(*****************************************************************************)
(*                                                                           *)
(* Open Source License                                                       *)
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(* Copyright (c) 2022 TriliTech <contact@trili.tech>                         *)
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open Alpha_context

type error +=
  | (* Permanent *) Sc_rollup_invalid_parameters_type
  | (* Permanent *) Sc_rollup_invalid_last_cemented_commitment
  | (* Permanent *) Sc_rollup_invalid_output_proof
  | (* Permanent *) Sc_rollup_invalid_outbox_level

type execute_outbox_message_result = {
  paid_storage_size_diff : Z.t;
  operations : Script_typed_ir.packed_internal_operation list;
}

let () =
  let description = "Invalid parameters type for rollup" in
  register_error_kind
    `Permanent
    ~id:"Sc_rollup_invalid_parameters_type"
    ~title:"Invalid parameters type"
    ~description
    ~pp:(fun fmt () -> Format.fprintf fmt "%s" description)
    Data_encoding.unit
    (function Sc_rollup_invalid_parameters_type -> Some () | _ -> None)
    (fun () -> Sc_rollup_invalid_parameters_type) ;
  let description = "Invalid last-cemented-commitment" in
  register_error_kind
    `Permanent
    ~id:"Sc_rollup_invalid_last_cemented_commitment"
    ~title:description
    ~description
    ~pp:(fun ppf () -> Format.fprintf ppf "%s" description)
    Data_encoding.empty
    (function
      | Sc_rollup_invalid_last_cemented_commitment -> Some () | _ -> None)
    (fun () -> Sc_rollup_invalid_last_cemented_commitment) ;
  let description = "Invalid output proof" in
  register_error_kind
    `Permanent
    ~id:"Sc_rollup_invalid_output_proof"
    ~title:description
    ~description
    ~pp:(fun ppf () -> Format.fprintf ppf "%s" description)
    Data_encoding.empty
    (function Sc_rollup_invalid_output_proof -> Some () | _ -> None)
    (fun () -> Sc_rollup_invalid_output_proof) ;
  let description = "Invalid outbox level" in
  register_error_kind
    `Permanent
    ~id:"Sc_rollup_invalid_outbox_level"
    ~title:description
    ~description
    ~pp:(fun ppf () -> Format.fprintf ppf "%s" description)
    Data_encoding.empty
    (function Sc_rollup_invalid_outbox_level -> Some () | _ -> None)
    (fun () -> Sc_rollup_invalid_outbox_level)

type origination_result = {
  address : Sc_rollup.Address.t;
  size : Z.t;
  genesis_commitment_hash : Sc_rollup.Commitment.Hash.t;
}

let origination_proof_of_string origination_proof kind =
  let open Lwt_tzresult_syntax in
  match kind with
  | Sc_rollup.Kind.Example_arith ->
      let* proof =
        match
          Data_encoding.Binary.of_string_opt
            Sc_rollup.ArithPVM.Protocol_implementation.proof_encoding
            origination_proof
        with
        | Some x -> return x
        | None ->
            fail
              (Sc_rollup_proof_repr.Sc_rollup_proof_check
                 "invalid encoding for Arith origination proof")
      in

      let (module PVM : Sc_rollup.PVM_with_proof
            with type proof = Sc_rollup.ArithPVM.Protocol_implementation.proof)
          =
        (module struct
          include Sc_rollup.ArithPVM.Protocol_implementation

          let proof = proof
        end)
      in
      return @@ Sc_rollup.Arith_pvm_with_proof (module PVM)
  | Sc_rollup.Kind.Wasm_2_0_0 ->
      let* proof =
        match
          Data_encoding.Binary.of_string_opt
            Sc_rollup.Wasm_2_0_0PVM.Protocol_implementation.proof_encoding
            origination_proof
        with
        | Some x -> return x
        | None ->
            fail
              (Sc_rollup_proof_repr.Sc_rollup_proof_check
                 "invalid encoding for Wasm_2_0_0 origination proof")
      in
      let (module PVM : Sc_rollup.PVM_with_proof
            with type proof =
              Sc_rollup.Wasm_2_0_0PVM.Protocol_implementation.proof) =
        (module struct
          include Sc_rollup.Wasm_2_0_0PVM.Protocol_implementation

          let proof = proof
        end)
      in
      return @@ Sc_rollup.Wasm_2_0_0_pvm_with_proof (module PVM)

type 'ret continuation = unit -> 'ret tzresult

(* Only a subset of types are supported for rollups.
   This function checks whether or not a type can be used for a rollup. *)
let rec validate_ty :
    type a ac ret.
    (a, ac) Script_typed_ir.ty -> ret continuation -> ret tzresult =
 fun ty k ->
  let open Script_typed_ir in
  match ty with
  (* Valid primitive types. *)
  | Unit_t -> (k [@ocaml.tailcall]) ()
  | Int_t -> (k [@ocaml.tailcall]) ()
  | Nat_t -> (k [@ocaml.tailcall]) ()
  | Signature_t -> (k [@ocaml.tailcall]) ()
  | String_t -> (k [@ocaml.tailcall]) ()
  | Bytes_t -> (k [@ocaml.tailcall]) ()
  | Key_hash_t -> (k [@ocaml.tailcall]) ()
  | Key_t -> (k [@ocaml.tailcall]) ()
  | Timestamp_t -> (k [@ocaml.tailcall]) ()
  | Address_t -> (k [@ocaml.tailcall]) ()
  | Bls12_381_g1_t -> (k [@ocaml.tailcall]) ()
  | Bls12_381_g2_t -> (k [@ocaml.tailcall]) ()
  | Bls12_381_fr_t -> (k [@ocaml.tailcall]) ()
  | Bool_t -> (k [@ocaml.tailcall]) ()
  | Never_t -> (k [@ocaml.tailcall]) ()
  | Tx_rollup_l2_address_t -> (k [@ocaml.tailcall]) ()
  | Chain_id_t -> (k [@ocaml.tailcall]) ()
  (* Valid collection types. *)
  | Ticket_t (ty, _) -> (validate_ty [@ocaml.tailcall]) ty k
  | Set_t (ty, _) -> (validate_ty [@ocaml.tailcall]) ty k
  | Option_t (ty, _, _) -> (validate_ty [@ocaml.tailcall]) ty k
  | List_t (ty, _) -> (validate_ty [@ocaml.tailcall]) ty k
  | Pair_t (ty1, ty2, _, _) -> (validate_two_tys [@ocaml.tailcall]) ty1 ty2 k
  | Union_t (ty1, ty2, _, _) -> (validate_two_tys [@ocaml.tailcall]) ty1 ty2 k
  | Map_t (key_ty, val_ty, _) ->
      (validate_two_tys [@ocaml.tailcall]) key_ty val_ty k
  (* Invalid types. *)
  | Mutez_t -> error Sc_rollup_invalid_parameters_type
  | Big_map_t (_key_ty, _val_ty, _) -> error Sc_rollup_invalid_parameters_type
  | Contract_t _ -> error Sc_rollup_invalid_parameters_type
  | Sapling_transaction_t _ -> error Sc_rollup_invalid_parameters_type
  | Sapling_transaction_deprecated_t _ ->
      error Sc_rollup_invalid_parameters_type
  | Sapling_state_t _ -> error Sc_rollup_invalid_parameters_type
  | Operation_t -> error Sc_rollup_invalid_parameters_type
  | Chest_t -> error Sc_rollup_invalid_parameters_type
  | Chest_key_t -> error Sc_rollup_invalid_parameters_type
  | Lambda_t (_, _, _) -> error Sc_rollup_invalid_parameters_type

and validate_two_tys :
    type a ac b bc ret.
    (a, ac) Script_typed_ir.ty ->
    (b, bc) Script_typed_ir.ty ->
    ret continuation ->
    ret tzresult =
 fun ty1 ty2 k ->
  (validate_ty [@ocaml.tailcall]) ty1 (fun () ->
      (validate_ty [@ocaml.tailcall]) ty2 k)

let validate_parameters_ty ctxt parameters_ty =
  let open Tzresult_syntax in
  let* ctxt =
    Gas.consume
      ctxt
      (Sc_rollup_costs.is_valid_parameters_ty_cost
         ~ty_size:Script_typed_ir.(ty_size parameters_ty |> Type_size.to_int))
  in
  let+ () = validate_ty parameters_ty ok in
  ctxt

let validate_untyped_parameters_ty ctxt parameters_ty =
  let open Tzresult_syntax in
  (* Parse the type and check that the entrypoints are well-formed. Using
     [parse_parameter_ty_and_entrypoints] restricts to [passable] types
     (everything but operations), which is OK since [validate_ty] constraints
     the type further. *)
  let* Ex_parameter_ty_and_entrypoints {arg_type; entrypoints = _}, ctxt =
    Script_ir_translator.parse_parameter_ty_and_entrypoints
      ctxt
      ~legacy:false
      (Micheline.root parameters_ty)
  in
  (* Check that the type is valid for rollups. *)
  validate_parameters_ty ctxt arg_type

let check_origination_proof kind boot_sector origination_proof =
  let open Lwt_tzresult_syntax in
  let (module PVM) = Sc_rollup.wrapped_proof_module origination_proof in
  let kind' = Sc_rollup.wrapped_proof_kind_exn origination_proof in
  let* () =
    fail_when
      Compare.String.(
        Sc_rollup.Kind.name_of kind <> Sc_rollup.Kind.name_of kind')
      (Sc_rollup_proof_repr.Sc_rollup_proof_check "incorrect kind proof")
  in
  let*! is_valid = PVM.verify_origination_proof PVM.proof boot_sector in
  let* () =
    fail_when
      (not is_valid)
      (Sc_rollup_proof_repr.Sc_rollup_proof_check "invalid origination proof")
  in
  return PVM.(proof_stop_state proof)

let originate ctxt ~kind ~boot_sector ~origination_proof ~parameters_ty =
  let open Lwt_tzresult_syntax in
  let*? ctxt =
    let open Tzresult_syntax in
    let* parameters_ty, ctxt =
      Script.force_decode_in_context
        ~consume_deserialization_gas:When_needed
        ctxt
        parameters_ty
    in
    validate_untyped_parameters_ty ctxt parameters_ty
  in

  let* origination_proof = origination_proof_of_string origination_proof kind in
  let* genesis_hash =
    check_origination_proof kind boot_sector origination_proof
  in
  let genesis_commitment =
    Sc_rollup.Commitment.genesis_commitment
      ~genesis_state_hash:genesis_hash
      ~origination_level:(Level.current ctxt).level
  in
  let+ address, size, genesis_commitment_hash, ctxt =
    Sc_rollup.originate
      ctxt
      ~kind
      ~boot_sector
      ~parameters_ty
      ~genesis_commitment
  in
  ({address; size; genesis_commitment_hash}, ctxt)

let to_transaction_operation ctxt ~source
    (Sc_rollup_management_protocol.Transaction
      {destination; entrypoint; parameters_ty; parameters; unparsed_parameters})
    =
  let open Tzresult_syntax in
  let* ctxt, nonce = fresh_internal_nonce ctxt in
  (* Validate the type of the parameters. Only types that can be transferred
     from Layer 1 to Layer 2 are permitted.

     In principal we could allow different types to be passed to the rollup and
     from the rollup. In order to avoid confusion, and given that we don't
     have any use case where they differ, we keep these sets identical.
  *)
  let* ctxt = validate_parameters_ty ctxt parameters_ty in
  let operation =
    Script_typed_ir.Transaction_to_smart_contract
      {
        destination;
        amount = Tez.zero;
        entrypoint;
        location = Micheline.dummy_location;
        parameters_ty;
        parameters;
        unparsed_parameters;
      }
  in
  return
    ( Script_typed_ir.Internal_operation
        {source = Contract.Implicit source; operation; nonce},
      ctxt )

(* Transfer some ticket-tokens from [source_destination] to [target_destination].
   This operation fails in case the [source_destination]'s balance is lower than
   amount. *)
let transfer_ticket_token ctxt ~source_destination ~target_destination ~amount
    ticket_token =
  let open Lwt_tzresult_syntax in
  let* source_key_hash, ctxt =
    Ticket_balance_key.of_ex_token ctxt ~owner:source_destination ticket_token
  in
  let* target_key_hash, ctxt =
    Ticket_balance_key.of_ex_token ctxt ~owner:target_destination ticket_token
  in
  let* source_storage_diff, ctxt =
    Ticket_balance.adjust_balance ctxt source_key_hash ~delta:(Z.neg amount)
  in
  let* target_storage_diff, ctxt =
    Ticket_balance.adjust_balance ctxt target_key_hash ~delta:amount
  in
  (* Adjust the recorded paid-for storage space for the ticket-table. *)
  let* storage_diff_to_pay, ctxt =
    Ticket_balance.adjust_storage_space
      ctxt
      ~storage_diff:(Z.add source_storage_diff target_storage_diff)
  in
  return (storage_diff_to_pay, ctxt)

let transfer_ticket_tokens ctxt ~source_destination ~acc_storage_diff
    {Ticket_operations_diff.ticket_token; total_amount = _; destinations} =
  let open Lwt_tzresult_syntax in
  List.fold_left_es
    (fun (acc_storage_diff, ctxt)
         (target_destination, (amount : Script_typed_ir.ticket_amount)) ->
      let* storage_diff, ctxt =
        transfer_ticket_token
          ctxt
          ~source_destination
          ~target_destination
          ~amount:Script_int.(to_zint (amount :> n num))
          ticket_token
      in
      return (Z.(add acc_storage_diff storage_diff), ctxt))
    (acc_storage_diff, ctxt)
    destinations

let validate_and_decode_output_proof ctxt ~cemented_commitment rollup
    ~output_proof =
  let open Lwt_tzresult_syntax in
  (* Lookup the PVM of the rollup. *)
  let* ctxt, (module PVM : Sc_rollup.PVM.S) =
    let+ ctxt, kind = Sc_rollup.kind ctxt rollup in
    (ctxt, Sc_rollup.Kind.pvm_of kind)
  in
  let*? ctxt =
    Gas.consume
      ctxt
      (Sc_rollup_costs.cost_deserialize_output_proof
         ~bytes_len:(String.length output_proof))
  in
  let*? output_proof =
    match
      Data_encoding.Binary.of_string_opt PVM.output_proof_encoding output_proof
    with
    | Some x -> ok x
    | None -> error Sc_rollup_invalid_output_proof
  in
  let output = PVM.output_of_output_proof output_proof in
  (* Verify that the states match. *)
  let* {Sc_rollup.Commitment.compressed_state; _}, ctxt =
    Sc_rollup.Commitment.get_commitment ctxt rollup cemented_commitment
  in
  let* () =
    let output_proof_state = PVM.state_of_output_proof output_proof in
    fail_unless
      Sc_rollup.State_hash.(output_proof_state = compressed_state)
      Sc_rollup_invalid_output_proof
  in
  (* Verify that the proof is valid. *)
  let* () =
    let*! proof_is_valid = PVM.verify_output_proof output_proof in
    fail_unless proof_is_valid Sc_rollup_invalid_output_proof
  in
  return (output, ctxt)

let validate_outbox_level ctxt ~outbox_level ~lcc_level =
  (* Check that outbox level is within the bounds of:
       [min_level < outbox_level <= lcc_level]
     Where
       [min_level = lcc_level - max_active_levels]

      This prevents the rollup from putting messages at a level that is greater
      than its corresponding inbox-level. It also prevents execution
      of messages that are older than the maximum number of active levels.
  *)
  let max_active_levels =
    Int32.to_int (Constants.sc_rollup_max_active_outbox_levels ctxt)
  in
  let outbox_level_is_active =
    let min_allowed_level =
      Int32.sub (Raw_level.to_int32 lcc_level) (Int32.of_int max_active_levels)
    in
    Compare.Int32.(min_allowed_level < Raw_level.to_int32 outbox_level)
  in
  fail_unless
    (Raw_level.(outbox_level <= lcc_level) && outbox_level_is_active)
    Sc_rollup_invalid_outbox_level

let execute_outbox_message ctxt ~validate_and_decode_output_proof rollup
    ~cemented_commitment ~source ~output_proof =
  let open Lwt_tzresult_syntax in
  (* TODO: #3211
     Allow older cemented commits as well.
     This has the benefits of eliminating any race condition where new commits
     are cemented and makes inclusion proofs obsolete. *)
  let* lcc_hash, lcc_level, ctxt =
    Sc_rollup.Commitment.last_cemented_commitment_hash_with_level ctxt rollup
  in
  (* Check that the last-cemented-commitment matches the one for the given
     rollup. This is important in order to guarantee that the inclusion-proof
     is for the correct state-hash. *)
  let* () =
    fail_unless
      Sc_rollup.Commitment.Hash.(lcc_hash = cemented_commitment)
      Sc_rollup_invalid_last_cemented_commitment
  in
  (* Validate and decode the output proofs. *)
  let* Sc_rollup.{outbox_level; message_index; message}, ctxt =
    validate_and_decode_output_proof
      ctxt
      ~cemented_commitment:lcc_hash
      rollup
      ~output_proof
  in
  (* Validate that the outbox level is within valid bounds. *)
  let* () = validate_outbox_level ctxt ~outbox_level ~lcc_level in
  let* ( Sc_rollup_management_protocol.Atomic_transaction_batch {transactions},
         ctxt ) =
    Sc_rollup_management_protocol.outbox_message_of_outbox_message_repr
      ctxt
      message
  in
  (* Turn the transaction batch into a list of operations. *)
  let*? ctxt, operations =
    List.fold_left_map_e
      (fun ctxt transaction ->
        let open Tzresult_syntax in
        let+ op, ctxt = to_transaction_operation ctxt ~source transaction in
        (ctxt, op))
      ctxt
      transactions
  in
  (* Record that the message for the given level has been applied. This fails
     in case a message for the rollup, outbox-level and message index has
     already been executed. The storage diff returned may be negative.
  *)
  let* applied_msg_size_diff, ctxt =
    Sc_rollup.Outbox.record_applied_message
      ctxt
      rollup
      outbox_level
      ~message_index:(Z.to_int message_index)
  in
  (* TODO: #3121
     Implement a more refined model. For instance a water-mark based one.
     For now we only charge for positive contributions. It means that over time
     we are overcharging for storage space.
  *)
  let paid_storage_size_diff = Z.max Z.zero applied_msg_size_diff in
  (* Extract the ticket-token diffs from the operations. We here make sure that
     there are no tickets with amount zero. Zero-amount tickets are not allowed
     as they cannot be tracked by the ticket-balance table.
  *)
  let* ticket_token_diffs, ctxt =
    Ticket_operations_diff.ticket_diffs_of_operations ctxt operations
  in
  (* Update the ticket-balance table by transferring ticket-tokens to new
     destinations for each transaction. This fails in case the rollup does not
     hold a sufficient amount of any of the ticket-tokens transferred.

     The updates must happen before any of the operations are executed to avoid
     a case where ticket-transfers are funded as a result of prior operations
     depositing new tickets to the rollup.
  *)
  let* paid_storage_size_diff, ctxt =
    let source_destination = Destination.Sc_rollup rollup in
    List.fold_left_es
      (fun (acc_storage_diff, ctxt) ticket_token_diff ->
        transfer_ticket_tokens
          ctxt
          ~source_destination
          ~acc_storage_diff
          ticket_token_diff)
      (paid_storage_size_diff, ctxt)
      ticket_token_diffs
  in
  return ({paid_storage_size_diff; operations}, ctxt)

module Internal_for_tests = struct
  let execute_outbox_message = execute_outbox_message

  let origination_proof_of_string = origination_proof_of_string
end

let execute_outbox_message ctxt =
  execute_outbox_message ctxt ~validate_and_decode_output_proof