add array maximun and minimum

Author: cherylEnkidu

Firestore/Swift/Source/ExpressionImplementation.swift

@@ -523,6 +523,14 @@ public extension Expression {
     return FunctionExpression(functionName: "array_get", args: [self, offsetExpression])
   }
 
+  func arrayMaximum() -> FunctionExpression {
+    return FunctionExpression(functionName: "maximum", args: [self])
+  }
+
+  func arrayMinimum() -> FunctionExpression {
+    return FunctionExpression(functionName: "minimum", args: [self])
+  }
+
   func greaterThan(_ other: Expression) -> BooleanExpression {
     return BooleanExpression(functionName: "greater_than", args: [self, other])
   }

Firestore/Swift/Source/SwiftAPI/Pipeline/Expressions/Expression.swift

@@ -461,6 +461,30 @@ public protocol Expression: Sendable {
   /// - Returns: A new `FunctionExpression` representing the "arrayGet" operation.
   func arrayGet(_ offsetExpression: Expression) -> FunctionExpression
 
+  /// Creates an expression that returns the maximum element of an array.
+  ///
+  /// Assumes `self` evaluates to an array.
+  ///
+  /// ```swift
+  /// // Get the maximum value in the "scores" array.
+  /// Field("scores").arrayMaximum()
+  /// ```
+  ///
+  /// - Returns: A new `FunctionExpression` representing the maximum element of the array.
+  func arrayMaximum() -> FunctionExpression
+
+  /// Creates an expression that returns the minimum element of an array.
+  ///
+  /// Assumes `self` evaluates to an array.
+  ///
+  /// ```swift
+  /// // Get the minimum value in the "scores" array.
+  /// Field("scores").arrayMinimum()
+  /// ```
+  ///
+  /// - Returns: A new `FunctionExpression` representing the minimum element of the array.
+  func arrayMinimum() -> FunctionExpression
+
   /// Creates a `BooleanExpression` that returns `true` if this expression is greater
   /// than the given expression.
   ///

Firestore/Swift/Tests/Integration/PipelineTests.swift

@@ -3917,4 +3917,33 @@ class PipelineIntegrationTests: FSTIntegrationTestCase {
 
     TestHelper.compare(snapshot: snapshot, expected: expectedResults, enforceOrder: true)
   }
+
+  func testArrayMaxMinWorks() async throws {
+    let collRef = collectionRef(withDocuments: [
+      "doc1": ["scores": [10, 20, 5]],
+      "doc2": ["scores": [-1, -5, 0]],
+      "doc3": ["scores": [100.5, 99.5, 100.6]],
+      "doc4": ["scores": []],
+    ])
+    let db = collRef.firestore
+
+    let pipeline = db.pipeline()
+      .collection(collRef.path)
+      .sort([Field(FieldPath.documentID()).ascending()])
+      .select([
+        Field("scores").arrayMaximum().as("maxScore"),
+        Field("scores").arrayMinimum().as("minScore"),
+      ])
+
+    let snapshot = try await pipeline.execute()
+
+    let expectedResults: [[String: Sendable?]] = [
+      ["maxScore": 20, "minScore": 5],
+      ["maxScore": 0, "minScore": -5],
+      ["maxScore": 100.6, "minScore": 99.5],
+      ["maxScore": nil, "minScore": nil],
+    ]
+
+    TestHelper.compare(snapshot: snapshot, expected: expectedResults, enforceOrder: true)
+  }
 }