Extract TranscriptionHistoryViewModel; remove dead UsageDashboardView (A2)

Sources/ViewModels/TranscriptionHistoryViewModel.swift

@@ -0,0 +1,105 @@
+import Foundation
+
+/// ViewModel for `TranscriptionHistoryView`. Owns the paged record data, the
+/// load/pagination state, and all `DataManager` interactions so the view never
+/// touches the store directly (audit item A2).
+///
+/// `dataManager` is injected via the initializer with a `DataManager.shared`
+/// default, mirroring `DashboardHomeView`'s constructor injection so tests can
+/// substitute a `MockDataManager`.
+@MainActor
+@Observable
+final class TranscriptionHistoryViewModel {
+    // MARK: - Data + Load State
+
+    private(set) var records: [TranscriptionRecord] = []
+    private(set) var page: Int = 0
+    private(set) var hasMore: Bool = true
+    private(set) var isLoading: Bool = false
+    private(set) var hasLoadedOnce: Bool = false
+
+    var showError = false
+    var errorMessage = ""
+
+    // MARK: - Dependencies
+
+    private let dataManager: DataManagerProtocol
+    private let pageSize: Int
+
+    // MARK: - Initialization
+
+    init(dataManager: DataManagerProtocol = DataManager.shared, pageSize: Int = 50) {
+        self.dataManager = dataManager
+        self.pageSize = pageSize
+    }
+
+    // MARK: - Paginated Loading
+
+    /// Loads the next page of records (or the first page when `reset` is true).
+    /// `search` is the raw search text from the view; it is trimmed here and
+    /// treated as "no filter" when empty.
+    func loadRecords(reset: Bool = false, search: String = "") async {
+        guard !isLoading else { return }
+        isLoading = true
+        defer {
+            isLoading = false
+            hasLoadedOnce = true
+        }
+
+        if reset {
+            page = 0
+            hasMore = true
+        }
+
+        let trimmed = search.trimmingCharacters(in: .whitespacesAndNewlines)
+        let searchTerm: String? = trimmed.isEmpty ? nil : trimmed
+
+        do {
+            let offset = page * pageSize
+            let batch = try await dataManager.fetchRecords(
+                limit: pageSize,
+                offset: offset,
+                search: searchTerm
+            )
+
+            if reset {
+                records = batch
+            } else {
+                records.append(contentsOf: batch)
+            }
+
+            hasMore = batch.count == pageSize
+            page += 1
+        } catch {
+            errorMessage = "Failed to load transcription history: \(error.localizedDescription)"
+            showError = true
+            hasMore = false
+        }
+    }
+
+    // MARK: - Mutations
+
+    /// Deletes a single record and reloads the first page on success.
+    func deleteRecord(_ record: TranscriptionRecord, search: String = "") async {
+        do {
+            try await dataManager.deleteRecord(record)
+            await loadRecords(reset: true, search: search)
+        } catch {
+            errorMessage = "Failed to delete record: \(error.localizedDescription)"
+            showError = true
+        }
+    }
+
+    /// Deletes every record and reloads the first page.
+    func clearAllRecords(search: String = "") async {
+        isLoading = true
+        do {
+            try await dataManager.deleteAllRecords()
+        } catch {
+            errorMessage = "Failed to clear all records: \(error.localizedDescription)"
+            showError = true
+        }
+        isLoading = false
+        await loadRecords(reset: true, search: search)
+    }
+}