package hop_test

import (
	"bytes"
	"reflect"
	"testing"

	"github.com/lightningnetwork/lnd/htlcswitch/hop"
	"github.com/lightningnetwork/lnd/lnwire"
	"github.com/lightningnetwork/lnd/record"
)

type decodePayloadTest struct {
	name          string
	payload       []byte
	expErr        error
	shouldHaveMPP bool
}

var decodePayloadTests = []decodePayloadTest{
	{
		name:    "final hop valid",
		payload: []byte{0x02, 0x00, 0x04, 0x00},
	},
	{
		name: "intermediate hop valid",
		payload: []byte{0x02, 0x00, 0x04, 0x00, 0x06, 0x08, 0x01, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
		},
	},
	{
		name:    "final hop no amount",
		payload: []byte{0x04, 0x00},
		expErr: hop.ErrInvalidPayload{
			Type:      record.AmtOnionType,
			Violation: hop.OmittedViolation,
			FinalHop:  true,
		},
	},
	{
		name: "intermediate hop no amount",
		payload: []byte{0x04, 0x00, 0x06, 0x08, 0x01, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00,
		},
		expErr: hop.ErrInvalidPayload{
			Type:      record.AmtOnionType,
			Violation: hop.OmittedViolation,
			FinalHop:  false,
		},
	},
	{
		name:    "final hop no expiry",
		payload: []byte{0x02, 0x00},
		expErr: hop.ErrInvalidPayload{
			Type:      record.LockTimeOnionType,
			Violation: hop.OmittedViolation,
			FinalHop:  true,
		},
	},
	{
		name: "intermediate hop no expiry",
		payload: []byte{0x02, 0x00, 0x06, 0x08, 0x01, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00,
		},
		expErr: hop.ErrInvalidPayload{
			Type:      record.LockTimeOnionType,
			Violation: hop.OmittedViolation,
			FinalHop:  false,
		},
	},
	{
		name: "final hop next sid present",
		payload: []byte{0x02, 0x00, 0x04, 0x00, 0x06, 0x08, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
		},
		expErr: hop.ErrInvalidPayload{
			Type:      record.NextHopOnionType,
			Violation: hop.IncludedViolation,
			FinalHop:  true,
		},
	},
	{
		name:    "required type after omitted hop id",
		payload: []byte{0x02, 0x00, 0x04, 0x00, 0x0a, 0x00},
		expErr: hop.ErrInvalidPayload{
			Type:      10,
			Violation: hop.RequiredViolation,
			FinalHop:  true,
		},
	},
	{
		name: "required type after included hop id",
		payload: []byte{0x02, 0x00, 0x04, 0x00, 0x06, 0x08, 0x01, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x0a, 0x00,
		},
		expErr: hop.ErrInvalidPayload{
			Type:      10,
			Violation: hop.RequiredViolation,
			FinalHop:  false,
		},
	},
	{
		name:    "required type zero final hop",
		payload: []byte{0x00, 0x00, 0x02, 0x00, 0x04, 0x00},
		expErr: hop.ErrInvalidPayload{
			Type:      0,
			Violation: hop.RequiredViolation,
			FinalHop:  true,
		},
	},
	{
		name: "required type zero final hop zero sid",
		payload: []byte{0x00, 0x00, 0x02, 0x00, 0x04, 0x00, 0x06, 0x08,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
		},
		expErr: hop.ErrInvalidPayload{
			Type:      record.NextHopOnionType,
			Violation: hop.IncludedViolation,
			FinalHop:  true,
		},
	},
	{
		name: "required type zero intermediate hop",
		payload: []byte{0x00, 0x00, 0x02, 0x00, 0x04, 0x00, 0x06, 0x08,
			0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
		},
		expErr: hop.ErrInvalidPayload{
			Type:      0,
			Violation: hop.RequiredViolation,
			FinalHop:  false,
		},
	},
	{
		name: "required type in custom range",
		payload: []byte{0x02, 0x00, 0x04, 0x00,
			0xfe, 0x00, 0x01, 0x00, 0x00, 0x00,
		},
	},
	{
		name: "valid intermediate hop",
		payload: []byte{0x02, 0x00, 0x04, 0x00, 0x06, 0x08, 0x01, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
		},
		expErr: nil,
	},
	{
		name:    "valid final hop",
		payload: []byte{0x02, 0x00, 0x04, 0x00},
		expErr:  nil,
	},
	{
		name: "intermediate hop with mpp",
		payload: []byte{
			// amount
			0x02, 0x00,
			// cltv
			0x04, 0x00,
			// next hop id
			0x06, 0x08,
			0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			// mpp
			0x08, 0x21,
			0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11,
			0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11,
			0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11,
			0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11,
			0x08,
		},
		expErr: hop.ErrInvalidPayload{
			Type:      record.MPPOnionType,
			Violation: hop.IncludedViolation,
			FinalHop:  false,
		},
	},
	{
		name: "final hop with mpp",
		payload: []byte{
			// amount
			0x02, 0x00,
			// cltv
			0x04, 0x00,
			// mpp
			0x08, 0x21,
			0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11,
			0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11,
			0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11,
			0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11,
			0x08,
		},
		expErr:        nil,
		shouldHaveMPP: true,
	},
}

// TestDecodeHopPayloadRecordValidation asserts that parsing the payloads in the
// tests yields the expected errors depending on whether the proper fields were
// included or omitted.
func TestDecodeHopPayloadRecordValidation(t *testing.T) {
	for _, test := range decodePayloadTests {
		t.Run(test.name, func(t *testing.T) {
			testDecodeHopPayloadValidation(t, test)
		})
	}
}

func testDecodeHopPayloadValidation(t *testing.T, test decodePayloadTest) {
	var (
		testTotalMsat = lnwire.MilliSatoshi(8)
		testAddr      = [32]byte{
			0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11,
			0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11,
			0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11,
			0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11,
		}
	)

	p, err := hop.NewPayloadFromReader(bytes.NewReader(test.payload))
	if !reflect.DeepEqual(test.expErr, err) {
		t.Fatalf("expected error mismatch, want: %v, got: %v",
			test.expErr, err)
	}
	if err != nil {
		return
	}

	// Assert MPP fields if we expect them.
	if test.shouldHaveMPP {
		if p.MPP == nil {
			t.Fatalf("payload should have MPP record")
		}
		if p.MPP.TotalMsat() != testTotalMsat {
			t.Fatalf("invalid total msat")
		}
		if p.MPP.PaymentAddr() != testAddr {
			t.Fatalf("invalid payment addr")
		}
	} else if p.MPP != nil {
		t.Fatalf("unexpected MPP payload")
	}
}