# 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
  eth/[common, rlp],
  results,
  "."/[aristo_constants, aristo_desc, aristo_get]

type
  ResolveVidFn = proc(
      vid: VertexID;
        ): Result[HashKey,AristoError]
        {.gcsafe, raises: [].}
    ## Resolve storage root vertex ID

# ------------------------------------------------------------------------------
# Private helper
# ------------------------------------------------------------------------------

proc serialise(
    pyl: LeafPayload;
    getKey: ResolveVidFn;
      ): Result[Blob,(VertexID,AristoError)] =
  ## Encode the data payload of the argument `pyl` as RLP `Blob` if it is of
  ## account type, otherwise pass the data as is.
  ##
  case pyl.pType:
  of RawData:
    ok pyl.rawBlob
  of AccountData:
    let
      vid = pyl.stoID
      key = block:
        if vid.isValid:
          vid.getKey.valueOr:
            let w = (vid,error)
            return err(w)
        else:
          VOID_HASH_KEY

    ok rlp.encode Account(
      nonce:       pyl.account.nonce,
      balance:     pyl.account.balance,
      storageRoot: key.to(Hash256),
      codeHash:    pyl.account.codeHash)
  of StoData:
    ok rlp.encode pyl.stoData

# ------------------------------------------------------------------------------
# Public RLP transcoder mixins
# ------------------------------------------------------------------------------

func append*(w: var RlpWriter; key: HashKey) =
  if 1 < key.len and key.len < 32:
    w.appendRawBytes key.data
  else:
    w.append key.data

# ---------------------

proc to*(w: tuple[key: HashKey, node: NodeRef]; T: type seq[(Blob,Blob)]): T =
  ## Convert the argument pait `w` to a single or a double pair of
  ## `(<key>,<rlp-encoded-node>)` tuples. Only in case of a combined extension
  ## and branch vertex argument, there are is a double pair result.
  var wr = initRlpWriter()
  case w.node.vType:
  of Branch:
    # Do branch node
    wr.startList(17)
    for n in 0..15:
      wr.append w.node.key[n]
    wr.append EmptyBlob

    if 0 < w.node.ePfx.len:
      # Do for embedded extension node
      let brHash = wr.finish().digestTo(HashKey)
      result.add (@(brHash.data), wr.finish())

      wr = initRlpWriter()
      wr.startList(2)
      wr.append w.node.ePfx.toHexPrefix(isleaf = false)
      wr.append brHash
    else:
      # Do for pure branch node
      result.add (@(w.key.data), wr.finish())

  of Leaf:
    proc getKey0(
        vid: VertexID;
          ): Result[HashKey,AristoError]
          {.gcsafe, raises: [].} =
      ok(w.node.key[0]) # always succeeds

    wr.startList(2)
    wr.append w.node.lPfx.toHexPrefix(isleaf = true)
    wr.append w.node.lData.serialise(getKey0).value

  result.add (@(w.key.data), wr.finish())

proc digestTo*(node: NodeRef; T: type HashKey): T =
  ## Convert the argument `node` to the corresponding Merkle hash key. Note
  ## that a `Dummy` node is encoded as as a `Leaf`.
  ##
  var wr = initRlpWriter()
  case node.vType:
  of Branch:
    # Do branch node
    wr.startList(17)
    for n in 0..15:
      wr.append node.key[n]
    wr.append EmptyBlob

    # Do for embedded extension node
    if 0 < node.ePfx.len:
      let brHash = wr.finish().digestTo(HashKey)
      wr= initRlpWriter()
      wr.startList(2)
      wr.append node.ePfx.toHexPrefix(isleaf = false)
      wr.append brHash

  of Leaf:
    proc getKey0(
        vid: VertexID;
          ): Result[HashKey,AristoError]
          {.gcsafe, raises: [].} =
      ok(node.key[0]) # always succeeds

    wr.startList(2)
    wr.append node.lPfx.toHexPrefix(isleaf = true)
    wr.append node.lData.serialise(getKey0).value

  wr.finish().digestTo(HashKey)

proc serialise*(
    db: AristoDbRef;
    root: VertexID;
    pyl: LeafPayload;
      ): Result[Blob,(VertexID,AristoError)] =
  ## Encode the data payload of the argument `pyl` as RLP `Blob` if it is of
  ## account type, otherwise pass the data as is.
  ##
  proc getKey(vid: VertexID): Result[HashKey,AristoError] =
    ok (?db.getKeyRc((root, vid)))[0]

  pyl.serialise getKey

# ------------------------------------------------------------------------------
# End
# ------------------------------------------------------------------------------