package customlists

import (
	"bufio"
	"net"
	"os"
	"strconv"
	"strings"

	"github.com/miekg/dns"
	"github.com/safing/portbase/log"
	"github.com/safing/portbase/notifications"
	"github.com/safing/portmaster/network/netutils"
)

var (
	countryCodesFilterList      map[string]struct{}
	ipAddressesFilterList       map[string]struct{}
	autonomousSystemsFilterList map[uint]struct{}
	domainsFilterList           map[string]struct{}
)

const numberOfZeroIPsUntilWarning = 100

func parseFile(filePath string) error {
	// reset all maps, previous (if any) settings will be lost
	countryCodesFilterList = make(map[string]struct{})
	ipAddressesFilterList = make(map[string]struct{})
	autonomousSystemsFilterList = make(map[uint]struct{})
	domainsFilterList = make(map[string]struct{})

	// ignore empty file path
	if filePath == "" {
		return nil
	}

	// open the file if possible
	file, err := os.Open(filePath)
	if err != nil {
		log.Warningf("intel/customlists: failed to parse file: \"%s\"", filePath)
		return err
	}
	defer file.Close()

	var numberOfZeroIPs uint64

	// read filter file line by line
	scanner := bufio.NewScanner(file)
	// the scanner will error out if the line is greater than 64K, in this case it is enough
	for scanner.Scan() {
		parseLine(scanner.Text(), &numberOfZeroIPs)
	}

	// check for scanner error
	if err := scanner.Err(); err != nil {
		return err
	}

	if numberOfZeroIPs >= numberOfZeroIPsUntilWarning {
		log.Warning("intel/customlists: Too many zero IP addresses.")
		notifications.NotifyWarn("too_many_zero_ips", "Too many zero IP addresses. Check your custom filter list.", "Hosts file format is not spported.")
	}

	log.Infof("intel/customlists: list loaded successful: %s", filePath)

	return nil
}

func parseLine(line string, numberOfZeroIPs *uint64) {
	// ignore empty lines and comment lines
	if len(line) == 0 || line[0] == '#' {
		return
	}

	// everything after the first field will be ignored
	field := strings.Fields(line)[0]

	// check if it'a a country code
	if isCountryCode(field) {
		countryCodesFilterList[field] = struct{}{}
	}

	// try to parse IP address
	ip := net.ParseIP(field)
	if ip != nil {
		ipAddressesFilterList[ip.String()] = struct{}{}

		// check if its zero ip
		for i := 0; i < len(ip); i++ {
			if ip[i] != 0 {
				*numberOfZeroIPs++
			}
		}
	}

	// check if it's a Autonomous system (example AS123)
	if isAutonomousSystem(field) {
		asNumber, err := strconv.ParseUint(field[2:], 10, 32)
		if err != nil {
			return
		}
		autonomousSystemsFilterList[uint(asNumber)] = struct{}{}
	}

	// check if it's a domain
	domain := dns.Fqdn(field)
	if netutils.IsValidFqdn(domain) {
		domainsFilterList[domain] = struct{}{}
	}
}