#!/usr/bin/env bash
set +x
set -Eeuo pipefail
umask 077

readonly EXPECTED_ACCOUNT="billy@livingip.xyz"
readonly PROJECT_ID="teleo-501523"
readonly INSTANCE="teleo-prod-1"
readonly ZONE="europe-west6-a"
readonly EXPECTED_INTERNAL_IP="10.60.0.3"
readonly KEYCHAIN_SERVICE="com.livingip.teleo.gcp-operator-reauth"
readonly KEYCHAIN_LABEL="Teleo GCP operator emergency password"
readonly WORKFLOW_PATH=".github/workflows/gcp-iap-operator.yml"
readonly RERUN_COMMAND="scripts/gcp-operator-reauth.sh --status"

HELPER_DIR=""
KEYCHAIN_HELPER=""

usage() {
  cat <<'EOF'
Usage: scripts/gcp-operator-reauth.sh [--status | --store-password]

  --status          Report Keychain presence and local gcloud/IAP prerequisites.
  --store-password  Securely store or update the emergency Google password, then report status.

With no option, the script asks before opening the secure password prompt.
EOF
}

die() {
  printf 'gcp-operator-reauth: %s\n' "$1" >&2
  exit 2
}

cleanup() {
  if [[ -n "$HELPER_DIR" && -d "$HELPER_DIR" ]]; then
    rm -rf -- "$HELPER_DIR"
  fi
}
trap cleanup EXIT

validate_test_overrides() {
  if [[ -n "${TELEO_GCP_REAUTH_KEYCHAIN_HELPER:-}${TELEO_GCP_REAUTH_PINENTRY:-}" && \
        "${TELEO_GCP_REAUTH_TESTING:-0}" != "1" ]]; then
    die "helper overrides are accepted only when TELEO_GCP_REAUTH_TESTING=1"
  fi
}

build_keychain_helper() {
  if [[ -n "${TELEO_GCP_REAUTH_KEYCHAIN_HELPER:-}" ]]; then
    [[ -x "$TELEO_GCP_REAUTH_KEYCHAIN_HELPER" ]] || die "test Keychain helper is not executable"
    KEYCHAIN_HELPER="$TELEO_GCP_REAUTH_KEYCHAIN_HELPER"
    return
  fi

  command -v swiftc >/dev/null 2>&1 || die "swiftc is required for secure macOS Keychain access"
  HELPER_DIR="$(mktemp -d "${TMPDIR:-/tmp}/teleo-gcp-keychain.XXXXXX")"
  chmod 0700 "$HELPER_DIR"
  local source="$HELPER_DIR/GcpOperatorKeychain.swift"
  KEYCHAIN_HELPER="$HELPER_DIR/gcp-operator-keychain"

  cat >"$source" <<'SWIFT'
import AppKit
import Foundation
import Security

func fail(_ message: String, _ code: Int32 = 2) -> Never {
    FileHandle.standardError.write(Data("gcp-operator-keychain: \(message)\n".utf8))
    exit(code)
}

guard CommandLine.arguments.count == 5 else {
    fail("expected action, service, account, and label")
}

let action = CommandLine.arguments[1]
let service = CommandLine.arguments[2]
let account = CommandLine.arguments[3]
let label = CommandLine.arguments[4]

func itemQuery() -> [String: Any] {
    [
        kSecClass as String: kSecClassGenericPassword,
        kSecAttrService as String: service,
        kSecAttrAccount as String: account,
        kSecAttrSynchronizable as String: kCFBooleanFalse as Any,
    ]
}

func itemExists() -> Bool {
    var query = itemQuery()
    query[kSecMatchLimit as String] = kSecMatchLimitOne
    let status = SecItemCopyMatching(query as CFDictionary, nil)
    if status == errSecSuccess {
        return true
    }
    if status == errSecItemNotFound {
        return false
    }
    fail("Keychain status failed with OSStatus \(status)")
}

func store(_ password: Data) -> String {
    guard !password.isEmpty else {
        fail("empty password was not stored")
    }
    guard password.count <= 4096 else {
        fail("password exceeds the 4096-byte limit")
    }

    let query = itemQuery()
    if itemExists() {
        let attributes: [String: Any] = [
            kSecValueData as String: password,
            kSecAttrLabel as String: label,
            kSecAttrAccessible as String: kSecAttrAccessibleWhenUnlockedThisDeviceOnly,
        ]
        let status = SecItemUpdate(query as CFDictionary, attributes as CFDictionary)
        guard status == errSecSuccess else {
            fail("Keychain update failed with OSStatus \(status)")
        }
        return "updated"
    }

    var item = query
    item[kSecValueData as String] = password
    item[kSecAttrLabel as String] = label
    item[kSecAttrAccessible as String] = kSecAttrAccessibleWhenUnlockedThisDeviceOnly
    let status = SecItemAdd(item as CFDictionary, nil)
    guard status == errSecSuccess else {
        fail("Keychain add failed with OSStatus \(status)")
    }
    return "stored"
}

func hexValue(_ byte: UInt8) -> UInt8? {
    switch byte {
    case 48...57: return byte - 48
    case 65...70: return byte - 55
    case 97...102: return byte - 87
    default: return nil
    }
}

func decodeAssuan(_ value: Substring) -> Data? {
    let input = Array(value.utf8)
    var output = Data()
    var index = 0
    while index < input.count {
        if input[index] == 37 {
            guard index + 2 < input.count,
                  let high = hexValue(input[index + 1]),
                  let low = hexValue(input[index + 2]) else {
                return nil
            }
            output.append((high << 4) | low)
            index += 3
        } else {
            output.append(input[index])
            index += 1
        }
    }
    return output
}

func passwordFromPinentry(_ response: Data) -> Data {
    guard let text = String(data: response, encoding: .utf8) else {
        fail("pinentry returned non-UTF-8 protocol data")
    }
    for line in text.split(separator: "\n", omittingEmptySubsequences: false) {
        if line.hasPrefix("D ") {
            guard let decoded = decodeAssuan(line.dropFirst(2)) else {
                fail("pinentry returned invalid escaped data")
            }
            return decoded
        }
    }
    fail("pinentry did not return a password")
}

switch action {
case "status":
    print(itemExists() ? "present" : "absent")
case "store-pinentry":
    let response = FileHandle.standardInput.readDataToEndOfFile()
    print(store(passwordFromPinentry(response)))
case "prompt-store":
    let app = NSApplication.shared
    app.setActivationPolicy(.accessory)
    app.activate(ignoringOtherApps: true)
    let alert = NSAlert()
    alert.alertStyle = .informational
    alert.messageText = "Store Teleo GCP emergency password"
    alert.informativeText = "This password is stored only in this Mac's encrypted Keychain. It cannot refresh gcloud OAuth by itself."
    alert.addButton(withTitle: "Store in Keychain")
    alert.addButton(withTitle: "Cancel")
    let field = NSSecureTextField(frame: NSRect(x: 0, y: 0, width: 360, height: 24))
    field.placeholderString = "Current Google password"
    let mainMenu = NSMenu()
    let editMenuItem = NSMenuItem(title: "Edit", action: nil, keyEquivalent: "")
    let editMenu = NSMenu(title: "Edit")
    editMenu.addItem(withTitle: "Paste", action: #selector(NSText.paste(_:)), keyEquivalent: "v")
    editMenuItem.submenu = editMenu
    mainMenu.addItem(editMenuItem)
    app.mainMenu = mainMenu
    let fieldMenu = NSMenu(title: "Edit")
    fieldMenu.addItem(withTitle: "Paste", action: #selector(NSText.paste(_:)), keyEquivalent: "")
    field.menu = fieldMenu
    alert.accessoryView = field
    alert.window.initialFirstResponder = field
    while true {
        app.activate(ignoringOtherApps: true)
        guard alert.runModal() == .alertFirstButtonReturn else {
            fail("password entry cancelled", 3)
        }
        if !field.stringValue.isEmpty {
            print(store(Data(field.stringValue.utf8)))
            break
        }
        NSSound.beep()
        alert.informativeText = "Enter the current Google password. Empty values are never stored."
        alert.window.initialFirstResponder = field
    }
default:
    fail("unsupported action")
}
SWIFT

  swiftc -O -framework AppKit -framework Security "$source" -o "$KEYCHAIN_HELPER"
  chmod 0700 "$KEYCHAIN_HELPER"
}

find_pinentry() {
  if [[ -n "${TELEO_GCP_REAUTH_PINENTRY:-}" ]]; then
    [[ -x "$TELEO_GCP_REAUTH_PINENTRY" ]] || die "test pinentry helper is not executable"
    printf '%s\n' "$TELEO_GCP_REAUTH_PINENTRY"
    return
  fi
  if command -v pinentry-mac >/dev/null 2>&1; then
    command -v pinentry-mac
    return
  fi
  for candidate in /opt/homebrew/bin/pinentry-mac /usr/local/bin/pinentry-mac; do
    if [[ -x "$candidate" ]]; then
      printf '%s\n' "$candidate"
      return
    fi
  done
  return 1
}

store_password() {
  local pinentry result
  if pinentry="$(find_pinentry)"; then
    result="$({
      printf 'SETTITLE Teleo GCP operator\n'
      printf 'SETDESC Store the current Google password in macOS Keychain. This does not authenticate gcloud.\n'
      printf 'SETPROMPT Google password:\n'
      printf 'GETPIN\n'
      printf 'BYE\n'
    } | "$pinentry" | "$KEYCHAIN_HELPER" store-pinentry "$KEYCHAIN_SERVICE" "$EXPECTED_ACCOUNT" "$KEYCHAIN_LABEL")" || {
      die "secure password entry was cancelled or failed"
    }
    printf 'secure_prompt=pinentry-mac\n'
  else
    result="$("$KEYCHAIN_HELPER" prompt-store "$KEYCHAIN_SERVICE" "$EXPECTED_ACCOUNT" "$KEYCHAIN_LABEL")" || {
      die "secure password entry was cancelled or failed"
    }
    printf 'secure_prompt=AppKit NSSecureTextField\n'
  fi
  case "$result" in
    stored | updated) printf 'keychain_password=%s\n' "$result" ;;
    *) die "Keychain helper returned an invalid result" ;;
  esac
}

emit_security_boundary() {
  printf '%s\n' \
    'security_truth=The stored Google password is emergency convenience only; it cannot satisfy or automate gcloud OAuth.' \
    'password_handling=The script never prints, copies, or submits the password and never places it in a command argument.' \
    "durable_unattended_route=$WORKFLOW_PATH uses GitHub OIDC/Workload Identity Federation and IAP after one-time bootstrap."
}

emit_reauth_cta() {
  printf '%s\n' \
    'oauth_state=stale_or_unavailable' \
    "clear_CTA=Run 'gcloud auth login $EXPECTED_ACCOUNT --force --no-launch-browser' in a terminal, paste the displayed URL into the dedicated Chrome GCP session, complete reauthentication, return the authorization code to gcloud, then rerun '$RERUN_COMMAND'."
}

report_status() {
  local keychain_state account project instance_state gcloud_bin
  keychain_state="$("$KEYCHAIN_HELPER" status "$KEYCHAIN_SERVICE" "$EXPECTED_ACCOUNT" "$KEYCHAIN_LABEL")"
  case "$keychain_state" in
    present | absent) ;;
    *) die "Keychain helper returned an invalid status" ;;
  esac

  emit_security_boundary
  printf 'keychain_password=%s\n' "$keychain_state"

  if ! gcloud_bin="$(command -v gcloud)"; then
    printf '%s\n' 'gcloud_state=missing' 'operator_readiness=not_ready'
    return 1
  fi
  printf 'gcloud_binary=%s\n' "$gcloud_bin"

  account="$(gcloud config get-value account --quiet 2>/dev/null || true)"
  project="$(gcloud config get-value project --quiet 2>/dev/null || true)"
  printf 'gcloud_account=%s\n' "${account:-unset}"
  printf 'gcloud_project=%s\n' "${project:-unset}"
  if [[ "$account" != "$EXPECTED_ACCOUNT" || "$project" != "$PROJECT_ID" ]]; then
    printf '%s\n' \
      'gcloud_config_state=mismatch' \
      "clear_CTA=Run 'gcloud config set account $EXPECTED_ACCOUNT && gcloud config set project $PROJECT_ID', then rerun '$RERUN_COMMAND'." \
      'operator_readiness=not_ready'
    return 1
  fi
  printf 'gcloud_config_state=ready\n'

  if ! gcloud auth print-access-token --account="$EXPECTED_ACCOUNT" >/dev/null 2>&1; then
    emit_reauth_cta
    printf 'operator_readiness=not_ready\n'
    return 1
  fi
  printf 'oauth_state=ready\n'

  if ! command -v ssh >/dev/null 2>&1; then
    printf '%s\n' 'ssh_binary=missing' 'operator_readiness=not_ready'
    return 1
  fi
  printf 'ssh_binary=ready\n'

  instance_state="$(
    gcloud compute instances describe "$INSTANCE" \
      --project="$PROJECT_ID" \
      --zone="$ZONE" \
      --format='value(name,status,networkInterfaces[0].networkIP)' \
      --quiet 2>/dev/null || true
  )"
  if [[ "$instance_state" != "$INSTANCE"$'\t'"RUNNING"$'\t'"$EXPECTED_INTERNAL_IP" ]]; then
    printf '%s\n' \
      'instance_readback=not_ready' \
      "clear_CTA=Confirm $INSTANCE is RUNNING at $EXPECTED_INTERNAL_IP in $PROJECT_ID/$ZONE, then rerun '$RERUN_COMMAND'." \
      'operator_readiness=not_ready'
    return 1
  fi
  printf 'instance_readback=%s RUNNING %s\n' "$INSTANCE" "$EXPECTED_INTERNAL_IP"

  if ! gcloud compute ssh "$INSTANCE" \
    --project="$PROJECT_ID" \
    --zone="$ZONE" \
    --tunnel-through-iap \
    --ssh-key-expire-after=5m \
    --dry-run \
    --quiet >/dev/null 2>&1; then
    printf '%s\n' \
      'iap_ssh_preflight=not_ready' \
      "clear_CTA=Repair the local gcloud IAP/SSH prerequisite reported by 'gcloud compute ssh $INSTANCE --project=$PROJECT_ID --zone=$ZONE --tunnel-through-iap --ssh-key-expire-after=5m --dry-run', then rerun '$RERUN_COMMAND'." \
      'operator_readiness=not_ready'
    return 1
  fi
  printf '%s\n' \
    'iap_ssh_preflight=ready_dry_run_only' \
    'iap_connection=not_attempted' \
    'operator_readiness=ready_for_explicit_operator_action'
}

main() {
  local mode="interactive" answer
  [[ $# -le 1 ]] || {
    usage >&2
    exit 2
  }
  if [[ $# -eq 1 ]]; then
    case "$1" in
      --status) mode="status" ;;
      --store-password) mode="store" ;;
      -h | --help) usage; exit 0 ;;
      *) usage >&2; exit 2 ;;
    esac
  fi

  validate_test_overrides
  build_keychain_helper

  if [[ "$mode" == "interactive" ]]; then
    if [[ ! -t 0 && "${TELEO_GCP_REAUTH_TESTING:-0}" != "1" ]]; then
      die "interactive mode requires a terminal; use --status or --store-password"
    fi
    printf 'Store or update the emergency Google password in macOS Keychain? [y/N] ' >&2
    IFS= read -r answer || answer=""
    case "$answer" in
      y | Y | yes | YES) store_password ;;
      *) printf 'keychain_password=unchanged\n' ;;
    esac
  elif [[ "$mode" == "store" ]]; then
    store_password
  fi

  report_status
}

main "$@"