#!/usr/bin/env bash
# T44 — istiod=컴파일러: CR 변경이 xDS로 전파되어 proxy-status가 SYNCED로 수렴하고
#        트래픽이 재시작 없이 바뀐다.
#
# Re-runnable verification script. Creates its own ephemeral namespace,
# applies client/echo workloads + a VirtualService (adds a route timeout),
# observes propagation via istioctl, and cleans up on exit.
set -euo pipefail

NS="istio-vt-t44"
DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"

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

echo ">>> creating namespace ${NS} (istio-injection=enabled)"
kubectl create namespace "${NS}"
kubectl label namespace "${NS}" istio-injection=enabled

echo ">>> applying client + echo workloads"
kubectl apply -f "${DIR}/client-echo.yaml"
kubectl -n "${NS}" wait --for=condition=Ready pod/client --timeout=90s
kubectl -n "${NS}" rollout status deploy/echo

CLIENT_START=$(kubectl -n "${NS}" get pod client -o jsonpath='{.status.startTime}')
echo "client_start=${CLIENT_START}"

echo ">>> snapshotting route BEFORE VirtualService apply"
istioctl proxy-config route "client.${NS}" -o json > /tmp/before-route.json
grep -c '2.500s' /tmp/before-route.json || true

echo ">>> applying VirtualService (adds timeout: 2.500s) with timestamps"
( date +%s.%N; kubectl apply -f "${DIR}/echo-verify-timeout.yaml"; date +%s.%N ) > /tmp/apply_ts.txt
cat /tmp/apply_ts.txt

echo ">>> polling for propagation (1s granularity, spec loop)"
for i in $(seq 1 20); do
  R=$(istioctl proxy-config route "client.${NS}" -o json 2>/dev/null | grep -c '2.500s')
  echo "t+${i}s route_has_timeout_count=${R}"
  if [ "$R" != "0" ]; then break; fi
  sleep 1
done

echo ">>> snapshotting route AFTER VirtualService apply"
istioctl proxy-config route "client.${NS}" -o json > /tmp/after-route.json
echo ">>> diff (timeout-related lines only)"
diff -u /tmp/before-route.json /tmp/after-route.json | grep -i timeout || true

echo ">>> proxy-status for client"
istioctl proxy-status | awk -v ns="client.${NS}" 'NR==1 || $0 ~ ns'

echo ">>> confirm no sidecar restart (startTime must equal ${CLIENT_START})"
kubectl -n "${NS}" get pod client -o jsonpath='{.status.startTime}'
echo
echo "(compare to CLIENT_START=${CLIENT_START})"

# --- Optional finer-grained (sub-second) propagation-window measurement ---
# The 1s-granularity loop above is often too coarse to resolve propagation
# on a lightly-loaded cluster (it may already show non-zero on the very
# first check). This block deletes+reapplies the VS and polls immediately
# (no pre-sleep) to bound the real window more precisely.
echo ">>> supplementary: tight-timing re-measurement of propagation window"
kubectl -n "${NS}" delete virtualservice echo-verify-timeout
for i in $(seq 1 15); do
  R=$(istioctl proxy-config route "client.${NS}" -o json 2>/dev/null | grep -c '2.500s')
  echo "revert_poll i=$i count=$R"
  if [ "$R" -eq 0 ] 2>/dev/null; then break; fi
  sleep 1
done

T0=$(date +%s.%N)
kubectl apply -f "${DIR}/echo-verify-timeout.yaml"
T1=$(date +%s.%N)
echo "apply_start=$T0 apply_end=$T1"
for i in $(seq 1 40); do
  TC=$(date +%s.%N)
  R=$(istioctl proxy-config route "client.${NS}" -o json 2>/dev/null | grep -c '2.500s')
  ELAPSED=$(python3 -c "print(round($TC-$T1,3))")
  echo "poll i=$i since_apply_end=${ELAPSED}s count=$R"
  if [ "$R" -gt 0 ] 2>/dev/null; then break; fi
done

echo ">>> done (namespace will be deleted by trap)"