From 7ecbb05510b87b31c6f3f4f527dbbd8fcddb7caf Mon Sep 17 00:00:00 2001
From: Philippe Weidmann <philippe.weidmann@infomaniak.com>
Date: Thu, 18 Jan 2024 09:40:00 +0100
Subject: [PATCH 1/2] feat: Identifiable collection

---
 .../Extensions/Collection+Identity.swift      | 31 +++++++++++++++++++
 1 file changed, 31 insertions(+)
 create mode 100644 Sources/InfomaniakCore/Extensions/Collection+Identity.swift

diff --git a/Sources/InfomaniakCore/Extensions/Collection+Identity.swift b/Sources/InfomaniakCore/Extensions/Collection+Identity.swift
new file mode 100644
index 0000000..2250f28
--- /dev/null
+++ b/Sources/InfomaniakCore/Extensions/Collection+Identity.swift
@@ -0,0 +1,31 @@
+/*
+ Infomaniak Core - iOS
+ Copyright (C) 2023 Infomaniak Network SA
+
+ This program is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+import Foundation
+import SwiftUI
+
+@available(iOS 13.0, *)
+public extension Collection where Element: Identifiable {
+    /// Compute a stable id for the given collection
+    func collectionId(baseId: AnyHashable? = nil) -> Int {
+        var hasher = Hasher()
+        hasher.combine(baseId)
+        forEach { hasher.combine($0.id) }
+        return hasher.finalize()
+    }
+}

From c82698045fc71727da9711ed51d9562a778c2b11 Mon Sep 17 00:00:00 2001
From: Philippe Weidmann <philippe.weidmann@infomaniak.com>
Date: Thu, 18 Jan 2024 10:55:52 +0100
Subject: [PATCH 2/2] test: Add tests for UTCollection+Identity

---
 .../Extensions/UTCollection+Identity.swift    | 107 ++++++++++++++++++
 1 file changed, 107 insertions(+)
 create mode 100644 Tests/InfomaniakCoreTests/Extensions/UTCollection+Identity.swift

diff --git a/Tests/InfomaniakCoreTests/Extensions/UTCollection+Identity.swift b/Tests/InfomaniakCoreTests/Extensions/UTCollection+Identity.swift
new file mode 100644
index 0000000..0a17895
--- /dev/null
+++ b/Tests/InfomaniakCoreTests/Extensions/UTCollection+Identity.swift
@@ -0,0 +1,107 @@
+/*
+ Infomaniak Core - iOS
+ Copyright (C) 2023 Infomaniak Network SA
+
+ This program is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+import InfomaniakCore
+import XCTest
+
+extension Int: Identifiable {
+    public var id: Int {
+        return self
+    }
+}
+
+@available(iOS 13.0, *)
+final class UTCollectionIdentity: XCTestCase {
+    func testIntSameArraySameHash() {
+        // GIVEN
+        let lhsArray = [1, 2, 3, 4]
+        let rhsArray = [1, 2, 3, 4]
+
+        // WHEN
+        let lhsId = lhsArray.collectionId()
+        let rhsId = rhsArray.collectionId()
+
+        // THEN
+        XCTAssertEqual(lhsId, rhsId, "We expect the ids to be the same")
+    }
+
+    func testIntSameArraySameHashWithBase() {
+        // GIVEN
+        let lhsArray = [1, 2, 3, 4]
+        let rhsArray = [1, 2, 3, 4]
+
+        // WHEN
+        let lhsId = lhsArray.collectionId(baseId: 10)
+        let rhsId = rhsArray.collectionId(baseId: 10)
+
+        // THEN
+        XCTAssertEqual(lhsId, rhsId, "We expect the ids to be the same")
+    }
+    
+    func testIntReversedArrayDifferentHash() {
+        // GIVEN
+        let lhsArray = [1, 2, 3, 4]
+        let rhsArray = [1, 2, 3, 4].reversed()
+        
+        // WHEN
+        let lhsId = lhsArray.collectionId()
+        let rhsId = rhsArray.collectionId()
+        
+        // THEN
+        XCTAssertNotEqual(lhsId, rhsId, "We expect the ids to not be the same")
+    }
+
+    func testIntDifferentArrayDifferentHash() {
+        // GIVEN
+        let lhsArray = [1, 2, 3, 4]
+        let rhsArray = [1, 2, 3, 5]
+
+        // WHEN
+        let lhsId = lhsArray.collectionId()
+        let rhsId = rhsArray.collectionId()
+
+        // THEN
+        XCTAssertNotEqual(lhsId, rhsId, "We expect the ids to not be the same")
+    }
+
+    func testIntDifferentArrayDifferentHashWithBase() {
+        // GIVEN
+        let lhsArray = [1, 2, 3, 4]
+        let rhsArray = [1, 2, 3, 5]
+
+        // WHEN
+        let lhsId = lhsArray.collectionId(baseId: 10)
+        let rhsId = rhsArray.collectionId(baseId: 10)
+
+        // THEN
+        XCTAssertNotEqual(lhsId, rhsId, "We expect the ids to not be the same")
+    }
+
+    func testIntDifferentArrayDifferentHashWithDifferentBase() {
+        // GIVEN
+        let lhsArray = [1, 2, 3, 4]
+        let rhsArray = [1, 2, 3, 5]
+
+        // WHEN
+        let lhsId = lhsArray.collectionId(baseId: 10)
+        let rhsId = rhsArray.collectionId(baseId: 11)
+
+        // THEN
+        XCTAssertNotEqual(lhsId, rhsId, "We expect the ids to not be the same")
+    }
+}