Merge pull request #78 from coinbase/patrick/intent-parser

Compare Intent vs Observed Operations and Signers

parser/intent.go

@@ -0,0 +1,154 @@
+// Copyright 2020 Coinbase, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package parser
+
+import (
+	"fmt"
+	"log"
+
+	"github.com/coinbase/rosetta-sdk-go/asserter"
+	"github.com/coinbase/rosetta-sdk-go/types"
+)
+
+// ExpectedOperation returns an error if an observed operation
+// differs from the intended operation. An operation is considered
+// to be different from the intent if the AccountIdentifier,
+// Amount, or Type has changed.
+func ExpectedOperation(intent *types.Operation, observed *types.Operation) error {
+	if types.Hash(intent.Account) != types.Hash(observed.Account) {
+		return fmt.Errorf(
+			"intended account %s did not match observed account %s",
+			types.PrettyPrintStruct(intent.Account),
+			types.PrettyPrintStruct(observed.Account),
+		)
+	}
+
+	if types.Hash(intent.Amount) != types.Hash(observed.Amount) {
+		return fmt.Errorf(
+			"intended amount %s did not match observed amount %s",
+			types.PrettyPrintStruct(intent.Amount),
+			types.PrettyPrintStruct(observed.Amount),
+		)
+	}
+
+	if intent.Type != observed.Type {
+		return fmt.Errorf(
+			"intended type %s did not match observed type %s",
+			intent.Type,
+			observed.Type,
+		)
+	}
+
+	return nil
+}
+
+// ExpectedOperations returns an error if a slice of intended
+// operations differ from observed operations. Optionally,
+// it is possible to error if any extra observed opertions
+// are found.
+func ExpectedOperations(
+	intent []*types.Operation,
+	observed []*types.Operation,
+	errExtra bool,
+) error {
+	matches := make(map[int]struct{})
+	unmatched := []*types.Operation{}
+
+	for _, obs := range observed {
+		foundMatch := false
+		for i, in := range intent {
+			if _, exists := matches[i]; exists {
+				continue
+			}
+
+			if ExpectedOperation(in, obs) == nil {
+				matches[i] = struct{}{}
+				foundMatch = true
+				break
+			}
+		}
+
+		if !foundMatch {
+			if errExtra {
+				return fmt.Errorf(
+					"found extra operation %s",
+					types.PrettyPrintStruct(obs),
+				)
+			}
+			unmatched = append(unmatched, obs)
+		}
+	}
+
+	for i := 0; i < len(intent); i++ {
+		if _, exists := matches[i]; !exists {
+			return fmt.Errorf(
+				"could not find operation with intent %s in observed",
+				types.PrettyPrintStruct(intent[i]),
+			)
+		}
+	}
+
+	if len(unmatched) > 0 {
+		log.Printf("found extra operations: %s\n", types.PrettyPrintStruct(unmatched))
+	}
+
+	return nil
+}
+
+// ExpectedSigners returns an error if a slice of SigningPayload
+// has different signers than what was observed (typically populated
+// using the signers returned from parsing a transaction).
+func ExpectedSigners(intent []*types.SigningPayload, observed []string) error {
+	// De-duplicate required signers (ex: multiple UTXOs from same address)
+	intendedSigners := make(map[string]struct{})
+	for _, payload := range intent {
+		intendedSigners[payload.Address] = struct{}{}
+	}
+
+	if err := asserter.StringArray("observed signers", observed); err != nil {
+		return fmt.Errorf("%w: found duplicate signer", err)
+	}
+
+	// Could exist here if len(intent) != len(observed) but
+	// more useful to print out a detailed error message.
+	seenSigners := make(map[string]struct{})
+	unmatched := []string{} // observed
+	for _, signer := range observed {
+		_, exists := intendedSigners[signer]
+		if !exists {
+			unmatched = append(unmatched, signer)
+		} else {
+			seenSigners[signer] = struct{}{}
+		}
+	}
+
+	for k := range intendedSigners {
+		if _, exists := seenSigners[k]; !exists {
+			return fmt.Errorf(
+				"could not find match for intended signer %s",
+				k,
+			)
+		}
+	}
+
+	if len(unmatched) != 0 {
+		return fmt.Errorf(
+			"found unexpected signers: %s",
+			types.PrettyPrintStruct(unmatched),
+		)
+	}
+
+	return nil
+}