// This example demonstrates how to generate a cryptographically random seed
// then use it to create a new master node (extended key).
func ExampleNewMaster() {
	// Generate a random seed at the recommended length.
	seed, err := hdkeychain.GenerateSeed(hdkeychain.RecommendedSeedLen)
	if err != nil {
		fmt.Println(err)
		return
	}

	// Generate a new master node using the seed.
	key, err := hdkeychain.NewMaster(seed)
	if err != nil {
		fmt.Println(err)
		return
	}

	// Show that the generated master node extended key is private.
	fmt.Println("Private Extended Key?:", key.IsPrivate())

	// Output:
	// Private Extended Key?: true
}
// TestGenenerateSeed ensures the GenerateSeed function works as intended.
func TestGenenerateSeed(t *testing.T) {
	wantErr := errors.New("seed length must be between 128 and 512 bits")

	tests := []struct {
		name   string
		length uint8
		err    error
	}{
		// Test various valid lengths.
		{name: "16 bytes", length: 16},
		{name: "17 bytes", length: 17},
		{name: "20 bytes", length: 20},
		{name: "32 bytes", length: 32},
		{name: "64 bytes", length: 64},

		// Test invalid lengths.
		{name: "15 bytes", length: 15, err: wantErr},
		{name: "65 bytes", length: 65, err: wantErr},
	}

	for i, test := range tests {
		seed, err := hdkeychain.GenerateSeed(test.length)
		if !reflect.DeepEqual(err, test.err) {
			t.Errorf("GenerateSeed #%d (%s): unexpected error -- "+
				"want %v, got %v", i, test.name, test.err, err)
			continue
		}

		if test.err == nil && len(seed) != int(test.length) {
			t.Errorf("GenerateSeed #%d (%s): length mismatch -- "+
				"got %d, want %d", i, test.name, len(seed),
				test.length)
			continue
		}
	}
}
// TestErrors performs some negative tests for various invalid cases to ensure
// the errors are handled properly.
func TestErrors(t *testing.T) {
	// Should get an error when seed has too few bytes.
	_, err := hdkeychain.NewMaster(bytes.Repeat([]byte{0x00}, 15))
	if err != hdkeychain.ErrInvalidSeedLen {
		t.Errorf("NewMaster: mismatched error -- got: %v, want: %v",
			err, hdkeychain.ErrInvalidSeedLen)
	}

	// Should get an error when seed has too many bytes.
	_, err = hdkeychain.NewMaster(bytes.Repeat([]byte{0x00}, 65))
	if err != hdkeychain.ErrInvalidSeedLen {
		t.Errorf("NewMaster: mismatched error -- got: %v, want: %v",
			err, hdkeychain.ErrInvalidSeedLen)
	}

	// Generate a new key and neuter it to a public extended key.
	seed, err := hdkeychain.GenerateSeed(hdkeychain.RecommendedSeedLen)
	if err != nil {
		t.Errorf("GenerateSeed: unexpected error: %v", err)
		return
	}
	extKey, err := hdkeychain.NewMaster(seed)
	if err != nil {
		t.Errorf("NewMaster: unexpected error: %v", err)
		return
	}
	pubKey, err := extKey.Neuter()
	if err != nil {
		t.Errorf("Neuter: unexpected error: %v", err)
		return
	}

	// Deriving a hardened child extended key should fail from a public key.
	_, err = pubKey.Child(hdkeychain.HardenedKeyStart)
	if err != hdkeychain.ErrDeriveHardFromPublic {
		t.Errorf("Child: mismatched error -- got: %v, want: %v",
			err, hdkeychain.ErrDeriveHardFromPublic)
	}

	// NewKeyFromString failure tests.
	tests := []struct {
		name      string
		key       string
		err       error
		neuter    bool
		neuterErr error
	}{
		{
			name: "invalid key length",
			key:  "xpub1234",
			err:  hdkeychain.ErrInvalidKeyLen,
		},
		{
			name: "bad checksum",
			key:  "xpub661MyMwAqRbcFtXgS5sYJABqqG9YLmC4Q1Rdap9gSE8NqtwybGhePY2gZ29ESFjqJoCu1Rupje8YtGqsefD265TMg7usUDFdp6W1EBygr15",
			err:  hdkeychain.ErrBadChecksum,
		},
		{
			name: "pubkey not on curve",
			key:  "xpub661MyMwAqRbcFtXgS5sYJABqqG9YLmC4Q1Rdap9gSE8NqtwybGhePY2gZ1hr9Rwbk95YadvBkQXxzHBSngB8ndpW6QH7zhhsXZ2jHyZqPjk",
			err:  errors.New("pubkey isn't on secp256k1 curve"),
		},
		{
			name:      "unsupported version",
			key:       "xbad4LfUL9eKmA66w2GJdVMqhvDmYGJpTGjWRAtjHqoUY17sGaymoMV9Cm3ocn9Ud6Hh2vLFVC7KSKCRVVrqc6dsEdsTjRV1WUmkK85YEUujAPX",
			err:       nil,
			neuter:    true,
			neuterErr: chaincfg.ErrUnknownHDKeyID,
		},
	}

	for i, test := range tests {
		extKey, err := hdkeychain.NewKeyFromString(test.key)
		if !reflect.DeepEqual(err, test.err) {
			t.Errorf("NewKeyFromString #%d (%s): mismatched error "+
				"-- got: %v, want: %v", i, test.name, err,
				test.err)
			continue
		}

		if test.neuter {
			_, err := extKey.Neuter()
			if !reflect.DeepEqual(err, test.neuterErr) {
				t.Errorf("Neuter #%d (%s): mismatched error "+
					"-- got: %v, want: %v", i, test.name,
					err, test.neuterErr)
				continue
			}
		}
	}
}