#!/usr/bin/env bash
# 监控数据网卡：IP/链路变化时自动 regenerate（避免 stale bind 或网卡改名导致 rep=0x01）
# 策略：
#   1) 默认配置只 bind_interface（不写死源 IP）—— 多数场景无需本脚本也能自愈
#   2) 本脚本仍负责：iface 丢失→重探、可选 BIND_SOURCE_IP 时同步源 IP、链路 down/up 后拉起
set -euo pipefail

ROOT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
# shellcheck source=lib.sh
source "$ROOT_DIR/scripts/lib.sh"

CONFIG_FILE="${CONFIG_FILE:-$ROOT_DIR/etc/settings.conf}"
if [[ ! -f "$CONFIG_FILE" && -f /opt/cellular-proxy/etc/settings.conf ]]; then
  CONFIG_FILE=/opt/cellular-proxy/etc/settings.conf
  ROOT_DIR=/opt/cellular-proxy
fi
export CONFIG_FILE

load_config

INTERVAL="${WATCH_INTERVAL_SEC:-60}"
DEBOUNCE_SEC="${WATCH_DEBOUNCE_SEC:-3}"
LOCK_DIR="${LOG_DIR:-/var/log/cellular-proxy}"
mkdir -p "$LOCK_DIR" 2>/dev/null || true
STATE_FILE="${LOCK_DIR}/watch.state"
LOG_TAG="cellular-proxy-watch"

logw() { printf '[%s] %s %s\n' "$(date '+%F %T')" "$LOG_TAG" "$*" >&2; }

current_cfg_iface() {
  python3 - <<'PY' 2>/dev/null || true
import json
from pathlib import Path
for p in ("/opt/cellular-proxy/etc/config.json",):
    try:
        c=json.loads(Path(p).read_text())
        for o in c.get("outbounds") or []:
            if o.get("tag")=="cellular":
                print(o.get("bind_interface") or "")
                raise SystemExit
    except Exception:
        pass
print("")
PY
}

current_cfg_src() {
  python3 - <<'PY' 2>/dev/null || true
import json
from pathlib import Path
try:
    c=json.loads(Path("/opt/cellular-proxy/etc/config.json").read_text())
    for o in c.get("outbounds") or []:
        if o.get("tag")=="cellular":
            print(o.get("inet4_bind_address") or "")
            raise SystemExit
except Exception:
    pass
print("")
PY
}

need_refresh() {
  load_config
  local cell="${CELLULAR_IFACE:-}"
  local live_src="" cfg_iface cfg_src
  cfg_iface="$(current_cfg_iface)"
  cfg_src="$(current_cfg_src)"

  if [[ -z "$cell" ]] || ! iface_exists "$cell"; then
    logw "iface missing or empty (CELLULAR_IFACE=${cell:-<空>}) → rebind"
    return 0
  fi

  live_src="$(detect_source_ip "$cell" || true)"
  if [[ -z "$live_src" ]]; then
    # 网卡在但无 IPv4：可能刚重拨；不立刻 die，等下一轮
    logw "wwan up but no IPv4 yet on $cell"
    # 若配置里仍绑旧源 IP，清掉/重生更安全
    if [[ -n "$cfg_src" ]]; then
      return 0
    fi
    return 1
  fi

  if [[ -n "$cfg_iface" && "$cfg_iface" != "$cell" ]]; then
    logw "cfg iface $cfg_iface != settings $cell"
    return 0
  fi

  # 仅当配置写了 inet4_bind_address 且与 live 不一致时才需要
  if [[ -n "$cfg_src" && "$cfg_src" != "$live_src" ]]; then
    logw "stale source IP cfg=$cfg_src live=$live_src"
    return 0
  fi

  # settings 里的 SOURCE_IP 过期也同步（即使 config 未 pin）
  if [[ -n "${CELLULAR_SOURCE_IP:-}" && "${CELLULAR_SOURCE_IP}" != "$live_src" ]]; then
    persist_cellular_to_settings "$CONFIG_FILE" "$cell" "$live_src" || true
  fi

  return 1
}

do_refresh() {
  load_config
  local cell="${CELLULAR_IFACE:-}"
  local src=""

  if [[ -z "$cell" ]] || ! iface_exists "$cell"; then
    cell="$(detect_cellular_iface "" || true)"
    if [[ -z "$cell" ]]; then
      logw "detect failed; skip"
      return 1
    fi
  fi
  src="$(detect_source_ip "$cell" || true)"
  if [[ -z "$src" ]]; then
    logw "no IPv4 on $cell yet; skip generate"
    return 1
  fi
  persist_cellular_to_settings "$CONFIG_FILE" "$cell" "$src" || true
  logw "refresh: iface=$cell src=$src"
  # 走 cpxy generate（含 check + restart）；失败则直接 scripts
  if command -v cpxy >/dev/null 2>&1; then
    cpxy generate >/dev/null 2>&1 || {
      # shellcheck source=/dev/null
      source "$ROOT_DIR/scripts/lib.sh"
      load_config
      "$ROOT_DIR/scripts/generate.sh" "$ROOT_DIR/generated"
      install -m 0644 "$ROOT_DIR/generated/config.json" "$ROOT_DIR/etc/config.json"
      install -m 0644 "$ROOT_DIR/generated/runtime.env" "$ROOT_DIR/etc/runtime.env" 2>/dev/null || true
      systemctl restart cellular-proxy 2>/dev/null || true
    }
  else
    "$ROOT_DIR/scripts/generate.sh" "$ROOT_DIR/generated"
    install -m 0644 "$ROOT_DIR/generated/config.json" "$ROOT_DIR/etc/config.json"
    systemctl restart cellular-proxy 2>/dev/null || true
  fi
  printf '%s iface=%s src=%s\n' "$(date -Iseconds)" "$cell" "$src" >"$STATE_FILE" 2>/dev/null || true
  logw "refresh done"
}

# oneshot mode (systemd timer)
if [[ "${1:-}" == "--once" ]]; then
  if need_refresh; then
    do_refresh || true
  fi
  exit 0
fi

# long-running: periodic + optional ip monitor events
logw "start interval=${INTERVAL}s (debounce=${DEBOUNCE_SEC}s)"
last_run=0
trigger() {
  local now
  now="$(date +%s)"
  if (( now - last_run < DEBOUNCE_SEC )); then
    return 0
  fi
  last_run=$now
  if need_refresh; then
    do_refresh || true
  fi
}

# initial
trigger

# Prefer event-driven if available; always keep poll as safety net
if command -v ip >/dev/null 2>&1; then
  (
    # address/link changes on any iface — cheap filter in shell
    ip -o monitor address link 2>/dev/null | while read -r line; do
      cell="${CELLULAR_IFACE:-}"
      # reload cell from settings occasionally
      if [[ -f "$CONFIG_FILE" ]]; then
        cell="$(awk -F= '/^CELLULAR_IFACE=/{print $2; exit}' "$CONFIG_FILE" 2>/dev/null || true)"
      fi
      if [[ -n "$cell" ]] && [[ "$line" == *"$cell"* || "$line" == *Deleted* || "$line" == *wwan* || "$line" == *usb* || "$line" == *enx* ]]; then
        sleep "$DEBOUNCE_SEC"
        trigger
      fi
    done
  ) &
  mon_pid=$!
  trap 'kill $mon_pid 2>/dev/null || true; exit 0' TERM INT
fi

while true; do
  sleep "$INTERVAL"
  trigger
done