From 33c1e2562a08224120fe7309ba4fb8ff4da95594 Mon Sep 17 00:00:00 2001
From: Bruno Andreghetti <brunoandreghetti@gmail.com>
Date: Mon, 7 Jun 2021 08:39:59 -0300
Subject: [PATCH] Implement target time in getHistory tx

---
 transactions/readAssetHistory.go | 73 ++++++++++++++++++++++++--------
 1 file changed, 55 insertions(+), 18 deletions(-)

diff --git a/transactions/readAssetHistory.go b/transactions/readAssetHistory.go
index e7d127b..25e5c16 100644
--- a/transactions/readAssetHistory.go
+++ b/transactions/readAssetHistory.go
@@ -24,11 +24,17 @@ var ReadAssetHistory = Transaction{
 			DataType:    "@key",
 			Required:    true,
 		},
+		{
+			Tag:         "timeTarget",
+			Description: "Optional parameter to retrieve specific version of the asset.",
+			DataType:    "datetime",
+		},
 	},
 	ReadOnly: true,
 	Routine: func(stub shim.ChaincodeStubInterface, req map[string]interface{}) ([]byte, errors.ICCError) {
 		// This is safe to do because validation is done before calling routine
 		key := req["key"].(assets.Key)
+		timeTarget := req["timeTarget"]
 
 		// Get asset's history from blockchain
 		historyIterator, err := stub.GetHistoryForKey(key.Key())
@@ -44,33 +50,64 @@ var ReadAssetHistory = Transaction{
 			return nil, errors.NewCCError("history not found", 404)
 		}
 
-		response := make([]map[string]interface{}, 0)
+		if timeTarget == nil {
+			response := make([]map[string]interface{}, 0)
+			for historyIterator.HasNext() {
+				queryResponse, err := historyIterator.Next()
+				if err != nil {
+					return nil, errors.WrapError(err, "error iterating response")
+				}
+
+				data := make(map[string]interface{})
 
-		for historyIterator.HasNext() {
-			queryResponse, err := historyIterator.Next()
+				if queryResponse.IsDelete {
+					data["_isDelete"] = queryResponse.IsDelete
+				} else {
+					err = json.Unmarshal(queryResponse.Value, &data)
+					if err != nil {
+						return nil, errors.WrapError(err, "failed to unmarshal queryResponse's values")
+					}
+				}
+				data["_timestamp"] = time.Unix(queryResponse.Timestamp.Seconds, int64(queryResponse.Timestamp.Nanos)).Format(time.RFC3339)
+				response = append(response, data)
+			}
+			responseJSON, err := json.Marshal(response)
 			if err != nil {
-				return nil, errors.WrapError(err, "error iterating response")
+				return nil, errors.WrapError(err, "error marshaling response")
 			}
 
-			data := make(map[string]interface{})
+			return responseJSON, nil
+		} else {
+			response := make(map[string]interface{})
+			target := timeTarget.(time.Time)
+			closestTime := time.Time{}
 
-			if queryResponse.IsDelete {
-				data["_isDelete"] = queryResponse.IsDelete
-			} else {
-				err = json.Unmarshal(queryResponse.Value, &data)
+			for historyIterator.HasNext() {
+				queryResponse, err := historyIterator.Next()
 				if err != nil {
-					return nil, errors.WrapError(err, "failed to unmarshal queryResponse's values")
+					return nil, errors.WrapError(err, "error iterating response")
+				}
+
+				timestamp := queryResponse.Timestamp.AsTime()
+				if timestamp.Before(target) && timestamp.After(closestTime) {
+					closestTime = timestamp
+					if !queryResponse.IsDelete {
+						err = json.Unmarshal(queryResponse.Value, &response)
+						if err != nil {
+							return nil, errors.WrapError(err, "failed to unmarshal queryResponse's values")
+						}
+					}
+					response["_isDelete"] = queryResponse.IsDelete
+					response["_timestamp"] = timestamp.Format(time.RFC3339)
 				}
 			}
-			data["_timestamp"] = time.Unix(queryResponse.Timestamp.Seconds, int64(queryResponse.Timestamp.Nanos)).Format(time.RFC3339)
-			response = append(response, data)
-		}
 
-		responseJSON, err := json.Marshal(response)
-		if err != nil {
-			return nil, errors.WrapError(err, "error marshaling response")
-		}
+			responseJSON, err := json.Marshal(response)
+			if err != nil {
+				return nil, errors.WrapError(err, "error marshaling response")
+			}
 
-		return responseJSON, nil
+			return responseJSON, nil
+		}
 	},
 }