# json_saves.ludic - Json.write_file writes a tree as JSON through a buffer the runtime keeps (the
# .tmp and the rename as Fs.write_text), so a game can save as often as it likes and keep nothing:
# the same text Json.encode gives, read back whole. Prints 1 2 3 and `saves grew 0` (the heap is
# read on the Mac; 0 elsewhere).
program JsonSaves {
  function tree(n: int) -> Val {
    let o = Value.object()
    Value.put(o, "name", Value.str("camp \"north\"\nshore\\"))
    Value.put(o, "day", Value.int(n))
    Value.put(o, "cold", Value.int(-2147483647))
    Value.put(o, "rep", Value.fixed(49152))
    Value.put(o, "pace", Value.float(float(7) / float(2)))
    Value.put(o, "wet", Value.bool(0))
    Value.put(o, "none", Value.null())
    let l = Value.list()
    for i in 0 .. 40 { Value.add(l, Value.int(i * 37 - 500)) }
    Value.put(o, "pack", l)
    let inner = Value.object()
    Value.put(inner, "x", Value.fixed(-8192))
    Value.put(o, "at", inner)
    return o
  }
  entry {
    let small = Value.object()
    Value.put(small, "a", Value.int(-7))
    Value.put(small, "b", Value.fixed(32768))
    Value.put(small, "c", Value.str("q\"\\\n"))
    let sl = Value.list()
    Value.add(sl, Value.bool(1))
    Value.add(sl, Value.null())
    Value.put(small, "d", sl)
    if Json.encode(small) == "{\"a\":-7,\"b\":0.5,\"c\":\"q\\\"\\\\\\n\",\"d\":[true,null]}" { print(1) }
    let path = Os.temp_dir() + "/json_saves_" + string(Os.pid()) + ".json"
    let t = tree(3)
    let wrote = Json.write_file(t, path)
    let back = Fs.read_text(path)
    let enc = Json.encode(t)
    if wrote and back == enc { print(2) }
    let again = Json.parse(back)
    if Json.encode(again) == enc { print(3) }
    for i in 0 .. 20 { Json.write_file(t, path) }
    let before = Os.heap_bytes()
    for i in 0 .. 1000 { Json.write_file(t, path) }
    let grew = Os.heap_bytes() - before
    Fs.remove(path)
    print(`saves grew {grew}`)
  }
}