import gleam/dynamic/decode.{type Decoder}
import gleam/json.{type Json}
import gleam/option.{type Option, None, Some}

pub type Encodable {
  Integer(Option(Int))
  Text(Option(String))
  Timestamptz(Option(String))
  Uuid(Option(String))
}

pub fn decoder() -> Decoder(Encodable) {
  use t <- decode.field("t", decode.string)
  case t {
    "Integer" -> {
      use c <- decode.field("c", decode.optional(decode.int))
      decode.success(Integer(c))
    }
    "Text" -> {
      use c <- decode.field("c", decode.optional(decode.string))
      decode.success(Text(c))
    }
    "Timestamptz" -> {
      use c <- decode.field("c", decode.optional(decode.string))
      decode.success(Timestamptz(c))
    }
    "Uuid" -> {
      use c <- decode.field("c", decode.optional(decode.string))
      decode.success(Uuid(c))
    }
    _ -> decode.failure(Text(Some("")), "Encodable")
  }
}

pub fn to_json(value: Encodable) -> Json {
  json.object([
    #(
      "t",
      json.string(case value {
        Integer(_) -> "Integer"
        Text(_) -> "Text"
        Timestamptz(_) -> "Timestamptz"
        Uuid(_) -> "Uuid"
      }),
    ),
    #("c", case value {
      Integer(Some(inner)) -> json.int(inner)
      Integer(None) -> json.null()
      Text(Some(inner)) -> json.string(inner)
      Text(None) -> json.null()
      Timestamptz(Some(inner)) -> json.string(inner)
      Timestamptz(None) -> json.null()
      Uuid(Some(inner)) -> json.string(inner)
      Uuid(None) -> json.null()
    }),
  ])
}