#!/bin/bash
# 1) 把 MTU 1400 固化下来（重启也在）
# 2) 在 MTU 1400 下对照 quic+6 / quic+8 / quic+10
#
# 为什么要固化 MTU：
#   QUIC 走 UDP，**我们那条 --set-mss 1400 的 iptables 规则只管 TCP**。
#   实测把 wlan0 MTU 从 1500 降到 1400 之后：
#     QUIC 建齐 6 条连接的时间  28 秒 -> 13 秒
#     dial 失败次数              2 -> 1
#   原因：UDP 丢包不会回 ICMP，QUIC 发了超出路径 MTU 的包只能等超时。
#   把接口 MTU 压到 1400，QUIC 的包就都在安全范围内。
#
# 为什么还要试更多连接：
#   已经看到 http2+8 建齐只要 12 秒且 0 失败（QUIC+6 是 28 秒/2 次失败）。
#   连接多 = 单条掉线影响小。但 QUIC 的连接建立更贵，得实测平衡点。
set -u

BASE=https://relay.xxmxxs.top
UA='LanRemote/1.8.2'
SVC=/etc/systemd/system/lanremote-tunnel.service
NETTUNE=/etc/systemd/system/lanremote-nettune.service
BACKUP=/root/tunnel.bak.v4.$(date +%s)
cp -a "$SVC" "$BACKUP"
N=60
MTU=1400
MSS=1360

echo "════════ 1. 固化 MTU（写进 net-tune 服务）════════"
echo "  现在的 net-tune 服务:"
systemctl cat lanremote-nettune 2>/dev/null | grep -E 'ExecStart' | sed 's/^/    /'

# 把 MTU 设置追加进去（幂等：已有的先删掉）
cp -a "$NETTUNE" "${NETTUNE}.bak.$(date +%s)" 2>/dev/null || true
python3 - <<'PYEOF'
from pathlib import Path
p = Path("/etc/systemd/system/lanremote-nettune.service")
if not p.is_file():
    print("    ! net-tune 服务不存在，跳过")
    raise SystemExit(0)
text = p.read_text(encoding="utf-8")
# 去掉旧的 MTU/MSS 行
lines = [l for l in text.splitlines()
         if "ip link set wlan0 mtu" not in l and "--set-mss" not in l]
out = []
for line in lines:
    out.append(line)
    # 在每个 ExecStart 之后补上 MTU 设置
    if line.strip().startswith("ExecStart="):
        out.append("ExecStart=/sbin/ip link set wlan0 mtu 1400")
        out.append("ExecStart=/sbin/iptables -t mangle -C OUTPUT -p tcp "
                   "--tcp-flags SYN,RST SYN -j TCPMSS --set-mss 1360 || "
                   "/sbin/iptables -t mangle -A OUTPUT -p tcp "
                   "--tcp-flags SYN,RST SYN -j TCPMSS --set-mss 1360")
p.write_text("\n".join(out) + "\n", encoding="utf-8")
print("    已写入 MTU 1400 + MSS 1360")
PYEOF

systemctl daemon-reload
echo "  立即执行一次:"
ip link set wlan0 mtu $MTU && echo "    wlan0 MTU -> $(cat /sys/class/net/wlan0/mtu)"
iptables -t mangle -C OUTPUT -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --set-mss $MSS 2>/dev/null \
    || iptables -t mangle -A OUTPUT -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --set-mss $MSS
echo "    MSS 规则: $(iptables -t mangle -S OUTPUT | grep TCPMSS | head -1)"
echo "  net-tune 现在的内容:"
systemctl cat lanremote-nettune 2>/dev/null | grep ExecStart | sed 's/^/    /'
echo "  服务状态: $(systemctl is-enabled lanremote-nettune 2>/dev/null) / $(systemctl is-active lanremote-nettune 2>/dev/null)"

wait_conns() {
    local want="$1" limit="$2" t0 t1 n
    t0=$(date +%s)
    while true; do
        n=$(curl -s --max-time 4 http://127.0.0.1:20241/metrics 2>/dev/null \
            | grep '^cloudflared_tunnel_ha_connections' | awk '{print $2}')
        n=${n:-0}
        t1=$(date +%s)
        [ "$n" -ge "$want" ] || [ $((t1 - t0)) -ge "$limit" ] && { echo "$n $((t1 - t0))"; return; }
        sleep 3
    done
}

run_group() {
    local conns="$1"
    echo "════════ quic + $conns （MTU $MTU）════════"
    cp -a "$BACKUP" "$SVC"
    sed -i "s/--protocol [a-z0-9]*/--protocol quic/" "$SVC"
    sed -i "s/--ha-connections [0-9]*/--ha-connections $conns/" "$SVC"
    systemctl daemon-reload
    local mark; mark=$(wc -l < /root/lanremote-relay/tunnel.log 2>/dev/null || echo 0)
    systemctl restart lanremote-tunnel
    local res; res=$(wait_conns "$conns" 150)
    local n s
    n=$(echo "$res" | awk '{print $1}'); s=$(echo "$res" | awk '{print $2}')
    local df; df=$(tail -n +$((mark+1)) /root/lanremote-relay/tunnel.log 2>/dev/null | grep -c 'Failed to dial' || echo 0)
    echo "    建齐 $n/$conns，用 ${s} 秒，dial 失败 ${df} 次"

    local ok=0 times=()
    for i in $(seq 1 "$N"); do
        out=$(curl -s -o /dev/null -w '%{http_code} %{time_total}' --max-time 25 -H "User-Agent: $UA" "$BASE/v1/health")
        c=$(echo "$out" | awk '{print $1}'); ms=$(echo "$out" | awk '{printf "%d", $2*1000}')
        [ "$c" = "200" ] && { ok=$((ok+1)); times+=("$ms"); }
    done
    local pct=$((ok * 100 / N))
    local stats="无数据"
    [ "${#times[@]}" -gt 0 ] && stats=$(printf '%s\n' "${times[@]}" | sort -n | awk '{a[NR]=$1} END {
        printf "中位 %d P90 %d P99 %d 最大 %d", a[int(NR/2)+1], a[int(NR*0.9)+1], a[int(NR*0.99)+1], a[NR]}')
    printf "    可用率 %d%% (%d/%d)   %s ms\n" "$pct" "$ok" "$N" "$stats"
    echo "quic+$conns|$n|$s|$df|$pct|$stats" >> /tmp/v4.txt
    echo
}

rm -f /tmp/v4.txt
run_group 6
run_group 8
run_group 10

echo "════════ 汇总 ════════"
printf "  %-10s %-14s %-10s %-8s %s\n" "配置" "建齐/耗时" "dial失败" "可用率" "延迟"
while IFS='|' read -r label n s df pct stats; do
    printf "  %-10s %-14s %-10s %-8s %s\n" "$label" "${n}条 ${s}s" "$df" "${pct}%" "$stats"
done < /tmp/v4.txt

echo
BESTN=$(sort -t'|' -k5 -rn /tmp/v4.txt | head -1 | sed 's/quic+//' | cut -d'|' -f1)
echo "  → 采用 quic + $BESTN"
cp -a "$BACKUP" "$SVC"
sed -i "s/--protocol [a-z0-9]*/--protocol quic/" "$SVC"
sed -i "s/--ha-connections [0-9]*/--ha-connections $BESTN/" "$SVC"
systemctl daemon-reload
systemctl restart lanremote-tunnel
sleep 5
echo "  最终参数: $(grep -oE '\-\-protocol [a-z0-9]+|--ha-connections [0-9]+' "$SVC" | tr '\n' ' ')"
echo "  MTU: $(cat /sys/class/net/wlan0/mtu)"
echo "  备份: $BACKUP"