(*****************************************************************************)
(*                                                                           *)
(* Open Source License                                                       *)
(* Copyright (c) 2018 Dynamic Ledger Solutions, Inc. <contact@tezos.com>     *)
(* Copyright (c) 2020 Nomadic Labs <contact@nomadic-labs.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 *)
(* the rights to use, copy, modify, merge, publish, distribute, sublicense,  *)
(* and/or sell copies of the Software, and to permit persons to whom the     *)
(* Software is furnished to do so, subject to the following conditions:      *)
(*                                                                           *)
(* The above copyright notice and this permission notice shall be included   *)
(* in all copies or substantial portions of the Software.                    *)
(*                                                                           *)
(* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR*)
(* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,  *)
(* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL   *)
(* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER*)
(* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING   *)
(* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER       *)
(* DEALINGS IN THE SOFTWARE.                                                 *)
(*                                                                           *)
(*****************************************************************************)

let id = "tez"

let name = "mutez"

include Compare.Int64 (* invariant: positive *)

type error +=
  | Addition_overflow of t * t (* `Temporary *)
  | Subtraction_underflow of t * t (* `Temporary *)
  | Multiplication_overflow of t * int64 (* `Temporary *)
  | Negative_multiplicator of t * int64 (* `Temporary *)
  | Invalid_divisor of t * int64

(* `Temporary *)

let zero = 0L

(* all other constant are defined from the value of one micro tez *)
let one_mutez = 1L

let one_cent = Int64.mul one_mutez 10_000L

let fifty_cents = Int64.mul one_cent 50L

(* 1 tez = 100 cents = 1_000_000 mutez *)
let one = Int64.mul one_cent 100L

let of_string s =
  let triplets = function
    | hd :: tl ->
        let len = String.length hd in
        Compare.Int.(
          len <= 3 && len > 0 && List.for_all (fun s -> String.length s = 3) tl)
    | [] ->
        false
  in
  let integers s = triplets (String.split_on_char ',' s) in
  let decimals s =
    let l = String.split_on_char ',' s in
    if Compare.Int.(List.length l > 2) then false else triplets (List.rev l)
  in
  let parse left right =
    let remove_commas s = String.concat "" (String.split_on_char ',' s) in
    let pad_to_six s =
      let len = String.length s in
      String.init 6 (fun i -> if Compare.Int.(i < len) then s.[i] else '0')
    in
    Int64.of_string_opt (remove_commas left ^ pad_to_six (remove_commas right))
  in
  match String.split_on_char '.' s with
  | [left; right] ->
      if String.contains s ',' then
        if integers left && decimals right then parse left right else None
      else if
        Compare.Int.(String.length right > 0)
        && Compare.Int.(String.length right <= 6)
      then parse left right
      else None
  | [left] ->
      if (not (String.contains s ',')) || integers left then parse left ""
      else None
  | _ ->
      None

let pp ppf amount =
  let mult_int = 1_000_000L in
  let rec left ppf amount =
    let (d, r) = (Int64.(div amount 1000L), Int64.(rem amount 1000L)) in
    if d > 0L then Format.fprintf ppf "%a%03Ld" left d r
    else Format.fprintf ppf "%Ld" r
  in
  let right ppf amount =
    let triplet ppf v =
      if Compare.Int.(v mod 10 > 0) then Format.fprintf ppf "%03d" v
      else if Compare.Int.(v mod 100 > 0) then
        Format.fprintf ppf "%02d" (v / 10)
      else Format.fprintf ppf "%d" (v / 100)
    in
    let (hi, lo) = (amount / 1000, amount mod 1000) in
    if Compare.Int.(lo = 0) then Format.fprintf ppf "%a" triplet hi
    else Format.fprintf ppf "%03d%a" hi triplet lo
  in
  let (ints, decs) =
    (Int64.(div amount mult_int), Int64.(to_int (rem amount mult_int)))
  in
  left ppf ints ;
  if Compare.Int.(decs > 0) then Format.fprintf ppf ".%a" right decs

let to_string t = Format.asprintf "%a" pp t

let ( -? ) t1 t2 =
  if t2 <= t1 then ok (Int64.sub t1 t2)
  else error (Subtraction_underflow (t1, t2))

let ( +? ) t1 t2 =
  let t = Int64.add t1 t2 in
  if t < t1 then error (Addition_overflow (t1, t2)) else ok t

let ( *? ) t m =
  let open Compare.Int64 in
  let open Int64 in
  let rec step cur pow acc =
    if cur = 0L then ok acc
    else
      pow +? pow
      >>? fun npow ->
      if logand cur 1L = 1L then
        acc +? pow >>? fun nacc -> step (shift_right_logical cur 1) npow nacc
      else step (shift_right_logical cur 1) npow acc
  in
  if m < 0L then error (Negative_multiplicator (t, m))
  else record_trace (Multiplication_overflow (t, m)) @@ step m t 0L

let ( /? ) t d =
  if d <= 0L then error (Invalid_divisor (t, d)) else ok (Int64.div t d)

let mul_exn t m =
  match t *? Int64.(of_int m) with
  | Ok v ->
      v
  | Error _ ->
      invalid_arg "mul_exn"

let of_mutez t = if t < 0L then None else Some t

let of_mutez_exn x =
  match of_mutez x with None -> invalid_arg "Tez.of_mutez" | Some v -> v

let to_int64 t = t

let to_mutez t = t

let encoding =
  let open Data_encoding in
  Data_encoding.def
    name
    (check_size 10 (conv Z.of_int64 (Json.wrap_error Z.to_int64) n))

let () =
  let open Data_encoding in
  register_error_kind
    `Temporary
    ~id:(id ^ ".addition_overflow")
    ~title:("Overflowing " ^ id ^ " addition")
    ~pp:(fun ppf (opa, opb) ->
      Format.fprintf
        ppf
        "Overflowing addition of %a %s and %a %s"
        pp
        opa
        id
        pp
        opb
        id)
    ~description:("An addition of two " ^ id ^ " amounts overflowed")
    (obj1 (req "amounts" (tup2 encoding encoding)))
    (function Addition_overflow (a, b) -> Some (a, b) | _ -> None)
    (fun (a, b) -> Addition_overflow (a, b)) ;
  register_error_kind
    `Temporary
    ~id:(id ^ ".subtraction_underflow")
    ~title:("Underflowing " ^ id ^ " subtraction")
    ~pp:(fun ppf (opa, opb) ->
      Format.fprintf
        ppf
        "Underflowing subtraction of %a %s and %a %s"
        pp
        opa
        id
        pp
        opb
        id)
    ~description:("An subtraction of two " ^ id ^ " amounts underflowed")
    (obj1 (req "amounts" (tup2 encoding encoding)))
    (function Subtraction_underflow (a, b) -> Some (a, b) | _ -> None)
    (fun (a, b) -> Subtraction_underflow (a, b)) ;
  register_error_kind
    `Temporary
    ~id:(id ^ ".multiplication_overflow")
    ~title:("Overflowing " ^ id ^ " multiplication")
    ~pp:(fun ppf (opa, opb) ->
      Format.fprintf
        ppf
        "Overflowing multiplication of %a %s and %Ld"
        pp
        opa
        id
        opb)
    ~description:
      ("A multiplication of a " ^ id ^ " amount by an integer overflowed")
    (obj2 (req "amount" encoding) (req "multiplicator" int64))
    (function Multiplication_overflow (a, b) -> Some (a, b) | _ -> None)
    (fun (a, b) -> Multiplication_overflow (a, b)) ;
  register_error_kind
    `Temporary
    ~id:(id ^ ".negative_multiplicator")
    ~title:("Negative " ^ id ^ " multiplicator")
    ~pp:(fun ppf (opa, opb) ->
      Format.fprintf
        ppf
        "Multiplication of %a %s by negative integer %Ld"
        pp
        opa
        id
        opb)
    ~description:("Multiplication of a " ^ id ^ " amount by a negative integer")
    (obj2 (req "amount" encoding) (req "multiplicator" int64))
    (function Negative_multiplicator (a, b) -> Some (a, b) | _ -> None)
    (fun (a, b) -> Negative_multiplicator (a, b)) ;
  register_error_kind
    `Temporary
    ~id:(id ^ ".invalid_divisor")
    ~title:("Invalid " ^ id ^ " divisor")
    ~pp:(fun ppf (opa, opb) ->
      Format.fprintf
        ppf
        "Division of %a %s by non positive integer %Ld"
        pp
        opa
        id
        opb)
    ~description:
      ("Multiplication of a " ^ id ^ " amount by a non positive integer")
    (obj2 (req "amount" encoding) (req "divisor" int64))
    (function Invalid_divisor (a, b) -> Some (a, b) | _ -> None)
    (fun (a, b) -> Invalid_divisor (a, b))

type tez = t