package tlsrpt

import (
	"context"
	"crypto/ed25519"
	cryptorand "crypto/rand"
	"crypto/tls"
	"crypto/x509"
	"encoding/json"
	"io"
	"math/big"
	"net"
	"os"
	"strings"
	"testing"
	"time"

	"github.com/mjl-/mox/mlog"
)

var pkglog = mlog.New("tlsrpt", nil)

const reportJSON = `{
     "organization-name": "Company-X",
     "date-range": {
       "start-datetime": "2016-04-01T00:00:00Z",
       "end-datetime": "2016-04-01T23:59:59Z"
     },
     "contact-info": "sts-reporting@company-x.example",
     "report-id": "5065427c-23d3-47ca-b6e0-946ea0e8c4be",
     "policies": [{
       "policy": {
         "policy-type": "sts",
         "policy-string": ["version: STSv1","mode: testing",
               "mx: *.mail.company-y.example","max_age: 86400"],
         "policy-domain": "company-y.example",
         "mx-host": ["*.mail.company-y.example"]
       },
       "summary": {
         "total-successful-session-count": 5326,
         "total-failure-session-count": 303
       },
       "failure-details": [{
         "result-type": "certificate-expired",
         "sending-mta-ip": "2001:db8:abcd:0012::1",
         "receiving-mx-hostname": "mx1.mail.company-y.example",
         "failed-session-count": 100
       }, {
         "result-type": "starttls-not-supported",
         "sending-mta-ip": "2001:db8:abcd:0013::1",
         "receiving-mx-hostname": "mx2.mail.company-y.example",
         "receiving-ip": "203.0.113.56",
         "failed-session-count": 200,
         "additional-information": "https://reports.company-x.example/report_info ? id = 5065427 c - 23 d3# StarttlsNotSupported "
       }, {
         "result-type": "validation-failure",
         "sending-mta-ip": "198.51.100.62",
         "receiving-ip": "203.0.113.58",
         "receiving-mx-hostname": "mx-backup.mail.company-y.example",
         "failed-session-count": 3,
         "failure-reason-code": "X509_V_ERR_PROXY_PATH_LENGTH_EXCEEDED"
       }]
     }]
   }`

// ../rfc/8460:1015
var tlsrptMessage = strings.ReplaceAll(`From: tlsrpt@mail.sender.example.com
Date: Fri, May 09 2017 16:54:30 -0800
To: mts-sts-tlsrpt@example.net
Subject: Report Domain: example.net
Submitter: mail.sender.example.com
Report-ID: <735ff.e317+bf22029@example.net>
TLS-Report-Domain: example.net
TLS-Report-Submitter: mail.sender.example.com
MIME-Version: 1.0
Content-Type: multipart/report; report-type="tlsrpt";
	boundary="----=_NextPart_000_024E_01CC9B0A.AFE54C00"
Content-Language: en-us

This is a multipart message in MIME format.

------=_NextPart_000_024E_01CC9B0A.AFE54C00
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit

This is an aggregate TLS report from mail.sender.example.com

------=_NextPart_000_024E_01CC9B0A.AFE54C00
Content-Type: application/tlsrpt+json
Content-Transfer-Encoding: 8bit
Content-Disposition: attachment;
	filename="mail.sender.example!example.com!1013662812!1013749130.json.gz"

`+reportJSON+`

------=_NextPart_000_024E_01CC9B0A.AFE54C00--
`, "\n", "\r\n")

// Message without multipart.
var tlsrptMessage2 = strings.ReplaceAll(`From: tlsrpt@mail.sender.example.com
To: mts-sts-tlsrpt@example.net
Subject: Report Domain: example.net
Report-ID: <735ff.e317+bf22029@example.net>
TLS-Report-Domain: example.net
TLS-Report-Submitter: mail.sender.example.com
MIME-Version: 1.0
Content-Type: application/tlsrpt+json
Content-Transfer-Encoding: 8bit
Content-Disposition: attachment;
	filename="mail.sender.example!example.com!1013662812!1013749130.json.gz"

`+reportJSON+`
`, "\n", "\r\n")

func TestReport(t *testing.T) {
	// ../rfc/8460:1756

	var report Report
	dec := json.NewDecoder(strings.NewReader(reportJSON))
	dec.DisallowUnknownFields()
	if err := dec.Decode(&report); err != nil {
		t.Fatalf("parsing report: %s", err)
	}

	if _, err := ParseMessage(pkglog.Logger, strings.NewReader(tlsrptMessage)); err != nil {
		t.Fatalf("parsing TLSRPT from message: %s", err)
	}

	if _, err := ParseMessage(pkglog.Logger, strings.NewReader(tlsrptMessage2)); err != nil {
		t.Fatalf("parsing TLSRPT from message: %s", err)
	}

	if _, err := ParseMessage(pkglog.Logger, strings.NewReader(strings.ReplaceAll(tlsrptMessage, "multipart/report", "multipart/related"))); err != ErrNoReport {
		t.Fatalf("got err %v, expected ErrNoReport", err)
	}

	if _, err := ParseMessage(pkglog.Logger, strings.NewReader(strings.ReplaceAll(tlsrptMessage, "application/tlsrpt+json", "application/json"))); err != ErrNoReport {
		t.Fatalf("got err %v, expected ErrNoReport", err)
	}

	files, err := os.ReadDir("../testdata/tlsreports")
	if err != nil {
		t.Fatalf("listing reports: %s", err)
	}
	for _, file := range files {
		f, err := os.Open("../testdata/tlsreports/" + file.Name())
		if err != nil {
			t.Fatalf("open %q: %s", file, err)
		}
		if _, err := ParseMessage(pkglog.Logger, f); err != nil {
			t.Fatalf("parsing TLSRPT from message %q: %s", file.Name(), err)
		}
		f.Close()
	}
}

func TestTLSFailureDetails(t *testing.T) {
	const alert70 = "tls-remote-alert-70-protocol-version-not-supported"

	test := func(expResultType ResultType, expReasonCode string, client func(net.Conn) error, server func(net.Conn)) {
		t.Helper()

		cconn, sconn := net.Pipe()
		defer cconn.Close()
		defer sconn.Close()
		go server(sconn)
		err := client(cconn)
		if err == nil {
			t.Fatalf("expected tls error")
		}

		resultType, reasonCode := TLSFailureDetails(err)
		if resultType != expResultType || !(reasonCode == expReasonCode || expReasonCode == alert70 && reasonCode == "tls-remote-alert-70") {
			t.Fatalf("got %v %v, expected %v %v", resultType, reasonCode, expResultType, expReasonCode)
		}
	}

	newPool := func(certs ...tls.Certificate) *x509.CertPool {
		pool := x509.NewCertPool()
		for _, cert := range certs {
			pool.AddCert(cert.Leaf)
		}
		return pool
	}

	// Expired certificate.
	expiredCert := fakeCert(t, "localhost", true)
	test(ResultCertificateExpired, "",
		func(conn net.Conn) error {
			config := tls.Config{ServerName: "localhost", RootCAs: newPool(expiredCert)}
			return tls.Client(conn, &config).Handshake()
		},
		func(conn net.Conn) {
			config := tls.Config{Certificates: []tls.Certificate{expiredCert}}
			tls.Server(conn, &config).Handshake()
		},
	)

	// Hostname mismatch.
	okCert := fakeCert(t, "localhost", false)
	test(ResultCertificateHostMismatch, "", func(conn net.Conn) error {
		config := tls.Config{ServerName: "otherhost", RootCAs: newPool(okCert)}
		return tls.Client(conn, &config).Handshake()
	},
		func(conn net.Conn) {
			config := tls.Config{Certificates: []tls.Certificate{okCert}}
			tls.Server(conn, &config).Handshake()
		},
	)

	// Not signed by trusted CA.
	test(ResultCertificateNotTrusted, "", func(conn net.Conn) error {
		config := tls.Config{ServerName: "localhost", RootCAs: newPool()}
		return tls.Client(conn, &config).Handshake()
	},
		func(conn net.Conn) {
			config := tls.Config{Certificates: []tls.Certificate{okCert}}
			tls.Server(conn, &config).Handshake()
		},
	)

	// We don't support the right protocol version.
	test(ResultValidationFailure, alert70, func(conn net.Conn) error {
		config := tls.Config{ServerName: "localhost", RootCAs: newPool(okCert), MinVersion: tls.VersionTLS10, MaxVersion: tls.VersionTLS10}
		return tls.Client(conn, &config).Handshake()
	},
		func(conn net.Conn) {
			config := tls.Config{Certificates: []tls.Certificate{okCert}, MinVersion: tls.VersionTLS12}
			tls.Server(conn, &config).Handshake()
		},
	)

	// todo: ideally a test for tls-local-alert-*

	// Remote is not speaking TLS.
	test(ResultValidationFailure, "tls-record-header-error", func(conn net.Conn) error {
		config := tls.Config{ServerName: "localhost", RootCAs: newPool(okCert)}
		return tls.Client(conn, &config).Handshake()
	},
		func(conn net.Conn) {
			go io.Copy(io.Discard, conn)
			buf := make([]byte, 128)
			for {
				_, err := conn.Write(buf)
				if err != nil {
					break
				}
			}
		},
	)

	// Context deadline exceeded during handshake.
	test(ResultValidationFailure, "io-timeout-during-handshake",
		func(conn net.Conn) error {
			config := tls.Config{ServerName: "localhost", RootCAs: newPool(okCert)}
			ctx, cancel := context.WithTimeout(context.Background(), 1)
			defer cancel()
			return tls.Client(conn, &config).HandshakeContext(ctx)
		},
		func(conn net.Conn) {},
	)

	// Timeout during handshake.
	test(ResultValidationFailure, "io-timeout-during-handshake",
		func(conn net.Conn) error {
			config := tls.Config{ServerName: "localhost", RootCAs: newPool(okCert)}
			conn.SetDeadline(time.Now())
			return tls.Client(conn, &config).Handshake()
		},
		func(conn net.Conn) {},
	)

	// Closing connection during handshake.
	test(ResultValidationFailure, "connection-closed-during-handshake", func(conn net.Conn) error {
		config := tls.Config{ServerName: "localhost", RootCAs: newPool(okCert)}
		return tls.Client(conn, &config).Handshake()
	},
		func(conn net.Conn) {
			conn.Close()
		},
	)
}

// Just a cert that appears valid.
func fakeCert(t *testing.T, name string, expired bool) tls.Certificate {
	notAfter := time.Now()
	if expired {
		notAfter = notAfter.Add(-time.Hour)
	} else {
		notAfter = notAfter.Add(time.Hour)
	}

	privKey := ed25519.NewKeyFromSeed(make([]byte, ed25519.SeedSize)) // Fake key, don't use this for real!
	template := &x509.Certificate{
		SerialNumber: big.NewInt(1), // Required field...
		DNSNames:     []string{name},
		NotBefore:    time.Now().Add(-time.Hour),
		NotAfter:     notAfter,
	}
	localCertBuf, err := x509.CreateCertificate(cryptorand.Reader, template, template, privKey.Public(), privKey)
	if err != nil {
		t.Fatalf("making certificate: %s", err)
	}
	cert, err := x509.ParseCertificate(localCertBuf)
	if err != nil {
		t.Fatalf("parsing generated certificate: %s", err)
	}
	c := tls.Certificate{
		Certificate: [][]byte{localCertBuf},
		PrivateKey:  privKey,
		Leaf:        cert,
	}
	return c
}

func FuzzParseMessage(f *testing.F) {
	f.Add(tlsrptMessage)
	f.Fuzz(func(t *testing.T, s string) {
		ParseMessage(pkglog.Logger, strings.NewReader(s))
	})
}