package yamlzone

import (
	"context"
	"fmt"
	"strconv"

	"github.com/coredns/caddy"
	"github.com/coredns/coredns/core/dnsserver"
	"github.com/coredns/coredns/plugin"
	clog "github.com/coredns/coredns/plugin/pkg/log"
	"github.com/coredns/coredns/request"

	"github.com/miekg/dns"
)

type YamlPlugin struct {
	Next   plugin.Handler
	Zone   *Zone
	Config YamlPluginConfig
}

type YamlPluginConfig struct {
	DefaultTtl uint64
}

var log = clog.NewWithPlugin("yaml")

func (y YamlPlugin) lookupRRs(qname string, qtype string) ([]dns.RR, bool) {
	records, ok := y.Zone.LookupType(qname, qtype)
	if !ok {
		return nil, false
	}
	rrs := []dns.RR{}
	for _, record := range records {
		ttl := record.Ttl
		if ttl == 0 {
			ttl = y.Config.DefaultTtl
		}
		rr, err := dns.NewRR(fmt.Sprintf("%s %d %s %s", qname, ttl, record.Type, record.Value))
		if err != nil {
			return nil, false
		}
		rrs = append(rrs, rr)
	}
	return rrs, true
}

func (y YamlPlugin) Name() string { return "yaml" }

func (y YamlPlugin) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
	state := request.Request{W: w, Req: r}
	qname := state.Name()
	qtype := state.Type()

	reply := new(dns.Msg)
	reply.SetReply(r)
	reply.Authoritative = true

	rrs, ok := y.lookupRRs(qname, qtype)
	if !ok {
		return dns.RcodeNameError, nil
	}
	reply.Answer = rrs
	w.WriteMsg(reply)
	return dns.RcodeSuccess, nil
}

func setup(c *caddy.Controller) error {
	c.Next() // yaml
	filename := "zones.yaml"
	if c.NextArg() {
		filename = c.Val()
	}
	defaultTtl := uint64(60)
	if c.NextArg() {
		var err error
		defaultTtl, err = strconv.ParseUint(c.Val(), 10, 32)
		if err != nil {
			return plugin.Error("yaml", fmt.Errorf("failed to parse default TTL: %w", err))
		}
	}
	zone, err := LoadZone(filename)
	if err != nil {
		return plugin.Error("yaml", fmt.Errorf("failed to load zone from %s: %w", filename, err))
	}
	dnsserver.GetConfig(c).AddPlugin(func(next plugin.Handler) plugin.Handler {
		return &YamlPlugin{
			Next: next,
			Zone: zone,
			Config: YamlPluginConfig{
				DefaultTtl: defaultTtl,
			},
		}
	})
	return nil
}

func init() { plugin.Register("yaml", setup) }