# props.ludic - an event's properties written as JSON into a buffer the state keeps, never a tree of
# values: a game says an event often, and Ludic gives nothing back
export const TELEMETRY_LINE: int = 2048   # the longest line an event may be; a longer one is dropped

export property TelemetryProps {
  sb: StrBuf = null
  n: int = 0                  # properties written at the top
  lv: []int = null            # inside an object or a list: how many written at each level
  d: int = 0                  # how deep
}

# the writer, emptied, for the next event's properties
export function telemetry_props(telemetry_st: mut TelemetryState) -> TelemetryProps {
  let p = telemetry_st.telemetry__props
  sb_clear(p.sb)
  p.n = 0
  p.d = 0
  return p
}
export function telemetry_str(p: TelemetryProps, k: string, s: string) -> void {
  tp_key(p, k)
  tj_str(p.sb, s)
}
export function telemetry_int(p: TelemetryProps, k: string, v: int) -> void {
  tp_key(p, k)
  sb_int(p.sb, v)
}
export function telemetry_bool(p: TelemetryProps, k: string, b: bool) -> void {
  tp_key(p, k)
  if b { sb_add(p.sb, "true") } else { sb_add(p.sb, "false") }
}
function tp_key(p: TelemetryProps, k: string) -> void {
  tp_next(p)
  tj_str(p.sb, k)
  sb_byte(p.sb, 58)
}
# a comma before all but the first at this level, and the count kept
function tp_next(p: TelemetryProps) -> void {
  if p.d == 0 {
    if p.n > 0 { sb_byte(p.sb, 44) }
    p.n += 1
    return
  }
  if p.lv[p.d] > 0 { sb_byte(p.sb, 44) }
  p.lv[p.d] += 1
}

# a JSON string: quoted, a quote or a backslash escaped, a control byte as \u00XX
function tj_str(sb: StrBuf, s: string) -> void {
  sb_byte(sb, 34)
  if s != null {
    let sp: string = s
    for i in 0 .. len(sp) {
      let c = sp[i]
      if c == 34 or c == 92 {
        sb_byte(sb, 92)
        sb_byte(sb, c)
      } else if c < 32 {
        sb_add(sb, "\\u00")
        sb_byte(sb, tj_hex(c / 16))
        sb_byte(sb, tj_hex(c % 16))
      } else { sb_byte(sb, c) }
    }
  }
  sb_byte(sb, 34)
}
function tj_hex(v: int) -> int {
  if v < 10 { return 48 + v }
  return 87 + v
}
# a line that reached the end of its buffer was cut: it is dropped rather than sent broken
function tj_full(sb: StrBuf) -> bool { return sb_len(sb) >= len(sb.b) - 1 }