(*****************************************************************************)
(*                                                                           *)
(* Open Source License                                                       *)
(* Copyright (c) 2018 Dynamic Ledger Solutions, Inc. <contact@tezos.com>     *)
(*                                                                           *)
(* Permission is hereby granted, free of charge, to any person obtaining a   *)
(* copy of this software and associated documentation files (the "Software"),*)
(* to deal in the Software without restriction, including without limitation *)
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(* Software is furnished to do so, subject to the following conditions:      *)
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(* DEALINGS IN THE SOFTWARE.                                                 *)
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(*****************************************************************************)

type kind = Proposal | Exploration | Cooldown | Promotion | Adoption

let string_of_kind = function
  | Proposal -> "proposal"
  | Exploration -> "exploration"
  | Cooldown -> "cooldown"
  | Promotion -> "promotion"
  | Adoption -> "adoption"

let pp_kind ppf kind = Format.fprintf ppf "%s" @@ string_of_kind kind

let kind_encoding =
  let open Data_encoding in
  union
    ~tag_size:`Uint8
    [
      case
        (Tag 0)
        ~title:"Proposal"
        (constant "proposal")
        (function Proposal -> Some () | _ -> None)
        (fun () -> Proposal);
      case
        (Tag 1)
        ~title:"exploration"
        (constant "exploration")
        (function Exploration -> Some () | _ -> None)
        (fun () -> Exploration);
      case
        (Tag 2)
        ~title:"Cooldown"
        (constant "cooldown")
        (function Cooldown -> Some () | _ -> None)
        (fun () -> Cooldown);
      case
        (Tag 3)
        ~title:"Promotion"
        (constant "promotion")
        (function Promotion -> Some () | _ -> None)
        (fun () -> Promotion);
      case
        (Tag 4)
        ~title:"Adoption"
        (constant "adoption")
        (function Adoption -> Some () | _ -> None)
        (fun () -> Adoption);
    ]

let succ_kind = function
  | Proposal -> Exploration
  | Exploration -> Cooldown
  | Cooldown -> Promotion
  | Promotion -> Adoption
  | Adoption -> Proposal

type voting_period = {index : int32; kind : kind; start_position : int32}

type t = voting_period

type info = {voting_period : t; position : int32; remaining : int32}

let root ~start_position = {index = 0l; kind = Proposal; start_position}

let pp ppf {index; kind; start_position} =
  Format.fprintf
    ppf
    "@[<hv 2>index: %ld,@ kind:%a,@ start_position: %ld@]"
    index
    pp_kind
    kind
    start_position

let pp_info ppf {voting_period; position; remaining} =
  Format.fprintf
    ppf
    "@[<hv 2>voting_period: %a,@ position:%ld,@ remaining: %ld@]"
    pp
    voting_period
    position
    remaining

let encoding =
  let open Data_encoding in
  conv
    (fun {index; kind; start_position} -> (index, kind, start_position))
    (fun (index, kind, start_position) -> {index; kind; start_position})
    (obj3
       (req
          "index"
          ~description:
            "The voting period's index. Starts at 0 with the first block of \
             the Alpha family of protocols."
          int32)
       (req
          ~description:
            "One of the several kinds of periods in the voting procedure."
          "kind"
          kind_encoding)
       (req
          ~description:
            "The relative position of the first level of the period with \
             respect to the first level of the Alpha family of protocols."
          "start_position"
          int32))

let info_encoding =
  let open Data_encoding in
  conv
    (fun {voting_period; position; remaining} ->
      (voting_period, position, remaining))
    (fun (voting_period, position, remaining) ->
      {voting_period; position; remaining})
    (obj3
       (req
          ~description:"The voting period to which the block belongs."
          "voting_period"
          encoding)
       (req
          ~description:"The position of the block within the voting period."
          "position"
          int32)
       (req
          ~description:
            "The number of blocks remaining till the end of the voting period."
          "remaining"
          int32))

include Compare.Make (struct
  type nonrec t = t

  let compare p p' = Compare.Int32.compare p.index p'.index
end)

let raw_reset period ~start_position =
  let index = Int32.succ period.index in
  let kind = Proposal in
  {index; kind; start_position}

let raw_succ period ~start_position =
  let index = Int32.succ period.index in
  let kind = succ_kind period.kind in
  {index; kind; start_position}

let position_since (level : Level_repr.t) (voting_period : t) =
  Int32.(sub level.level_position voting_period.start_position)

let remaining_blocks (level : Level_repr.t) (voting_period : t)
    ~blocks_per_voting_period =
  let position = position_since level voting_period in
  Int32.(sub blocks_per_voting_period (succ position))