#!/bin/sh

BASE_URL="https://hacker.htpeo.com"

post_form() {
  path="$1"
  shift

  curl -fsSL -X POST "$BASE_URL$path" "$@"
}

read_required() {
  prompt="$1"

  while true; do
    printf "%s: " "$prompt" >&2
    IFS= read -r value

    if [ -n "$value" ]; then
      printf "%s" "$value"
      return
    fi

    echo "This field is required." >&2
  done
}

has_unsafe_adjacent_digit() {
  pin="$1"
  i=2
  same_run=1
  asc_run=1
  desc_run=1

  while [ "$i" -le 4 ]; do
    prev=$(printf "%s" "$pin" | cut -c $((i - 1)))
    curr=$(printf "%s" "$pin" | cut -c "$i")

    if [ "$curr" -eq $((prev + 1)) ]; then asc_run=$((asc_run + 1));   else asc_run=1;  fi
    if [ "$curr" -eq $((prev - 1)) ]; then desc_run=$((desc_run + 1)); else desc_run=1; fi
    if [ "$curr" -eq "$prev" ];        then same_run=$((same_run + 1)); else same_run=1; fi

    if [ "$asc_run" -ge 3 ] || [ "$desc_run" -ge 3 ] || [ "$same_run" -ge 4 ]; then
      return 0
    fi

    i=$((i + 1))
  done

  return 1
}

read_pin() {
  prompt="$1"

  while true; do
    printf "%s: " "$prompt" >&2
    pin=""

    if [ -t 0 ]; then
      _saved_tty=$(stty -g 2>/dev/null)
      stty -echo -icanon min 1 time 0 2>/dev/null
      while true; do
        _ch=$(dd if=/dev/tty bs=1 count=1 2>/dev/null)
        if [ -z "$_ch" ]; then
          printf '\n' >&2
          break
        fi
        _hex=$(printf '%s' "$_ch" | od -An -tx1 | tr -d ' \n')
        case "$_hex" in
          0d)
            printf '\n' >&2
            break
            ;;
          7f|08)
            if [ -n "$pin" ]; then
              pin=$(printf '%s' "$pin" | sed 's/.$//')
              printf '\b \b' >&2
            fi
            ;;
          *)
            case "$_ch" in
              [0-9])
                pin="$pin$_ch"
                printf '*' >&2
                ;;
            esac
            ;;
        esac
      done
      stty "$_saved_tty" 2>/dev/null
    else
      IFS= read -r pin
    fi

    case "$pin" in
      *[!0-9]*|"")
        echo "PIN must be 4 digits." >&2
        continue
        ;;
    esac

    pin_len=$(printf "%s" "$pin" | wc -c | tr -d " ")

    if [ "$pin_len" -ne 4 ]; then
      echo "PIN must be 4 digits." >&2
      continue
    fi

    if has_unsafe_adjacent_digit "$pin"; then
      echo "Avoid sequential digits or the same digit 4 times. Not allowed: 1234, 9876, 1111" >&2
      continue
    fi

    printf "%s" "$pin"
    return
  done
}

login_flow() {
  id="$1"
  pin="$2"

  if [ -z "$pin" ]; then
    pin="$(read_pin "PIN")"
  fi

  _is_refresh=0
  while true; do
    if [ "$_is_refresh" -eq 1 ]; then
      printf '\033[90mRefreshing...\033[0m'
    else
      printf '\033[90mSigning in...\033[0m'
    fi
    login="$(post_form "/api/login" \
      --data-urlencode "id=$id" \
      --data-urlencode "pin=$pin" \
      --data-urlencode "format=text" 2>/dev/null)"
    printf '\r              \r'

    echo ""

    if echo "$login" | grep -q "account was deleted"; then
      echo "$login"
      echo ""
      register_flow "$id"
      return
    fi

    if echo "$login" | grep -q "INVALID_PIN"; then
      echo "$login"
      echo ""
      pin="$(read_pin "PIN")"
      continue
    fi

    _is_refresh=1
    clear 2>/dev/null
    printf '\033[90m%s\033[0m\n\n' "$(date '+%H:%M:%S')"
    echo "$login"

    _urls=$(echo "$login" | grep -oE 'https?://[^ ]+')

    if [ -n "$_urls" ]; then
      _first_url=$(echo "$_urls" | head -n 1)
      printf "\n[Enter] Open most recent  [r] Refresh: "
      IFS= read -r _action </dev/tty
      case "$_action" in
        r|R) continue ;;
        *)
          open "$_first_url" 2>/dev/null || xdg-open "$_first_url" 2>/dev/null || termux-open-url "$_first_url" 2>/dev/null || true
          return
          ;;
      esac
    fi

    printf '\nPress Enter to refresh, or Ctrl+C to exit: '
    IFS= read -r dummy </dev/tty
    continue
  done
}

register_flow() {
  id="$1"
  is_pending="$2"

  echo ""
  if [ "$is_pending" = "1" ]; then
    echo "Email not yet verified. Re-enter your details to claim this account."
  else
    echo "Sign-up is only required the first time."
  fi
  echo ""
  echo "Enter your real name."
  echo "Your Korean legal name is fine (e.g. 홍길동)."

  name="$(read_required "Name")"

  echo ""
  echo "Set a 4-digit PIN you do not use anywhere else."
  echo "Avoid sequential digits or the same digit 4 times in a row."
  echo "Not allowed: 1234, 9876, 1111"
  echo ""

  while true; do
    pin1="$(read_pin "PIN")"
    pin2="$(read_pin "PIN (again)")"

    if [ "$pin1" != "$pin2" ]; then
      echo "PINs do not match. Please try again."
      continue
    fi

    break
  done

  printf '\033[90mRegistering...\033[0m'
  register="$(post_form "/api/register" \
    --data-urlencode "id=$id" \
    --data-urlencode "name=$name" \
    --data-urlencode "pin=$pin1" \
    --data-urlencode "format=text" 2>/dev/null)"
  printf '\r               \r'

  echo "$register" | grep -q "^\[ERROR\]"
  if [ "$?" -eq 0 ]; then
    echo ""
    echo "$register"
    exit 1
  fi

  echo ""
  echo "[OK] check your $id@khu.ac.kr email"
  echo "If you do not see it, check your spam folder."
  echo ""

  while true; do
    printf "Click the verification link, then press Enter"
    IFS= read -r dummy

    printf '\033[90mChecking...\033[0m'
    check="$(post_form "/api/status" \
      --data-urlencode "id=$id" \
      --data-urlencode "format=text" 2>/dev/null)"
    printf '\r           \r'

    echo "$check" | grep -q "REGISTERED" && ! echo "$check" | grep -q "NOT_REGISTERED"
    if [ "$?" -eq 0 ]; then
      echo ""
      echo "[OK] Verified"
      echo ""
      break
    fi

    echo "Not verified yet."
    echo "Click the link in the email, then press Enter again."
    echo ""
  done

  login_flow "$id" "$pin1"
}

clear 2>/dev/null

echo ""
echo ""
printf '\033[36m'
echo ' ██╗  ██╗ █████╗  ██████╗██╗  ██╗███████╗██████╗'
echo ' ██║  ██║██╔══██╗██╔════╝██║ ██╔╝██╔════╝██╔══██╗'
echo ' ███████║███████║██║     █████╔╝ █████╗  ██████╔╝'
echo ' ██╔══██║██╔══██║██║     ██╔═██╗ ██╔══╝  ██╔══██╗'
echo ' ██║  ██║██║  ██║╚██████╗██║  ██╗███████╗██║  ██║'
echo ' ╚═╝  ╚═╝╚═╝  ╚═╝ ╚═════╝╚═╝  ╚═╝╚══════╝╚═╝  ╚═╝'
printf '\033[0m'

printf '\033[90mKyung Hee University - Dept. of Computer Engineering Student Club\033[0m\n'
echo "Claude Verification Code"
echo ""
echo "Enter your school email ID."
echo "e.g. for abc@khu.ac.kr, enter only abc"
echo ""

printf "ID: "
IFS= read -r id

id="$(printf "%s" "$id" | tr '[:upper:]' '[:lower:]')"

case "$id" in
  *"@"*)
    echo "Enter only the part before @khu.ac.kr"
    echo "e.g. for abc@khu.ac.kr, enter abc"
    exit 1
    ;;
esac

if ! printf "%s" "$id" | grep -Eq '^[a-z0-9._%+-]+$'; then
  echo "[ERROR] Invalid ID format."
  exit 1
fi

printf '\033[90mChecking account...\033[0m'
status="$(post_form "/api/status" \
  --data-urlencode "id=$id" \
  --data-urlencode "format=text" 2>/dev/null)"
printf '\r                   \r'

echo "$status" | grep -Eq "NOT_REGISTERED|PENDING_VERIFY"
if [ "$?" -eq 0 ]; then
  _is_pending=0
  echo "$status" | grep -q "PENDING_VERIFY" && _is_pending=1
  register_flow "$id" "$_is_pending"
  exit 0
fi

echo "$status" | grep -q "REGISTERED" && ! echo "$status" | grep -q "NOT_REGISTERED"
if [ "$?" -eq 0 ]; then
  login_flow "$id"
  exit 0
fi

echo "$status"