feat: Add support for finding the log event that's closest to a target timestamp.

src/clp_ffi_js/ir/StreamReader.cpp

@@ -145,7 +145,11 @@ EMSCRIPTEN_BINDINGS(ClpStreamReader) {
             )
             .function("filterLogEvents", &clp_ffi_js::ir::StreamReader::filter_log_events)
             .function("deserializeStream", &clp_ffi_js::ir::StreamReader::deserialize_stream)
-            .function("decodeRange", &clp_ffi_js::ir::StreamReader::decode_range);
+            .function("decodeRange", &clp_ffi_js::ir::StreamReader::decode_range)
+            .function(
+                    "getLogEventIndexByTimestamp",
+                    &clp_ffi_js::ir::StreamReader::find_timestamp_last_occurrence
+            );
 }
 }  // namespace
 

src/clp_ffi_js/ir/StreamReader.hpp

@@ -5,6 +5,7 @@
 #include <concepts>
 #include <cstddef>
 #include <cstdint>
+#include <ir/types.hpp>
 #include <memory>
 #include <optional>
 #include <string>
@@ -124,6 +125,10 @@ class StreamReader {
     [[nodiscard]] virtual auto decode_range(size_t begin_idx, size_t end_idx, bool use_filter) const
             -> DecodedResultsTsType = 0;
 
+    [[nodiscard]] virtual auto find_timestamp_last_occurrence(
+            clp::ir::epoch_time_ms_t input_timestamp
+    ) -> std::ptrdiff_t = 0;
+
 protected:
     explicit StreamReader() = default;
 

src/clp_ffi_js/ir/StructuredIrStreamReader.cpp

@@ -147,6 +147,30 @@ auto StructuredIrStreamReader::decode_range(size_t begin_idx, size_t end_idx, bo
     );
 }
 
+auto StructuredIrStreamReader::find_timestamp_last_occurrence(
+        clp::ir::epoch_time_ms_t input_timestamp
+) -> std::ptrdiff_t {
+    // Use std::lower_bound with a custom comparator
+    auto it = std::lower_bound(
+            m_deserialized_log_events->begin(),
+            m_deserialized_log_events->end(),
+            input_timestamp,
+            [](const LogEventWithFilterData<StructuredLogEvent>& event, clp::ir::epoch_time_ms_t timestamp) {
+                return event.get_timestamp() <= timestamp;
+            }
+    );
+
+    // Adjust the iterator to find the last valid index
+    if (it == m_deserialized_log_events->end() || it->get_timestamp() > input_timestamp) {
+        if (it == m_deserialized_log_events->begin()) {
+            return -1;  // No element satisfies the condition
+        }
+        --it;
+    }
+
+    return std::distance(m_deserialized_log_events->begin(), it);
+}
+
 StructuredIrStreamReader::StructuredIrStreamReader(
         StreamReaderDataContext<StructuredIrDeserializer>&& stream_reader_data_context,
         std::shared_ptr<StructuredLogEvents> deserialized_log_events

src/clp_ffi_js/ir/StructuredIrStreamReader.hpp

@@ -74,6 +74,9 @@ class StructuredIrStreamReader : public StreamReader {
     [[nodiscard]] auto decode_range(size_t begin_idx, size_t end_idx, bool use_filter) const
             -> DecodedResultsTsType override;
 
+    [[nodiscard]] auto find_timestamp_last_occurrence(clp::ir::epoch_time_ms_t input_timestamp
+    ) -> std::ptrdiff_t override;
+
 private:
     // Constructor
     explicit StructuredIrStreamReader(

src/clp_ffi_js/ir/UnstructuredIrStreamReader.cpp

@@ -158,6 +158,29 @@ auto UnstructuredIrStreamReader::decode_range(size_t begin_idx, size_t end_idx,
     );
 }
 
+auto UnstructuredIrStreamReader::find_timestamp_last_occurrence(
+        clp::ir::epoch_time_ms_t input_timestamp
+) -> std::ptrdiff_t {
+    // Use std::lower_bound with a custom comparator
+    auto it = std::lower_bound(
+            m_encoded_log_events.begin(),
+            m_encoded_log_events.end(),
+            input_timestamp,
+            [](LogEventWithFilterData<UnstructuredLogEvent> const& event,
+               clp::ir::epoch_time_ms_t timestamp) { return event.get_timestamp() <= timestamp; }
+    );
+
+    // Adjust the iterator to find the last valid index
+    if (it == m_encoded_log_events.end() || it->get_timestamp() > input_timestamp) {
+        if (it == m_encoded_log_events.begin()) {
+            return -1;  // No element satisfies the condition
+        }
+        --it;
+    }
+
+    return std::distance(m_encoded_log_events.begin(), it);
+}
+
 UnstructuredIrStreamReader::UnstructuredIrStreamReader(
         StreamReaderDataContext<UnstructuredIrDeserializer>&& stream_reader_data_context
 )

src/clp_ffi_js/ir/UnstructuredIrStreamReader.hpp

@@ -71,6 +71,9 @@ class UnstructuredIrStreamReader : public StreamReader {
     [[nodiscard]] auto decode_range(size_t begin_idx, size_t end_idx, bool use_filter) const
             -> DecodedResultsTsType override;
 
+    [[nodiscard]] auto find_timestamp_last_occurrence(clp::ir::epoch_time_ms_t input_timestamp
+    ) -> std::ptrdiff_t override;
+
 private:
     // Constructor
     explicit UnstructuredIrStreamReader(