#!/bin/bash
# 隧道对照 v3：验证「QUIC 失败是因为 MTU」这个假设，并选出最稳的组合。
#
# 已查明的事实：
#   1. cloudflared 用 QUIC 时反复报
#        "failed to dial to edge with quic: timeout: no recent network activity"
#      连十几个 IP 才成功一次 —— 握手阶段就掉包。
#   2. 我们给 TCP 做了 MSS 钳制（--set-mss 1400），
#      但 **QUIC 走 UDP，TCPMSS 规则完全不生效**。
#   3. 路径 MTU 实测 1472（1500 的包不通）。
#      QUIC 默认用 ~1452 字节的包，很容易被中间设备丢掉，
#      而 UDP 丢了不会回 ICMP，客户端只能等到超时。
#
# 所以对照三组：
#   A. quic + 6（现状，MTU 1500）           —— 预期握手仍不稳
#   B. quic + 6 + wlan0 MTU 1400            —— 如果假设成立，握手会变稳
#   C. http2 + 8（TCP 吃 MSS 钳制，连接多）  —— 对照组
#
# 每组记录：连接建齐耗时 / 建齐几条 / 60 次 HTTP 可用率
set -u

BASE=https://relay.xxmxxs.top
UA='LanRemote/1.8.1'
SVC=/etc/systemd/system/lanremote-tunnel.service
BACKUP=/root/tunnel.bak.v3.$(date +%s)
cp -a "$SVC" "$BACKUP"
N=60

set_params() {
    local proto="$1" conns="$2"
    cp -a "$BACKUP" "$SVC"
    sed -i "s/--protocol [a-z0-9]*/--protocol $proto/" "$SVC"
    sed -i "s/--ha-connections [0-9]*/--ha-connections $conns/" "$SVC"
    systemctl daemon-reload
    systemctl restart lanremote-tunnel
}

set_mtu() {
    local mtu="$1"
    ip link set wlan0 mtu "$mtu" 2>/dev/null && echo "    wlan0 MTU -> $(cat /sys/class/net/wlan0/mtu)"
}

# 等连接建齐，返回耗时秒数
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=$(date +%s)
        if [ "$n" -ge "$want" ] || [ $((t1 - t0)) -ge "$limit" ]; then
            echo "$n $((t1 - t0))"
            return
        fi
        sleep 3
    done
}

run_group() {
    local label="$1" proto="$2" conns="$3" mtu="$4"
    echo "════════ $label ════════"

    [ "$mtu" != "keep" ] && set_mtu "$mtu"

    local mark; mark=$(wc -l < /root/lanremote-relay/tunnel.log 2>/dev/null || echo 0)
    set_params "$proto" "$conns"

    local res; res=$(wait_conns "$conns" 150)
    local n; n=$(echo "$res" | awk '{print $1}')
    local secs; s=$(echo "$res" | awk '{print $2}')
    echo "    建齐 $n/$conns 条，用了 ${s} 秒"

    # 这一轮建立过程中失败了多少次
    local dialfail; dialfail=$(tail -n +$((mark+1)) /root/lanremote-relay/tunnel.log 2>/dev/null \
                               | grep -c 'Failed to dial' || echo 0)
    echo "    建立期间 dial 失败 $dialfail 次"

    # 可用率
    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", $2*1000}')
        if [ "$c" = "200" ]; then ok=$((ok+1)); times+=("$ms"); fi
    done
    local pct=$((ok * 100 / N))
    local stats="无数据"
    if [ "${#times[@]}" -gt 0 ]; then
        stats=$(printf '%s\n' "${times[@]}" | sort -n | awk '{a[NR]=$1} END {
            printf "中位 %d P90 %d P99 %d 最大 %d", a[int(NR/2)+1], a[int(NR*0.9)+1], a[int(NR*0.99)+1], a[NR]}')
    fi
    printf "    可用率 %d%% (%d/%d)   耗时 %s ms\n" "$pct" "$ok" "$N" "$stats"
    echo "$label|$proto|$conns|$mtu|$n|$s|$dialfail|$pct|$stats" >> /tmp/v3.txt
    echo
}

rm -f /tmp/v3.txt
echo "  原始 wlan0 MTU: $(cat /sys/class/net/wlan0/mtu)"
echo

run_group "A. quic+6 MTU1500" quic 6 keep
run_group "B. quic+6 MTU1400" quic 6 1400
run_group "C. http2+8 MTU1400" http2 8 keep

# 恢复 MTU
set_mtu 1500

echo "════════ 汇总 ════════"
printf "  %-22s %-6s %-4s %-8s %-9s %-8s %s\n" "组" "协议" "连接" "建齐/耗时" "dial失败" "可用率" "延迟"
while IFS='|' read -r label proto conns mtu n s dialfail pct stats; do
    printf "  %-22s %-6s %-4s %-8s %-9s %-8s %s\n" \
        "$label" "$proto" "$conns" "${n}/${conns} ${s}s" "$dialfail" "${pct}%" "$stats"
done < /tmp/v3.txt

echo
echo "════════ 决策：可用率优先，其次看建齐速度 ════════"
BEST=$(sort -t'|' -k8 -rn /tmp/v3.txt | head -1)
BL=$(echo "$BEST" | cut -d'|' -f1)
BP=$(echo "$BEST" | cut -d'|' -f2)
BC=$(echo "$BEST" | cut -d'|' -f3)
BM=$(echo "$BEST" | cut -d'|' -f4)
echo "  最好: $BL（可用率 $(echo "$BEST" | cut -d'|' -f8)%）"

cp -a "$BACKUP" "$SVC"
sed -i "s/--protocol [a-z0-9]*/--protocol $BP/" "$SVC"
sed -i "s/--ha-connections [0-9]*/--ha-connections $BC/" "$SVC"
systemctl daemon-reload
systemctl restart lanremote-tunnel
echo "  已采用: --protocol $BP --ha-connections $BC"
echo "  MTU: $(cat /sys/class/net/wlan0/mtu)"
echo "  备份: $BACKUP"