package pancheri

import (
	"crypto/sha256"
	"errors"
	"fmt"
	"gopkg.in/yaml.v2"
	"net"
	"os"
	"strings"
)

type ZoneConfig struct {
	Zone struct {
		Root    string      `yaml:"root"`
		Records []CfgRecord `yaml:"records"`
	} `yaml:"zone"`
}

type CfgRecord struct {
	RecordType string   `yaml:"type"`
	Domains    []string `yaml:"domains"`
	Ipv4       net.IP   `yaml:"ipv4"`
	Ipv6       net.IP   `yaml:"ipv6"`
	Target     string   `yaml:"target"`
	Content    []string `yaml:"content"`
	TTL        uint     `yaml:"ttl"`
}

func LoadZone(path string) (*Zone, error) {
	f, err := os.Open(path)
	if err != nil {
		return nil, err
	}

	var cfg ZoneConfig
	decoder := yaml.NewDecoder(f)

	err = decoder.Decode(&cfg)
	if err != nil {
		return nil, err
	}

	err = f.Close()
	if err != nil {
		return nil, err
	}

	reduced, err := yaml.Marshal(cfg)
	if err != nil {
		return nil, err
	}
	// ReducedHash is a hash of the zonefile after it has been re-marshaled by libyaml.
	// This is intended to prevent pointless changes of the serial when only minor formatting changes have been made
	// ex. adding an extra space somewhere won't trigger a new serial
	reducedHash := fmt.Sprintf("%x", sha256.Sum256(reduced))
	// The serial is the first few bytes of this converted to an integer

	// validate and convert
	zone := Zone{
		Root:         cfg.Zone.Root,
		ReducedHash:  reducedHash,
		Zonefile:     path,
		ARecords:     nil,
		AAAARecords:  nil,
		CNAMERecords: nil,
		TXTRecords:   nil,
	}

	for _, record := range cfg.Zone.Records {
		if record.RecordType == RuleTypeA {
			// req.d fields: in, ip, ttl
			if len(record.Domains) == 0 {
				return nil, errors.New("A record must contain at least one domain")
			}
			if record.Ipv4 == nil {
				return nil, errors.New("A record must contain ipv4 address")
			}
			if record.TTL == 0 {
				return nil, errors.New("A record TTL cannot be 0 or empty")
			}
			for _, domain := range record.Domains {
				if !strings.HasSuffix(domain, ".") {
					domain = domain + "." + cfg.Zone.Root + "."
				}
				zone.ARecords = append(zone.ARecords, RecordA{
					In:  domain,
					Ip:  record.Ipv4.To4(),
					TTL: record.TTL,
				})
			}
		} else if record.RecordType == RuleTypeAAAA {
			// req.d fields: in, ip, ttl
			if len(record.Domains) == 0 {
				return nil, errors.New("AAAA record must contain at least one domain")
			}
			if record.Ipv6 == nil {
				return nil, errors.New("AAAA record must contain ipv6 address")
			}
			if record.TTL == 0 {
				return nil, errors.New("AAAA record TTL cannot be 0 or empty")
			}
			for _, domain := range record.Domains {
				if !strings.HasSuffix(domain, ".") {
					domain = domain + "." + cfg.Zone.Root + "."
				}
				zone.AAAARecords = append(zone.AAAARecords, RecordAAAA{
					In:  domain,
					Ip:  record.Ipv6,
					TTL: record.TTL,
				})
			}
		} else if record.RecordType == RuleTypeCNAME {
			// req.d fields: in, ip, ttl
			if len(record.Domains) == 0 {
				return nil, errors.New("CNAME record must contain at least one domain")
			}
			if len(record.Target) == 0 {
				return nil, errors.New("CNAME record must contain target")
			}
			if record.TTL == 0 {
				return nil, errors.New("CNAME record TTL cannot be 0 or empty")
			}
			for _, domain := range record.Domains {
				if !strings.HasSuffix(domain, ".") {
					domain = domain + "." + cfg.Zone.Root + "."
				}
				zone.CNAMERecords = append(zone.CNAMERecords, RecordCNAME{
					In:     domain,
					Target: record.Target,
					TTL:    record.TTL,
				})
			}
		} else if record.RecordType == RuleTypeTXT {
			// req.d fields: in, content, ttl
			if len(record.Domains) == 0 {
				return nil, errors.New("TXT record must contain at least one domain")
			}
			if len(record.Content) == 0 {
				return nil, errors.New("TXT record must contain content")
			}
			if record.TTL == 0 {
				return nil, errors.New("TXT record TTL cannot be 0 or empty")
			}
			for _, domain := range record.Domains {
				if !strings.HasSuffix(domain, ".") {
					domain = domain + "." + cfg.Zone.Root + "."
				}
				zone.TXTRecords = append(zone.TXTRecords, RecordTXT{
					In:      domain,
					Content: record.Content,
					TTL:     record.TTL,
				})
			}
		}
	}

	return &zone, nil
}