package certs

import (
	"crypto/ecdsa"
	"crypto/ed25519"
	"crypto/elliptic"
	"crypto/rand"
	"crypto/rsa"
	"crypto/x509"
	"net"
	"os"
	"os/exec"
	"strings"
	"testing"
	"time"

	. "github.com/smartystreets/goconvey/convey"
)

const testOrganization = "yoorie.de"

func parseLeafCertificate(t *testing.T, gc *GenerateCertificate) *x509.Certificate {
	t.Helper()

	result, err := gc.GenerateTLSConfig()
	if err != nil {
		t.Fatalf("GenerateTLSConfig returned error: %v", err)
	}
	if result == nil || len(result.Certificates) != 1 {
		t.Fatalf("expected one certificate, got %#v", result)
	}
	if len(result.Certificates[0].Certificate) == 0 {
		t.Fatal("expected leaf certificate bytes")
	}

	leaf, err := x509.ParseCertificate(result.Certificates[0].Certificate[0])
	if err != nil {
		t.Fatalf("ParseCertificate returned error: %v", err)
	}

	return leaf
}

func TestPublicKey(t *testing.T) {
	Convey("publicKey returns the matching public key type", t, func() {
		gc := &GenerateCertificate{}

		rsaKey, err := rsa.GenerateKey(rand.Reader, 1024)
		So(err, ShouldBeNil)
		So(gc.publicKey(rsaKey), ShouldResemble, &rsaKey.PublicKey)

		ecdsaKey, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
		So(err, ShouldBeNil)
		So(gc.publicKey(ecdsaKey), ShouldResemble, &ecdsaKey.PublicKey)

		_, ed25519Key, err := ed25519.GenerateKey(rand.Reader)
		So(err, ShouldBeNil)
		So(gc.publicKey(ed25519Key), ShouldResemble, ed25519Key.Public().(ed25519.PublicKey))

		So(gc.publicKey(struct{}{}), ShouldBeNil)
	})
}

func TestGenerateTLSConfig(t *testing.T) {
	Convey("GenerateTLSConfig creates valid certificates for supported key types", t, func() {
		Convey("RSA certificates include configured SANs and CA settings", func() {
			validFrom := "Jan 2 15:04:05 2006"
			leaf := parseLeafCertificate(t, &GenerateCertificate{
				Organization: testOrganization,
				Host:         "127.0.0.1,example.com",
				ValidFrom:    validFrom,
				ValidFor:     24 * time.Hour,
				IsCA:         true,
				RSABits:      1024,
			})

			expectedNotBefore, err := time.Parse("Jan 2 15:04:05 2006", validFrom)
			So(err, ShouldBeNil)

			So(leaf.PublicKeyAlgorithm, ShouldEqual, x509.RSA)
			So(leaf.Subject.Organization, ShouldResemble, []string{testOrganization})
			So(leaf.IsCA, ShouldBeTrue)
			So(leaf.NotBefore.Equal(expectedNotBefore), ShouldBeTrue)
			So(leaf.NotAfter.Sub(leaf.NotBefore), ShouldEqual, 24*time.Hour)
			So(leaf.DNSNames, ShouldResemble, []string{"example.com"})
			So(len(leaf.IPAddresses), ShouldEqual, 1)
			So(leaf.IPAddresses[0].Equal(net.ParseIP("127.0.0.1")), ShouldBeTrue)
		})

		Convey("Ed25519 certificates are supported when explicitly requested", func() {
			leaf := parseLeafCertificate(t, &GenerateCertificate{
				Organization: testOrganization,
				Host:         "localhost",
				ValidFor:     12 * time.Hour,
				Ed25519Key:   true,
			})

			So(leaf.PublicKeyAlgorithm, ShouldEqual, x509.Ed25519)
			So(leaf.IsCA, ShouldBeFalse)
			So(leaf.DNSNames, ShouldResemble, []string{"localhost"})
		})

		Convey("all supported ECDSA curves generate server certificates", func() {
			curves := []string{"P224", "P256", "P384", "P521"}

			for _, curve := range curves {
				leaf := parseLeafCertificate(t, &GenerateCertificate{
					Organization: testOrganization,
					Host:         "certs.example.test",
					ValidFor:     6 * time.Hour,
					EcdsaCurve:   curve,
				})

				So(leaf.PublicKeyAlgorithm, ShouldEqual, x509.ECDSA)
				So(leaf.DNSNames, ShouldResemble, []string{"certs.example.test"})
			}
		})
	})
}

func TestGenerateTLSConfigFatalScenarios(t *testing.T) {
	if testCase := os.Getenv("CERTS_FATAL_TEST_CASE"); testCase != "" {
		gc := &GenerateCertificate{RSABits: 1024, ValidFor: time.Hour}

		switch testCase {
		case "invalid-curve":
			gc.EcdsaCurve = "invalid"
		case "invalid-valid-from":
			gc.ValidFrom = "not-a-date"
		default:
			t.Fatalf("unknown fatal test case: %s", testCase)
		}

		_, _ = gc.GenerateTLSConfig()
		return
	}

	Convey("GenerateTLSConfig terminates on invalid input", t, func() {
		testCases := []struct {
			name    string
			message string
		}{
			{name: "invalid-curve", message: "Unrecognized elliptic curve"},
			{name: "invalid-valid-from", message: "Failed to parse creation date"},
		}

		for _, testCase := range testCases {
			cmd := exec.Command(os.Args[0], "-test.run", "^TestGenerateTLSConfigFatalScenarios$")
			cmd.Env = append(os.Environ(), "CERTS_FATAL_TEST_CASE="+testCase.name)

			output, err := cmd.CombinedOutput()
			So(err, ShouldNotBeNil)
			So(strings.Contains(string(output), testCase.message), ShouldBeTrue)
		}
	})
}