#!/usr/bin/env bash
# gstack-auth — authenticate with Supabase via email OTP
#
# Usage:
#   gstack-auth [email]        — start auth flow (prompts if no email)
#   gstack-auth status         — show current auth status
#   gstack-auth logout         — remove saved tokens
#
# Sends a 6-digit verification code to the user's email.
# User enters the code in the terminal to authenticate.
#
# Env overrides (for testing):
#   GSTACK_STATE_DIR           — override ~/.gstack state directory
#   GSTACK_DIR                 — override auto-detected gstack root
set -euo pipefail

GSTACK_DIR="${GSTACK_DIR:-$(cd "$(dirname "$0")/.." && pwd)}"
STATE_DIR="${GSTACK_STATE_DIR:-$HOME/.gstack}"
AUTH_FILE="$STATE_DIR/auth-token.json"

# Source Supabase config
if [ -f "$GSTACK_DIR/supabase/config.sh" ]; then
  . "$GSTACK_DIR/supabase/config.sh"
fi
SUPABASE_URL="${GSTACK_SUPABASE_URL:-}"
ANON_KEY="${GSTACK_SUPABASE_ANON_KEY:-}"

if [ -z "$SUPABASE_URL" ] || [ -z "$ANON_KEY" ]; then
  echo "Error: Supabase not configured. Check supabase/config.sh"
  exit 1
fi

AUTH_URL="${SUPABASE_URL}/auth/v1"

# ─── Helper: write auth token file ──────────────────────────
save_token() {
  local access_token="$1"
  local refresh_token="$2"
  local expires_in="$3"
  local email="$4"
  local user_id="$5"

  local expires_at
  expires_at=$(( $(date +%s) + expires_in ))

  mkdir -p "$STATE_DIR"
  cat > "$AUTH_FILE" <<TOKJSON
{
  "access_token": "${access_token}",
  "refresh_token": "${refresh_token}",
  "expires_at": ${expires_at},
  "email": "${email}",
  "user_id": "${user_id}"
}
TOKJSON
  chmod 600 "$AUTH_FILE"
}

# ─── Helper: extract JSON field (portable, no jq dependency) ─
json_field() {
  local json="$1"
  local field="$2"
  echo "$json" | grep -o "\"${field}\":[^,}]*" | head -1 | sed "s/\"${field}\"://;s/\"//g;s/ //g"
}

# ─── Subcommand: status ─────────────────────────────────────
if [ "${1:-}" = "status" ]; then
  if [ ! -f "$AUTH_FILE" ]; then
    echo "Not authenticated. Run: gstack auth <email>"
    exit 0
  fi
  AUTH_JSON="$(cat "$AUTH_FILE")"
  EMAIL="$(json_field "$AUTH_JSON" "email")"
  EXPIRES_AT="$(json_field "$AUTH_JSON" "expires_at")"
  NOW="$(date +%s)"
  if [ "$NOW" -lt "$EXPIRES_AT" ] 2>/dev/null; then
    REMAINING=$(( (EXPIRES_AT - NOW) / 60 ))
    echo "Authenticated as: $EMAIL"
    echo "Token expires in: ${REMAINING}m"
  else
    echo "Authenticated as: $EMAIL (token expired — will auto-refresh)"
  fi
  exit 0
fi

# ─── Subcommand: logout ─────────────────────────────────────
if [ "${1:-}" = "logout" ]; then
  rm -f "$AUTH_FILE"
  echo "Logged out. Auth token removed."
  exit 0
fi

# ─── Main: auth flow ────────────────────────────────────────
EMAIL="${1:-}"
if [ -z "$EMAIL" ]; then
  printf "Enter your email: "
  read -r EMAIL
fi

if [ -z "$EMAIL" ]; then
  echo "Error: email is required"
  exit 1
fi

if ! echo "$EMAIL" | grep -qE '^[^@]+@[^@]+\.[^@]+$'; then
  echo "Error: invalid email format"
  exit 1
fi

# ─── Step 1: Send OTP ────────────────────────────────────────
echo ""
echo "Sending verification code to ${EMAIL}..."

OTP_BODY="{\"email\":\"${EMAIL}\"}"

HTTP_RESPONSE="$(curl -s -w "\n%{http_code}" \
  -X POST "${AUTH_URL}/otp" \
  -H "Content-Type: application/json" \
  -H "apikey: ${ANON_KEY}" \
  -d "$OTP_BODY" 2>/dev/null || echo -e "\n000")"

HTTP_CODE="$(echo "$HTTP_RESPONSE" | tail -1)"
HTTP_BODY="$(echo "$HTTP_RESPONSE" | sed '$d')"

case "$HTTP_CODE" in
  2*)
    ;; # success
  429)
    if echo "$HTTP_BODY" | grep -q "email_send_rate_limit"; then
      echo ""
      echo "Email rate limit exceeded (Supabase free tier: ~3 emails/hour)."
      echo "Try again in a few minutes, or set up custom SMTP in the Supabase"
      echo "dashboard for unlimited sends."
      exit 1
    fi
    echo "Cooldown active — waiting 60s before retrying..."
    for i in $(seq 60 -1 1); do
      printf "\r  Retrying in %2ds..." "$i"
      sleep 1
    done
    printf "\r                      \r"
    echo "Retrying..."
    HTTP_RESPONSE="$(curl -s -w "\n%{http_code}" \
      -X POST "${AUTH_URL}/otp" \
      -H "Content-Type: application/json" \
      -H "apikey: ${ANON_KEY}" \
      -d "$OTP_BODY" 2>/dev/null || echo -e "\n000")"
    HTTP_CODE="$(echo "$HTTP_RESPONSE" | tail -1)"
    HTTP_BODY="$(echo "$HTTP_RESPONSE" | sed '$d')"
    case "$HTTP_CODE" in
      2*) ;; # success on retry
      *) echo "Error sending OTP (HTTP ${HTTP_CODE}): ${HTTP_BODY}"; exit 1 ;;
    esac
    ;;
  *)
    echo "Error sending OTP (HTTP ${HTTP_CODE}): ${HTTP_BODY}"
    exit 1
    ;;
esac

echo ""
echo "Check your email for a 6-digit code."
echo ""

# ─── Step 2: Read OTP code ───────────────────────────────────
printf "Enter code: "
read -r OTP_CODE

if [ -z "$OTP_CODE" ]; then
  echo "No code entered."
  exit 1
fi

# ─── Step 3: Verify OTP ─────────────────────────────────────
OTP_CODE="$(echo "$OTP_CODE" | tr -d '[:space:]')"

if ! echo "$OTP_CODE" | grep -qE '^[0-9]{6}$'; then
  echo "Error: code must be exactly 6 digits"
  exit 1
fi

VERIFY_RESPONSE="$(curl -s \
  -X POST "${AUTH_URL}/verify" \
  -H "Content-Type: application/json" \
  -H "apikey: ${ANON_KEY}" \
  -d "{\"email\":\"${EMAIL}\",\"token\":\"${OTP_CODE}\",\"type\":\"email\"}" \
  2>/dev/null || echo "{}")"

ACCESS_TOKEN="$(json_field "$VERIFY_RESPONSE" "access_token")"
REFRESH_TOKEN="$(json_field "$VERIFY_RESPONSE" "refresh_token")"
EXPIRES_IN="$(json_field "$VERIFY_RESPONSE" "expires_in")"
USER_ID="$(json_field "$VERIFY_RESPONSE" "id" 2>/dev/null || true)"

if [ -z "$USER_ID" ]; then
  USER_ID="$(echo "$VERIFY_RESPONSE" | grep -o '"id":"[^"]*"' | head -1 | sed 's/"id":"//;s/"//')"
fi

if [ -z "$ACCESS_TOKEN" ] || [ "$ACCESS_TOKEN" = "null" ]; then
  ERROR_MSG="$(json_field "$VERIFY_RESPONSE" "error_description" 2>/dev/null || json_field "$VERIFY_RESPONSE" "msg" 2>/dev/null || echo "unknown error")"
  echo ""
  echo "Verification failed: $ERROR_MSG"
  echo "Check the code and try again."
  exit 1
fi

save_token "$ACCESS_TOKEN" "$REFRESH_TOKEN" "${EXPIRES_IN:-3600}" "$EMAIL" "$USER_ID"

# ─── Step 4: Save email to config ────────────────────────────
"$GSTACK_DIR/bin/gstack-config" set email "$EMAIL"

echo ""
echo "Authenticated as: ${EMAIL}"
echo "Token saved to: ${AUTH_FILE}"