add ts parsing helper for requests

README.md

@@ -130,6 +130,7 @@ a request does not satisfy the maybeFn logic.
 - `rest.NewErrorLogger` - creates a struct providing shorter form of logger call
 - `rest.FileServer` - creates a file server for static assets with directory listing disabled
 - `realip.Get` - returns client's IP address
+- `rest.ParseFromTo` - parses "from" and "to" request's query params with various formats
 
 ## Profiler
 

rest.go

@@ -5,6 +5,7 @@ import (
 	"bytes"
 	"encoding/json"
 	"net/http"
+	"time"
 
 	"github.com/pkg/errors"
 )
@@ -67,3 +68,33 @@ func renderJSONWithStatus(w http.ResponseWriter, data interface{}, code int) {
 	w.WriteHeader(code)
 	_, _ = w.Write(buf.Bytes())
 }
+
+// ParseFromTo parses from and to query params of the request
+func ParseFromTo(r *http.Request) (from, to time.Time, err error) {
+	parseTimeStamp := func(ts string) (time.Time, error) {
+		formats := []string{
+			"2006-01-02T15:04:05.000000000",
+			"2006-01-02T15:04:05",
+			"2006-01-02T15:04",
+			"20060102",
+			time.RFC3339,
+			time.RFC3339Nano,
+		}
+
+		for _, f := range formats {
+			if t, e := time.Parse(f, ts); e == nil {
+				return t, nil
+			}
+		}
+		return time.Time{}, errors.Errorf("can't parse date %q", ts)
+	}
+
+	if from, err = parseTimeStamp(r.URL.Query().Get("from")); err != nil {
+		return from, to, errors.Wrap(err, "incorrect from time")
+	}
+
+	if to, err = parseTimeStamp(r.URL.Query().Get("to")); err != nil {
+		return from, to, errors.Wrap(err, "incorrect to time")
+	}
+	return from, to, nil
+}

rest_test.go

@@ -5,8 +5,11 @@ import (
 	"io"
 	"net/http"
 	"net/http/httptest"
+	"strconv"
 	"testing"
+	"time"
 
+	"github.com/pkg/errors"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -73,6 +76,53 @@ func TestRest_RenderJSONWithHTML(t *testing.T) {
 	assert.Equal(t, "application/json; charset=utf-8", resp.Header.Get("Content-Type"))
 }
 
+func TestParseFromTo(t *testing.T) {
+
+	tbl := []struct {
+		query    string
+		from, to time.Time
+		err      error
+	}{
+		{
+			query: "from=20220406&to=20220501",
+			from:  time.Date(2022, time.April, 6, 0, 0, 0, 0, time.UTC),
+			to:    time.Date(2022, time.May, 1, 0, 0, 0, 0, time.UTC),
+			err:   nil,
+		},
+		{
+			query: "from=2022-04-06T18:30:25&to=2022-05-01T17:50",
+			from:  time.Date(2022, time.April, 6, 18, 30, 25, 0, time.UTC),
+			to:    time.Date(2022, time.May, 1, 17, 50, 0, 0, time.UTC),
+			err:   nil,
+		},
+		{
+			query: "from=2022-04-06T18:30:25&to=xyzbad",
+			err:   errors.New(`incorrect to time: can't parse date "xyzbad"`),
+		},
+		{
+			query: "from=123455&to=2022-05-01T17:50",
+			err:   errors.New(`incorrect from time: can't parse date "123455"`),
+		},
+		{"", time.Time{}, time.Time{}, errors.New("incorrect from time: can't parse date \"\"")},
+	}
+
+	for i, tt := range tbl {
+		t.Run(strconv.Itoa(i), func(t *testing.T) {
+			req, err := http.NewRequest("GET", "http://localhost?"+tt.query, http.NoBody)
+			require.NoError(t, err)
+			from, to, err := ParseFromTo(req)
+			if tt.err != nil {
+				assert.EqualError(t, err, tt.err.Error())
+				return
+			}
+			require.NoError(t, err)
+			assert.Equal(t, tt.from, from)
+			assert.Equal(t, tt.to, to)
+		})
+	}
+
+}
+
 func getTestHandlerBlah() http.HandlerFunc {
 	fn := func(rw http.ResponseWriter, req *http.Request) {
 		_, _ = rw.Write([]byte("blah"))