## random_oscillator.nim — perpendicular strafing with randomized reversal timing.
## Harder to predict than fixed-period oscillation; same wall-lockout guard as oscillator.nim.

import std/math
import std/random
import std/times
import gun_harness/gun_interface
import movement_harness/movement_interface

const
  MaxSpeed*    = 8.0   ## Tank Royale max speed
  MinPeriod*   = 15    ## shortest reversal interval (ticks)
  MaxPeriod*   = 45    ## longest reversal interval (ticks)
  WallMargin*  = 80.0  ## px from wall to trigger forced reversal
  WallLockout* = 20    ## ticks to suppress further wall-reversals after one fires

type RandomOscillatorModule* = object
  sign:        float  ## +1 or -1
  elapsed:     int    ## ticks since last reversal
  nextPeriod:  int    ## random period chosen at last reversal
  wallLockout: int    ## remaining suppression ticks
  rng:         Rand

proc initRandomOscillator*(): RandomOscillatorModule =
  var rng = initRand(getTime().toUnix())
  let period = rng.rand(MinPeriod..MaxPeriod)
  RandomOscillatorModule(sign: 1.0, elapsed: 0, nextPeriod: period,
                         wallLockout: 0, rng: rng)

proc computeMove*(m: var RandomOscillatorModule, ws: WorldState): MoveCommand =
  inc m.elapsed
  if m.wallLockout > 0: dec m.wallLockout

  let nearWall = ws.selfX < WallMargin or ws.selfX > ws.arenaWidth - WallMargin or
                 ws.selfY < WallMargin or ws.selfY > ws.arenaHeight - WallMargin

  if m.elapsed >= m.nextPeriod or (nearWall and m.wallLockout == 0):
    m.sign       *= -1.0
    m.elapsed     = 0
    m.nextPeriod  = m.rng.rand(MinPeriod..MaxPeriod)
    if nearWall: m.wallLockout = WallLockout

  # Perpendicular heading to enemy bearing (same dot-product trick as phantom_meteor)
  let enemyBearingRad = arctan2(ws.enemyY - ws.selfY, ws.enemyX - ws.selfX)
  let perpHeadingDeg  = radToDeg(enemyBearingRad) + 90.0

  var delta = perpHeadingDeg - ws.selfHeading
  while delta >  180.0: delta -= 360.0
  while delta < -180.0: delta += 360.0

  # Dot-product trick: if going backward, flip turn to stay perpendicular
  var normDelta = if m.sign < 0: delta - 180.0 else: delta
  while normDelta >  180.0: normDelta -= 360.0
  while normDelta < -180.0: normDelta += 360.0

  (speed: m.sign * MaxSpeed, turnRate: normDelta.clamp(-10.0, 10.0))