Set timestamp on time-filter output file

If the input file has a timestamp set in the header and the specified *TO-TIME*
is before that timestamp in the header, the header of the output file will have
the timestamp set to the *TO-TIME* (or *TO-TIME* minus one second if a
*FROM-TIME* was also set).

See #285

Author: joto

man/osmium-time-filter.md

@@ -29,6 +29,10 @@ This commands reads its input file only once and writes its output file
 in one go so it can be streamed, ie. it can read from STDIN and write to
 STDOUT.
 
+If the input file has a timestamp set in the header and the specified *TO-TIME*
+is before that timestamp in the header, the header of the output file will have
+the timestamp set to the *TO-TIME* (or *TO-TIME* minus one second if a
+*FROM-TIME* was also set).
 
 @MAN_COMMON_OPTIONS@
 @MAN_PROGRESS_OPTIONS@

src/command_time_filter.cpp

@@ -134,6 +134,19 @@ bool CommandTimeFilter::run() {
 
     m_vout << "Opening output file...\n";
     osmium::io::Header header{reader.header()};
+    try {
+        osmium::Timestamp const input_timestamp{header.get("osmosis_replication_timestamp")};
+        if (input_timestamp.valid() && input_timestamp >= m_to) {
+            auto ts = m_to;
+            if (m_from != m_to) {
+                ts -= 1;
+            }
+            m_vout << "Set output timestamp to " << ts.to_iso() << "\n";
+            header.set("osmosis_replication_timestamp", ts.to_iso());
+        }
+    } catch (const std::invalid_argument&) { // NOLINT(bugprone-empty-catch)
+        // Ignore unset or invalid timestamp from input file
+    }
     setup_header(header);
 
     osmium::io::Writer writer{m_output_file, header, m_output_overwrite, m_fsync};