feat: Begin working on configuration client.

Sources/CliClient/Internal/FileClient+semVar.swift

@@ -0,0 +1,48 @@
+import Dependencies
+import FileClient
+import Foundation
+import GitClient
+
+@_spi(Internal)
+public extension FileClient {
+  private func getVersionString(
+    fileUrl: URL,
+    gitDirectory: String?
+  ) async throws -> (version: String, usesOptionalType: Bool) {
+    @Dependency(\.gitClient) var gitClient
+    @Dependency(\.logger) var logger
+
+    let targetUrl = fileUrl
+
+    guard fileExists(targetUrl) else {
+      throw CliClientError.fileDoesNotExist(path: fileUrl.cleanFilePath)
+    }
+
+    let contents = try await read(targetUrl)
+    let versionLine = contents.split(separator: "\n")
+      .first { $0.hasPrefix("let VERSION:") }
+
+    guard let versionLine else {
+      throw CliClientError.failedToParseVersionFile
+    }
+    logger.debug("Version line: \(versionLine)")
+
+    let isOptional = versionLine.contains("String?")
+    logger.debug("Uses optional: \(isOptional)")
+
+    let versionString = versionLine.split(separator: "let VERSION: \(isOptional ? "String?" : "String") = ").last
+    guard let versionString else {
+      throw CliClientError.failedToParseVersionFile
+    }
+    return (String(versionString), isOptional)
+  }
+
+  func semVar(
+    file: URL,
+    gitDirectory: String?
+  ) async throws -> (semVar: SemVar?, usesOptionalType: Bool) {
+    let (string, usesOptionalType) = try await getVersionString(fileUrl: file, gitDirectory: gitDirectory)
+    return (SemVar(string: string), usesOptionalType)
+  }
+
+}