From 7696a86fecda329292205bf1a28b6774afc91011 Mon Sep 17 00:00:00 2001
From: Chris <speedytwenty@gmail.com>
Date: Wed, 18 Sep 2024 23:16:52 -0600
Subject: [PATCH] Adding $reduce operator (#28)

* Adding $reduce operator

* Tweak to argument order for $setField

* Adding test for $rand and $rank
---
 index.ts         |  9 ++++++++-
 pipeline.test.ts | 38 +++++++++++++++++++++++++++++++++++++-
 2 files changed, 45 insertions(+), 2 deletions(-)

diff --git a/index.ts b/index.ts
index b174b5b..577ee75 100644
--- a/index.ts
+++ b/index.ts
@@ -2988,6 +2988,11 @@ const $rand = ne('$rand');
 // TODO
 const $rank = ne('$rank');
 
+// TODO
+const $reduce = (input: ObjectExpression, initialValue: Expression, inExpr: Expression) => ({
+  $reduce: { input, initialValue, in: inExpr },
+});
+
 type RoundOperator = {
   $round: NumberExpression,
 };
@@ -3108,7 +3113,7 @@ const $setDifference = at('$setDifference');
 const $setEquals = pta('$setEquals');
 
 // TODO
-const $setField = (field: string, value: Expression, input: ObjectExpression) => ({
+const $setField = (input: ObjectExpression, field: string, value: Expression) => ({
   $setField: { field, input, value },
 });
 
@@ -3956,6 +3961,8 @@ export = {
   rank: $rank,
   $redact,
   redact: $redact,
+  $reduce,
+  reduce: $reduce,
   $replaceRoot,
   replaceRoot: $replaceRoot,
   $replaceWith,
diff --git a/pipeline.test.ts b/pipeline.test.ts
index c481f63..f122ed1 100644
--- a/pipeline.test.ts
+++ b/pipeline.test.ts
@@ -1470,6 +1470,42 @@ describe('aggregation', () => {
         expect($.radiansToDegrees('$value')).toEqual({ $radiansToDegrees: '$value' });
       });
     });
+    describe('$rand', () => {
+      it('exports expected vars', () => {
+        expect($.rand).toBeDefined();
+        expect($.$rand).toBeDefined();
+        expect($.rand).toStrictEqual($.$rand);
+      });
+      it('returns expected result', () => {
+        expect($.rand()).toEqual({ $rand: {} });
+      });
+    });
+    describe('$rank', () => {
+      it('exports expected vars', () => {
+        expect($.rank).toBeDefined();
+        expect($.$rank).toBeDefined();
+        expect($.rank).toStrictEqual($.$rank);
+      });
+      it('returns expected result', () => {
+        expect($.rank()).toEqual({ $rank: {} });
+      });
+    });
+    describe('$reduce', () => {
+      it('exports expected vars', () => {
+        expect($.reduce).toBeDefined();
+        expect($.$reduce).toBeDefined();
+        expect($.reduce).toStrictEqual($.$reduce);
+      });
+      it('returns expected result', () => {
+        expect($.reduce('$input', 'foo', '$bar')).toEqual({
+          $reduce: {
+            input: '$input',
+            initialValue: 'foo',
+            in: '$bar',
+          },
+        })
+      });
+    });
     describe('$round', () => {
       it('exports expected vars', () => {
         expect($.round).toBeDefined();
@@ -1555,7 +1591,7 @@ describe('aggregation', () => {
         expect($.setField).toStrictEqual($.$setField);
       });
       it('returns expected result', () => {
-        expect($.setField('foo', '$value', '$doc')).toEqual({
+        expect($.setField('$doc', 'foo', '$value')).toEqual({
           $setField: {
             field: 'foo',
             value: '$value',