feat: Begin working on configuration client.

Sources/ConfigurationClient/ConfigurationClient.swift

@@ -0,0 +1,72 @@
+import Dependencies
+import DependenciesMacros
+import FileClient
+import Foundation
+
+public extension DependencyValues {
+  var configurationClient: ConfigurationClient {
+    get { self[ConfigurationClient.self] }
+    set { self[ConfigurationClient.self] = newValue }
+  }
+}
+
+@DependencyClient
+public struct ConfigurationClient: Sendable {
+  public var find: @Sendable (URL?) async throws -> ConfigruationFile?
+  public var load: @Sendable (ConfigruationFile) async throws -> Configuration
+  public var write: @Sendable (Configuration, ConfigruationFile) async throws -> Void
+
+  public func findAndLoad(_ url: URL? = nil) async throws -> Configuration {
+    guard let url = try await find(url) else {
+      throw ConfigurationClientError.configurationNotFound
+    }
+    return try await load(url)
+  }
+}
+
+extension ConfigurationClient: DependencyKey {
+  public static let testValue: ConfigurationClient = Self()
+
+  public static var liveValue: ConfigurationClient {
+    .init(
+      find: { try await findConfiguration($0) },
+      load: { try await $0.load() ?? .init() },
+      write: { try await $1.write($0) }
+    )
+  }
+}
+
+private func findConfiguration(_ url: URL?) async throws -> ConfigruationFile? {
+  @Dependency(\.fileClient) var fileClient
+
+  var url: URL! = url
+  if url == nil {
+    url = try await URL(filePath: fileClient.currentDirectory())
+  }
+
+  // Check if url is a valid configuration url.
+  var configurationFile = ConfigruationFile(url: url)
+  if let configurationFile { return configurationFile }
+
+  guard try await fileClient.isDirectory(url.cleanFilePath) else {
+    throw ConfigurationClientError.invalidConfigurationDirectory(path: url.cleanFilePath)
+  }
+
+  // Check for toml file.
+  let tomlUrl = url.appending(path: "\(ConfigurationClient.Constants.defaultFileNameWithoutExtension).toml")
+  configurationFile = ConfigruationFile(url: tomlUrl)
+  if let configurationFile { return configurationFile }
+
+  // Check for json file.
+  let jsonUrl = url.appending(path: "\(ConfigurationClient.Constants.defaultFileNameWithoutExtension).json")
+  configurationFile = ConfigruationFile(url: jsonUrl)
+  if let configurationFile { return configurationFile }
+
+  // Couldn't find valid configuration file.
+  return nil
+}
+
+enum ConfigurationClientError: Error {
+  case configurationNotFound
+  case invalidConfigurationDirectory(path: String)
+}