#!/usr/bin/env bash
# preflight_kubecontext.sh
#
# Shared helper to detect the "wrong shell context for the install mode"
# class of bug. Sourced by install.sh and deploy.sh.
#
# Exposes two functions:
#
#   verify_kubecontext_matches_config <config-path>
#       Strict gate. Reads APP_CLUSTER_KUBECONTEXT from the config's [Global]
#       section and refuses to proceed if `kubectl config current-context`
#       doesn't match. Used by deploy.sh (unattended path: silent mismatches
#       are dangerous).
#
#       Returns 0 on match (or when the config has no APP_CLUSTER_KUBECONTEXT,
#       e.g. fresh k3d setup). Exits 1 with a clear error on mismatch.
#       Set KNOE_SKIP_KUBECONTEXT_GUARD=true to bypass (escape hatch for
#       deliberate cross-cluster maintenance).
#
#   print_kubecontext_notice
#       Informational. Prints the current kubectl context (or "(none)") so
#       the user sees what install.sh is about to inherit before the TUI
#       launches. Never exits or fails. Used by install.sh.
#
# History: this guard was filed in response to the 2026-04-28 14:00 UTC
# outage. An install.sh run in k3d mode with the shell pointed at GKE
# overwrote the GKE-cluster ObjectStore + ScheduledBackup with k3d-mode
# defaults, and CNPG backups silently failed for hours until the next
# manual check. See CLAUDE.md §"Env-contamination warning" and
# docs/TODO.md queue item #1 (drift R4).

# Read APP_CLUSTER_KUBECONTEXT from the [Global] section of an INI-style
# config. Empty string if absent. Quote-stripping is best-effort.
_kubectx_from_config() {
  local cfg="$1"
  [[ -f "$cfg" ]] || { echo ""; return 0; }
  # awk: print value when we're in [Global] and key matches.
  # Strips surrounding whitespace and quotes.
  awk '
    /^\[/{section=$0; next}
    section=="[Global]" && /^[[:space:]]*APP_CLUSTER_KUBECONTEXT[[:space:]]*=/ {
      sub(/^[^=]*=[[:space:]]*/, "", $0)
      sub(/^"/, "", $0); sub(/"$/, "", $0)
      sub(/^'\''/, "", $0); sub(/'\''$/, "", $0)
      print $0
      exit
    }
  ' "$cfg"
}

# Read the live current-context, or empty if kubectl/config unavailable.
_kubectx_current() {
  command -v kubectl >/dev/null 2>&1 || { echo ""; return 0; }
  kubectl config current-context 2>/dev/null || true
}

# verify_kubecontext_matches_config <config-path>
#   Strict gate. Exits 1 on mismatch unless KNOE_SKIP_KUBECONTEXT_GUARD=true.
verify_kubecontext_matches_config() {
  local cfg_path="${1:-}"
  if [[ -z "$cfg_path" ]]; then
    echo "preflight_kubecontext: usage: verify_kubecontext_matches_config <config-path>" >&2
    return 2
  fi
  if [[ "${KNOE_SKIP_KUBECONTEXT_GUARD:-false}" == "true" ]]; then
    echo "preflight_kubecontext: KNOE_SKIP_KUBECONTEXT_GUARD=true — skipping check (escape hatch)." >&2
    return 0
  fi

  local expected
  expected="$(_kubectx_from_config "$cfg_path")"

  # No baked context in the config (e.g. fresh k3d.cfg) → nothing to check.
  if [[ -z "$expected" ]]; then
    return 0
  fi

  local actual
  actual="$(_kubectx_current)"

  # No live current-context → user hasn't selected one; the config is
  # authoritative and downstream code will pass --context explicitly.
  if [[ -z "$actual" ]]; then
    return 0
  fi

  if [[ "$expected" == "$actual" ]]; then
    return 0
  fi

  cat >&2 <<EOF

==============================================================================
  ABORTING: kubectl context mismatch
==============================================================================

  Config:   $cfg_path
  Expected: APP_CLUSTER_KUBECONTEXT = $expected
  Actual:   kubectl config current-context = $actual

  These don't match. The installer would dispatch kubectl operations
  against the WRONG cluster, which has caused real outages in the past
  (see CLAUDE.md §"Env-contamination warning"). Refusing to proceed.

  To fix:
    1) Switch context to the expected cluster:
         kubectl config use-context $expected
       Re-run this command afterward.

    2) Or, if you really need to deploy against the active context, edit
       \`$cfg_path\` and update [Global] APP_CLUSTER_KUBECONTEXT to match.

    3) Override (only when you know what you're doing):
         KNOE_SKIP_KUBECONTEXT_GUARD=true ./deploy.sh

==============================================================================
EOF
  return 1
}

# print_kubecontext_notice
#   Informational. Never fails; just shows the user what's about to be
#   inherited so they can abort before the TUI launches if it looks wrong.
print_kubecontext_notice() {
  local actual
  actual="$(_kubectx_current)"
  if [[ -z "$actual" ]]; then
    echo "==> kubectl current-context: (none set)"
  else
    echo "==> kubectl current-context: $actual"
  fi
  echo "    The mode you select must target this cluster, OR you must switch"
  echo "    context (kubectl config use-context …) before proceeding."
}