initial runs

include/file_reader.hpp

@@ -0,0 +1,22 @@
+#pragma once
+#include "record.hpp"
+#include <fstream>
+#include <optional>
+#include <span>
+
+class FileReader {
+private:
+    std::ifstream stream_;
+    std::vector<Record> buffer_;
+    size_t current_pos_;
+    size_t valid_items_;
+    size_t total_reads_;
+
+    void refill_buffer();
+
+public:
+    FileReader(const std::string& filename, size_t buffer_size = 8);
+    std::optional<Record> read();
+    size_t read_chunk(std::span<Record>& chunk);
+    size_t total_reads() const;
+};