#!/usr/bin/env bash
# T34: hc-mock FSM (OPEN/DRAINING/CLOSING/CLOSED) + illegal-transition guard +
#      DRAIN_TIMEOUT forced-advance, reproducing gt__src-w2-hc-fsm C4-C7.
set -euo pipefail

NS=istio-vt-t34
SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
MANIFEST="$SCRIPT_DIR/manifest.yaml"

cleanup() {
  echo "--- cleanup: deleting namespace $NS ---"
  kubectl delete namespace "$NS" --wait=false --ignore-not-found
}
trap cleanup EXIT

echo "=== create namespace ==="
kubectl create namespace "$NS"
kubectl label namespace "$NS" istio-injection=enabled

echo "=== apply manifest ==="
kubectl apply -f "$MANIFEST"

echo "=== wait for workloads ready ==="
kubectl -n "$NS" wait --for=condition=Ready pod/client --timeout=120s
kubectl -n "$NS" wait --for=condition=Ready pod/hc-mock --timeout=120s
kubectl -n "$NS" wait --for=condition=available deploy/echo --timeout=120s
kubectl -n "$NS" wait --for=condition=available deploy/slow-echo --timeout=120s

hc() { # $1 = method(GET/POST) $2 = path
  if [ "$1" = "POST" ]; then
    kubectl -n "$NS" exec client -c curl -- curl -s -o /dev/null -w '%{http_code}\n' -X POST \
      "http://hc-mock.$NS.svc.homelab.local:18180/$2"
  else
    kubectl -n "$NS" exec client -c curl -- curl -s -o /dev/null -w '%{http_code}\n' \
      "http://hc-mock.$NS.svc.homelab.local:18180/$2"
  fi
}

restart_hc_mock() {
  kubectl -n "$NS" delete pod hc-mock --wait=true
  kubectl apply -f "$MANIFEST"
  kubectl -n "$NS" wait --for=condition=Ready pod/hc-mock --timeout=60s
  sleep 5 # let endpoints propagate
}

echo "=== illegal transition: OPEN -> close-lb directly must be 409 ==="
hc POST close-lb

echo "=== 2-step: drain then close-lb must succeed (200) ==="
hc POST drain
hc POST close-lb

echo "=== reset to clean OPEN, walk state table ==="
restart_hc_mock
for ep in health_check.html health live; do
  echo -n "OPEN $ep="; hc GET "$ep"
done

hc POST drain
for ep in health_check.html health live; do
  echo -n "DRAINING $ep="; hc GET "$ep"
done

echo "=== reopen from DRAINING must immediately return to OPEN ==="
hc POST reopen
echo -n "OPEN_after_reopen health_check.html="; hc GET health_check.html

hc POST drain
hc POST close-lb
for ep in health_check.html health live; do
  echo -n "CLOSING $ep="; hc GET "$ep"
done

hc POST close
for ep in health_check.html health live; do
  echo -n "CLOSED $ep="; hc GET "$ep"
done

echo "=== DRAIN_TIMEOUT forced-advance under real in-mesh load ==="
restart_hc_mock
hc POST drain

# Sustain overlapping in-mesh traffic to slow-echo across the poll window
# (a single 125s-delay request does not work: kennethreitz/httpbin classic
# image caps /delay/<n> at min(n,10) regardless of requested n).
for i in $(seq 1 25); do
  kubectl -n "$NS" exec client -c curl -- curl -s -o /dev/null \
    "http://slow-echo.$NS.svc.homelab.local/delay/10" &
  sleep 6
done &
TRAFFIC_PID=$!

POLL_INTERVAL=2
DRAIN_TIMEOUT=120
START=$(date +%s)
while true; do
  ACTIVE=$(kubectl -n "$NS" exec deploy/slow-echo -c istio-proxy -- \
    curl -s 'localhost:15000/stats?filter=downstream_rq_active' 2>/dev/null \
    | awk -F': ' '{sum+=$2} END{print sum+0}')
  NOW=$(date +%s); EL=$((NOW-START))
  echo "t=${EL}s active=${ACTIVE}"
  if [ "$EL" -ge "$DRAIN_TIMEOUT" ]; then
    echo "DRAIN_TIMEOUT reached -- forcing close-lb regardless of active"
    hc POST close-lb
    break
  fi
  sleep "$POLL_INTERVAL"
done
wait "$TRAFFIC_PID" 2>/dev/null || true

echo "=== done ==="