refactor: own daily currency calculation lifetime

Sources/Conjure/LauncherWindowController.swift

@@ -17,11 +17,7 @@ final class LauncherWindowController: NSWindowController, NSWindowDelegate, NSSe
     private var results: [Application] = []
     private var calculation: CalculatorResult?
     private var isCurrencyCalculation = false
-    private var currencyRates: CurrencyRates?
-    private var currencyFetchedAt: Date?
-    private var currencyTask: Task<Void, Never>?
-    private var currencyError: String?
-    private var currencyFailureQuery: String?
+    private let currency = CurrencyCalculation()
     private var locationLabels: [URL: String] = [:]
     private var discoveryTask: Task<Void, Never>?
     private var isLaunching = false
@@ -104,6 +100,7 @@ final class LauncherWindowController: NSWindowController, NSWindowDelegate, NSSe
             if NSApp.isActive { self.window?.makeFirstResponder(self.searchField) }
             else { self.dismiss(restoringFocus: false) }
         }
+        currency.changed = { [weak self] in self?.updateResults(preservingSelection: true) }
         restorePosition()
     }
 
@@ -111,10 +108,6 @@ final class LauncherWindowController: NSWindowController, NSWindowDelegate, NSSe
         fatalError("Conjure creates its window programmatically")
     }
 
-    deinit {
-        currencyTask?.cancel()
-    }
-
     func present(command: Application.Command? = nil) {
         guard !isLaunching, window?.attachedSheet == nil else { return }
         if launcherFrameBeforeReview != nil {
@@ -413,28 +406,6 @@ final class LauncherWindowController: NSWindowController, NSWindowDelegate, NSSe
         }
     }
 
-    private func refreshCurrencyRates() {
-        guard currencyTask == nil else { return }
-        currencyTask = Task { [weak self] in
-            let result: Result<CurrencyRates, any Error>
-            do { result = .success(try await CurrencyAPI.fetch()) }
-            catch { result = .failure(error) }
-            guard !Task.isCancelled, let self else { return }
-            self.currencyTask = nil
-            switch result {
-            case .success(let rates):
-                self.currencyRates = rates
-                self.currencyFetchedAt = Date()
-                self.currencyError = nil
-                self.currencyFailureQuery = nil
-            case .failure(let error):
-                self.currencyError = error.localizedDescription
-                self.currencyFailureQuery = self.searchField.stringValue
-            }
-            self.updateResults(preservingSelection: true, allowingCurrencyFetch: false)
-        }
-    }
-
     private func updateLocationLabels() {
         var nameCounts: [String: Int] = [:]
         nameCounts.reserveCapacity(applications.count)
@@ -457,38 +428,14 @@ final class LauncherWindowController: NSWindowController, NSWindowDelegate, NSSe
         }
     }
 
-    private func updateResults(preservingSelection: Bool = false, allowingCurrencyFetch: Bool = true) {
+    private func updateResults(preservingSelection: Bool = false) {
         guard !isCommandOpen else { return }
         let selectedURL = preservingSelection && results.indices.contains(tableView.selectedRow)
             ? results[tableView.selectedRow].id : nil
         let query = searchField.stringValue
-        if currencyFailureQuery != query {
-            currencyError = nil
-            currencyFailureQuery = nil
-        }
-        isCurrencyCalculation = Calculator.isCurrencyQuery(query, currencyRates: currencyRates)
-        let needsCurrencyRefresh = isCurrencyCalculation && (currencyFetchedAt.map {
-            !Calendar.current.isDate($0, inSameDayAs: Date())
-        } ?? true)
-        if allowingCurrencyFetch, needsCurrencyRefresh, currencyError == nil {
-            refreshCurrencyRates()
-        }
-        calculation = Calculator.evaluate(query, currencyRates: currencyRates)
-        if isCurrencyCalculation, let currencyError {
-            let cached = currencyRates.map { " Cached snapshot \($0.date) is not used." } ?? ""
-            calculation = CalculatorResult(
-                displayValue: "Currency rates unavailable", copyValue: nil,
-                detail: "Daily rates: \(currencyError). Change the query to retry.\(cached)"
-            )
-        } else if isCurrencyCalculation, currencyRates != nil, let answer = calculation {
-            let cacheStatus = needsCurrencyRefresh
-                ? (currencyTask == nil ? "Stale cached daily rates" : "Stale cache; refreshing daily rates…")
-                : "Cached daily rates"
-            calculation = CalculatorResult(
-                displayValue: answer.displayValue, copyValue: answer.copyValue,
-                detail: "\(answer.detail) · \(cacheStatus)"
-            )
-        }
+        currency.update(query)
+        isCurrencyCalculation = currency.isCurrency
+        calculation = currency.result
         if calculation != nil { (window as? LauncherPanel)?.resetNumberHints() }
         if calculation != nil {
             results = []