package cooldns

import (
	"io/ioutil"
	"log"
	"net"
	"os"

	"github.com/miekg/dns"
	"gopkg.in/yaml.v3"
)

// config format of the config file
type config struct {
	Zones     []configZone      `yaml:"zones"`
	ACL       []configACL       `yaml:"acl"`
	Forward   configForward     `yaml:"forward"`
	Address   string            `yaml:"address"`
	Blacklist []configBlacklist `yaml:"blacklist"`
	TLS       configTLS         `yaml:"tls"`
	Lego      configLego        `yaml:"lego"`
}

type configForward struct {
	Enable bool     `yaml:"enable"`
	ACL    []string `yaml:"acl"`
	Server string   `yaml:"server"`
}

type configACL struct {
	Name string `yaml:"name"`
	CIDR string `yaml:"cidr"`
}

type configZone struct {
	Zone string   `yaml:"zone"`
	File string   `yaml:"file"`
	ACL  []string `yaml:"acl"`
}

type configBlacklist struct {
	URL    string `yaml:"url"`
	Format string `yaml:"format"`
}

type configTLS struct {
	Enable  bool   `yaml:"enable"`
	Address string `yaml:"address"`
	Cert    string `yaml:"cert"`
	Key     string `yaml:"key"`
}

func loadConfig(configPath string) (*config, error) {
	file, err := ioutil.ReadFile(configPath)
	if err != nil {
		return nil, err
	}

	var loadedConfig config

	err = yaml.Unmarshal(file, &loadedConfig)
	if err != nil {
		return nil, err
	}

	return &loadedConfig, nil
}

func loadZones(configZones []configZone) (zoneMap, error) {
	zones := make(zoneMap)
	for _, z := range configZones {
		rrs, err := loadZonefile(z.File, z.Zone)
		if err != nil {
			return nil, err
		}
		if zones[z.Zone] == nil {
			zones[z.Zone] = make([]zoneView, 0)
		}
		zones[z.Zone] = append(zones[z.Zone], zoneView{
			rr:  createRRMap(rrs),
			acl: z.ACL,
		})

		log.Printf("Loaded zone %s\n", z.Zone)
	}

	return zones, nil
}

// createRRMap order the rr into a structure that is more easy to use
func createRRMap(rrs []dns.RR) rrMap {
	rrMap := make(rrMap)
	for _, rr := range rrs {
		if rrMap[rr.Header().Rrtype] == nil {
			rrMap[rr.Header().Rrtype] = make(map[string][]dns.RR)
		}

		if rrMap[rr.Header().Rrtype][rr.Header().Name] == nil {
			rrMap[rr.Header().Rrtype][rr.Header().Name] = make([]dns.RR, 0)
		}
		rrMap[rr.Header().Rrtype][rr.Header().Name] = append(rrMap[rr.Header().Rrtype][rr.Header().Name], rr)
	}

	return rrMap
}

func loadZonefile(filepath, origin string) ([]dns.RR, error) {
	file, err := os.Open(filepath)

	if err != nil {
		return nil, err
	}

	parser := dns.NewZoneParser(file, origin, filepath)

	var rrs = make([]dns.RR, 0)

	for rr, ok := parser.Next(); ok; rr, ok = parser.Next() {
		rrs = append(rrs, rr)
	}

	if err := parser.Err(); err != nil {
		log.Println(err)
	}

	return rrs, nil
}

// createACLList create a map with the CIDR and the name of the rule
func createACLList(config []configACL) (map[string]*net.IPNet, error) {
	acls := make(map[string]*net.IPNet)

	for _, aclRule := range config {
		_, mask, err := net.ParseCIDR(aclRule.CIDR)

		if err != nil {
			return nil, err
		}

		acls[aclRule.Name] = mask
	}

	return acls, nil
}