From 4de599d419bc63c3fc4fb413aa1bf82aaa95f742 Mon Sep 17 00:00:00 2001
From: Christoph Hagen <github@christophhagen.de>
Date: Wed, 6 Dec 2023 11:59:57 +0100
Subject: [PATCH] Fix history batch bug, add tests

---
 .../Clairvoyant/Metric/LogFileWriter.swift    |  2 +-
 Tests/ClairvoyantTests/ClairvoyantTests.swift | 30 +++++++++++++++++++
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/Sources/Clairvoyant/Metric/LogFileWriter.swift b/Sources/Clairvoyant/Metric/LogFileWriter.swift
index 1d116a9..eca602e 100644
--- a/Sources/Clairvoyant/Metric/LogFileWriter.swift
+++ b/Sources/Clairvoyant/Metric/LogFileWriter.swift
@@ -346,7 +346,7 @@ final class LogFileWriter<T> where T: MetricValue {
         if start <= end {
             return await getHistory(in: start...end, count: count)
         } else {
-            return await getHistory(in: start...end, count: count)
+            return await getHistoryReversed(in: end...start, count: count)
         }
     }
     
diff --git a/Tests/ClairvoyantTests/ClairvoyantTests.swift b/Tests/ClairvoyantTests/ClairvoyantTests.swift
index dab3617..ddbd8e2 100644
--- a/Tests/ClairvoyantTests/ClairvoyantTests.swift
+++ b/Tests/ClairvoyantTests/ClairvoyantTests.swift
@@ -232,6 +232,29 @@ final class ClairvoyantTests: XCTestCase {
         let last = await metric.lastValue()
         XCTAssertEqual(last?.value, 2)
     }
+    
+    func testReverseHistoryBatch() async throws {
+        let observer = createObserver()
+        let metric: Metric<Int> = observer.addMetric(id: "myInt")
+        let now = Date.now
+        let values = (1...100).reversed().map { Timestamped(value: $0, timestamp: now.advanced(by: TimeInterval(-$0))) }
+        try await metric.update(values)
+        
+        let newestBatch = await metric.history(from: now, to: .distantPast, limit: 100)
+        XCTAssertEqual(newestBatch, values.suffix(100).reversed())
+    }
+    
+    func testEncodedReverseHistoryBatch() async throws {
+        let observer = createObserver()
+        let metric: Metric<Int> = observer.addMetric(id: "myInt")
+        let now = Date.now
+        let values = (1...100).reversed().map { Timestamped(value: $0, timestamp: now.advanced(by: TimeInterval(-$0))) }
+        try await metric.update(values)
+        
+        let newestBatchData = await metric.encodedHistoryData(from: now, to: .distantPast, maximumValueCount: 100)
+        let newestBatch: [Timestamped<Int>] = try JSONDecoder().decode(from: newestBatchData)
+        XCTAssertEqual(newestBatch, values.suffix(100).reversed())
+    }
 
 }
 
@@ -253,3 +276,10 @@ private extension Date {
         .init(timeIntervalSince1970: time)
     }
 }
+
+extension Timestamped: Equatable where Value: Equatable {
+    
+    public static func == (lhs: Timestamped, rhs: Timestamped) -> Bool {
+        lhs.value == rhs.value && lhs.timestamp == rhs.timestamp
+    }
+}