#!/usr/bin/env bash
set -euo pipefail

# Incident mode automation
# - Enables a feature-flag JSON when burn rate crosses threshold
# - Writes retention override parameters for downstream storage/ingest systems
# - Resets automatically after a cooldown period once burn subsides
# All inputs are provided via CLI flags or env vars to remain offline-friendly.

usage() {
  cat <<'USAGE'
Usage: incident-mode.sh --burn-rate <float> [--threshold 2.0] [--reset-threshold 0.5] \
                        [--state-dir out/incident-mode] [--retention-hours 24] \
                        [--cooldown-mins 30] [--note "text"]

Environment overrides:
  INCIDENT_STATE_DIR   default: out/incident-mode
  INCIDENT_THRESHOLD   default: 2.0 (fast burn multiple)
  INCIDENT_RESET_TH    default: 0.5 (burn multiple to exit)
  INCIDENT_COOLDOWN    default: 30 (minutes below reset threshold)
  INCIDENT_RETENTION_H default: 24 (hours)

Outputs (in state dir):
  flag.json            feature flag payload (enabled/disabled + metadata)
  retention.json       retention override (hours, applied_at)
  last_burn.txt        last burn rate observed
  cooldown.txt         consecutive minutes below reset threshold

Examples:
  incident-mode.sh --burn-rate 3.1 --note "fast burn"          # enter incident mode
  incident-mode.sh --burn-rate 0.2                              # progress cooldown / exit
USAGE
}

if [[ $# -eq 0 ]]; then usage; exit 1; fi

BURN_RATE=""
NOTE=""
STATE_DIR=${INCIDENT_STATE_DIR:-out/incident-mode}
THRESHOLD=${INCIDENT_THRESHOLD:-2.0}
RESET_TH=${INCIDENT_RESET_TH:-0.5}
COOLDOWN_MINS=${INCIDENT_COOLDOWN:-30}
RETENTION_H=${INCIDENT_RETENTION_H:-24}

while [[ $# -gt 0 ]]; do
  case "$1" in
    --burn-rate) BURN_RATE="$2"; shift 2;;
    --threshold) THRESHOLD="$2"; shift 2;;
    --reset-threshold) RESET_TH="$2"; shift 2;;
    --state-dir) STATE_DIR="$2"; shift 2;;
    --retention-hours) RETENTION_H="$2"; shift 2;;
    --cooldown-mins) COOLDOWN_MINS="$2"; shift 2;;
    --note) NOTE="$2"; shift 2;;
    -h|--help) usage; exit 0;;
    *) echo "Unknown arg: $1" >&2; usage; exit 1;;
  esac
done

if [[ -z "$BURN_RATE" ]]; then echo "--burn-rate is required" >&2; exit 1; fi
mkdir -p "$STATE_DIR"
FLAG_FILE="$STATE_DIR/flag.json"
RET_FILE="$STATE_DIR/retention.json"
LAST_FILE="$STATE_DIR/last_burn.txt"
COOLDOWN_FILE="$STATE_DIR/cooldown.txt"

jq_escape() { python - <<PY "$1"
import json,sys
print(json.dumps(sys.argv[1]))
PY
}

now_utc=$(date -u +%Y-%m-%dT%H:%M:%SZ)
burn_float=$(python - <<PY "$BURN_RATE"
import sys
print(float(sys.argv[1]))
PY)

cooldown_current=0
if [[ -f "$COOLDOWN_FILE" ]]; then
  cooldown_current=$(cat "$COOLDOWN_FILE")
fi

enter_incident=false
exit_incident=false

if (( $(echo "$burn_float >= $THRESHOLD" | bc -l) )); then
  enter_incident=true
  cooldown_current=0
elif (( $(echo "$burn_float <= $RESET_TH" | bc -l) )); then
  cooldown_current=$((cooldown_current + 1))
  if (( cooldown_current >= COOLDOWN_MINS )); then
    exit_incident=true
  fi
else
  cooldown_current=0
fi

echo "$burn_float" > "$LAST_FILE"
echo "$cooldown_current" > "$COOLDOWN_FILE"

write_flag() {
  local enabled="$1"
  cat > "$FLAG_FILE" <<JSON
{
  "enabled": $enabled,
  "updated_at": "$now_utc",
  "reason": "incident-mode",
  "note": $(jq_escape "$NOTE"),
  "burn_rate": $burn_float
}
JSON
}

if $enter_incident; then
  write_flag true
  cat > "$RET_FILE" <<JSON
{
  "retention_hours": $RETENTION_H,
  "applied_at": "$now_utc"
}
JSON
  echo "incident-mode: activated (burn_rate=$burn_float)" >&2
elif $exit_incident; then
  write_flag false
  echo "incident-mode: cleared after cooldown (burn_rate=$burn_float)" >&2
else
  # no change; preserve prior flag if exists
  if [[ ! -f "$FLAG_FILE" ]]; then
    write_flag false
  fi
  echo "incident-mode: steady (burn_rate=$burn_float, cooldown=$cooldown_current/$COOLDOWN_MINS)" >&2
fi

exit 0