From 85c6ca0e5f97ef744364892b42fc8cdb941af302 Mon Sep 17 00:00:00 2001
From: gillespi314 <73313222+gillespi314@users.noreply.github.com>
Date: Wed, 25 May 2022 10:54:56 -0500
Subject: [PATCH] Improve precision in reporting of unseen hosts via host
 status webhook automations (#5889)

---
 changes/issue-5614-timestamp         |  1 +
 server/datastore/mysql/hosts.go      |  9 +++++++--
 server/datastore/mysql/hosts_test.go | 18 ++++++++++++++++++
 3 files changed, 26 insertions(+), 2 deletions(-)
 create mode 100644 changes/issue-5614-timestamp

diff --git a/changes/issue-5614-timestamp b/changes/issue-5614-timestamp
new file mode 100644
index 0000000000..71cbe9f904
--- /dev/null
+++ b/changes/issue-5614-timestamp
@@ -0,0 +1 @@
+- Switched from `DATEDIFF` to `TIMESTAMPDIFF` to improve precision when calculating unseen hosts reported by host status webhook
diff --git a/server/datastore/mysql/hosts.go b/server/datastore/mysql/hosts.go
index eb53ed851b..124dc21c91 100644
--- a/server/datastore/mysql/hosts.go
+++ b/server/datastore/mysql/hosts.go
@@ -981,15 +981,20 @@ func (ds *Datastore) TotalAndUnseenHostsSince(ctx context.Context, daysCount int
 		Total  int `db:"total"`
 		Unseen int `db:"unseen"`
 	}
+
+	// convert daysCount to integer number of seconds for more precision in sql query
+	unseenSeconds := daysCount * 24 * 60 * 60
+
 	err = sqlx.GetContext(ctx, ds.reader, &counts,
 		`SELECT
 			COUNT(*) as total,
-			SUM(IF(DATEDIFF(CURRENT_DATE, COALESCE(hst.seen_time, h.created_at)) >= ?, 1, 0)) as unseen
+			SUM(IF(TIMESTAMPDIFF(SECOND, COALESCE(hst.seen_time, h.created_at), CURRENT_TIMESTAMP) >= ?, 1, 0)) as unseen
 		FROM hosts h
 		LEFT JOIN host_seen_times hst
 		ON h.id = hst.host_id`,
-		daysCount,
+		unseenSeconds,
 	)
+
 	if err != nil {
 		return 0, 0, ctxerr.Wrap(ctx, err, "getting total and unseen host counts")
 	}
diff --git a/server/datastore/mysql/hosts_test.go b/server/datastore/mysql/hosts_test.go
index 06f691578f..ec236a5ea0 100644
--- a/server/datastore/mysql/hosts_test.go
+++ b/server/datastore/mysql/hosts_test.go
@@ -1815,6 +1815,24 @@ func testHostsTotalAndUnseenSince(t *testing.T, ds *Datastore) {
 	require.NoError(t, err)
 	assert.Equal(t, 3, total)
 	assert.Equal(t, 2, unseen)
+
+	// host not counted as unseen if less than a full 24 hours has passed
+	_, err = ds.writer.ExecContext(context.Background(), `UPDATE host_seen_times SET seen_time = ? WHERE host_id = 2`, time.Now().Add(-1*time.Duration(1)*86399*time.Second))
+	require.NoError(t, err)
+
+	total, unseen, err = ds.TotalAndUnseenHostsSince(context.Background(), 1)
+	require.NoError(t, err)
+	assert.Equal(t, 3, total)
+	assert.Equal(t, 1, unseen)
+
+	// host counted as unseen if more than 24 hours has passed
+	_, err = ds.writer.ExecContext(context.Background(), `UPDATE host_seen_times SET seen_time = ? WHERE host_id = 2`, time.Now().Add(-1*time.Duration(1)*86401*time.Second))
+	require.NoError(t, err)
+
+	total, unseen, err = ds.TotalAndUnseenHostsSince(context.Background(), 1)
+	require.NoError(t, err)
+	assert.Equal(t, 3, total)
+	assert.Equal(t, 2, unseen)
 }
 
 func testHostsListByPolicy(t *testing.T, ds *Datastore) {