From e5aec3a726e76277b72f910b5409013fd7967d93 Mon Sep 17 00:00:00 2001
From: Chris Hager <chris@linuxuser.at>
Date: Thu, 21 Nov 2024 20:48:51 +0100
Subject: [PATCH] Log events: allow custom timestamps

---
 README.md                | 27 ++++++++++++++++++++++++---
 systemapi/server.go      | 19 +++++++++++++++++++
 systemapi/server_test.go | 31 ++++++++++++++++++++++++++++++-
 3 files changed, 73 insertions(+), 4 deletions(-)

diff --git a/README.md b/README.md
index fe1320b..3ac1f16 100644
--- a/README.md
+++ b/README.md
@@ -63,10 +63,31 @@ $ curl localhost:3535/logs
 2024-10-23T12:04:07Z     this is a test
 ```
 
- ## Actions
+#### Event timestamps
 
- Actions are shell commands that can be executed via API. The commands are defined in the config file,
- see [systemapi-config.toml](./systemapi-config.toml) for examples.
+By default, events are timestamped with the current time. However, the timestamp can be overridden by
+providing a valid unix timestamp (in seconds or milliseconds) as first part of the message:
+
+```bash
+# Start the server
+$ go run cmd/system-api/main.go
+
+# Add regular event
+$ echo "hello world" > pipe.fifo
+
+# Add event with custom timestamp
+$ echo "1634966400 this is a test" > pipe.fifo
+
+# Query events
+$ curl localhost:3535/logs
+2024-11-21T19:48:04Z     hello world
+2021-10-23T05:20:00Z     this is a test          <--- custom timestamp on this entry
+```
+
+## Actions
+
+Actions are shell commands that can be executed via API. The commands are defined in the config file,
+see [systemapi-config.toml](./systemapi-config.toml) for examples.
 
 Actions are recorded in the event log.
 
diff --git a/systemapi/server.go b/systemapi/server.go
index c4d5ccf..39b6177 100644
--- a/systemapi/server.go
+++ b/systemapi/server.go
@@ -12,6 +12,7 @@ import (
 	"io"
 	"net/http"
 	"os"
+	"strconv"
 	"strings"
 	"sync"
 	"syscall"
@@ -205,6 +206,24 @@ func (s *Server) handleLivenessCheck(w http.ResponseWriter, r *http.Request) {
 func (s *Server) addEvent(event Event) {
 	// Add event to the list and prune if necessary
 	s.eventsLock.Lock()
+
+	// check for replacement timestamp. if the first part of the message is a timestamp, use it
+	// instead of the current time. must be a number to be a timestamp (10 characters for seconds, 13 for milliseconds)
+	eventMsg := event.Message
+	timestampStr := strings.Fields(eventMsg)[0]
+	timeInt, err := strconv.ParseInt(timestampStr, 10, 64)
+	if err == nil {
+		if len(timestampStr) == 10 {
+			// timestamp in seconds, update event
+			event.ReceivedAt = time.Unix(timeInt, 0).UTC()
+			event.Message = strings.TrimSpace(eventMsg[len(timestampStr):])
+		} else if len(timestampStr) == 13 {
+			// timestamp in milliseconds, update event
+			event.ReceivedAt = time.UnixMilli(timeInt).UTC()
+			event.Message = strings.TrimSpace(eventMsg[len(timestampStr):])
+		}
+	}
+
 	s.events = append(s.events, event)
 	if len(s.events) > s.cfg.General.LogMaxEntries {
 		s.events = s.events[1:]
diff --git a/systemapi/server_test.go b/systemapi/server_test.go
index 5db1622..0529add 100644
--- a/systemapi/server_test.go
+++ b/systemapi/server_test.go
@@ -156,7 +156,7 @@ func TestBasicAuth(t *testing.T) {
 }
 
 func TestMaxEntries(t *testing.T) {
-	// Verify maximum number of log entries is working correctly
+	// Ensure maximum number of log entries is working correctly
 	maxEntries := 5
 
 	cfg := NewConfig()
@@ -177,3 +177,32 @@ func TestMaxEntries(t *testing.T) {
 	require.Equal(t, "4", srv.events[3].Message)
 	require.Equal(t, "5", srv.events[4].Message)
 }
+
+func TestAddEntryTimestampParsing(t *testing.T) {
+	// Ensure that messages with timestamps are correctly parsed
+	srv := newTestServer(t)
+
+	testTime1 := time.Date(2021, 1, 2, 3, 4, 5, 0, time.UTC)
+	testTime2 := time.Date(2022, 1, 2, 3, 4, 6, 0, time.UTC)
+	testTime2TimestampSec := testTime2.Unix()
+	testTime2TimestampMs := testTime2.UnixMilli()
+
+	// Add regular message
+	srv.addEvent(Event{ReceivedAt: testTime1, Message: "1"})
+
+	// Add message with timestamp prefix
+	srv.addEvent(Event{ReceivedAt: testTime1, Message: fmt.Sprintf("%d 2", testTime2TimestampSec)})
+	srv.addEvent(Event{ReceivedAt: testTime1, Message: fmt.Sprintf("%d 3", testTime2TimestampMs)})
+
+	// Check entry 1 (regular message)
+	require.Equal(t, "1", srv.events[0].Message)
+	require.Equal(t, testTime1, srv.events[0].ReceivedAt)
+
+	// Check entry 2 (timestamp in seconds)
+	require.Equal(t, "2", srv.events[1].Message)
+	require.Equal(t, testTime2, srv.events[1].ReceivedAt)
+
+	// Check entry 3 (timestamp in milliseconds)
+	require.Equal(t, "3", srv.events[2].Message)
+	require.Equal(t, testTime2, srv.events[2].ReceivedAt)
+}