package keychain

import (
	"fmt"
	"io/ioutil"
	"math/rand"
	"os"
	"testing"

	"github.com/roasbeef/btcd/chaincfg"
	"github.com/roasbeef/btcd/chaincfg/chainhash"
	"github.com/roasbeef/btcwallet/wallet"
	"github.com/roasbeef/btcwallet/walletdb"

	_ "github.com/roasbeef/btcwallet/walletdb/bdb" // Required in order to create the default database.
)

// versionZeroKeyFamilies is a slice of all the known key families for first
// version of the key derivation schema defined in this package.
var versionZeroKeyFamilies = []KeyFamily{
	KeyFamilyMultiSig,
	KeyFamilyRevocationBase,
	KeyFamilyHtlcBase,
	KeyFamilyPaymentBase,
	KeyFamilyDelayBase,
	KeyFamilyRevocationRoot,
	KeyFamilyNodeKey,
}

var (
	testHDSeed = chainhash.Hash{
		0xb7, 0x94, 0x38, 0x5f, 0x2d, 0x1e, 0xf7, 0xab,
		0x4d, 0x92, 0x73, 0xd1, 0x90, 0x63, 0x81, 0xb4,
		0x4f, 0x2f, 0x6f, 0x25, 0x98, 0xa3, 0xef, 0xb9,
		0x69, 0x49, 0x18, 0x83, 0x31, 0x98, 0x47, 0x53,
	}
)

func createTestBtcWallet() (func(), *wallet.Wallet, error) {
	tempDir, err := ioutil.TempDir("", "keyring-lnwallet")
	if err != nil {
		return nil, nil, err
	}
	loader := wallet.NewLoader(&chaincfg.SimNetParams, tempDir)

	pass := []byte("test")

	baseWallet, err := loader.CreateNewWallet(pass, pass, testHDSeed[:])
	if err != nil {
		return nil, nil, err
	}

	if err := baseWallet.Unlock(pass, nil); err != nil {
		return nil, nil, err
	}

	// We'll now ensure that the KeyScope: (201, 1) exists within the
	// internal waddrmgr. We'll need this in order to properly generate the
	// keys required for signing various contracts.
	_, err = baseWallet.Manager.FetchScopedKeyManager(lightningKeyScope)
	if err != nil {
		err := walletdb.Update(baseWallet.Database(), func(tx walletdb.ReadWriteTx) error {
			addrmgrNs := tx.ReadWriteBucket(waddrmgrNamespaceKey)

			_, err := baseWallet.Manager.NewScopedKeyManager(
				addrmgrNs, lightningKeyScope, lightningAddrSchema,
			)
			return err
		})
		if err != nil {
			return nil, nil, err
		}
	}

	cleanUp := func() {
		baseWallet.Lock()
		os.RemoveAll(tempDir)
	}

	return cleanUp, baseWallet, nil
}

// secretKeyRingConstructor is a function signature that's used as a generic
// constructor for various implementations of the KeyRing interface. A string
// naming the returned interface, a function closure that cleans up any
// resources, and the clean up interface itself are to be returned.
type keyRingConstructor func() (string, func(), KeyRing, error)

// TestKeyRingDerivation tests that each known KeyRing implementation properly
// adheres to the expected behavior of the set of interfaces.
func TestKeyRingDerivation(t *testing.T) {
	t.Parallel()

	keyRingImplementations := []keyRingConstructor{
		func() (string, func(), KeyRing, error) {
			cleanUp, wallet, err := createTestBtcWallet()
			if err != nil {
				t.Fatalf("unable to create wallet: %v", err)
			}

			keyRing := NewBtcWalletKeyRing(wallet)

			return "btcwallet", cleanUp, keyRing, nil
		},
	}

	// For each implementation constructor registered above, we'll execute
	// an identical set of tests in order to ensure that the interface
	// adheres to our nominal specification.
	for _, keyRingConstructor := range keyRingImplementations {
		keyRingName, cleanUp, keyRing, err := keyRingConstructor()
		if err != nil {
			t.Fatalf("unable to create key ring %v: %v", keyRingName,
				err)
		}
		defer cleanUp()

		success := t.Run(fmt.Sprintf("%v", keyRingName), func(t *testing.T) {
			// First, we'll ensure that we're able to derive keys
			// from each of the known key families.
			for _, keyFam := range versionZeroKeyFamilies {
				// First, we'll ensure that we can derive the
				// *next* key in the keychain.
				keyDesc, err := keyRing.DeriveNextKey(keyFam)
				if err != nil {
					t.Fatalf("unable to derive next for "+
						"keyFam=%v: %v", keyFam, err)
				}

				// If we now try to manually derive the *first*
				// key, then we should get an identical public
				// key back.
				keyLoc := KeyLocator{
					Family: keyFam,
					Index:  0,
				}
				firstKeyDesc, err := keyRing.DeriveKey(keyLoc)
				if err != nil {
					t.Fatalf("unable to derive first key for "+
						"keyFam=%v: %v", keyFam, err)
				}

				if !keyDesc.PubKey.IsEqual(firstKeyDesc.PubKey) {
					t.Fatalf("mismatched keys: expected %v, "+
						"got %x",
						keyDesc.PubKey.SerializeCompressed(),
						firstKeyDesc.PubKey.SerializeCompressed())
				}

				// If this succeeds, then we'll also try to
				// derive a random index within the range.
				randKeyIndex := uint32(rand.Int31())
				keyLoc = KeyLocator{
					Family: keyFam,
					Index:  randKeyIndex,
				}
				_, err = keyRing.DeriveKey(keyLoc)
				if err != nil {
					t.Fatalf("unable to derive key_index=%v "+
						"for keyFam=%v: %v",
						randKeyIndex, keyFam, err)
				}
			}
		})
		if !success {
			break
		}
	}
}

// secretKeyRingConstructor is a function signature that's used as a generic
// constructor for various implementations of the SecretKeyRing interface. A
// string naming the returned interface, a function closure that cleans up any
// resources, and the clean up interface itself are to be returned.
type secretKeyRingConstructor func() (string, func(), SecretKeyRing, error)

// TestSecretKeyRingDerivation tests that each known SecretKeyRing
// implementation properly adheres to the expected behavior of the set of
// interface.
func TestSecretKeyRingDerivation(t *testing.T) {
	t.Parallel()

	secretKeyRingImplementations := []secretKeyRingConstructor{
		func() (string, func(), SecretKeyRing, error) {
			cleanUp, wallet, err := createTestBtcWallet()
			if err != nil {
				t.Fatalf("unable to create wallet: %v", err)
			}

			keyRing := NewBtcWalletKeyRing(wallet)

			return "btcwallet", cleanUp, keyRing, nil
		},
	}

	// For each implementation constructor registered above, we'll execute
	// an identical set of tests in order to ensure that the interface
	// adheres to our nominal specification.
	for _, secretKeyRingConstructor := range secretKeyRingImplementations {
		keyRingName, cleanUp, secretKeyRing, err := secretKeyRingConstructor()
		if err != nil {
			t.Fatalf("unable to create secret key ring %v: %v",
				keyRingName, err)
		}
		defer cleanUp()

		success := t.Run(fmt.Sprintf("%v", keyRingName), func(t *testing.T) {
			// First, each key family, we'll ensure that we're able
			// to obtain the private key of a randomly select child
			// index within the key family.
			for _, keyFam := range versionZeroKeyFamilies {
				randKeyIndex := uint32(rand.Int31())
				keyLoc := KeyLocator{
					Family: keyFam,
					Index:  randKeyIndex,
				}

				// First, we'll query for the public key for
				// this target key locator.
				pubKeyDesc, err := secretKeyRing.DeriveKey(keyLoc)
				if err != nil {
					t.Fatalf("unable to derive pubkey "+
						"(fam=%v, index=%v): %v",
						keyLoc.Family,
						keyLoc.Index, err)
				}

				// With the public key derive, ensure that
				// we're able to obtain the corresponding
				// private key correctly.
				privKey, err := secretKeyRing.DerivePrivKey(KeyDescriptor{
					KeyLocator: keyLoc,
				})
				if err != nil {
					t.Fatalf("unable to derive priv "+
						"(fam=%v, index=%v): %v", keyLoc.Family,
						keyLoc.Index, err)
				}

				// Finally, ensure that the keys match up
				// properly.
				if !pubKeyDesc.PubKey.IsEqual(privKey.PubKey()) {
					t.Fatalf("pubkeys mismatched: expected %x, got %x",
						pubKeyDesc.PubKey.SerializeCompressed(),
						privKey.PubKey().SerializeCompressed())
				}

				// TODO(roasbeef): scalar mult once integrated
			}
		})
		if !success {
			break
		}
	}
}