# nimbus-eth1
# Copyright (c) 2023-2024 Status Research & Development GmbH
# Licensed under either of
#  * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or
#    http://www.apache.org/licenses/LICENSE-2.0)
#  * MIT license ([LICENSE-MIT](LICENSE-MIT) or
#    http://opensource.org/licenses/MIT)
# at your option. This file may not be copied, modified, or distributed
# except according to those terms.

{.push raises: [].}

import
  std/sets,
  eth/[common, trie/nibbles],
  ./aristo_desc/desc_identifiers

const
  EmptyBlob* = seq[byte].default
    ## Useful shortcut (borrowed from `sync/snap/constants.nim`)

  EmptyNibbleSeq* = EmptyBlob.initNibbleRange
    ## Useful shortcut (borrowed from `sync/snap/constants.nim`)

  EmptyVidSeq* = seq[VertexID].default
    ## Useful shortcut

  EmptyVidSet* = EmptyVidSeq.toHashSet
    ## Useful shortcut

  VOID_CODE_HASH* = EMPTY_CODE_HASH
    ## Equivalent of `nil` for `Account` object code hash field

  VOID_HASH_KEY* = HashKey()
    ## Void equivalent for Merkle hash value

  VOID_PATH_ID* = PathID()
    ## Void equivalent for Merkle hash value

  EmptyQidPairSeq* = seq[(QueueID,QueueID)].default
    ## Useful shortcut

  DEFAULT_QID_QUEUES* = [
    (128, 0), # Consecutive list of (at least) 128 filter slots
    ( 16, 3), # Overflow list with (at least) 16 filter slots (with gap size 3)
              # each slot covering 4 filters from previous list
    (  1, 1), # ..
    (  1, 1)]
    ## The `DEFAULT_QID_QUEUES` schedule has the following properties:
    ## * most recent consecutive slots: 128
    ## * maximal slots used: 151
    ## * covered backlog savings: between 216..231
    ## This was calculated via the `capacity()` function from the
    ## `filter_scheduler.nim` source. So, saving each block after executing
    ## it, the previous 128 block chain states will be directly accessible.
    ## For older block chain states (of at least back to 216), the system can
    ## be positioned before the desired state and block by block executed
    ## forward.

  SUB_TREE_DISPOSAL_MAX* = 200_000
    ## Some limit for disposing sub-trees in one go using `delete()`.

  LEAST_FREE_VID* = 100
    ## Vids smaller are used as known state roots and cannot be recycled. Only
    ## the `VertexID(1)` state root is used by the `Aristo` methods. The other
    ## numbers smaller than `LEAST_FREE_VID` may be used by application
    ## functions with fixed assignments of the type of a state root (e.g. for
    ## a receipt or a transaction root.)

  LOOSE_STORAGE_TRIE_COUPLING* = true
    ## Enabling the `LOOSE_STORAGE_TRIE_COUPLING` flag a sub-trie is considered
    ## empty if the root vertex ID is zero or at least `LEAST_FREE_VID` and
    ## there is no vertex available. If the vertex ID is not zero and should
    ## be considered as such will affect calculating the Merkel hash node key
    ## for an accou.t leaf of payload type `AccountData`.
    ##
    ## Setting this flag `true` might be helpful for running an API supporting
    ## both, a legacy and# the `Aristo` database backend.
    ##

static:
  doAssert 1 < LEAST_FREE_VID # must stay away from `VertexID(1)`

# End