package app

import (
	"encoding/json"
	"net/netip"
	"os"
	"strings"
	"time"

	egressutilpkg "selective-vpn-api/app/egressutil"
)

func egressIPEndpoints() []string {
	return egressutilpkg.IPEndpoints(os.Getenv("SVPN_EGRESS_IP_ENDPOINTS"))
}

func egressGeoEndpointsForIP(ip string) []string {
	return egressutilpkg.GeoEndpointsForIP(os.Getenv("SVPN_EGRESS_GEO_ENDPOINTS"), ip)
}

func egressLimitEndpointsForNetns(in []string) []string {
	maxN := envInt("SVPN_EGRESS_NETNS_MAX_ENDPOINTS", 1)
	return egressutilpkg.LimitEndpoints(in, maxN)
}

func egressJoinErrorsCompact(errs []string) string {
	return egressutilpkg.JoinErrorsCompact(errs)
}

func egressSingBoxSOCKSProxyURL(client TransportClient) string {
	if client.Kind != TransportClientSingBox {
		return ""
	}
	path := transportSingBoxConfigPath(client)
	if strings.TrimSpace(path) == "" {
		return ""
	}
	data, err := os.ReadFile(path)
	if err != nil || len(data) == 0 {
		return ""
	}
	var root map[string]any
	if err := json.Unmarshal(data, &root); err != nil {
		return ""
	}
	return egressutilpkg.ParseSingBoxSOCKSProxyURL(root)
}

func egressInterfaceBindAddress(iface string) string {
	iface = strings.TrimSpace(iface)
	if iface == "" {
		return ""
	}
	stdout, _, code, err := runCommandTimeout(1500*time.Millisecond, "ip", "-4", "-o", "addr", "show", "dev", iface, "scope", "global")
	if err != nil || code != 0 {
		return ""
	}
	for _, line := range strings.Split(stdout, "\n") {
		fields := strings.Fields(strings.TrimSpace(line))
		for i := 0; i < len(fields); i++ {
			if fields[i] != "inet" || i+1 >= len(fields) {
				continue
			}
			ip := strings.TrimSpace(fields[i+1])
			if slash := strings.Index(ip, "/"); slash > 0 {
				ip = ip[:slash]
			}
			if addr, err := netip.ParseAddr(ip); err == nil && addr.Is4() {
				return addr.String()
			}
		}
	}
	return ""
}