#!/usr/bin/env bash

# ============================================
# Lifecycle
# ============================================

function fw::on_load() {
  system::require_command iptables
}

# ============================================
# Rule Management
# ============================================

function fw::block_ip() {
  local client_ip="${1:-}" target_ip="${2:-}"

  fw::_forward_exists -s "$client_ip" -d "$target_ip" -j DROP \
  || iptables -I FORWARD 1 -s "$client_ip" -d "$target_ip" -j DROP

  fw::_forward_exists -s "$client_ip" -d "$target_ip" -j NFLOG --nflog-group 1 --nflog-prefix "wgctl-drop:" \
  || iptables -I FORWARD 1 -s "$client_ip" -d "$target_ip" -j NFLOG --nflog-group 1 --nflog-prefix "wgctl-drop:"
}

function fw::unblock_ip() {
  local client_ip="${1:-}" target_ip="${2:-}"
  
  fw::_forward_exists -s "$client_ip" -d "$target_ip" -j NFLOG --nflog-group 1 --nflog-prefix "wgctl-drop:" \
  && iptables -D FORWARD -s "$client_ip" -d "$target_ip" -j NFLOG --nflog-group 1 --nflog-prefix "wgctl-drop:" 2>/dev/null || true

  fw::_forward_exists -s "$client_ip" -d "$target_ip" -j DROP \
  && iptables -D FORWARD -s "$client_ip" -d "$target_ip" -j DROP 2>/dev/null || true
}

function fw::block_port() {
  local client_ip="${1:-}" target_ip="${2:-}" port="${3:-}" proto="${4:-tcp}"

  fw::_forward_exists -s "$client_ip" -d "$target_ip" -p "$proto" --dport "$port" -j DROP \
  || iptables -I FORWARD 1 -s "$client_ip" -d "$target_ip" -p "$proto" --dport "$port" -j DROP

  fw::_forward_exists -s "$client_ip" -d "$target_ip" -p "$proto" --dport "$port" -j NFLOG --nflog-group 1 --nflog-prefix "wgctl-drop:" \
  || iptables -I FORWARD 1 -s "$client_ip" -d "$target_ip" -p "$proto" --dport "$port" -j NFLOG --nflog-group 1 --nflog-prefix "wgctl-drop:"

}

function fw::unblock_port() {
  local client_ip="${1:-}" target_ip="${2:-}" port="${3:-}" proto="${4:-tcp}"

  fw::_forward_exists -s "$client_ip" -d "$target_ip" -p "$proto" --dport "$port" -j NFLOG --nflog-group 1 --nflog-prefix "wgctl-drop:" \
  && iptables -D FORWARD -s "$client_ip" -d "$target_ip" -p "$proto" --dport "$port" -j NFLOG --nflog-group 1 --nflog-prefix "wgctl-drop:" 2>/dev/null || true

  fw::_forward_exists -s "$client_ip" -d "$target_ip" -p "$proto" --dport "$port" -j DROP \
  && iptables -D FORWARD -s "$client_ip" -d "$target_ip" -p "$proto" --dport "$port" -j DROP 2>/dev/null || true
}

function fw::block_all() {
  local client_ip="${1:-}" client_name="${2:-}"

  fw::_forward_exists -s "$client_ip" -j DROP \
  || iptables -A FORWARD -s "$client_ip" -j DROP

  log::debug "Blocked all traffic from: ${client_ip}"
}

function fw::unblock_all() {
  local client_ip="${1:-}"

  fw::_forward_exists -s "$client_ip" -j DROP \
  && iptables -D FORWARD -s "$client_ip" -j DROP 2>/dev/null || true

  monitor::unwatch "$client_ip"
  log::debug "Unblocked all traffic from: ${client_ip}"
}

function fw::block_subnet() {
  local client_ip="${1:-}" target_subnet="${2:-}"

  fw::_forward_exists -s "$client_ip" -d "$target_subnet" -j NFLOG --nflog-group 1 --nflog-prefix "wgctl-drop:" \
  || iptables -A FORWARD -s "$client_ip" -d "$target_subnet" -j NFLOG --nflog-group 1 --nflog-prefix "wgctl-drop:"

  fw::_forward_exists -s "$client_ip" -d "$target_subnet" -j DROP \
  || iptables -A FORWARD -s "$client_ip" -d "$target_subnet" -j DROP
    
  log::wg_block "Blocked ${client_ip} → subnet ${target_subnet}"
}

function fw::unblock_subnet() {
  local client_ip="${1:-}" target_subnet="${2:-}"

  fw::_forward_exists -s "$client_ip" -d "$target_subnet" -j NFLOG --nflog-group 1 --nflog-prefix "wgctl-drop:" \
  && iptables -D FORWARD -s "$client_ip" -d "$target_subnet" -j NFLOG --nflog-group 1 --nflog-prefix "wgctl-drop:" 2>/dev/null || true

  fw::_forward_exists -s "$client_ip" -d "$target_subnet" -j DROP \
  && iptables -D FORWARD -s "$client_ip" -d "$target_subnet" -j DROP 2>/dev/null || true

  log::wg_unblock "Unblocked ${client_ip} → subnet ${target_subnet}"
}

function fw::allow_ip() {
  local client_ip="${1:-}" target_ip="${2:-}"

  fw::_forward_exists -s "$client_ip" -d "$target_ip" -j ACCEPT \
  || iptables -I FORWARD 1 -s "$client_ip" -d "$target_ip" -j ACCEPT
}

function fw::unallow_ip() {
  local client_ip="${1:-}" target_ip="${2:-}"

  fw::_forward_exists -s "$client_ip" -d "$target_ip" -j ACCEPT \
  && iptables -D FORWARD -s "$client_ip" -d "$target_ip" -j ACCEPT 2>/dev/null || true
}

function fw::allow_port() {
  local client_ip="${1:-}" target_ip="${2:-}" port="${3:-}" proto="${4:-tcp}"

  fw::_forward_exists -s "$client_ip" -d "$target_ip" -p "$proto" --dport "$port" -j ACCEPT \
  || iptables -I FORWARD 1 -s "$client_ip" -d "$target_ip" -p "$proto" --dport "$port" -j ACCEPT
}

function fw::unallow_port() {
  local client_ip="${1:-}" target_ip="${2:-}" port="${3:-}" proto="${4:-tcp}"

  fw::_forward_exists -s "$client_ip" -d "$target_ip" -p "$proto" --dport "$port" -j ACCEPT \
  && iptables -D FORWARD -s "$client_ip" -d "$target_ip" -p "$proto" --dport "$port" -j ACCEPT 2>/dev/null || true
}

function fw::flush_peer() {
  local client_ip="${1:?client_ip required}"
  log::debug "flush_peer: starting for $client_ip"

  # Collect line numbers into array
  local linenums=()
  while IFS= read -r linenum; do
    [[ -n "$linenum" ]] && linenums+=("$linenum")
  done < <(iptables -L FORWARD -n --line-numbers | grep -F "$client_ip" | awk '{print $1}')

  # Delete in reverse order (highest number first)
  local count=0
  local i
  for (( i=${#linenums[@]}-1; i>=0; i-- )); do
    iptables -D FORWARD "${linenums[$i]}" 2>/dev/null || true
    (( count++ )) || true
  done

  log::debug "flush_peer: removed $count FORWARD rules for: $client_ip"
}

# ============================================
# Guest Subnet Rules
# ============================================

function fw::apply_dns_redirect() {
  if iptables -t nat -C PREROUTING -s "$(config::subnet_for guest).0/24" -p udp --dport 53 -j DNAT --to-destination "$(config::dns):53" 2>/dev/null; then
    log::wg "Guest DNS redirect already applied"
    return 0
  fi

  local guest_subnet dns
  guest_subnet="$(config::subnet_for "guest").0/24"
  dns="$(config::dns)"

  # Log DNS bypass attempts (queries not directed at Pi-hole)
  iptables -t nat -A PREROUTING -s "$guest_subnet" -p udp --dport 53 \
    ! -d "$dns" \
    -j LOG --log-prefix "wgctl-dns-redirect: " --log-level 4
  iptables -t nat -A PREROUTING -s "$guest_subnet" -p tcp --dport 53 \
    ! -d "$dns" \
    -j LOG --log-prefix "wgctl-dns-redirect: " --log-level 4

  # Redirect all DNS to Pi-hole
  iptables -t nat -A PREROUTING -s "$guest_subnet" -p udp --dport 53 -j DNAT --to-destination "${dns}:53"
  iptables -t nat -A PREROUTING -s "$guest_subnet" -p tcp --dport 53 -j DNAT --to-destination "${dns}:53"

  log::wg_block "Guest DNS redirected to Pi-hole (${dns}), bypass attempts will be logged"
}

function fw::remove_dns_redirect() {
  local guest_subnet dns
  guest_subnet="$(config::subnet_for "guest").0/24"
  dns="$(config::dns)"

  iptables -t nat -D PREROUTING -s "$guest_subnet" -p udp --dport 53 \
    ! -d "$dns" \
    -j LOG --log-prefix "wgctl-dns-redirect: " --log-level 4 2>/dev/null || true
  iptables -t nat -D PREROUTING -s "$guest_subnet" -p tcp --dport 53 \
    ! -d "$dns" \
    -j LOG --log-prefix "wgctl-dns-redirect: " --log-level 4 2>/dev/null || true
  iptables -t nat -D PREROUTING -s "$guest_subnet" -p udp --dport 53 -j DNAT --to-destination "${dns}:53" 2>/dev/null || true
  iptables -t nat -D PREROUTING -s "$guest_subnet" -p tcp --dport 53 -j DNAT --to-destination "${dns}:53" 2>/dev/null || true

  log::debug "Removed guest DNS redirect"
}

# ============================================
# Persistence — block files
# ============================================

function fw::save_block() {
  local name="$1"
  local client_ip="$2"
  local target="${3:-}"
  local port="${4:-}"
  local proto="${5:-}"

  local block_file
  block_file="$(ctx::block::path "${name}.block")"

  echo "${client_ip} ${target} ${port} ${proto}" >> "$block_file"
  log::debug "Persisted block rule for: ${name}"
}

function fw::remove_block_file() {
  local name="$1"
  local block_file
  block_file="$(ctx::block::path "${name}.block")"

  rm -f "$block_file"
  log::debug "Removed block file for: ${name}"
}

function fw::restore_blocks() {
  local blocks_dir
  blocks_dir="$(ctx::blocks)"

  # Restore rules from meta files (new system)
  rule::restore_all

  # Restore per-client full-blocks (wgctl block/unblock system)
  for block_file in "${blocks_dir}"/*.block; do
    [[ -f "$block_file" ]] || continue
    local name
    name=$(basename "$block_file" .block)
    while IFS=" " read -r client_ip target port proto; do
      if [[ -z "$target" ]]; then
        fw::block_all "$client_ip" "$name"
      elif [[ -n "$port" ]]; then
        fw::block_port "$client_ip" "$target" "$port" "${proto:-tcp}"
      else
        fw::block_ip "$client_ip" "$target"
      fi
    done < "$block_file"
    log::debug "Restored block rules for: ${name}"
  done
}

# ============================================
# Helpers
# ============================================

function fw::_nat_exists() {
  fw::_rule_exists nat PREROUTING "$@"
}

# ============================================
# private
# ============================================

function fw::_rule_exists() {
  local table="${1:-filter}" chain="${2:-FORWARD}"
  shift 2
  iptables -t "$table" -C "$chain" "$@" 2>/dev/null
}

function fw::_forward_exists() {
  iptables -C FORWARD "$@" 2>/dev/null
}