Reorganize directory structure

pipeline/src/json_handling/json_loader.cpp

@@ -0,0 +1,65 @@
+#include <chrono>
+
+#include <spdlog/spdlog.h>
+
+#include "json_handling/json_loader.h"
+#include "json_handling/stream_parser.h"
+
+void JsonLoader::LoadWorldCities(const std::string &jsonPath,
+                                 SqliteDatabase &db) {
+  constexpr size_t kBatchSize = 10000;
+
+  auto startTime = std::chrono::high_resolution_clock::now();
+  spdlog::info("\nLoading {} (streaming RapidJSON SAX)...", jsonPath);
+
+  db.BeginTransaction();
+  bool transactionOpen = true;
+
+  size_t citiesProcessed = 0;
+  try {
+    StreamingJsonParser::Parse(
+        jsonPath, db,
+        [&](const CityRecord &record) {
+          db.InsertCity(record.id, record.state_id, record.country_id,
+                        record.name, record.latitude, record.longitude);
+          ++citiesProcessed;
+
+          if (citiesProcessed % kBatchSize == 0) {
+            db.CommitTransaction();
+            db.BeginTransaction();
+          }
+        },
+        [&](size_t current, size_t /*total*/) {
+          if (current % kBatchSize == 0 && current > 0) {
+            spdlog::info("  [Progress] Parsed {} cities...", current);
+          }
+        });
+
+    spdlog::info("  OK: Parsed all cities from JSON");
+
+    if (transactionOpen) {
+      db.CommitTransaction();
+      transactionOpen = false;
+    }
+  } catch (...) {
+    if (transactionOpen) {
+      db.CommitTransaction();
+    }
+    throw;
+  }
+
+  auto endTime = std::chrono::high_resolution_clock::now();
+  auto duration = std::chrono::duration_cast<std::chrono::milliseconds>(
+      endTime - startTime);
+
+  spdlog::info("\n=== World City Data Loading Summary ===\n");
+  spdlog::info("Cities inserted: {}", citiesProcessed);
+  spdlog::info("Elapsed time:    {} ms", duration.count());
+  long long throughput =
+      (citiesProcessed > 0 && duration.count() > 0)
+          ? (1000LL * static_cast<long long>(citiesProcessed)) /
+                static_cast<long long>(duration.count())
+          : 0LL;
+  spdlog::info("Throughput:      {} cities/sec", throughput);
+  spdlog::info("=======================================\n");
+}