From f28ae29755c34b72a5479615de5b46ed5d678848 Mon Sep 17 00:00:00 2001
From: Ian Leitch <ian@leitch.io>
Date: Sun, 9 Jun 2024 11:36:28 +0200
Subject: [PATCH] Carry over previous baseline when reading and writing

---
 Sources/Frontend/Commands/ScanBehavior.swift      | 15 ++++++++++++---
 Sources/PeripheryKit/Results/Baseline.swift       |  2 +-
 .../Results/OutputDeclarationFilter.swift         |  6 ++----
 3 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/Sources/Frontend/Commands/ScanBehavior.swift b/Sources/Frontend/Commands/ScanBehavior.swift
index 37d19e123..d1c0b2524 100644
--- a/Sources/Frontend/Commands/ScanBehavior.swift
+++ b/Sources/Frontend/Commands/ScanBehavior.swift
@@ -63,14 +63,23 @@ final class ScanBehavior {
             results = try block(project)
 
             let interval = logger.beginInterval("result:output")
-            let filteredResults = try OutputDeclarationFilter().filter(results)
+            var baseline: Baseline?
+
+            if let baselinePath = configuration.baseline {
+                let data = try Data(contentsOf: baselinePath.url)
+                baseline = try JSONDecoder().decode(Baseline.self, from: data)
+            }
+
+            let filteredResults = try OutputDeclarationFilter().filter(results, with: baseline)
 
             if configuration.autoRemove {
                 try ScanResultRemover().remove(results: filteredResults)
             }
 
-            if !filteredResults.isEmpty, let baselinePath = configuration.writeBaseline {
-                let usrs = filteredResults.flatMapSet { $0.usrs }
+            if let baselinePath = configuration.writeBaseline {
+                let usrs = filteredResults
+                    .flatMapSet { $0.usrs }
+                    .union(baseline?.usrs ?? [])
                 let baseline = Baseline.v1(usrs: usrs.sorted())
                 let data = try JSONEncoder().encode(baseline)
                 try data.write(to: baselinePath.url)
diff --git a/Sources/PeripheryKit/Results/Baseline.swift b/Sources/PeripheryKit/Results/Baseline.swift
index ca764091d..8a6fb5ae8 100644
--- a/Sources/PeripheryKit/Results/Baseline.swift
+++ b/Sources/PeripheryKit/Results/Baseline.swift
@@ -4,7 +4,7 @@ import Foundation
 public enum Baseline: Codable {
     case v1(usrs: [String])
 
-    var usrs: Set<String> {
+    public var usrs: Set<String> {
         switch self {
         case .v1(let usrs):
             return Set(usrs)
diff --git a/Sources/PeripheryKit/Results/OutputDeclarationFilter.swift b/Sources/PeripheryKit/Results/OutputDeclarationFilter.swift
index 8997fecd4..745a24ff7 100644
--- a/Sources/PeripheryKit/Results/OutputDeclarationFilter.swift
+++ b/Sources/PeripheryKit/Results/OutputDeclarationFilter.swift
@@ -14,12 +14,10 @@ public final class OutputDeclarationFilter {
         self.contextualLogger = logger.contextualized(with: "report:filter")
     }
 
-    public func filter(_ declarations: [ScanResult]) throws -> [ScanResult] {
+    public func filter(_ declarations: [ScanResult], with baseline: Baseline?) throws -> [ScanResult] {
         var declarations = declarations
 
-        if let baselinePath = configuration.baseline {
-            let data = try Data(contentsOf: baselinePath.url)
-            let baseline = try JSONDecoder().decode(Baseline.self, from: data)
+        if let baseline {
             var didFilterDeclaration = false
             declarations = declarations.filter {
                 let isDisjoint = $0.usrs.isDisjoint(with: baseline.usrs)