From e1fc4b1db2f53fbae64088b34134a756239d5d70 Mon Sep 17 00:00:00 2001
From: Fred Boniface <fred@fjla.uk>
Date: Sun, 30 Jun 2024 20:46:37 +0100
Subject: [PATCH] Add pipeline for finding station by distance

Signed-off-by: Fred Boniface <fred@fjla.uk>
---
 src/utils/ldbPipeline.utils.ts | 42 ++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)
 create mode 100644 src/utils/ldbPipeline.utils.ts

diff --git a/src/utils/ldbPipeline.utils.ts b/src/utils/ldbPipeline.utils.ts
new file mode 100644
index 0000000..7a26a4f
--- /dev/null
+++ b/src/utils/ldbPipeline.utils.ts
@@ -0,0 +1,42 @@
+export function findStationsByDistancePipeline(count: number) {
+  return [
+    {
+      '$geoNear': {
+        'near': {
+          'type': 'Point', 
+          'coordinates': [
+            -5.149929, 58.350661
+          ]
+        }, 
+        'distanceField': 'distance'
+      }
+    }, {
+      '$limit': count
+    }, {
+      '$addFields': {
+        'miles': {
+          '$divide': [
+            {
+              '$round': {
+                '$multiply': [
+                  {
+                    '$divide': [
+                      '$distance', 1609.34
+                    ]
+                  }, 4
+                ]
+              }
+            }, 4
+          ]
+        }
+      }
+    }, {
+      '$project': {
+        '_id': 0, 
+        '3ALPHA': 1, 
+        'NLCDESC': 1, 
+        'miles': 1
+      }
+    }
+  ]
+}
\ No newline at end of file