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open Protocol
open Alpha_context

(** Access DAL slots and pages content.

    This module is a wrapper on top of {!Store.Dal_slot_pages} module to
    access DAL slots and pages' data that have been previously fetched by
    the rollup node.
*)

(** This error is returned when a slot, identified by its ID, is not found in
    the store. *)
type error += Dal_slot_not_found_in_store of Dal.Slot.Header.id

(** Retrieve the pages' content of the given slot ID's from the store.

    The function returns [Dal_slot_not_found_in_store] if no entry is found in
    the store for the given ID (i.e. no page is registered with or without content).

    If the returned value is [Some pages], the slot whose ID is given is
    supposed to be confirmed and [pages] correspond to the pages of the slot.
    Otherwise [None] is returned.

    The function relies on {!Store.Dal_slot_pages}'s invariants to guarantee that:
    - the pages are returned in increasing order w.r.t. their indexes in the slot;
    - the size of the list, in case it is not empty, is equal to the expected
      number of pages in a slot.

    [dal_attestation_lag] is used to retrieve the correct entry in [store].
*)
val slot_pages :
  Octez_smart_rollup.Rollup_constants.dal_constants ->
  dal_activation_level:Raw_level.t option ->
  inbox_level:int32 ->
  _ Node_context.t ->
  Dal.slot_id ->
  dal_attested_slots_validity_lag:int ->
  Dal.Page.content list option tzresult Lwt.t

(** Retrieve the content of the page identified by the given ID from the store.

    The function returns [Dal_slot_not_found_in_store] if no entry is found in
    the store for the given ID. It returns [None] in case the level of the
    requested page is out of bounds (e.g. in the future). Said otherwise,
    some content is only returned for confirmed pages (slots) for
    which the content has already been downloaded and saved to the store.

    [dal_attestation_lag] is used to retrieve the correct entry in [store].
*)
val page_content :
  Octez_smart_rollup.Rollup_constants.dal_constants ->
  dal_activation_level:Raw_level.t option ->
  inbox_level:int32 ->
  _ Node_context.t ->
  Dal.Page.t ->
  dal_attested_slots_validity_lag:int ->
  Dal.Page.content option tzresult Lwt.t