## Direct proof of the BotDeath drop mechanism in `robocode_tankroyale_botapi`
## 1.0.7, at the API level (no battle required).
##
## `event_queue.isCritical` contains only `ekDeath`, `ekWonRound` and
## `ekSkippedTurn` — NOT `ekBotDeath`. `removeOldEvents` deletes every
## non-critical event whose `turnNumber < currentTurn - MAX_EVENTS_AGE`.
## Therefore a `BotDeathEvent` for ANOTHER bot is silently dropped whenever the
## bot falls more than two turns behind, which is why `onBotDeath` cannot be the
## tracker's only death signal.
##
## Run: nim c -r common_libs/tests/test_event_drop_mechanism.nim

import robocode_tankroyale_botapi

var failures = 0
proc check(name: string, ok: bool) =
  if ok: echo "PASS: ", name
  else: echo "FAIL: ", name; inc failures

const CurrentTurn = 8

proc botDeathAt(turn: int): BotEvent =
  BotEvent(kind: ekBotDeath, turnNumber: turn,
           botDeath: BotDeathEvent(turnNumber: turn, victimId: 2))

proc deathAt(turn: int): BotEvent =
  BotEvent(kind: ekDeath, turnNumber: turn,
           death: BotDeathEvent(turnNumber: turn, victimId: 1))

proc testBotDeathIsNotCritical() =
  let e = botDeathAt(5)
  check "ekBotDeath is not critical", not e.isCritical
  check "ekDeath IS critical", deathAt(5).isCritical

proc testBotDeathDroppedWhenOlderThanMaxAge() =
  var eq = initEventQueue()
  eq.addEvent(botDeathAt(CurrentTurn - MAX_EVENTS_AGE - 1))  # age 3
  eq.removeOldEvents(CurrentTurn)
  check "ekBotDeath older than MAX_EVENTS_AGE is dropped",
        eq.events.len == 0

proc testBotDeathKeptAtMaxAge() =
  var eq = initEventQueue()
  eq.addEvent(botDeathAt(CurrentTurn - MAX_EVENTS_AGE))      # age 2
  eq.removeOldEvents(CurrentTurn)
  check "ekBotDeath at exactly MAX_EVENTS_AGE age is kept",
        eq.events.len == 1

proc testCriticalDeathSurvives() =
  var eq = initEventQueue()
  eq.addEvent(deathAt(CurrentTurn - MAX_EVENTS_AGE - 5))
  eq.removeOldEvents(CurrentTurn)
  check "critical ekDeath survives any age",
        eq.events.len == 1

proc testScannedBotAlsoDropped() =
  # Every other non-critical event is dropped too, so a lagging bot also loses
  # scans/hits; BotDeath is the one with a permanent consequence.
  var eq = initEventQueue()
  eq.addEvent(BotEvent(kind: ekScannedBot, turnNumber: CurrentTurn - 3,
    scannedBot: ScannedBotEvent(`type`: "ScannedBotEvent",
      turnNumber: CurrentTurn - 3, scannedByBotId: 0, scannedBotId: 2,
      energy: 100.0, x: 0.0, y: 0.0, direction: 0.0, speed: 0.0)))
  eq.removeOldEvents(CurrentTurn)
  check "ekScannedBot older than MAX_EVENTS_AGE is dropped too",
        eq.events.len == 0

testBotDeathIsNotCritical()
testBotDeathDroppedWhenOlderThanMaxAge()
testBotDeathKeptAtMaxAge()
testCriticalDeathSurvives()
testScannedBotAlsoDropped()

if failures > 0:
  echo "\n", failures, " check(s) FAILED"
  quit(1)
echo "\nAll event-drop mechanism checks passed."