package hcdns_test

import (
	"database/sql"
	"fmt"
	"math/rand"
	"os"
	"sync"
	"testing"

	"git.hatecomputers.club/hatecomputers/hatecomputers.club/args"
	"git.hatecomputers.club/hatecomputers/hatecomputers.club/database"
	"git.hatecomputers.club/hatecomputers/hatecomputers.club/hcdns"
	"git.hatecomputers.club/hatecomputers/hatecomputers.club/utils"
	"github.com/miekg/dns"
)

func randomPort() int {
	return rand.Intn(3000) + 5192
}

func setup(arguments *args.Arguments) (*sql.DB, *dns.Server, string, func()) {
	randomDb := utils.RandomId()

	testDb := database.MakeConn(&randomDb)
	database.Migrate(testDb)
	testUser := &database.User{
		ID: "test",
	}
	database.FindOrSaveUser(testDb, testUser)

	dnsArguments := arguments
	if dnsArguments == nil {
		dnsArguments = &args.Arguments{
			DnsPort: randomPort(),
		}
	}

	waitLock := &sync.Mutex{}
	server := hcdns.MakeServer(dnsArguments, testDb)
	server.NotifyStartedFunc = func() {
		waitLock.Unlock()
	}
	waitLock.Lock()

	go func() {
		server.ListenAndServe()
	}()
	waitLock.Lock()

	address := fmt.Sprintf("127.0.0.1:%d", dnsArguments.DnsPort)
	return testDb, server, address, func() {
		waitLock.Unlock()
		server.Shutdown()

		testDb.Close()
		os.Remove(randomDb)
	}
}

func TestWhenCNAMEIsResolved(t *testing.T) {
	testDb, _, addr, cleanup := setup(nil)
	defer cleanup()

	records := []*database.DNSRecord{
		{
			ID:       "0",
			UserID:   "test",
			Name:     "cname.internal.example.com.",
			Type:     "CNAME",
			Content:  "next.internal.example.com.",
			TTL:      300,
			Internal: true,
		}, {
			ID:       "1",
			UserID:   "test",
			Name:     "next.internal.example.com.",
			Type:     "CNAME",
			Content:  "res.example.com.",
			TTL:      300,
			Internal: true,
		},
		{
			ID:       "2",
			UserID:   "test",
			Name:     "res.example.com.",
			Type:     "A",
			Content:  "1.2.3.2",
			TTL:      300,
			Internal: true,
		},
	}

	for _, record := range records {
		database.SaveDNSRecord(testDb, record)
	}

	qtype := dns.TypeA
	domain := dns.Fqdn("cname.internal.example.com.")
	client := &dns.Client{}
	message := &dns.Msg{}
	message.SetQuestion(domain, qtype)

	in, _, err := client.Exchange(message, addr)
	if err != nil {
		t.Fatal(err)
	}

	if len(in.Answer) != 3 {
		t.Fatalf("expected 3 answers, got %d", len(in.Answer))
	}

	for i, record := range records {
		if in.Answer[i].Header().Name != record.Name {
			t.Fatalf("expected %s, got %s", record.Name, in.Answer[i].Header().Name)
		}

		if in.Answer[i].Header().Rrtype != dns.StringToType[record.Type] {
			t.Fatalf("expected %s, got %d", record.Type, in.Answer[i].Header().Rrtype)
		}

		if int(in.Answer[i].Header().Ttl) != record.TTL {
			t.Fatalf("expected %d, got %d", record.TTL, in.Answer[i].Header().Ttl)
		}

		if !in.Authoritative {
			t.Fatalf("expected authoritative response")
		}
	}

	if in.Answer[2].(*dns.A).A.String() != "1.2.3.2" {
		t.Fatalf("expected final record to be the A record with correct IP")
	}
}

func TestWhenNoRecordNxDomain(t *testing.T) {
	_, _, addr, cleanup := setup(nil)
	defer cleanup()

	qtype := dns.TypeA
	domain := dns.Fqdn("nonexistant.example.com.")
	client := &dns.Client{}
	message := &dns.Msg{}
	message.SetQuestion(domain, qtype)

	in, _, err := client.Exchange(message, addr)

	if err != nil {
		t.Fatal(err)
	}

	if len(in.Answer) != 0 {
		t.Fatalf("expected 0 answers, got %d", len(in.Answer))
	}

	if in.Rcode != dns.RcodeNameError {
		t.Fatalf("expected NXDOMAIN, got %d", in.Rcode)
	}
}

func TestWhenUnresolvingCNAME(t *testing.T) {
	testDb, _, addr, cleanup := setup(nil)
	defer cleanup()

	cname := &database.DNSRecord{
		ID:       "1",
		UserID:   "test",
		Name:     "cname.internal.example.com.",
		Type:     "CNAME",
		Content:  "nonexistant.example.com.",
		TTL:      300,
		Internal: true,
	}
	database.SaveDNSRecord(testDb, cname)

	qtype := dns.TypeA
	domain := dns.Fqdn(cname.Name)
	client := &dns.Client{}
	message := &dns.Msg{}
	message.SetQuestion(domain, qtype)

	in, _, err := client.Exchange(message, addr)

	if err != nil {
		t.Fatal(err)
	}

	if len(in.Answer) != 1 {
		t.Fatalf("expected 1 answer, got %d", len(in.Answer))
	}

	if !in.Authoritative {
		t.Fatalf("expected authoritative response")
	}

	if in.Answer[0].Header().Name != cname.Name {
		t.Fatalf("expected cname.internal.example.com., got %s", in.Answer[0].Header().Name)
	}

	if in.Answer[0].Header().Rrtype != dns.TypeCNAME {
		t.Fatalf("expected CNAME, got %d", in.Answer[0].Header().Rrtype)
	}

	if in.Answer[0].(*dns.CNAME).Target != cname.Content {
		t.Fatalf("expected nonexistant.example.com., got %s", in.Answer[0].(*dns.CNAME).Target)
	}

	if in.Rcode == dns.RcodeNameError {
		t.Fatalf("expected no NXDOMAIN, got %d", in.Rcode)
	}
}

func TestWhenUnresolvingCNAMEWithMaxDepth(t *testing.T) {
	testDb, _, addr, cleanup := setup(nil)
	defer cleanup()

	cname := &database.DNSRecord{
		ID:       "1",
		UserID:   "test",
		Name:     "cname.internal.example.com.",
		Type:     "CNAME",
		Content:  "cname.internal.example.com.",
		TTL:      300,
		Internal: true,
	}
	database.SaveDNSRecord(testDb, cname)

	qtype := dns.TypeA
	domain := dns.Fqdn(cname.Name)
	client := &dns.Client{}
	message := &dns.Msg{}
	message.SetQuestion(domain, qtype)

	in, _, err := client.Exchange(message, addr)

	if err != nil {
		t.Fatal(err)
	}

	if len(in.Answer) > 0 {
		t.Fatalf("expected 0 answers, got %d", len(in.Answer))
	}

	if in.Rcode != dns.RcodeServerFailure {
		t.Fatalf("expected SERVFAIL, got %d", in.Rcode)
	}
}

func TestWhenExternalDomain(t *testing.T) {
	externalDb, _, externalAddr, externalCleanup := setup(nil)
	internalDb, _, internalAddr, internalCleanup := setup(&args.Arguments{
		DnsPort:      randomPort(),
		DnsResolvers: []string{externalAddr},
	})
	defer internalCleanup()
	defer externalCleanup()

	authoritativeRecords := []database.DNSRecord{
		{
			ID:      "1",
			UserID:  "test",
			Name:    "external.example.com.",
			Type:    "CNAME",
			Content: "external.internal.example.com.",
		},
		{
			ID:      "2",
			UserID:  "test",
			Name:    "final.example.com.",
			Type:    "A",
			Content: "127.0.0.1",
		},
	}
	internalRecords := []database.DNSRecord{
		{
			ID:      "1",
			UserID:  "test",
			Name:    "external.internal.example.com.",
			Type:    "CNAME",
			Content: "final.example.com",
		},
		{
			ID:      "2",
			UserID:  "test",
			Name:    "test.internal.example.com.",
			Type:    "CNAME",
			Content: "external.example.com.",
		},
	}

	for _, record := range authoritativeRecords {
		database.SaveDNSRecord(externalDb, &record)
	}
	for _, record := range internalRecords {
		database.SaveDNSRecord(internalDb, &record)
	}

	// ensure that if the record doesn't exist in the internal database, it will
	// go and query the external dns resolvers, then loop back to the internal

	qtype := dns.TypeA
	domain := dns.Fqdn("test.internal.example.com.")
	client := &dns.Client{}
	message := &dns.Msg{}
	message.SetQuestion(domain, qtype)

	in, _, err := client.Exchange(message, internalAddr)

	if err != nil {
		t.Fatal(err)
	}

	if len(in.Answer) != 4 {
		t.Fatalf("expected 4 answers, got %d", len(in.Answer))
	}

	aRecord := in.Answer[3]
	if aRecord.Header().Name != authoritativeRecords[1].Name {
		t.Fatalf("expected %s, got %s", domain, aRecord.Header().Name)
	}
	if aRecord.Header().Rrtype != dns.TypeA {
		t.Fatalf("expected %s, got %s", dns.TypeToString[aRecord.Header().Rrtype], internalRecords[1].Type)
	}
	if aRecord.(*dns.A).A.String() != authoritativeRecords[1].Content {
		t.Fatalf("expected %s, got %s", authoritativeRecords[1].Content, aRecord.(*dns.A).A.String())
	}
	if in.Authoritative {
		t.Fatalf("expected non-authoritative response")
	}
}