#!/usr/bin/env bash
# Prepare Headplane files or issue one protected login key; Komodo owns deployment.
set -euo pipefail
export LC_ALL=C
fail() { printf 'ERROR: %s\n' "$*" >&2; return 1; }
safe_path() {
  local path=$1
  [[ "$path" =~ ^/([a-zA-Z0-9_-]+/){2,}[a-zA-Z0-9_-]+$ ]] || { fail 'Explicit service path required'; return 1; }
  while [[ "$path" != / ]]; do
    [[ ! -L "$path" ]] || { fail 'Symlink in service path'; return 1; }
    path=${path%/*}; path=${path:-/}
  done
}
prepare() {
  local root=$1 port=$2 binding=$3 listeners
  if [[ -e "$root/headplane-prepared" ]]; then
    [[ -f "$root/headplane-prepared" && $(cat "$root/headplane-prepared") == "$binding" ]] || { fail 'Headplane binding differs'; return 1; }
    [[ -d "$root/headplane-data" && -d "$root/headplane-secrets" && -f "$root/headplane-secrets/cookie" ]] || { fail 'Incomplete preparation'; return 1; }
    [[ $(stat -c '%u:%a:%h' "$root/headplane-secrets/cookie") == 0:600:1 && $(wc -c < "$root/headplane-secrets/cookie") == 32 ]] || { fail 'Cookie file ownership, mode or length differs'; return 1; }
    printf 'Headplane preparation reused; cookie and data preserved.\n'
    return 0
  fi
  [[ ! -e "$root/headplane-data" && ! -e "$root/headplane-secrets" ]] || { fail 'Unregistered or interrupted Headplane preparation; inspect before recovery'; return 1; }
  listeners=$(ss -H -lnt "sport = :$port") || { fail 'Cannot inspect Headplane port'; return 1; }
  [[ -z "$listeners" ]] || { fail 'Headplane port occupied'; return 1; }
  mkdir -m 0700 "$root/headplane-data" "$root/headplane-secrets"
  openssl rand -hex 16 | tr -d '\r\n' > "$root/headplane-secrets/cookie"
  chmod 0600 "$root/headplane-secrets/cookie"
  [[ $(wc -c < "$root/headplane-secrets/cookie") == 32 ]] || return 1
  printf '%s\n' "$binding" > "$root/headplane-prepared"
  printf 'Headplane directories and protected cookie prepared.\n'
}
issue_key() {
  local root=$1 project=$2 container actual output="$1/headplane-secrets/admin-api-key"
  [[ -f "$root/headplane-prepared" && -d "$root/headplane-secrets" ]] || { fail 'Run prepare first'; return 1; }
  container=$(docker ps --filter "label=com.docker.compose.project=$project" --filter label=com.docker.compose.service=headscale --format '{{.ID}}') || return 1
  [[ "$container" =~ ^[a-f0-9]{12,64}$ ]] || { fail 'Exactly one running Headscale container required'; return 1; }
  actual=$(docker inspect --format '{{index .Config.Labels "com.docker.compose.project"}}/{{index .Config.Labels "com.docker.compose.service"}}/{{.State.Health.Status}}{{range .Mounts}}{{if eq .Destination "/var/lib/headscale"}}/{{.Source}}{{end}}{{end}}' "$container") || return 1
  [[ "$actual" == "$project/headscale/healthy/$root/data" ]] || { fail 'Container project, data directory or health differs'; return 1; }
  [[ ! -e "$output.pending" ]] || { fail 'Interrupted key issuance; inspect original operation'; return 1; }
  if [[ -e "$output" ]]; then
    [[ -f "$output" && -s "$output" && $(stat -c '%u:%a:%h' "$output") == 0:600:1 ]] || { fail 'Existing credential incomplete or unsafe; inspect original operation'; return 1; }
    printf 'Existing login key preserved; verify expiration separately.\n'
    return 0
  fi
  # Reserve first: interruption leaves an empty file, never silently issues another key.
  (set -o noclobber; : > "$output")
  if ! docker exec "$container" headscale apikeys create --expiration 90d > "$output.pending"; then
    rm -f -- "$output.pending"
    fail 'Key creation failed; reserved empty file prevents duplicate issuance'; return 1
  fi
  [[ -s "$output.pending" ]] || { fail 'Key creation result missing; inspect original operation'; return 1; }
  chmod 0600 "$output.pending"
  mv -T -- "$output.pending" "$output"
  printf '90-day login key written to protected file; retrieve over the verified management connection.\n'
}
main() {
  local mode='' name='' root='' port='' project='' command binding path
  while (($#)); do
    case "$1" in
      --help|-h) echo 'Usage: headplane-prepare.sh --mode prepare|key --hostname NAME --root ABSOLUTE_SERVICE_PATH --port PORT --project STACK_PROJECT'; return 0;;
      --mode|--hostname|--root|--port|--project)
        (($# >= 2)) || { fail 'Missing value'; return 1; }
        case "$1" in --mode) mode=$2;; --hostname) name=$2;; --root) root=$2;; --port) port=$2;; --project) project=$2;; esac; shift 2;;
      *) fail 'Unknown option'; return 1;;
    esac
  done
  [[ "$mode" == prepare || "$mode" == key ]] || { fail 'Explicit mode required'; return 1; }
  [[ "$name" =~ ^(dev|test|stage|prod)-[a-z0-9-]+-[0-9]{2}$ && "$project" =~ ^(dev|test|stage|prod)-[a-z0-9-]+$ && "${name%%-*}" == "${project%%-*}" ]] || { fail 'Registered hostname and matching project required'; return 1; }
  [[ "$port" =~ ^[1-9][0-9]{3,4}$ ]] && ((port <= 65535 && port >= 1024)) || { fail 'Unprivileged port required'; return 1; }
  case "$port" in 2019|9090|50443) fail 'Reserved management port'; return 1;; esac
  [[ $EUID == 0 && $(uname -s) == Linux && $(hostname) == "$name" ]] || { fail 'Run on the exact Linux host as root'; return 1; }
  for command in systemctl nft ss openssl flock stat sha256sum cut tr wc; do command -v "$command" >/dev/null; done
  safe_path "$root"
  [[ -d "$root" && -f "$root/prepared.sha256" ]] || { fail 'Headscale prepared root required'; return 1; }
  [[ $(stat -c '%u:%a' "$root") == 0:700 ]] || { fail 'Service root must be root-owned mode 0700'; return 1; }
  for path in prepared.sha256 headplane-prepared headplane-data headplane-secrets headplane-secrets/cookie headplane-secrets/admin-api-key headplane-secrets/admin-api-key.pending headplane-lock; do
    # File basenames contain dots; inspect every existing component separately.
    [[ ! -L "$root/$path" ]] || { fail 'Symlink in Headplane files'; return 1; }
  done
  systemctl is-active --quiet platform-firewall.service
  test ! -e /run/platform-firewall/pending.nft
  nft list table inet platform_host >/dev/null
  umask 077
  exec 9>>"$root/headplane-lock"; flock -n 9 || { fail 'Another Headplane preparation is running'; return 1; }
  binding=$(printf '%s\n' "$name" "$root" "$port" "$project" | sha256sum | cut -d ' ' -f 1)
  if [[ "$mode" == prepare ]]; then prepare "$root" "$port" "$binding"
  else
    [[ -f "$root/headplane-prepared" && $(cat "$root/headplane-prepared") == "$binding" ]] || { fail 'Headplane binding differs'; return 1; }
    issue_key "$root" "$project"
  fi
}
if [[ ${BASH_SOURCE[0]:-} == "$0" || ${BASH_SOURCE[0]:-} == '' ]]; then main "$@"; fi