-- Iteration 19, the forcing function: `{"price": 9.99}` used to fail the
-- whole checked decode because the language had no Float. Now a Float field
-- decodes fractions and exponents, encodes shortest-round-trip, and an Int
-- field's strictness is UNCHANGED (a fraction there is still malformed).
-- A ?Float carries its own nil sentinel, and a Bytes field crosses the JSON
-- boundary as base64.
use json

class Item {
  name: Text
  price: Float
  discount: ?Float
  blob: Bytes
}

class Counted {
  n: Int
}

fn main() -> Int {
  -- encode: shortest form, a nil ?Float is null, Bytes is base64
  print(json.encode(Item {
    name: "mug",
    price: 9.99,
    discount: nil,
    blob: bytes_of_text("hi")
  }))

  -- decode a fraction into a Float field: the hole this iteration closes
  let a = json.decode("{\"name\":\"mug\",\"price\":9.99,\"discount\":0.25,\"blob\":\"aGk=\"}") as Item
  if a != nil {
    print("${a.price}")
    let d = a.discount
    if d != nil { print("${d}") }
    print(text_of_bytes(a.blob))
    print(json.encode(a))
  }

  -- exponent and integer-shaped forms both land in a Float field
  let b = json.decode("{\"name\":\"x\",\"price\":2.5e-3,\"discount\":null,\"blob\":\"\"}") as Item
  if b != nil {
    print("${b.price} ${bytes_len(b.blob)}")
    -- a JSON null in a ?Float field must read back as nil, which is the whole
    -- job of the reserved-NaN sentinel: the zero word would be +0.0
    let bd = b.discount
    if bd == nil { print("null discount read back as nil") }
  }
  let c = json.decode("{\"name\":\"x\",\"price\":42,\"discount\":null,\"blob\":\"\"}") as Item
  if c != nil { print("${c.price}") }

  -- Int strictness is untouched: a fraction in an Int field is still
  -- malformed, so the checked decode fails whole
  let bad = json.decode("{\"n\":3.7}") as Counted
  if bad == nil { print("int fraction still rejected") }

  -- a non-finite Float has no JSON literal, so it encodes as null rather
  -- than as invalid JSON
  print(json.encode(Item {
    name: "inf",
    price: 1.0 / 0.0,
    discount: 0.0 / 0.0,
    blob: bytes_of_text("")
  }))
  return 0
}