# SPDX-FileCopyrightText: ☭ Emery Hemingway
# SPDX-License-Identifier: Unlicense

import std/[hashes, options, tables]
import pkg/cps
import preserves
import ./[actors, patterns, skeletons]

from ./protocols/protocol import Handle
from ./protocols/dataspace import Observe

type
  Dataspace {.final.} = ref object of Entity
    index: Index
    handleMap: Table[Handle, Value]

proc dsPublish(e: Entity; v: Value; h: Handle) {.cps: Cont.} =
  var ds = Dataspace(e)
  if ds.index.add(v):
    var obs = v.preservesTo(Observe)
    if obs.isSome and obs.get.observer of Cap:
      ds.index.add(obs.get.pattern, Cap(obs.get.observer))
  ds.handleMap[h] = v

proc dsRetract(e: Entity; h: Handle) {.cps: Cont.} =
  var ds = Dataspace(e)
  var v = ds.handleMap[h]
  if ds.index.remove(v):
    ds.handleMap.del h
    var obs = v.preservesTo(Observe)
    if obs.isSome and obs.get.observer of Cap:
      ds.index.remove(obs.get.pattern, Cap(obs.get.observer))

proc dsMessage(e: Entity; v: Value) {.cps: Cont.} =
  var ds = Dataspace(e)
  ds.index.deliverMessage(v)

proc newDataspace*(f: Facet): Cap =
  var ds = Dataspace(
      index: initIndex(),
    ).setActions(
      publish = whelp dsPublish,
      retract = whelp dsRetract,
      message = whelp dsMessage,
    )
  newCap(f, ds)

proc observe*(cap: Cap; pat: Pattern; peer: Cap): Handle =
  publish(cap, Observe(pattern: pat, observer: peer))

proc observe*(cap: Cap; pat: Pattern; e: Entity): Handle =
  observe(cap, pat, newCap(cap.relay, e))