# SPDX-FileCopyrightText: 2021 ☭ Emery Hemingway
# SPDX-License-Identifier: Unlicense

import std/[json, tables]
import preserves

proc toPreserveHook*(js: JsonNode): Preserve =
  case js.kind
  of JString:
    result = Preserve(kind: pkString, string: js.str)
  of JInt:
    result = Preserve(kind: pkSignedInteger, int: js.num)
  of JFloat:
    result = Preserve(kind: pkDouble, double: js.fnum)
  of JBool:
    result = case js.bval
      of false: symbol"false"
      of true: symbol"true"
  of JNull:
    result = symbol"null"
  of JObject:
    result = Preserve(kind: pkDictionary)
    for key, val in js.fields.pairs:
      result[Preserve(kind: pkString, string: key)] = toPreserveHook(val)
  of JArray:
    result = Preserve(kind: pkSequence,
        sequence: newSeq[Preserve](js.elems.len))
    for i, e in js.elems:
      result.sequence[i] = toPreserveHook(e)

proc toJsonHook*(prs: Preserve): JsonNode =
  case prs.kind:
  of pkBoolean:
    result = newJBool(prs.bool)
  of pkFloat:
    result = newJFloat(prs.float)
  of pkDouble:
    result = newJFloat(prs.double)
  of pkSignedInteger:
    result = newJInt(prs.int)
  of pkBigInteger:
    raise newException(ValueError, "cannot convert big integer to JSON")
  of pkString:
    result = newJString(prs.string)
  of pkByteString:
    raise newException(ValueError, "cannot convert bytes to JSON")
  of pkSymbol:
    case prs.symbol
    of "false":
      result = newJBool(false)
    of "true":
      result = newJBool(true)
    of "null":
      result = newJNull()
    else:
      raise newException(ValueError, "cannot convert symbol to JSON")
  of pkRecord:
    raise newException(ValueError, "cannot convert record to JSON")
  of pkSequence:
    result = newJArray()
    for val in prs.sequence:
      result.add(toJsonHook(val))
  of pkSet:
    raise newException(ValueError, "cannot convert set to JSON")
  of pkDictionary:
    result = newJObject()
    for (key, val) in prs.dict.items:
      if key.kind != pkString:
        raise newException(ValueError, "cannot convert non-string dictionary key to JSON")
      result[key.string] = toJsonHook(val)
  of pkEmbedded:
    raise newException(ValueError, "cannot convert embedded value to JSON")