[FEATURE] Merkle Airdrop

examples/gno.land/p/demo/airdrop/airdrop.gno

@@ -0,0 +1,6 @@
+package airdrop
+
+type Airdrop interface {
+	Claim(amount uint64, proof []string)
+	TotalClaimed() uint64
+}

examples/gno.land/p/demo/airdrop/airdrop_test.gno

@@ -0,0 +1,103 @@
+package airdrop
+
+import (
+	"std"
+	"testing"
+
+	"gno.land/p/demo/grc/grc20"
+	"gno.land/p/demo/merkle"
+	"gno.land/r/demo/foo20"
+	"gno.land/r/demo/users"
+)
+
+var leaves []merkle.Hashable = []AirdropData{
+	{
+		Address: "g1qhuef2450xh7g7na8s865nreu2xw8j84kgkvt5",
+		Amount:  10000,
+	},
+	{
+		Address: "g1zyvskpxg5lv4qpygtuvp93zprrrjpk2exa9rfx",
+		Amount:  10000,
+	},
+	{
+		Address: "g14szvkruznx49sxe4m9dmg3m8606sm6yp4a0wv8",
+		Amount:  10000,
+	},
+}
+
+func TestRegisterMerkle(t *testing.T) {
+	tree := merkle.NewTree(leaves)
+	root := tree.Root()
+	contractAddr := std.DerivePkgAddr("gno.land/r/demo/tok20-airdrop")
+
+	token := grc20.NewAdminToken("TOKEN", "TOK", 6)
+	token.Mint(contractAddr, 50000) // Airdrop contract
+
+	tok20airdrop := NewMerkleAirdrop(root, token.GRC20())
+}
+
+func TestClaimAirdrop(t *testing.T) {
+	contractAddr := std.DerivePkgAddr("gno.land/r/demo/tok20-airdrop")
+	std.TestSetOrigCaller(contractAddr)
+
+	// instantiate foo20 airdrop contract
+	tree := merkle.NewTree(leaves)
+	root := tree.Root()
+
+	token := grc20.NewAdminToken("TOKEN", "TOK", 6)
+	token.Mint(contractAddr, 50_000) // Airdrop contract
+
+	tok20airdrop := NewMerkleAirdrop(root, token.GRC20())
+
+	sumClaimed := uint64(0)
+	for _, leaf := range leaves {
+		data := leaf.(AirdropData)
+
+		proof, err := tree.Proof(leaf)
+		if err != nil {
+			t.Fatalf("failed to generate proof, %v", err)
+			return
+		}
+
+		// claim airdrop
+		err = tok20airdrop.Claim(data, proof)
+		if err != nil {
+			t.Fatalf("error: Claim: got %s", err.Error())
+		}
+
+		sumClaimed += data.Amount
+	}
+
+	ttClaimed := tok20airdrop.TotalClaimed()
+	if ttClaimed != sumClaimed {
+		t.Fatalf("expected: %d, got: %d", sumClaimed, ttClaimed)
+	}
+}
+
+func TestDoubleClaim(t *testing.T) {
+	contractAddr := std.DerivePkgAddr("gno.land/r/demo/tok20-airdrop")
+	std.TestSetOrigCaller(contractAddr)
+
+	tree := merkle.NewTree(leaves)
+	token := grc20.NewAdminToken("TOKEN", "TOK", 6)
+	token.Mint(contractAddr, 50000)
+
+	tok20airdrop := NewMerkleAirdrop(tree.Root(), token.GRC20())
+
+	leaf := leaves[0]
+	proofs, err := tree.Proof(leaf)
+	if err != nil {
+		t.Fatalf("failed to generate proof, %v", err)
+		return
+	}
+
+	err = tok20airdrop.Claim(leaf.(AirdropData), proofs)
+	if err != nil {
+		t.Fatalf("failed to claim airdrop: %v", err)
+	}
+
+	err = tok20airdrop.Claim(leaf.(AirdropData), proofs)
+	if err != ErrAlreadyClaimed {
+		t.Fatalf("want: %v, got: %v", ErrAlreadyClaimed, err)
+	}
+}

examples/gno.land/p/demo/airdrop/merkle-airdrop.gno

@@ -0,0 +1,89 @@
+package airdrop
+
+import (
+	"crypto/sha256"
+	"encoding/hex"
+	"fmt"
+	"errors"
+	"std"
+
+	"gno.land/p/demo/avl"
+	"gno.land/p/demo/grc/grc20"
+	"gno.land/p/demo/merkle"
+	"gno.land/r/demo/users"
+)
+
+var (
+	ErrAlreadyClaimed = errors.New("already claimed")
+	ErrInvalidProof = errors.New("invalid merkle proof")
+)
+
+type AirdropData struct {
+	Address std.Address
+	// TODO: use std.Coin
+	Amount uint64
+	// Amount std.Coin
+}
+
+func (data AirdropData) Bytes() []byte {
+	// TODO: use binary.Write
+	// var buf bytes.Buffer
+	// binary.Write(&buf, binary.BigEndian, d)
+	// return buf.Bytes()
+	// OR: use json.Marshal for frontend compatibilities
+
+	s := fmt.Sprintf("%v", data)
+	return []byte(s)
+}
+
+type MerkleAirdrop struct {
+	root string
+
+	token   grc20.IGRC20
+	claimed *avl.Tree
+}
+
+func NewMerkleAirdrop(merkleroot string, token grc20.IGRC20) *MerkleAirdrop {
+	return &MerkleAirdrop{
+		root: merkleroot,
+
+		token:   token,
+		claimed: avl.NewTree(),
+	}
+}
+
+func (ma *MerkleAirdrop) Root() string {
+	return ma.root
+}
+
+func (ma *MerkleAirdrop) Claim(data AirdropData, proofs []merkle.Node) error {
+	shasum := sha256.Sum256(data.Bytes())
+	hash := hex.EncodeToString(shasum[:])
+
+	if ma.claimed.Has(hash) {
+		return ErrAlreadyClaimed
+	}
+
+	if !merkle.Verify(ma.root, data, proofs) {
+		return ErrInvalidProof
+	}
+
+	err := ma.token.Transfer(data.Address, data.Amount)
+	if err != nil {
+		return err
+	}
+
+	ma.claimed.Set(hash, data.Amount)
+	return nil
+}
+
+func (ma MerkleAirdrop) TotalClaimed() uint64 {
+	var claimed uint64 = 0
+
+	ma.claimed.Iterate("", "", func(k string, v interface{}) bool {
+		claimed += v.(uint64)
+		return false
+	})
+
+	return claimed
+}

examples/gno.land/r/demo/foo20-airdrop/airdrop.gno

@@ -0,0 +1,39 @@
+package foo20airdrop
+
+import (
+	"gno.land/p/demo/airdrop"
+	"gno.land/p/demo/grc/grc20"
+	"gno.land/p/demo/merkle"
+	"gno.land/r/demo/foo20"
+)
+
+var (
+	token grc20.IGRC20 = foo20.GRC20()
+
+	// admin std.Address = "g1sw5xklxjjuv0yvuxy5f5s3l3mnj0nqq626a9wr" // albttx.gno
+
+	foo20airdrop *airdrop.MerkleAirdrop
+)
+
+func RegisterMerkleRoot(root string) {
+	if foo20airdrop != nil {
+		panic("foo20 airdrop merkle root is already registered")
+	}
+	foo20airdrop = airdrop.NewMerkleAirdrop(root, token)
+}
+
+func Claim(data airdrop.AirdropData, proofs []merkle.Node) {
+	err := foo20airdrop.Claim(data, proofs)
+	if err != nil {
+		panic(err.Error())
+	}
+}
+
+func TotalClaimed() uint64 {
+	return foo20airdrop.TotalClaimed()
+}
+
+// for tests purpose
+func reset() {
+	foo20airdrop = nil
+}

examples/gno.land/r/demo/foo20-airdrop/airdrop_test.gno

@@ -0,0 +1,65 @@
+package foo20airdrop
+
+import (
+	"std"
+	"testing"
+
+	"gno.land/p/demo/airdrop"
+	"gno.land/p/demo/merkle"
+	"gno.land/r/demo/foo20"
+	"gno.land/r/demo/users"
+)
+
+var leaves []merkle.Hashable = []airdrop.AirdropData{
+	{
+		Address: "g1qhuef2450xh7g7na8s865nreu2xw8j84kgkvt5",
+		Amount:  1_000_000,
+	},
+	{
+		Address: "g1zyvskpxg5lv4qpygtuvp93zprrrjpk2exa9rfx",
+		Amount:  1_000_000,
+	},
+	{
+		Address: "g14szvkruznx49sxe4m9dmg3m8606sm6yp4a0wv8",
+		Amount:  1_000_000,
+	},
+}
+
+func TestRegisterMerkle(t *testing.T) {
+	tree := merkle.NewTree(leaves)
+	root := tree.Root()
+
+	RegisterMerkleRoot(root)
+	reset()
+}
+
+func TestClaimAirdrop(t *testing.T) {
+	contractAddr := std.DerivePkgAddr("gno.land/r/demo/foo20-airdrop")
+	std.TestSetOrigCaller(contractAddr)
+
+	// instantiate foo20 airdrop contract
+	tree := merkle.NewTree(leaves)
+	RegisterMerkleRoot(tree.Root())
+	defer reset()
+
+	sumClaimed := uint64(0)
+	for _, leaf := range leaves {
+		data := leaf.(airdrop.AirdropData)
+		user := data.Address
+		sumClaimed += data.Amount
+
+		proofs, err := tree.Proof(leaf)
+		if err != nil {
+			t.Fatalf("failed to generate proof, %v", err)
+			return
+		}
+
+		// claim airdrop
+		Claim(leaf.(airdrop.AirdropData), proofs)
+	}
+
+	ttClaimed := TotalClaimed()
+	if ttClaimed != sumClaimed {
+		t.Fatalf("expected: %d", sumClaimed)
+	}
+}

examples/gno.land/r/demo/foo20/foo20.gno

@@ -16,15 +16,21 @@ var (
 
 func init() {
 	foo = grc20.NewAdminToken("Foo", "FOO", 4)
-	foo.Mint(admin, 1000000*10000)                                    // @administrator (1M)
-	foo.Mint("g1u7y667z64x2h7vc6fmpcprgey4ck233jaww9zq", 10000*10000) // @manfred (10k)
+	foo.Mint(admin, 10_000_000_000)                                   // @administrator (1M)
+	foo.Mint("g1u7y667z64x2h7vc6fmpcprgey4ck233jaww9zq", 100_000_000) // @manfred (10k)
+	foo.Mint(std.DerivePkgAddr("gno.land/r/demo/foo20-airdrop"), 10_000_000)
+	_ = foo.GRC20()
 }
 
 // method proxies as public functions.
 //
 
 // getters.
 
+func GRC20() grc20.IGRC20 {
+	return foo.GRC20()
+}
+
 func TotalSupply() uint64 {
 	return foo.TotalSupply()
 }

examples/gno.land/r/demo/foo20/foo20_test.gno

@@ -21,7 +21,7 @@ func TestReadOnlyPublicMethods(t *testing.T) {
 	// check balances #1.
 	{
 		tests := []test{
-			{"TotalSupply", 10100000000, func() uint64 { return TotalSupply() }},
+			{"TotalSupply", 10110000000, func() uint64 { return TotalSupply() }},
 			{"BalanceOf(admin)", 10000000000, func() uint64 { return BalanceOf(admin) }},
 			{"BalanceOf(manfred)", 100000000, func() uint64 { return BalanceOf(manfred) }},
 			{"Allowance(admin, manfred)", 0, func() uint64 { return Allowance(admin, manfred) }},
@@ -41,7 +41,7 @@ func TestReadOnlyPublicMethods(t *testing.T) {
 	// check balances #2.
 	{
 		tests := []test{
-			{"TotalSupply", 10110000000, func() uint64 { return TotalSupply() }},
+			{"TotalSupply", 10120000000, func() uint64 { return TotalSupply() }},
 			{"BalanceOf(admin)", 10000000000, func() uint64 { return BalanceOf(admin) }},
 			{"BalanceOf(manfred)", 100000000, func() uint64 { return BalanceOf(manfred) }},
 			{"Allowance(admin, manfred)", 0, func() uint64 { return Allowance(admin, manfred) }},