// Package libstring provides various string related functions.
package libstring

import (
	"net/http"
	"strings"
)

// StringInSlice finds needle in a slice of strings.
func StringInSlice(sliceString []string, needle string) bool {
	for _, b := range sliceString {
		if b == needle {
			return true
		}
	}
	return false
}

func ipAddrFromRemoteAddr(s string) string {
	idx := strings.LastIndex(s, ":")
	if idx == -1 {
		return s
	}
	return s[:idx]
}

// RemoteIP finds IP Address given http.Request struct.
func RemoteIP(ipLookups []string, r *http.Request) string {
	realIP := r.Header.Get("X-Real-IP")
	forwardedFor := r.Header.Get("X-Forwarded-For")

	for _, lookup := range ipLookups {
		if lookup == "RemoteAddr" {
			return ipAddrFromRemoteAddr(r.RemoteAddr)
		}
		if lookup == "X-Forwarded-For" && forwardedFor != "" {
			// X-Forwarded-For is potentially a list of addresses separated with ","
			parts := strings.Split(forwardedFor, ",")
			for i, p := range parts {
				parts[i] = strings.TrimSpace(p)
			}
			return parts[0]
		}
		if lookup == "X-Real-IP" && realIP != "" {
			return realIP
		}
	}

	return ""
}