(*****************************************************************************)
(*                                                                           *)
(* Open Source License                                                       *)
(* Copyright (c) 2021 Nomadic Labs, <contact@nomadic-labs.com>               *)
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module Selected_distribution_for_cycle = struct
  module Cache_client = struct
    type cached_value = (Signature.Public_key_hash.t * Stake_repr.t) list

    let namespace = Cache_repr.create_namespace "stake_distribution"

    let cache_index = 1

    let value_of_identifier ctxt identifier =
      let cycle = Cycle_repr.of_string_exn identifier in
      Storage.Stake.Selected_distribution_for_cycle.get ctxt cycle
  end

  module Cache = (val Cache_repr.register_exn (module Cache_client))

  let identifier_of_cycle cycle = Format.asprintf "%a" Cycle_repr.pp cycle

  let init ctxt cycle stakes =
    let open Lwt_result_syntax in
    let id = identifier_of_cycle cycle in
    let* ctxt =
      Storage.Stake.Selected_distribution_for_cycle.init ctxt cycle stakes
    in
    let size = 1 (* that's symbolic: 1 cycle = 1 entry *) in
    let*? ctxt = Cache.update ctxt id (Some (stakes, size)) in
    return ctxt

  let get ctxt cycle =
    let open Lwt_result_syntax in
    let id = identifier_of_cycle cycle in
    let* value_opt = Cache.find ctxt id in
    match value_opt with
    | None -> Storage.Stake.Selected_distribution_for_cycle.get ctxt cycle
    | Some v -> return v

  let find ctxt cycle =
    let open Lwt_result_syntax in
    let id = identifier_of_cycle cycle in
    let* value_opt = Cache.find ctxt id in
    match value_opt with
    | None -> Storage.Stake.Selected_distribution_for_cycle.find ctxt cycle
    | Some _ as some_v -> return some_v

  let remove_existing ctxt cycle =
    let open Lwt_result_syntax in
    let id = identifier_of_cycle cycle in
    let*? ctxt = Cache.update ctxt id None in
    Storage.Stake.Selected_distribution_for_cycle.remove_existing ctxt cycle
end

let get_full_staking_balance ctxt delegate =
  let open Lwt_result_syntax in
  let+ staking_balance_opt = Storage.Stake.Staking_balance.find ctxt delegate in
  Option.value staking_balance_opt ~default:Full_staking_balance_repr.zero

let get_initialized_stake ctxt delegate =
  let open Lwt_result_syntax in
  let* balance_opt = Storage.Stake.Staking_balance.find ctxt delegate in
  match balance_opt with
  | Some staking_balance -> return (staking_balance, ctxt)
  | None ->
      let balance = Full_staking_balance_repr.zero in
      let* ctxt = Storage.Stake.Staking_balance.init ctxt delegate balance in
      return (balance, ctxt)

let has_minimal_stake ctxt
    {Full_staking_balance_repr.own_frozen; staked_frozen; delegated} =
  let open Result_syntax in
  let open Tez_repr in
  let minimal_stake = Constants_storage.minimal_stake ctxt in
  let sum =
    let* frozen = own_frozen +? staked_frozen in
    frozen +? delegated
  in
  match sum with
  | Error _sum_overflows ->
      true (* If the sum overflows, we are definitely over the minimal stake. *)
  | Ok staking_balance -> Tez_repr.(staking_balance >= minimal_stake)

let has_minimal_stake_and_frozen_stake ctxt
    ({own_frozen; _} as full_staking_balance : Full_staking_balance_repr.t) =
  let minimal_frozen_stake = Constants_storage.minimal_frozen_stake ctxt in
  Tez_repr.(own_frozen >= minimal_frozen_stake)
  && has_minimal_stake ctxt full_staking_balance

let update_stake ~f ctxt delegate =
  let open Lwt_result_syntax in
  let* staking_balance_before, ctxt = get_initialized_stake ctxt delegate in
  let*? staking_balance = f staking_balance_before in
  let* ctxt =
    Storage.Stake.Staking_balance.update ctxt delegate staking_balance
  in
  (* Since the staking balance has changed, the delegate might have
     moved across the minimal stake barrier. If so we may need to
     update the set of active delegates with minimal stake. *)
  let had_minimal_stake_before =
    has_minimal_stake ctxt staking_balance_before
  in
  let has_minimal_stake_after = has_minimal_stake ctxt staking_balance in
  match (had_minimal_stake_before, has_minimal_stake_after) with
  | true, false ->
      (* Decrease below the minimal stake. *)
      let* inactive = Delegate_activation_storage.is_inactive ctxt delegate in
      if inactive then
        (* The delegate is inactive so it wasn't in the set and we
           don't need to update it. *)
        return ctxt
      else
        let*! ctxt =
          Storage.Stake.Active_delegates_with_minimal_stake.remove ctxt delegate
        in
        return ctxt
  | false, true ->
      (* Increase above the minimal stake. *)
      let* inactive = Delegate_activation_storage.is_inactive ctxt delegate in
      if inactive then
        (* The delegate is inactive so we don't need to add it to the
           set. *)
        return ctxt
      else
        let*! ctxt =
          Storage.Stake.Active_delegates_with_minimal_stake.add ctxt delegate ()
        in
        return ctxt
  | false, false | true, true -> return ctxt

let remove_delegated_stake ctxt delegate amount =
  let open Result_syntax in
  update_stake ctxt delegate ~f:(fun {own_frozen; staked_frozen; delegated} ->
      let+ delegated = Tez_repr.(delegated -? amount) in
      Full_staking_balance_repr.make ~own_frozen ~staked_frozen ~delegated)

let remove_own_frozen_stake ctxt delegate amount =
  let open Result_syntax in
  update_stake ctxt delegate ~f:(fun {own_frozen; staked_frozen; delegated} ->
      let+ own_frozen = Tez_repr.(own_frozen -? amount) in
      Full_staking_balance_repr.make ~own_frozen ~staked_frozen ~delegated)

let remove_staked_frozen_stake ctxt delegate amount =
  let open Result_syntax in
  update_stake ctxt delegate ~f:(fun {own_frozen; staked_frozen; delegated} ->
      let+ staked_frozen = Tez_repr.(staked_frozen -? amount) in
      Full_staking_balance_repr.make ~own_frozen ~staked_frozen ~delegated)

let remove_shared_frozen_stake ctxt delegate amount =
  let open Result_syntax in
  update_stake ctxt delegate ~f:(fun {own_frozen; staked_frozen; delegated} ->
      if Tez_repr.(staked_frozen = zero) then
        let+ own_frozen = Tez_repr.(own_frozen -? amount) in
        Full_staking_balance_repr.make ~own_frozen ~staked_frozen ~delegated
      else
        let* total_frozen = Tez_repr.(own_frozen +? staked_frozen) in
        let* own_part =
          Tez_repr.mul_ratio
            amount
            ~num:(Tez_repr.to_mutez own_frozen)
            ~den:(Tez_repr.to_mutez total_frozen)
        in
        let* own_frozen = Tez_repr.(own_frozen -? own_part) in
        let* staked_part = Tez_repr.(amount -? own_part) in
        let+ staked_frozen = Tez_repr.(staked_frozen -? staked_part) in
        Full_staking_balance_repr.make ~own_frozen ~staked_frozen ~delegated)

let remove_frozen_stake ctxt staker amount =
  match staker with
  | Staker_repr.Single (contract, delegate)
    when Contract_repr.(contract = Implicit delegate) ->
      remove_own_frozen_stake ctxt delegate amount
  | Single (_staker, delegate) ->
      remove_staked_frozen_stake ctxt delegate amount
  | Shared delegate -> remove_shared_frozen_stake ctxt delegate amount

let add_delegated_stake ctxt delegate amount =
  let open Result_syntax in
  update_stake ctxt delegate ~f:(fun {own_frozen; staked_frozen; delegated} ->
      let+ delegated = Tez_repr.(delegated +? amount) in
      Full_staking_balance_repr.make ~own_frozen ~staked_frozen ~delegated)

let add_own_frozen_stake ctxt delegate amount =
  let open Result_syntax in
  update_stake ctxt delegate ~f:(fun {own_frozen; staked_frozen; delegated} ->
      let+ own_frozen = Tez_repr.(own_frozen +? amount) in
      Full_staking_balance_repr.make ~own_frozen ~staked_frozen ~delegated)

let add_staked_frozen_stake ctxt delegate amount =
  let open Result_syntax in
  update_stake ctxt delegate ~f:(fun {own_frozen; staked_frozen; delegated} ->
      let+ staked_frozen = Tez_repr.(staked_frozen +? amount) in
      Full_staking_balance_repr.make ~own_frozen ~staked_frozen ~delegated)

let add_shared_frozen_stake ctxt delegate amount =
  let open Result_syntax in
  update_stake ctxt delegate ~f:(fun {own_frozen; staked_frozen; delegated} ->
      if Tez_repr.(staked_frozen = zero) then
        let+ own_frozen = Tez_repr.(own_frozen +? amount) in
        Full_staking_balance_repr.make ~own_frozen ~staked_frozen ~delegated
      else
        let* total_frozen = Tez_repr.(own_frozen +? staked_frozen) in
        let* own_part =
          Tez_repr.mul_ratio
            amount
            ~num:(Tez_repr.to_mutez own_frozen)
            ~den:(Tez_repr.to_mutez total_frozen)
        in
        let* own_frozen = Tez_repr.(own_frozen +? own_part) in
        let* staked_part = Tez_repr.(amount -? own_part) in
        let+ staked_frozen = Tez_repr.(staked_frozen +? staked_part) in
        Full_staking_balance_repr.make ~own_frozen ~staked_frozen ~delegated)

let add_frozen_stake ctxt staker amount =
  match staker with
  | Staker_repr.Single (contract, delegate)
    when Contract_repr.(contract = Implicit delegate) ->
      add_own_frozen_stake ctxt delegate amount
  | Single (_staker, delegate) -> add_staked_frozen_stake ctxt delegate amount
  | Shared delegate -> add_shared_frozen_stake ctxt delegate amount

let set_inactive ctxt delegate =
  let open Lwt_syntax in
  let* ctxt = Delegate_activation_storage.set_inactive ctxt delegate in
  Storage.Stake.Active_delegates_with_minimal_stake.remove ctxt delegate

let set_active ctxt delegate =
  let open Lwt_result_syntax in
  let* ctxt, inactive = Delegate_activation_storage.set_active ctxt delegate in
  if not inactive then return ctxt
  else
    let* staking_balance, ctxt = get_initialized_stake ctxt delegate in
    if has_minimal_stake ctxt staking_balance then
      let*! ctxt =
        Storage.Stake.Active_delegates_with_minimal_stake.add ctxt delegate ()
      in
      return ctxt
    else return ctxt

let snapshot ctxt =
  let open Lwt_result_syntax in
  let* index = Storage.Stake.Last_snapshot.get ctxt in
  let* ctxt = Storage.Stake.Last_snapshot.update ctxt (index + 1) in
  let* ctxt = Storage.Stake.Staking_balance.snapshot ctxt index in
  Storage.Stake.Active_delegates_with_minimal_stake.snapshot ctxt index

let max_snapshot_index = Storage.Stake.Last_snapshot.get

let set_selected_distribution_for_cycle ctxt cycle stakes total_stake =
  let open Lwt_result_syntax in
  let stakes = List.sort (fun (_, x) (_, y) -> Stake_repr.compare y x) stakes in
  let* ctxt = Selected_distribution_for_cycle.init ctxt cycle stakes in
  let*! ctxt = Storage.Stake.Total_active_stake.add ctxt cycle total_stake in
  (* cleanup snapshots *)
  let*! ctxt = Storage.Stake.Staking_balance.Snapshot.clear ctxt in
  let*! ctxt =
    Storage.Stake.Active_delegates_with_minimal_stake.Snapshot.clear ctxt
  in
  Storage.Stake.Last_snapshot.update ctxt 0

let clear_cycle ctxt cycle =
  let open Lwt_result_syntax in
  let* ctxt = Storage.Stake.Total_active_stake.remove_existing ctxt cycle in
  Selected_distribution_for_cycle.remove_existing ctxt cycle

let fold_on_active_delegates_with_minimal_stake_es ctxt ~f ~order ~init =
  let open Lwt_result_syntax in
  Storage.Stake.Active_delegates_with_minimal_stake.fold
    ctxt
    ~order
    ~init:(Ok init)
    ~f:(fun delegate () acc ->
      let*? acc in
      f delegate acc)

let fold_snapshot ctxt ~index ~f ~init =
  let open Lwt_result_syntax in
  Storage.Stake.Active_delegates_with_minimal_stake.fold_snapshot
    ctxt
    index
    ~order:`Sorted
    ~init
    ~f:(fun delegate () acc ->
      let* stake =
        Storage.Stake.Staking_balance.Snapshot.get ctxt (index, delegate)
      in
      f (delegate, stake) acc)

let clear_at_cycle_end ctxt ~new_cycle =
  let max_slashing_period = Constants_repr.max_slashing_period in
  match Cycle_repr.sub new_cycle max_slashing_period with
  | None -> return ctxt
  | Some cycle_to_clear -> clear_cycle ctxt cycle_to_clear

let fold_on_active_delegates_with_minimal_stake_s =
  Storage.Stake.Active_delegates_with_minimal_stake.fold

let get_selected_distribution = Selected_distribution_for_cycle.get

let find_selected_distribution = Selected_distribution_for_cycle.find

let prepare_stake_distribution ctxt =
  let open Lwt_result_syntax in
  let level = Level_storage.current ctxt in
  let* stakes = Selected_distribution_for_cycle.get ctxt level.cycle in
  let stake_distribution =
    List.fold_left
      (fun map (pkh, stake) -> Signature.Public_key_hash.Map.add pkh stake map)
      Signature.Public_key_hash.Map.empty
      stakes
  in
  return
    (Raw_context.init_stake_distribution_for_current_cycle
       ctxt
       stake_distribution)

let get_total_active_stake = Storage.Stake.Total_active_stake.get

let remove_contract_delegated_stake ctxt contract amount =
  let open Lwt_result_syntax in
  let* delegate_opt = Contract_delegate_storage.find ctxt contract in
  match delegate_opt with
  | None -> return ctxt
  | Some delegate -> remove_delegated_stake ctxt delegate amount

let add_contract_delegated_stake ctxt contract amount =
  let open Lwt_result_syntax in
  let* delegate_opt = Contract_delegate_storage.find ctxt contract in
  match delegate_opt with
  | None -> return ctxt
  | Some delegate -> add_delegated_stake ctxt delegate amount

module For_RPC = struct
  let get_staking_balance ctxt delegate =
    let open Lwt_result_syntax in
    let* {own_frozen; staked_frozen; delegated} =
      Storage.Stake.Staking_balance.get ctxt delegate
    in
    let*? frozen = Tez_repr.(own_frozen +? staked_frozen) in
    let*? staking_balance = Tez_repr.(frozen +? delegated) in
    return staking_balance
end

module Internal_for_tests = struct
  let get ctxt delegate =
    let open Lwt_result_syntax in
    let*! result =
      Storage.Stake.Active_delegates_with_minimal_stake.mem ctxt delegate
    in
    match result with
    | true -> For_RPC.get_staking_balance ctxt delegate
    | false -> return Tez_repr.zero
end