

  let unset_trusted pool point =
    Option.iter
      P2p_point_state.Info.unset_trusted
      (P2p_point.Table.find pool.known_points point)

  let fold_known pool ~init ~f = P2p_point.Table.fold f pool.known_points init

  let iter_known f pool = P2p_point.Table.iter f pool.known_points

  let fold_connected pool ~init ~f =
    P2p_point.Table.fold f pool.connected_points init

  let add_connected t point point_info =
    P2p_point.Table.add t.connected_points point point_info

  let remove_connected t point_info =
    P2p_point.Table.remove
      t.connected_points
      (P2p_point_state.Info.point point_info)

  let banned pool (addr, _port) = P2p_acl.banned_addr pool.acl addr

  let ban pool ?(ban_peers = true) (addr, _port) =
    P2p_acl.IPBlacklist.add pool.acl addr ;
    (* Kick [addr]:* if it is in `Running` state. *)
    Seq.iter_p
      (fun conn ->
        if ban_peers then
          P2p_acl.PeerBlacklist.add pool.acl (P2p_conn.peer_id conn) ;
        P2p_conn.disconnect ~reason:IP_manually_banned conn)
      (connections_of_addr pool addr)

  let unban pool (addr, _port) =
    P2p_acl.unban_addr pool.acl addr ;
    Seq.iter
      (fun conn -> P2p_acl.unban_peer pool.acl (P2p_conn.peer_id conn))
      (connections_of_addr pool addr)

  let trust pool point =
    unban pool point ;
    set_trusted pool (point, None)

  let untrust pool point = unset_trusted pool point

  let get_greylisted_list pool = P2p_acl.IPGreylist.list pool.acl

  let greylisted_list_not_reliable_since pool =
    P2p_acl.IPGreylist.list_not_reliable_since pool.acl
end

module Peers = struct
  type ('msg, 'peer, 'conn) info =
    (('msg, 'peer, 'conn) P2p_conn.t, 'peer, 'conn) P2p_peer_state.Info.t

  let info {known_peer_ids; _} peer_id =
    P2p_peer.Table.find known_peer_ids peer_id

  let get_peer_metadata pool peer_id =
    match P2p_peer.Table.find pool.known_peer_ids peer_id with
    | Some peer -> P2p_peer_state.Info.peer_metadata peer
    | None -> pool.peer_meta_config.peer_meta_initial ()

  let get_score pool peer_id =
    pool.peer_meta_config.score (get_peer_metadata pool peer_id)

  let set_peer_metadata pool peer_id data =
    P2p_peer_state.Info.set_peer_metadata (register_peer pool peer_id) data

  let get_trusted pool peer_id =
    Option.fold
      (P2p_peer.Table.find pool.known_peer_ids peer_id)
      ~some:P2p_peer_state.Info.trusted
      ~none:false

  let set_trusted pool peer_id =
    P2p_peer_state.Info.set_trusted (register_peer pool peer_id)

  let unset_trusted pool peer_id =
    Option.iter
      P2p_peer_state.Info.unset_trusted
      (P2p_peer.Table.find pool.known_peer_ids peer_id)

  let fold_known pool ~init ~f = P2p_peer.Table.fold f pool.known_peer_ids init

  let iter_known f pool = P2p_peer.Table.iter f pool.known_peer_ids

  let fold_connected pool ~init ~f =
    P2p_peer.Table.fold f pool.connected_peer_ids init

  let iter_connected f pool = P2p_peer.Table.iter f pool.connected_peer_ids

  let add_connected pool peer_id peer_info =
    P2p_peer.Table.add pool.connected_peer_ids peer_id peer_info

  let remove_connected t peer_id =
    P2p_peer.Table.remove t.connected_peer_ids peer_id

  let ban pool peer =
    P2p_acl.PeerBlacklist.add pool.acl peer ;
    (* Kick [peer] if it is in `Running` state. *)
    match connection_of_peer_id pool peer with
    | Some conn -> P2p_conn.disconnect ~reason:Peer_id_manually_banned conn
    | None -> Lwt.return_unit

  let unban pool peer = P2p_acl.unban_peer pool.acl peer

  let trust pool peer =
    unban pool peer ;
    set_trusted pool peer

  let untrust pool peer = unset_trusted pool peer

  let banned pool peer = P2p_acl.banned_peer pool.acl peer

  let get_greylisted_list pool = P2p_acl.PeerGreylist.list pool.acl

  let find_by_peer_id pool peer_id =
    Option.bind (info pool peer_id) (fun p ->
        match P2p_peer_state.get p with
        | Running {data; _} -> Some data
        | _ -> None)

  let info_of_peer_info pool i =
    let open P2p_peer.Info in
    let open P2p_peer.State in
    let state, id_point =
      match P2p_peer_state.get i with
      | Accepted {current_point; _} -> (Accepted, Some current_point)
      | Running {current_point; _} -> (Running, Some current_point)
      | Disconnected -> (Disconnected, None)
    in
    let peer_id = P2p_peer_state.Info.peer_id i in
    let score = get_score pool peer_id in
    let conn_opt = find_by_peer_id pool peer_id in
    let stat =
      match conn_opt with
      | None -> P2p_stat.empty
      | Some conn -> P2p_conn.stat conn
    in
    let meta_opt = Option.map P2p_conn.remote_metadata conn_opt in
    P2p_peer_state.Info.
      {
        score;
        trusted = trusted i;
        conn_metadata = meta_opt;
        peer_metadata = peer_metadata i;
        state;
        id_point;
        stat;
        last_failed_connection = last_failed_connection i;
        last_rejected_connection = last_rejected_connection i;
        last_established_connection = last_established_connection i;
        last_disconnection = last_disconnection i;
        last_seen = last_seen i;
        last_miss = last_miss i;
      }
end

module Connection = struct
  let fold pool ~init ~f =
    Peers.fold_connected pool ~init ~f:(fun peer_id peer_info acc ->
        match P2p_peer_state.get peer_info with
        | Running {data; _} -> f peer_id data acc
        | _ -> acc)

  let iter f pool =
    Peers.iter_connected
      (fun peer_id peer_info ->
        match P2p_peer_state.get peer_info with
        | Running {data; _} -> f peer_id data
        | _ -> ())
      pool

  let list pool =
    fold pool ~init:[] ~f:(fun peer_id c acc -> (peer_id, c) :: acc)

  let random_elt = function
    | [] -> None
    | _ :: _ as l ->
        let n = List.length l in
        let r = Random.int n in
        List.nth l r

  let random_addr ?different_than ~no_private pool =
    let candidates =
      fold pool ~init:[] ~f:(fun _peer conn acc ->
          if no_private && P2p_conn.private_node conn then acc
          else
            match different_than with
            | Some excluded_conn when P2p_conn.equal_sock conn excluded_conn ->
                acc
            | Some _ | None -> (
                let ci = P2p_conn.info conn in
                match ci.id_point with
                | _, None -> acc
                | addr, Some port -> ((addr, port), ci.peer_id) :: acc))
    in
    random_elt candidates

  (** [random_connection ?conn no_private t] returns a random connection from
      the pool of connections. It ignores:
      - connections to private peers if [no_private] is set to [true]
      - connection [conn]
      Unlike [random_addr], it may return a connection to a peer who didn't
      provide a listening port *)
  let random_connection ?different_than ~no_private pool =
    let candidates =
      fold pool ~init:[] ~f:(fun _peer conn acc ->
          if no_private && P2p_conn.private_node conn then acc
          else
            match different_than with
            | Some excluded_conn when P2p_conn.equal_sock conn excluded_conn ->
                acc
            | Some _ | None -> conn :: acc)
    in
    random_elt candidates

  let propose_swap_request pool =
    let open Option_syntax in
    let* recipient = random_connection ~no_private:true pool in
    let* proposed_point, proposed_peer_id =
      random_addr ~different_than:recipient ~no_private:true pool
    in
    Some (proposed_point, proposed_peer_id, recipient)

  let find_by_peer_id pool peer_id =
    Option.bind (Peers.info pool peer_id) (fun p ->
        match P2p_peer_state.get p with
        | Running {data; _} -> Some data
        | _ -> None)

  let find_by_point pool point =
    Option.bind (Points.info pool point) (fun p ->
        match P2p_point_state.get p with
        | Running {data; _} -> Some data
        | _ -> None)
end

let connected_peer_ids pool = pool.connected_peer_ids

let greylist_peer pool peer =
  Option.iter
    (fun (addr, _port) ->
      greylist_addr pool addr ;
      P2p_acl.PeerGreylist.add pool.acl peer)
    (get_addr pool peer)

let acl_clear pool = P2p_acl.clear pool.acl

let clear_greylist pool = P2p_acl.IPGreylist.clear pool.acl

let gc_greylist pool = P2p_acl.IPGreylist.gc pool.acl

let config {config; _} = config

let score {peer_meta_config = {score; _}; _} meta = score meta

let active_connections pool = P2p_peer.Table.length pool.connected_peer_ids

let create config peer_meta_config triggers ~log =
  let open Lwt_syntax in
  let pool =
    {
      config;
      peer_meta_config;
      my_id_points = Point_LRU_set.create 7;
      known_peer_ids = P2p_peer.Table.create ~random:true 53;
      connected_peer_ids = P2p_peer.Table.create ~random:true 53;
      known_points = P2p_point.Table.create ~random:true 53;
      connected_points = P2p_point.Table.create ~random:true 53;
      triggers;
      acl =
        P2p_acl.create
          ~peer_id_size:config.peer_greylist_size
          ~ip_size:config.ip_greylist_size_in_kilobytes
          ~ip_cleanup_delay:config.ip_greylist_cleanup_delay;
      log;
    }
  in
  List.iter (Points.set_trusted pool) config.trusted_points ;
  let* r =
    P2p_peer_state.Info.File.load
      config.peers_file
      peer_meta_config.peer_meta_encoding
  in
  match r with
  | Ok peer_ids ->
      let* () =
        Event.(emit create_pool)
          (pool.known_points |> P2p_point.Table.to_seq_keys |> List.of_seq)
      in
      List.iter
        (fun peer_info ->
          let peer_id = P2p_peer_state.Info.peer_id peer_info in
          P2p_peer.Table.add pool.known_peer_ids peer_id peer_info ;
          match P2p_peer_state.Info.last_seen peer_info with
          | None | Some ((_, None) (* no reachable port stored*), _) -> ()
          | Some ((addr, Some port), _) ->
              register_point pool (addr, port) |> ignore)
        peer_ids ;
      Lwt.return pool
  | Error err ->
      let* () = Event.(emit parse_error) err in
      Lwt.return pool

let save_peers {config; peer_meta_config; known_peer_ids; _} =
  let open Lwt_syntax in
  let* () = Event.(emit saving_metadata) config.peers_file in
  let* r =
    P2p_peer_state.Info.File.save
      config.peers_file
      peer_meta_config.peer_meta_encoding
      (P2p_peer.Table.fold (fun _ a b -> a :: b) known_peer_ids [])
  in
  Result.iter_error_s Event.(emit save_peers_error) r

let tear_down_connections ~reason {known_peer_ids; known_points; _} =
  let open Lwt_syntax in
  let* () =
    P2p_peer.Table.iter_p
      (fun _peer_id peer_info ->
        match P2p_peer_state.get peer_info with
        | Accepted {cancel; _} -> Error_monad.cancel_with_exceptions cancel
        | Running {data = conn; _} -> P2p_conn.disconnect ~reason conn
        | Disconnected -> Lwt.return_unit)
      known_peer_ids
  in
  P2p_point.Table.iter_p
    (fun _point point_info ->
      match P2p_point_state.get point_info with
      | Requested {cancel} | Accepted {cancel; _} ->
          Error_monad.cancel_with_exceptions cancel
      | Running {data = conn; _} -> P2p_conn.disconnect ~reason conn
      | Disconnected -> Lwt.return_unit)
    known_points

let destroy pool =
  let open Lwt_syntax in
  let* () = save_peers pool in
  tear_down_connections ~reason:Pool_destroyed pool

let add_to_id_points t point =
  Point_LRU_set.add t.my_id_points point ;
  P2p_point.Table.remove t.known_points point

(* [sample best other points] return a list of elements selected in [points].
   The [best] first elements are taken, then [other] elements are chosen
   randomly in the rest of the list.
   Note that it might select fewer elements than [other] if it the same index
   close to the end of the list is picked multiple times.

   @raise Invalid_argument if either [best] or [other] is strictly negative.
*)
let sample best other points =
  if best < 0 || other < 0 then raise (Invalid_argument "P2p_pool.sample") ;
  let l = List.length points in
  if l <= best + other then points
  else
    (* This is safe because we checked the value of [best] and [other] *)
    let list_init n f =
      WithExceptions.Result.get_ok ~loc:__LOC__
      @@ List.init ~when_negative_length:() n f
    in
    let best_indexes = list_init best Fun.id in
    let other_indexes =
      List.sort compare
      @@ list_init other (fun _ -> best + Random.int (l - best))
    in
    let indexes = best_indexes @ other_indexes in
    (* Note: we are doing a [fold_left_i] by hand, passing [i] manually *)
    List.fold_left_e (* [_e] is for early return *)
      (fun (i, indexes, acc) point ->
        match indexes with
        | [] -> Error acc (* early return *)
        | index :: indexes when i >= index ->
            (* We compare `i >= index` (rather than `i = index`) to avoid a
                corner case whereby two identical `index`es are present in the
                list. In that case, using `>=` makes it so that if `i` overtakes
                `index` we still pick elements. *)
            Ok (succ i, indexes, point :: acc)
        | _ -> Ok (succ i, indexes, acc))
      (0, indexes, [])
      points
    |> function
    | Ok (_, _, result) | Error result -> result

let compare_known_point_info p1 p2 =
  (* The most-recently disconnected peers are greater. *)
  (* Then come long-standing connected peers. *)
  let disconnected1 = P2p_point_state.is_disconnected p1
  and disconnected2 = P2p_point_state.is_disconnected p2 in
  let compare_last_seen p1 p2 =
    match
      (P2p_point_state.Info.last_seen p1, P2p_point_state.Info.last_seen p2)
    with
    | None, None -> (Random.int 2 * 2) - 1 (* HACK... *)
    | Some _, None -> 1
    | None, Some _ -> -1
    | Some (_, time1), Some (_, time2) -> (
        match compare time1 time2 with
        | 0 -> (Random.int 2 * 2) - 1 (* HACK... *)
        | x -> x)
  in
  match (disconnected1, disconnected2) with
  | false, false -> compare_last_seen p1 p2
  | false, true -> -1
  | true, false -> 1
  | true, true -> compare_last_seen p2 p1

let list_known_points ~ignore_private ?(size = 50) pool =
  if size < 0 then Lwt.fail (Invalid_argument "P2p_pool.list_known_points")
  else
    let other = size * 2 / 5 in
    let best = size - other in
    P2p_point.Table.fold
      (fun point_id point_info acc ->
        if
          (ignore_private && not (P2p_point_state.Info.known_public point_info))
          || Points.banned pool point_id
        then acc
        else point_info :: acc)
      pool.known_points
      []
    |> List.sort compare_known_point_info
    |> sample best other
    |> List.map P2p_point_state.Info.point
    |> Lwt.return

module Internal_for_tests = struct
  let dumb_config : config =
    let identity = P2p_identity.generate_with_pow_target_0 () in
    let trusted_points = [(P2p_point.Id.of_string_exn "0.0.0.0:0", None)] in
    let peers_file = "/dev/null" in
    let private_mode = true in
    let max_known_points = Some (400, 300) in
    let max_known_peer_ids = Some (400, 300) in
    let peer_greylist_size = 100 in
    let ip_greylist_size_in_kilobytes = 1024 in
    let ip_greylist_cleanup_delay = Time.System.Span.of_seconds_exn 60. in
    {
      identity;
      trusted_points;
      peers_file;
      private_mode;
      max_known_points;
      max_known_peer_ids;
      peer_greylist_size;
      ip_greylist_size_in_kilobytes;
      ip_greylist_cleanup_delay;
    }

  let create peer_meta_encoding initial_peer =
    let triggers = P2p_trigger.create () in
    let config = dumb_config in
    let peer_meta_config : 'peer P2p_params.peer_meta_config =
      {
        peer_meta_encoding;
        peer_meta_initial = (fun () -> initial_peer);
        score = (fun _ -> 0.);
      }
    in
    let watcher = Lwt_watcher.create_input () in
    let log event = Lwt_watcher.notify watcher event in
    {
      config;
      peer_meta_config;
      my_id_points = Point_LRU_set.create 7;
      known_peer_ids = P2p_peer.Table.create ~random:true 53;
      connected_peer_ids = P2p_peer.Table.create ~random:true 53;
      known_points = P2p_point.Table.create ~random:true 53;
      connected_points = P2p_point.Table.create ~random:true 53;
      triggers;
      acl =
        P2p_acl.create
          ~peer_id_size:config.peer_greylist_size
          ~ip_size:config.ip_greylist_size_in_kilobytes
          ~ip_cleanup_delay:config.ip_greylist_cleanup_delay;
      log;
    }
end