## Offline chatter measurement for the gun selector's hysteresis.
##
## Replays real recorded DrussGT movement (and the synthetic set) through the 13
## ModularBot guns and drives the SAME stateful selector the live bot uses
## (`selectGun`), counting how often the chosen gun changes. This is the
## deterministic analogue of counting the live `[config]` gun-switch lines: the
## replay feeds the identical per-tick fitness the live tracker builds, so the
## switch sequence is the same up to the seeded tie-break RNG.
##
## The env knobs (`GUN_SELECTOR_DWELL`, `GUN_SELECTOR_MARGIN`) are read once per
## process at module init, so sweep by running the binary under different values:
##
##   nim c -r common_libs/tests/measure_hysteresis.nim                       # shipped
##   GUN_SELECTOR_DWELL=0 GUN_SELECTOR_MARGIN=0 \
##       common_libs/tests/measure_hysteresis                   # pre-hysteresis baseline
##
## This is a MEASUREMENT tool, not a test; it always exits 0.

import std/[os, strformat, algorithm, random]
import gun_harness/offline_range
import gun_harness/virtual_bullets
import range_guns

const
  repoRoot = currentSourcePath().parentDir.parentDir.parentDir
  fixturesDir = repoRoot / "tools" / "fixtures"

type RunStat = object
  name:     string
  ticks:    int
  switches: int

proc measure(path: string, seed: int): RunStat =
  let fx = loadFixture(path)
  let drivers = buildAllGunDrivers(seed = seed, enableTmSelector = false)
  var last = -1
  var t = 0
  var switches = 0
  discard replayFixture(fx, drivers,
    liveActual = (fx.meta.source == "live"),
    tickCb = proc(tr: ptr VirtualTracker) =
      let g = selectGun(tr[], fx.enemyId, t)
      if last >= 0 and g != last: inc switches
      last = g
      inc t)
  RunStat(name: extractFilename(path), ticks: fx.states.len, switches: switches)

proc main() =
  randomize(12345)
  var paths: seq[string]
  for f in walkFiles(fixturesDir / "drussgt_vs_*.jsonl"): paths.add f
  for f in walkFiles(fixturesDir / "tr_drussgt_vs_*.jsonl"): paths.add f
  paths.sort()

  var totalTicks = 0
  var totalSwitches = 0
  echo fmt"dwell={ActiveDwellTicks} ticks  margin={ActiveSwitchMargin:.3f}  " &
       fmt"mode={ActiveSelectorMode}  rank={ActiveRank}"
  echo "fixture                              ticks  switches  sw/100t"
  echo "----------------------------------------------------------------"
  var stats: seq[RunStat]
  for p in paths:
    let s = measure(p, seed = 12345)
    stats.add s
    totalTicks += s.ticks
    totalSwitches += s.switches
    echo fmt"{s.name:<34}{s.ticks:>7}{s.switches:>10}{100.0*float(s.switches)/float(max(1,s.ticks)):>9.2f}"
  echo "----------------------------------------------------------------"
  let label = "TOTAL"
  echo fmt"{label:<34}{totalTicks:>7}{totalSwitches:>10}{100.0*float(totalSwitches)/float(max(1,totalTicks)):>9.2f}"

when isMainModule:
  main()