#!/bin/bash
# Name: ipfn
# Version: 1.1.0
# Date: 2026-01-22

if [ "$(id -u)" -ne 0 ]; then
    exec sudo "$0" "$@"
fi

TABLE_NAME="ipf_wrapper"
PROTO="tcp"
FORCE_FLAG=false
SKIP_TEST=false

init_nft() {
    nft add table inet ${TABLE_NAME} 2>/dev/null
    nft add chain inet ${TABLE_NAME} prerouting { type nat hook prerouting priority -100 \; } 2>/dev/null
    nft add chain inet ${TABLE_NAME} output { type nat hook output priority -100 \; } 2>/dev/null
    nft add chain inet ${TABLE_NAME} postrouting { type nat hook postrouting priority 100 \; } 2>/dev/null
    nft add chain inet ${TABLE_NAME} forward { type filter hook forward priority 0 \; policy accept \; } 2>/dev/null
}

list_rules() {
    local highlight_uuid=$1
    init_nft
    echo "Forwarding Rules (ipfn):"
    printf "%-10s %-6s %-20s %-20s %-10s\n" "HANDLE" "PROTO" "LOCAL" "TARGET" "UUID"
    echo "-----------------------------------------------------------------------------------"
    nft -a list chain inet ${TABLE_NAME} prerouting | grep "dnat" | while read -r line; do
        handle=$(echo "$line" | grep -o 'handle [0-9]*' | awk '{print $2}')
        proto=$(echo "$line" | grep -q "udp" && echo "udp" || echo "tcp")
        target=$(echo "$line" | grep -oE '[0-9.]*:[0-9]+' | head -n 1)
        lport=$(echo "$line" | grep -o 'dport [0-9]*' | awk '{print $2}')
        full_uuid=$(echo "$line" | grep -o 'ipf-id:[a-z0-9-]*' | cut -d':' -f2)
        if [[ -n "$highlight_uuid" && "$full_uuid" == "$highlight_uuid" ]]; then
            printf "\e[1;36m*%-9s %-6s %-20s %-20s %-10s\e[0m\n" "$handle" "$proto" ":$lport" "$target" "${full_uuid:0:8}"
        else
            printf "%-10s %-6s %-20s %-20s %-10s\n" "$handle" "$proto" ":$lport" "$target" "${full_uuid:0:8}"
        fi
    done
}

test_rule_by_port() {
    local lp=$1
    echo -n "Testing connectivity to :$lp... "
    if nc -z -v -w 2 127.0.0.1 "$lp" 2>&1 | grep -iqE "succeeded|connected|open"; then
        echo -e "\e[32mOK\e[0m"
    else
        echo -e "\e[31mFAILED\e[0m"
    fi
}

get_port_by_handle() {
    local h=$1
    nft -a list chain inet ${TABLE_NAME} prerouting | grep "handle $h" | grep -o 'dport [0-9]*' | awk '{print $2}'
}

parse_handles() {
    local input=$1
    local -a result=()
    IFS=',' read -r -a parts <<< "$input"
    for part in "${parts[@]}"; do
        if [[ "$part" =~ ^([0-9]+)-([0-9]+)$ ]]; then
            for ((i=${BASH_REMATCH[1]}; i<=${BASH_REMATCH[2]}; i++)); do result+=("$i"); done
        else
            result+=("$part")
        fi
    done
    echo "${result[@]}"
}

add_rule() {
    init_nft
    local lp=$(echo "$1" | cut -d':' -f1)
    local tip=$(echo "$1" | cut -d':' -f2)
    local tp=$(echo "$1" | cut -d':' -f3)
    nft list chain inet ${TABLE_NAME} prerouting | grep -q "dport $lp" && echo -e "\e[33mWarning: Port :$lp is already in use.\e[0m"
    local raw_uuid=$(cat /proc/sys/kernel/random/uuid)
    local uuid="ipf-id:$raw_uuid"
    local family="ip"; [[ "$tip" =~ : ]] && family="ip6"
    nft add rule inet ${TABLE_NAME} prerouting "$PROTO" dport "$lp" dnat $family to "$tip:$tp" comment "\"$uuid\""
    nft add rule inet ${TABLE_NAME} output "$PROTO" dport "$lp" dnat $family to "$tip:$tp" comment "\"$uuid\""
    nft add rule inet ${TABLE_NAME} forward iifname "lo" accept comment "\"$uuid\""
    nft add rule inet ${TABLE_NAME} forward $family daddr "$tip" "$PROTO" dport "$tp" ct state new,established,related accept comment "\"$uuid\""
    nft add rule inet ${TABLE_NAME} forward $family saddr "$tip" "$PROTO" sport "$tp" ct state established,related accept comment "\"$uuid\""
    nft add rule inet ${TABLE_NAME} postrouting $family daddr "$tip" "$PROTO" dport "$tp" masquerade comment "\"$uuid\""
    list_rules "$raw_uuid"
    [[ "$SKIP_TEST" == false ]] && { echo ""; test_rule_by_port "$lp"; }
}

# --- メインロジック ---
if [[ $# -eq 0 ]]; then list_rules; exit 0; fi

# フラグ先読み
for arg in "$@"; do
    [[ "$arg" == "-f" ]] && FORCE_FLAG=true && SKIP_TEST=true
done

while [[ $# -gt 0 ]]; do
    case "$1" in
        -L|-l) list_rules; exit 0 ;;
        -df*|-d*)
            [[ "$1" == -df* ]] && FORCE_FLAG=true
            h_str="${1#-df}"; h_str="${h_str#-d}"
            [[ -z "$h_str" ]] && { h_str="$2"; shift; }
            handles=($(parse_handles "$h_str"))
            if [[ "$FORCE_FLAG" == false ]]; then
                echo "Review handles to delete:"
                for h in "${handles[@]}"; do nft -a list table inet ${TABLE_NAME} | grep "handle $h" | sed 's/^/  /'; done
                read -p "Delete these rules? (y/N): " confirm
                [[ ! "$confirm" =~ ^[yY]$ ]] && exit 0
            fi
            for h in "${handles[@]}"; do
                rule_info=$(nft -a list chain inet ${TABLE_NAME} prerouting | grep "handle $h")
                [[ -z "$rule_info" ]] && continue
                uuid=$(echo "$rule_info" | grep -o 'ipf-id:[a-z0-9-]*' | head -n 1)
                for c in prerouting output forward postrouting; do
                    nft -a list chain inet ${TABLE_NAME} "$c" | grep "$uuid" | grep -o 'handle [0-9]*' | awk '{print $2}' | while read -r rh; do
                        nft delete rule inet ${TABLE_NAME} "$c" handle "$rh"
                    done
                done
                echo "Handle $h deleted."
            done
            echo ""; list_rules; exit 0 ;;
        -t*)
            h_str="${1#-t}"
            if [[ -z "$h_str" && ( "$2" =~ ^[0-9,-]+$ ) ]]; then h_str="$2"; shift; fi
            
            if [[ -z "$h_str" ]]; then
                # ハンドル指定がない場合、ルールが1つならそれを採用
                count=$(nft list chain inet ${TABLE_NAME} prerouting | grep -c "dnat")
                if [ "$count" -eq 1 ]; then
                    h_str=$(nft -a list chain inet ${TABLE_NAME} prerouting | grep "handle" | awk '{print $NF}')
                else
                    echo "Error: Multiple rules exist. Specify a handle."; exit 1
                fi
            fi
            lp=$(get_port_by_handle "$h_str")
            [[ -n "$lp" ]] && test_rule_by_port "$lp" || echo "Error: Handle $h_str not found."
            exit 0 ;;
        -f)
            if [[ $# -eq 1 ]]; then
                sysctl -w net.ipv4.ip_forward=1 >/dev/null
                sysctl -w net.ipv4.conf.all.route_localnet=1 >/dev/null
                echo "Kernel parameters updated."; exit 0
            fi ;;
        *)
            if [[ "$1" =~ ^[0-9]+: ]]; then add_rule "$1"; exit 0; fi ;;
    esac
    shift
done