#!/usr/bin/env bash

set -Eeuo pipefail
set +x
umask 077

readonly EXPECTED_CANDIDATE_SHA256="5c5cd74b4992f537fd27c50cf2209573a80a9904e0b19b58c3154717be6ff4a5"
readonly EXPECTED_PRE_CUTOVER_SHA256="de7ebd4f69cd7d2204ee633e074bf6a4370a6f5e3f3fac9067b099d5d75269b5"
readonly REPOSITORY_ROOT="/home/donghyeon/workspace/platform"
readonly CANDIDATE="${REPOSITORY_ROOT}/infrastructure/networking/host-nginx/learn-services-keycloak.conf"
readonly ACTIVE="/etc/nginx/sites-available/learn-services"
readonly ENABLED="/etc/nginx/sites-enabled/learn-services"
readonly GITEA_HOST="git.learn.hyeonworks.com"
readonly KEYCLOAK_HOST="id.learn.hyeonworks.com"
readonly KEYCLOAK_ISSUER="https://${KEYCLOAK_HOST}/realms/hyeonworks"
readonly CURL_BIN="/usr/bin/curl"
readonly JQ_BIN="/usr/bin/jq"
readonly NGINX_BIN="/usr/sbin/nginx"
readonly SYSTEMCTL_BIN="/usr/bin/systemctl"
readonly INSTALL_BIN="/usr/bin/install"
readonly SHA256SUM_BIN="/usr/bin/sha256sum"
readonly STAT_BIN="/usr/bin/stat"
readonly READLINK_BIN="/usr/bin/readlink"
readonly MKTEMP_BIN="/usr/bin/mktemp"
readonly RM_BIN="/usr/bin/rm"
readonly DATE_BIN="/usr/bin/date"
readonly AWK_BIN="/usr/bin/awk"
readonly SLEEP_BIN="/usr/bin/sleep"

fail() {
  printf 'ERROR: %s\n' "$*" >&2
  return 1
}

usage() {
  printf '%s\n' \
    'Usage: sudo bash scripts/bootstrap/apply-host-nginx-keycloak.sh --execute' \
    '' \
    'Replaces the static id.learn response with the reviewed Keycloak proxy.' \
    'The active site is backed up first; a failed test or health check restores' \
    'the prior Gitea-only configuration and reloads Nginx automatically.'
}

[[ "${1:-}" == "--execute" && "$#" -eq 1 ]] || {
  usage
  exit 2
}
[[ "$EUID" -eq 0 ]] || fail "run this script through sudo"
[[ -t 0 ]] || fail "an interactive terminal is required"

for required_binary in \
  "$CURL_BIN" "$JQ_BIN" "$NGINX_BIN" "$SYSTEMCTL_BIN" "$INSTALL_BIN" \
  "$SHA256SUM_BIN" "$STAT_BIN" "$READLINK_BIN" "$MKTEMP_BIN" \
  "$RM_BIN" "$DATE_BIN" "$AWK_BIN" "$SLEEP_BIN"; do
  [[ -x "$required_binary" ]] || fail "required executable is missing: ${required_binary}"
done

[[ -f "$CANDIDATE" && ! -L "$CANDIDATE" ]] || fail "unsafe candidate: ${CANDIDATE}"
[[ -f "$ACTIVE" && ! -L "$ACTIVE" ]] || fail "unsafe active file: ${ACTIVE}"
[[ -L "$ENABLED" ]] || fail "enabled path is not a symlink: ${ENABLED}"
[[ "$("$READLINK_BIN" -f "$ENABLED")" == "$ACTIVE" ]] || \
  fail "enabled symlink target changed"
[[ "$("$STAT_BIN" --format='%U:%G %a' "$ACTIVE")" == "root:root 644" ]] || \
  fail "active file owner or mode changed"
"$SYSTEMCTL_BIN" is-active --quiet nginx || fail "nginx is not active"

readonly TEMP_DIR="$("$MKTEMP_BIN" -d /tmp/nginx-keycloak-cutover.XXXXXX)"
readonly CANDIDATE_SNAPSHOT="${TEMP_DIR}/learn-services.candidate"
readonly GITEA_HEALTH="${TEMP_DIR}/gitea-health.json"
readonly KEYCLOAK_DISCOVERY="${TEMP_DIR}/keycloak-discovery.json"
readonly LOGIN_HEADERS="${TEMP_DIR}/gitea-login-headers"
rollback_armed=0
backup=""

cleanup() {
  case "$TEMP_DIR" in
    /tmp/nginx-keycloak-cutover.*)
      "$RM_BIN" -rf -- "$TEMP_DIR"
      ;;
    *)
      printf 'WARNING: refusing to remove unexpected temp path: %s\n' \
        "$TEMP_DIR" >&2
      ;;
  esac
}

check_gitea_health() {
  "$JQ_BIN" -e '
    .status == "pass" and
    ([.checks["database:ping"][], .checks["cache:ping"][]] |
      all(.status == "pass"))
  ' "$GITEA_HEALTH" >/dev/null
}

check_keycloak_discovery() {
  "$JQ_BIN" -e \
    --arg issuer "$KEYCLOAK_ISSUER" '
      .issuer == $issuer and
      (.authorization_endpoint | startswith($issuer)) and
      (.token_endpoint | startswith($issuer)) and
      (.userinfo_endpoint | startswith($issuer)) and
      (.jwks_uri | startswith($issuer))
    ' "$KEYCLOAK_DISCOVERY" >/dev/null
}

pre_cutover_checks() {
  "$CURL_BIN" --disable --noproxy '*' --fail-with-body --silent --show-error --max-time 10 \
    --header "Host: ${GITEA_HOST}" \
    --header 'X-Forwarded-Proto: https' \
    http://127.0.0.1:30080/api/healthz >"$GITEA_HEALTH"
  check_gitea_health

  "$CURL_BIN" --disable --noproxy '*' --fail-with-body --silent --show-error --max-time 10 \
    --header "Host: ${KEYCLOAK_HOST}" \
    --header 'X-Forwarded-Host: id.learn.hyeonworks.com' \
    --header 'X-Forwarded-Proto: https' \
    --header 'X-Forwarded-Port: 443' \
    "http://127.0.0.1:30080/realms/hyeonworks/.well-known/openid-configuration" \
    >"$KEYCLOAK_DISCOVERY"
  check_keycloak_discovery
}

wait_for_proxy_state() {
  local attempt

  for ((attempt = 1; attempt <= 12; attempt++)); do
    if "$CURL_BIN" --disable --noproxy '*' --fail --silent --show-error \
      --connect-timeout 1 --max-time 3 \
      --resolve "${GITEA_HOST}:443:127.0.0.1" \
      "https://${GITEA_HOST}/api/healthz" >"$GITEA_HEALTH" 2>/dev/null &&
      check_gitea_health 2>/dev/null &&
      "$CURL_BIN" --disable --noproxy '*' --fail --silent --show-error \
        --connect-timeout 1 --max-time 3 \
        --resolve "${KEYCLOAK_HOST}:443:127.0.0.1" \
        "https://${KEYCLOAK_HOST}/realms/hyeonworks/.well-known/openid-configuration" \
        >"$KEYCLOAK_DISCOVERY" 2>/dev/null &&
      check_keycloak_discovery 2>/dev/null; then
      if (( attempt > 1 )); then
        printf 'Nginx proxy state stabilized after %d probes.\n' "$attempt"
      fi
      return 0
    fi
    (( attempt < 12 )) && "$SLEEP_BIN" 1
  done

  return 1
}

wait_for_rollback_state() {
  local attempt
  local id_body

  for ((attempt = 1; attempt <= 12; attempt++)); do
    id_body="$(
      "$CURL_BIN" --disable --noproxy '*' --fail --silent --show-error \
        --connect-timeout 1 --max-time 3 \
        --resolve "${KEYCLOAK_HOST}:443:127.0.0.1" \
        "https://${KEYCLOAK_HOST}/" 2>/dev/null
    )" || id_body=""
    if [[ "$id_body" == "Keycloak domain reached Nginx successfully" ]] &&
      "$CURL_BIN" --disable --noproxy '*' --fail --silent --show-error \
        --connect-timeout 1 --max-time 3 \
        --resolve "${GITEA_HOST}:443:127.0.0.1" \
        "https://${GITEA_HOST}/api/healthz" >"$GITEA_HEALTH" 2>/dev/null &&
      check_gitea_health 2>/dev/null; then
      return 0
    fi
    (( attempt < 12 )) && "$SLEEP_BIN" 1
  done

  return 1
}

rollback() {
  local restore_rc=0

  set +e
  printf '\nROLLBACK: restoring %s\n' "$backup" >&2
  "$INSTALL_BIN" -o root -g root -m 0644 "$backup" "$ACTIVE" || restore_rc=1
  "$NGINX_BIN" -t || restore_rc=1
  if (( restore_rc == 0 )); then
    "$SYSTEMCTL_BIN" reload nginx || restore_rc=1
    "$SYSTEMCTL_BIN" is-active --quiet nginx || restore_rc=1
    wait_for_rollback_state || restore_rc=1
  fi

  if (( restore_rc == 0 )); then
    rollback_armed=0
    printf 'ROLLBACK complete. The Gitea proxy and static Keycloak hold were restored.\n' >&2
  else
    printf 'CRITICAL: automatic rollback failed; backup remains at %s\n' \
      "$backup" >&2
  fi
}

on_exit() {
  local rc=$?

  trap - EXIT INT TERM
  if (( rc != 0 && rollback_armed == 1 )); then
    rollback
  fi
  cleanup
  exit "$rc"
}

trap on_exit EXIT
trap 'exit 130' INT
trap 'exit 143' TERM

"$INSTALL_BIN" -o root -g root -m 0600 "$CANDIDATE" "$CANDIDATE_SNAPSHOT"
readonly CANDIDATE_SHA256="$(
  "$SHA256SUM_BIN" "$CANDIDATE_SNAPSHOT" | "$AWK_BIN" '{print $1}'
)"
readonly ACTIVE_SHA256="$(
  "$SHA256SUM_BIN" "$ACTIVE" | "$AWK_BIN" '{print $1}'
)"
[[ "$CANDIDATE_SHA256" == "$EXPECTED_CANDIDATE_SHA256" ]] || \
  fail "candidate digest changed: ${CANDIDATE_SHA256}"
if [[ "$ACTIVE_SHA256" != "$EXPECTED_PRE_CUTOVER_SHA256" &&
  "$ACTIVE_SHA256" != "$CANDIDATE_SHA256" ]]; then
  fail "active config has an unexpected digest: ${ACTIVE_SHA256}"
fi

pre_cutover_checks
"$NGINX_BIN" -t

post_cutover_checks() {
  local host
  local redirect_result

  wait_for_proxy_state || fail "Gitea and Keycloak HTTPS proxies did not converge"

  for host in "$GITEA_HOST" "$KEYCLOAK_HOST"; do
    redirect_result="$(
      "$CURL_BIN" --disable --noproxy '*' --silent --show-error --max-time 10 \
        --resolve "${host}:80:127.0.0.1" \
        --output /dev/null \
        --write-out $'%{http_code}\n%{redirect_url}' \
        "http://${host}/"
    )"
    [[ "$redirect_result" == $'301\nhttps://'"${host}/" ]] || \
      fail "${host} HTTP redirect check failed: ${redirect_result}"
  done

  "$CURL_BIN" --disable --noproxy '*' --fail --silent --show-error --max-time 10 \
    --resolve "${GITEA_HOST}:443:127.0.0.1" \
    --dump-header "$LOGIN_HEADERS" --output /dev/null \
    "https://${GITEA_HOST}/user/login"
  "$AWK_BIN" '
    BEGIN { found = 0; insecure = 0 }
    tolower($0) ~ /^set-cookie:/ {
      found++
      if (tolower($0) !~ /; secure([;[:space:]]|$)/) insecure = 1
    }
    END { exit(found == 0 || insecure) }
  ' "$LOGIN_HEADERS" || fail "Gitea login cookie Secure check failed"

  if "$CURL_BIN" --disable --noproxy '*' --insecure --silent --output /dev/null --max-time 5 \
    --resolve unconfigured.invalid:443:127.0.0.1 \
    https://unconfigured.invalid/ 2>/dev/null; then
    fail "unknown TLS hostname was not rejected"
  fi
}

if [[ "$ACTIVE_SHA256" == "$CANDIDATE_SHA256" ]]; then
  post_cutover_checks
  printf 'The reviewed Keycloak Host Nginx configuration is already active and healthy.\n'
  exit 0
fi

backup="${ACTIVE}.before-keycloak-$("$DATE_BIN" +%Y%m%d%H%M%S)"
[[ ! -e "$backup" && ! -L "$backup" ]] || fail "backup path already exists: ${backup}"

printf '\nActive SHA-256:    %s\n' "$ACTIVE_SHA256"
printf 'Candidate SHA-256: %s\n' "$CANDIDATE_SHA256"
printf 'Planned backup:      %s\n' "$backup"
printf 'Type APPLY to expose Keycloak through Host Nginx: '
read -r confirmation
[[ "$confirmation" == "APPLY" ]] || fail "cancelled"

"$INSTALL_BIN" -o root -g root -m 0644 "$ACTIVE" "$backup"
[[ "$("$SHA256SUM_BIN" "$backup" | "$AWK_BIN" '{print $1}')" == \
  "$ACTIVE_SHA256" ]] || fail "backup digest mismatch"

rollback_armed=1
"$INSTALL_BIN" -o root -g root -m 0644 "$CANDIDATE_SNAPSHOT" "$ACTIVE"
[[ "$("$SHA256SUM_BIN" "$ACTIVE" | "$AWK_BIN" '{print $1}')" == \
  "$CANDIDATE_SHA256" ]] || fail "installed digest mismatch"
"$NGINX_BIN" -t
"$SYSTEMCTL_BIN" reload nginx
"$SYSTEMCTL_BIN" is-active --quiet nginx
post_cutover_checks

rollback_armed=0
printf '\nKEYCLOAK CUTOVER SUCCESS\n'
printf 'Backup: %s\n' "$backup"
printf 'Candidate SHA-256: %s\n' "$CANDIDATE_SHA256"
printf 'Gitea health, Keycloak discovery issuer, HTTPS cookies, redirects, and unknown-host rejection: PASS\n'