## Guard test for the TFIL commitment knobs:
##   TR_TFIL_TILE_REPLAN  (self | off | enemy)   default `self` = shipped
##   TR_TFIL_COMMIT_TICKS (int)                  default 15  = shipped
##   TR_TFIL_NO_REV       (0/1)                  default 0   = shipped
##   TR_TFIL_COMMIT_LOG   (path)                 default off
##
## NO battle, NO Java, NO server. Run with:
##   nim c -r --path:common_libs common_libs/tests/test_tfil_commit_env.nim
##
## The important check is #1: with EVERY knob unset the mover must reproduce,
## byte-for-byte, the move commands recorded from the PRE-CHANGE build. The
## golden `tests/fixtures/tfil_commit_default.golden` was generated from the
## shipped mover at commit f842ac0 by compiling THIS file with
## `-d:tfilGenGolden` against `git archive f842ac0` (see the golden's header).
## Regenerating it from the new code would defeat the check — only do that after
## a DELIBERATE change to the shipped defaults.
##
## The knob-dependent half of this file is wrapped in
## `when declared(loadTfilCommitEnv)` so the SAME file still compiles against
## the pre-change module and can regenerate the golden there. That is the whole
## point: the golden must come from the old code, not from the new one.
##
## The remaining checks prove the non-default arms actually do something (an
## A/B whose treatment did not apply is worthless) and that the soft
## no-reversal preference can never empty the candidate pool.

import std/[os, json, random, math, sequtils]
import std/strutils except fromHex   # `fromHex` would clash with color.fromHex
import gun_harness/gun_interface
# Private-field access: include (do NOT import) the shipped mover.
include movements/the_floor_is_lava

const repoRoot   = currentSourcePath().parentDir.parentDir.parentDir
const fixtureRel = "tr_drussgt_vs_modularbot.jsonl"
const goldenPath = currentSourcePath().parentDir / "fixtures" /
                   "tfil_commit_default.golden"
const Seed       = 20250923
const ArenaW     = 800.0
const ArenaH     = 600.0

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

# ── fixture replay (works on BOTH the old and the new module) ────────────────

type
  TickRec = object
    call: int
    spd, trn: float
    tx, ty:  float
    ct:      int

proc loadStates(): seq[WorldState] =
  let path = repoRoot / "tools" / "fixtures" / fixtureRel
  for rawLine in lines(path):
    let line = rawLine.strip()
    if line.len == 0: continue
    let n = parseJson(line)
    if n.hasKey("meta") or n.hasKey("end"): continue
    let ex = n["ex"].getFloat()
    let ey = n["ey"].getFloat()
    result.add WorldState(
      enemyX: ex, enemyY: ey,
      enemyHeading: n["eh"].getFloat(), enemySpeed: n["es"].getFloat(),
      enemyEnergy: n["ee"].getFloat(),
      selfX: n["sx"].getFloat(), selfY: n["sy"].getFloat(),
      selfHeading: n["sh"].getFloat(), selfSpeed: n["ss"].getFloat(),
      selfEnergy: n["se"].getFloat(),
      arenaWidth: ArenaW, arenaHeight: ArenaH,
      tick: n["tick"].getInt(),
      enemies: @[EnemyInfo(id: 1, x: ex, y: ey,
                           heading: n["eh"].getFloat(), speed: n["es"].getFloat(),
                           energy: n["ee"].getFloat())])

proc loadRoundStarts(): seq[int] =
  let side = repoRoot / "tools" / "fixtures" / "drussgt_meta" /
             (fixtureRel & ".rounds.json")
  if not fileExists(side): return
  for r in parseFile(side)["rounds"]:
    result.add r["startTick"].getInt()

proc replay(states: seq[WorldState], starts: seq[int]): seq[TickRec] =
  ## Drive the REAL computeMove over the recorded WorldState stream with a fixed
  ## RNG seed, exactly as `measure_tfil_heat_field.nim` does. Touches NO env
  ## knob, so it is identical on the old and the new module.
  randomize(Seed)
  var m = initTFIL()
  for i in 0..<states.len:
    if i == 0 or i in starts: m.resetRound()
    let cmd = m.computeMove(states[i])
    result.add TickRec(call: m.callCount, spd: cmd.speed, trn: cmd.turnRate,
                       tx: m.commitTarget.x, ty: m.commitTarget.y,
                       ct: m.commitTicks)

proc recLine(r: TickRec): string =
  $r.call & " " & $r.spd & " " & $r.trn & " " & $r.tx & " " & $r.ty & " " & $r.ct

# ── golden generation (OLD module only) ──────────────────────────────────────

when defined(tfilGenGolden):
  block:
    let recs = replay(loadStates(), loadRoundStarts())
    var g = "# TFIL default-path parity golden.\n"
    g.add "# Generated from commit f842ac0 (shipped mover, BEFORE the commit knobs)\n"
    g.add "# by `nim c -r -d:tfilGenGolden` on this file against `git archive f842ac0`.\n"
    g.add "# Format: call speed turnRate targetX targetY commitTicks\n"
    for r in recs: g.add recLine(r) & "\n"
    createDir(goldenPath.parentDir)
    writeFile(goldenPath, g)
    echo "wrote ", goldenPath, " (", recs.len, " ticks)"
    quit(0)

# ── 1. default-path parity against the pre-change build ──────────────────────

proc testDefaultParity() =
  doAssert fileExists(goldenPath), "missing golden: " & goldenPath
  let recs = replay(loadStates(), loadRoundStarts())
  var golden: seq[string]
  for rawLine in lines(goldenPath):
    if rawLine.startsWith("#"): continue
    let line = rawLine.strip()
    if line.len > 0: golden.add line
  check "golden covers the whole fixture (>= 15000 ticks)", golden.len >= 15000
  check "default replay covers the same number of ticks", recs.len == golden.len
  var firstDiff = -1
  for i in 0..<min(recs.len, golden.len):
    if recLine(recs[i]) != golden[i]:
      firstDiff = i
      break
  check "DEFAULT PATH IS BYTE-FOR-BYTE THE PRE-CHANGE MOVER (call/speed/turnRate/target/commitTicks)",
        firstDiff < 0
  if firstDiff >= 0:
    echo "  first divergence at tick index ", firstDiff, ": got [",
         recLine(recs[firstDiff]), "] want [", golden[firstDiff], "]"

# ── everything below needs the NEW knob API ──────────────────────────────────

when declared(loadTfilCommitEnv):

  type ArmStats = object
    ticks:     int
    picks:     int
    byReason:  array[TfilReplanReason, int]
    intervals: seq[int]
    reversals: int
    meanSpeed: float

  proc setArm(tileReplan: string, commitTicks: string, noRev: string) =
    putEnv("TR_TFIL_TILE_REPLAN",  tileReplan)
    putEnv("TR_TFIL_COMMIT_TICKS", commitTicks)
    putEnv("TR_TFIL_NO_REV",       noRev)
    loadTfilCommitEnv()

  proc parseLog(path: string): seq[JsonNode] =
    if not fileExists(path): return
    for rawLine in lines(path):
      let line = rawLine.strip()
      if line.len > 0: result.add parseJson(line)

  proc stats(log: seq[JsonNode]): ArmStats =
    var spSum = 0.0
    result.ticks = log.len
    for o in log:
      spSum += o["sp"].getFloat()
      if o["pick"].getInt() == 1:
        inc result.picks
        result.intervals.add o["interval"].getInt()
        if o["rev"].getInt() == 1: inc result.reversals
        let r = o["reason"].getStr()
        for rr in TfilReplanReason:
          if reasonName(rr) == r: inc result.byReason[rr]
    if log.len > 0: result.meanSpeed = spSum / log.len.float

  proc meanInterval(s: ArmStats): float =
    if s.intervals.len == 0: return 0.0
    var t = 0
    for v in s.intervals: t += v
    t.float / s.intervals.len.float

  proc reversalRate(s: ArmStats): float =
    if s.picks == 0: return 0.0
    100.0 * s.reversals.float / s.picks.float

  proc replayLogged(tag: string): ArmStats =
    let logPath = getTempDir() / ("tfil_commit_" & tag & ".jsonl")
    removeFile(logPath)
    closeTfilCommitLog()
    putEnv("TR_TFIL_COMMIT_LOG", logPath)
    loadTfilCommitEnv()
    discard replay(loadStates(), loadRoundStarts())
    closeTfilCommitLog()
    putEnv("TR_TFIL_COMMIT_LOG", "")
    loadTfilCommitEnv()
    result = stats(parseLog(logPath))

  # ── 2. knob parsing ────────────────────────────────────────────────────────

  proc testKnobParsing() =
    setArm("off", "15", "0")
    check "TR_TFIL_TILE_REPLAN=off -> ttrOff", TfilTileReplanMode == ttrOff
    setArm("enemy", "15", "0")
    check "TR_TFIL_TILE_REPLAN=enemy -> ttrEnemy", TfilTileReplanMode == ttrEnemy
    setArm("self", "15", "0")
    check "TR_TFIL_TILE_REPLAN=self -> ttrSelf", TfilTileReplanMode == ttrSelf
    setArm("bogus", "15", "0")
    check "unknown TR_TFIL_TILE_REPLAN falls back to the shipped ttrSelf",
          TfilTileReplanMode == ttrSelf
    setArm("self", "30", "0")
    check "TR_TFIL_COMMIT_TICKS=30 is honoured", TfilCommitTicks == 30
    setArm("self", "0", "0")
    check "TR_TFIL_COMMIT_TICKS=0 is clamped to >= 1", TfilCommitTicks == 1
    setArm("self", "15", "1")
    check "TR_TFIL_NO_REV=1 -> TfilNoRev", TfilNoRev
    setArm("self", "15", "0")
    check "TR_TFIL_NO_REV unset -> false (shipped)", not TfilNoRev
    setArm("self", "15", "0")

  # ── 3. the treatments actually bite ────────────────────────────────────────

  proc testArms() =
    # arm A: control (shipped defaults)
    setArm("self", "15", "0")
    let a = replayLogged("a")
    check "arm A (control): tile-change replans dominate the picks",
          a.byReason[rrTileSelf].float / max(1, a.picks).float > 0.5
    check "arm A (control): mean decision interval is ~5 ticks (commitment cancelled by motion)",
          meanInterval(a) < 8.0
    check "arm A (control): reversal-pick rate is high (> 20%)",
          reversalRate(a) > 20.0

    # arm B: honour the commitment
    setArm("off", "15", "0")
    let b = replayLogged("b")
    check "arm B (TR_TFIL_TILE_REPLAN=off): ZERO tile-change replans",
          b.byReason[rrTileSelf] == 0 and b.byReason[rrTileEnemy] == 0
    check "arm B: commitment is only ended by expiry or the danger valve (plus the first pick of each round)",
          b.byReason[rrExpiry] + b.byReason[rrDanger] + b.byReason[rrInit] == b.picks
    check "arm B: the danger valve is a real but minor part of the replans (<10%)",
          b.byReason[rrDanger].float / max(1, b.picks).float < 0.10
    check "arm B: decision interval rises to the commit length (~15)",
          meanInterval(b) > 12.0
    check "arm B: FEWER decisions than arm A", b.picks < a.picks

    # arm C: B + soft no-reversal
    setArm("off", "15", "1")
    let c = replayLogged("c")
    check "arm C: reversal-pick rate drops vs arm B",
          reversalRate(c) < reversalRate(b)
    check "arm C: the candidate pool is never emptied (pick count within 2% of arm B)",
          abs(c.picks - b.picks).float <= 0.02 * b.picks.float
    check "arm C: no tile-change replans (same commitment as B)",
          c.byReason[rrTileSelf] == 0
    # The preference is a WEIGHT, never a filter: no candidate can get weight 0.
    let wAllBack = noRevWeights(@[91.0, 120.0, 180.0, -179.0, -91.0], 0.0)
    check "arm C: no-reversal weights are never 0 (pool cannot empty)",
          wAllBack.allIt(it >= 1)
    check "arm C: an all-backward pool falls back to uniform (every weight 1)",
          wAllBack.allIt(it == 1)
    let wMixed = noRevWeights(@[0.0, 45.0, 90.0, 90.1, 180.0], 0.0)
    check "arm C: forward tiles (<=90 deg) are down-weighted by 3:1",
          wMixed[0] == NoRevForwardWeight and wMixed[1] == NoRevForwardWeight and
          wMixed[2] == NoRevForwardWeight and wMixed[3] == 1 and wMixed[4] == 1

    # arm D: keyed to the enemy's tile
    setArm("enemy", "15", "0")
    let d = replayLogged("d")
    check "arm D (TR_TFIL_TILE_REPLAN=enemy): some replans are keyed to the TARGET's tile",
          d.byReason[rrTileEnemy] > 0
    check "arm D: no self-tile cancels", d.byReason[rrTileSelf] == 0
    check "arm D: the replan trigger differs from arm A (different pick count)",
          d.picks != a.picks and d.byReason[rrTileEnemy] > d.byReason[rrTileSelf]

    # arm E: commit duration
    setArm("off", "30", "0")
    let e = replayLogged("e")
    check "arm E (TR_TFIL_COMMIT_TICKS=30): interval rises to ~30",
          meanInterval(e) > 27.0
    check "arm E: fewer decisions than arm B (15)", e.picks < b.picks

    setArm("self", "15", "0")

    echo "\n  arm diagnostics (offline fixture replay):"
    for (nm, s) in [("A control", a), ("B commit", b), ("C commit+noRev", c),
                    ("D enemyTile", d), ("E commit30", e)]:
      echo "    ", nm.alignLeft(15), " ticks=", s.ticks, " picks=", s.picks,
           " interval=", meanInterval(s).formatFloat(ffDecimal, 2),
           " tileSelf=", s.byReason[rrTileSelf],
           " tileEnemy=", s.byReason[rrTileEnemy],
           " danger=", s.byReason[rrDanger],
           " expiry=", s.byReason[rrExpiry],
           " rev=", reversalRate(s).formatFloat(ffDecimal, 1), "%"

# ── driver ───────────────────────────────────────────────────────────────────

testDefaultParity()
when declared(loadTfilCommitEnv):
  testKnobParsing()
  testArms()

if failures > 0:
  echo "\n", failures, " check(s) FAILED"
  quit(1)
echo "\nAll TFIL commit-env checks passed."