Use full metadata struct as previous results

Change is part of #33

Author: dempseyatgithub

Sources/EvolutionMetadataExtraction/ExtractionJob.swift

@@ -34,7 +34,7 @@ public struct ExtractionJob: Sendable {
     let branchInfo: GitHubBranch?
     let proposalListing: [GitHubContentItem]? // Ad-hoc snapshots may not have these
     let proposalSpecs: [ProposalSpec]
-    let previousResults: [Proposal]
+    let previousResults: EvolutionMetadata?
     let expectedResults: EvolutionMetadata?
     let forcedExtractionIDs: [String]
     let toolVersion: String
@@ -43,7 +43,7 @@ public struct ExtractionJob: Sendable {
     let temporarySnapshotDirectory: URL?
     var temporaryProposalsDirectory: URL? { temporarySnapshotDirectory?.appending(component: "proposals") }
 
-    private init(source: Source, output: Output, branchInfo: GitHubBranch? = nil, proposalListing: [GitHubContentItem]?, proposalSpecs: [ProposalSpec], previousResults: [Proposal], expectedResults: EvolutionMetadata?, forcedExtractionIDs: [String], toolVersion: String, extractionDate: Date = Date()) {
+    private init(source: Source, output: Output, branchInfo: GitHubBranch? = nil, proposalListing: [GitHubContentItem]?, proposalSpecs: [ProposalSpec], previousResults: EvolutionMetadata?, expectedResults: EvolutionMetadata?, forcedExtractionIDs: [String], toolVersion: String, extractionDate: Date = Date()) {
         self.source = source
         self.branchInfo = branchInfo
         self.proposalListing = proposalListing
@@ -92,8 +92,7 @@ extension ExtractionJob {
 
         assert(source == .network, "makeNetworkExtractionJob() requires network source")
 
-        async let previousResults = ignorePreviousResults ? [] : PreviousResultsFetcher.fetchPreviousResults()
-        
+        async let previousResults = ignorePreviousResults ? nil : PreviousResultsFetcher.fetchPreviousResults()
         let mainBranchInfo = try await GitHubFetcher.fetchMainBranch()
         let proposalContentItems = try await GitHubFetcher.fetchProposalContentItems(for: mainBranchInfo.commit.sha)
 
@@ -130,7 +129,7 @@ extension ExtractionJob {
         var proposalListing: [GitHubContentItem]? = nil
         var directoryContents: [ProposalSpec]
         var proposalSpecs: [ProposalSpec] = []
-        var previousResults: [Proposal] = []
+        var previousResults: EvolutionMetadata? = nil
 
         let branchInfo = try FileUtilities.decode(GitHubBranch.self, from: branchInfoURL)
 
@@ -152,7 +151,7 @@ extension ExtractionJob {
         }
 
         if !ignorePreviousResults {
-            if let previous = try FileUtilities.decode([Proposal].self, from: previousResultsURL) {
+            if let previous = try FileUtilities.decode(EvolutionMetadata.self, from: previousResultsURL) {
                 previousResults = previous
                 previousResultsFound = true
             }

Sources/EvolutionMetadataExtraction/Extractors/EvolutionMetadataExtractor.swift

@@ -106,15 +106,14 @@ struct EvolutionMetadataExtractor {
 
     private static func filterProposalSpecs(for extractionJob: ExtractionJob) -> ([ProposalSpec], [SortableProposalWrapper]) {
 
-        let sortablePreviousResults = extractionJob.previousResults
+        // If there are no previous results, there can be no reuse. Return early.
+        guard let previousResults = extractionJob.previousResults else {
+            return (extractionJob.proposalSpecs, [SortableProposalWrapper]())
+        }
+        
+        let sortablePreviousResults = previousResults.proposals
             .enumerated()
             .map { SortableProposalWrapper(proposal: $1, sortIndex: $0)}
-
-        
-        // If reusableProposals is empty, there can be no reuse. Return early.
-        guard !extractionJob.previousResults.isEmpty else {
-            return (extractionJob.proposalSpecs, sortablePreviousResults)
-        }
 
         var parsedProposalsById = sortablePreviousResults.reduce(into: [String:SortableProposalWrapper]()) { $0[$1.id] = $1 }
         var reusableProposals: [SortableProposalWrapper] = []

Sources/EvolutionMetadataExtraction/Utilities/Networking.swift

@@ -14,16 +14,15 @@ struct PreviousResultsFetcher {
 
     static let previousResultsURL = URL(string: "https://download.swift.org/swift-evolution/v1/evolution.json")!
 
-    static func fetchPreviousResults() async throws -> [Proposal] {
+    static func fetchPreviousResults() async throws -> EvolutionMetadata {
         let request = URLRequest(url: previousResultsURL, cachePolicy: .reloadIgnoringLocalCacheData)
         verbosePrint("Fetching with URLRequest:\n\(request.verboseDescription)")
         do {
             let (data, _) = try await URLSession.customized.data(for: request)
 
             do {
                 let decoder = JSONDecoder()
-                let evolutionMetadata = try decoder.decode(EvolutionMetadata.self, from: data)
-                return evolutionMetadata.proposals
+                return try decoder.decode(EvolutionMetadata.self, from: data)
             } catch {
                 print("Unable to decode \(EvolutionMetadata.self) from:")
                 print(String(decoding: data, as: UTF8.self))