Feature/search after before on (#9219)

* initial implementation of after, before, on search flags allowing to restrict the search to a specific day or a date range

* missed setting beforeDate in SearchParams in one place

* fixed condition when only flags are used for search without any plain terms

* changed date format used for after/before/on flags to be in ISO8601 format as suggested in PR comments, added a helper function to pad month and day with zeroes allowing the user user either format, with or without leading zeroes

* corrected expected compare to date setting for the TestParseDateFilterToTimeISO8601 test

* fixed a bug for the scenario when you only have the date flags without any terms, added a couple of tests for that scenario

* updated the date filter logic to use parameters to construct the query instead of simply appending strings together, as suggested in the pull request comments

* added search unit test using date flags

* added a helper function to create a test post with a createat date manually set, updated the test for search using date flags to create test posts with different createat dates to be able to better test the functionality

* MM-11817 Add support for after/before/on search flags with Elasticsearch

* add support to search posts to perform the search in context of the client's timezone when filtering by createat date using on: after: before: flags

* updated tests to match the new signature

store/sqlstore/post_store.go

@@ -783,7 +783,7 @@ func (s *SqlPostStore) Search(teamId string, userId string, params *model.Search
 		termMap := map[string]bool{}
 		terms := params.Terms
 
-		if terms == "" && len(params.InChannels) == 0 && len(params.FromUsers) == 0 {
+		if terms == "" && len(params.InChannels) == 0 && len(params.FromUsers) == 0 && len(params.OnDate) == 0 && len(params.AfterDate) == 0 && len(params.BeforeDate) == 0 {
 			result.Data = []*model.Post{}
 			return
 		}
@@ -829,6 +829,7 @@ func (s *SqlPostStore) Search(teamId string, userId string, params *model.Search
 							AND UserId = :UserId
 							` + deletedQueryPart + `
 							CHANNEL_FILTER)
+				CREATEDATE_CLAUSE							
 				SEARCH_CLAUSE
 				ORDER BY CreateAt DESC
 			LIMIT 100`
@@ -889,6 +890,41 @@ func (s *SqlPostStore) Search(teamId string, userId string, params *model.Search
 			searchQuery = strings.Replace(searchQuery, "POST_FILTER", "", 1)
 		}
 
+		// handle after: before: on: filters
+		if len(params.AfterDate) > 1 || len(params.BeforeDate) > 1 || len(params.OnDate) > 1 {
+			if len(params.OnDate) > 1 {
+				onDateStart, onDateEnd := params.GetOnDateMillis()
+				queryParams["OnDateStart"] = strconv.FormatInt(onDateStart, 10)
+				queryParams["OnDateEnd"] = strconv.FormatInt(onDateEnd, 10)
+
+				// between `on date` start of day and end of day
+				searchQuery = strings.Replace(searchQuery, "CREATEDATE_CLAUSE", "AND CreateAt BETWEEN :OnDateStart AND :OnDateEnd ", 1)
+			} else if len(params.AfterDate) > 1 && len(params.BeforeDate) > 1 {
+				afterDate := params.GetAfterDateMillis()
+				beforeDate := params.GetBeforeDateMillis()
+				queryParams["OnDateStart"] = strconv.FormatInt(afterDate, 10)
+				queryParams["OnDateEnd"] = strconv.FormatInt(beforeDate, 10)
+
+				// between clause
+				searchQuery = strings.Replace(searchQuery, "CREATEDATE_CLAUSE", "AND CreateAt BETWEEN :OnDateStart AND :OnDateEnd ", 1)
+			} else if len(params.AfterDate) > 1 {
+				afterDate := params.GetAfterDateMillis()
+				queryParams["AfterDate"] = strconv.FormatInt(afterDate, 10)
+
+				// greater than `after date`
+				searchQuery = strings.Replace(searchQuery, "CREATEDATE_CLAUSE", "AND CreateAt >= :AfterDate ", 1)
+			} else if len(params.BeforeDate) > 1 {
+				beforeDate := params.GetBeforeDateMillis()
+				queryParams["BeforeDate"] = strconv.FormatInt(beforeDate, 10)
+
+				// less than `before date`
+				searchQuery = strings.Replace(searchQuery, "CREATEDATE_CLAUSE", "AND CreateAt <= :BeforeDate ", 1)
+			}
+		} else {
+			// no create date filters set
+			searchQuery = strings.Replace(searchQuery, "CREATEDATE_CLAUSE", "", 1)
+		}
+
 		if terms == "" {
 			// we've already confirmed that we have a channel or user to search for
 			searchQuery = strings.Replace(searchQuery, "SEARCH_CLAUSE", "", 1)