Initial commit

Sources/ContainerPersistence/EntityStore.swift

@@ -0,0 +1,126 @@
+//===----------------------------------------------------------------------===//
+// Copyright © 2025 Apple Inc. and the container project authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//   https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//===----------------------------------------------------------------------===//
+
+import ContainerizationError
+import Foundation
+import Logging
+
+let metadataFilename: String = "entity.json"
+
+public protocol EntityStore<T> {
+    associatedtype T: Codable & Identifiable<String> & Sendable
+
+    func list() async throws -> [T]
+    func create(_ entity: T) async throws
+    func retrieve(_ id: String) async throws -> T?
+    func update(_ entity: T) async throws
+    func upsert(_ entity: T) async throws
+    func delete(_ id: String) async throws
+}
+
+public actor FilesystemEntityStore<T>: EntityStore where T: Codable & Identifiable<String> & Sendable {
+    typealias Index = [String: T]
+
+    private let path: URL
+    private let type: String
+    private var index: Index
+    private let log: Logger
+    private let encoder = JSONEncoder()
+
+    public init(path: URL, type: String, log: Logger) throws {
+        self.path = path
+        self.type = type
+        self.log = log
+        self.index = try Self.load(path: path, log: log)
+    }
+
+    public func list() async throws -> [T] {
+        Array(index.values)
+    }
+
+    public func create(_ entity: T) async throws {
+        let metadataUrl = metadataUrl(entity.id)
+        guard !FileManager.default.fileExists(atPath: metadataUrl.path) else {
+            throw ContainerizationError(.exists, message: "Entity \(entity.id) already exist")
+        }
+
+        try FileManager.default.createDirectory(at: entityUrl(entity.id), withIntermediateDirectories: true)
+        let data = try encoder.encode(entity)
+        try data.write(to: metadataUrl)
+        index[entity.id] = entity
+    }
+
+    public func retrieve(_ id: String) throws -> T? {
+        index[id]
+    }
+
+    public func update(_ entity: T) async throws {
+        let metadataUrl: URL = metadataUrl(entity.id)
+        guard FileManager.default.fileExists(atPath: metadataUrl.path) else {
+            throw ContainerizationError(.notFound, message: "Entity \(entity.id) not found")
+        }
+
+        let data = try encoder.encode(entity)
+        try data.write(to: metadataUrl)
+        index[entity.id] = entity
+    }
+
+    public func upsert(_ entity: T) async throws {
+        let metadataUrl: URL = metadataUrl(entity.id)
+        let data = try encoder.encode(entity)
+        try data.write(to: metadataUrl)
+        index[entity.id] = entity
+    }
+
+    public func delete(_ id: String) async throws {
+        let metadataUrl = entityUrl(id)
+        guard FileManager.default.fileExists(atPath: metadataUrl.path) else {
+            throw ContainerizationError(.notFound, message: "entity \(id) not found")
+        }
+        try FileManager.default.removeItem(at: metadataUrl)
+        index.removeValue(forKey: id)
+    }
+
+    public func entityUrl(_ id: String) -> URL {
+        path.appendingPathComponent(id)
+    }
+
+    private static func load(path: URL, log: Logger) throws -> Index {
+        let directories = try FileManager.default.contentsOfDirectory(at: path, includingPropertiesForKeys: nil)
+        var index: FilesystemEntityStore<T>.Index = Index()
+
+        for entityUrl in directories {
+            do {
+                let metadataUrl = entityUrl.appendingPathComponent(metadataFilename)
+                let data = try Data(contentsOf: metadataUrl)
+                let entity = try JSONDecoder().decode(T.self, from: data)
+                index[entity.id] = entity
+            } catch {
+                log.warning(
+                    "failed to load entity, ignoring",
+                    metadata: [
+                        "path": "\(entityUrl)"
+                    ])
+            }
+        }
+
+        return index
+    }
+
+    private func metadataUrl(_ id: String) -> URL {
+        entityUrl(id).appendingPathComponent(metadataFilename)
+    }
+}