feat: Add function to retrieve layer info for a stage

Author: Producdevity

src/utils/getLayerInfoForStage.ts

@@ -0,0 +1,48 @@
+import { TCP_IP_LAYER_NAMES, type TCPIPLayerName } from '@/data'
+
+/**
+ * Up the stack = receiving data (e.g. parsing headers, delivering data to app)
+ * Down the stack = sending data (e.g. wrapping data with headers to send)
+ */
+const layerInfoMap: Record<TCPIPLayerName, { down: string; up: string }> = {
+  [TCP_IP_LAYER_NAMES.application]: {
+    down: 'Application Layer: Creating data payload',
+    up: 'Application Layer: Consuming data payload',
+  },
+  [TCP_IP_LAYER_NAMES.transport]: {
+    down: 'Transport Layer: Adding TCP header (ports, sequence numbers)',
+    up: 'Transport Layer: Parsing TCP header (ports, sequence numbers)',
+  },
+  [TCP_IP_LAYER_NAMES.internet]: {
+    down: 'Internet Layer: Adding IP header (addresses, routing)',
+    up: 'Internet Layer: Parsing IP header (addresses, routing)',
+  },
+  [TCP_IP_LAYER_NAMES.network_interface]: {
+    down: 'Network Interface Layer: Adding Ethernet frame header (MAC addressing)',
+    up: 'Network Interface Layer: Parsing Ethernet frame header (MAC addressing)',
+  },
+  [TCP_IP_LAYER_NAMES.transmission]: {
+    down: 'Transmission Layer: Transmitting data across the network',
+    up: 'Transmission Layer: Receiving data across the network',
+  },
+}
+
+const STAGE_TO_LAYER: Record<number, TCPIPLayerName> = {
+  0: TCP_IP_LAYER_NAMES.application,
+  1: TCP_IP_LAYER_NAMES.transport,
+  2: TCP_IP_LAYER_NAMES.internet,
+  3: TCP_IP_LAYER_NAMES.network_interface,
+  4: TCP_IP_LAYER_NAMES.transmission,
+  5: TCP_IP_LAYER_NAMES.network_interface,
+  6: TCP_IP_LAYER_NAMES.internet,
+  7: TCP_IP_LAYER_NAMES.transport,
+  8: TCP_IP_LAYER_NAMES.application,
+}
+
+function getLayerInfoForStage(stage: number, isClientToServer: boolean) {
+  const layerName = STAGE_TO_LAYER[stage]
+  const layerInfo = layerInfoMap[layerName]
+  return isClientToServer ? layerInfo.down : layerInfo.up
+}
+
+export default getLayerInfoForStage