feat: Prep to update current version container in cli-client.

Sources/CliClient/Internal/CurrentVersionContainer.swift

@@ -0,0 +1,103 @@
+import ConfigurationClient
+import CustomDump
+import Dependencies
+import FileClient
+import Foundation
+
+// TODO: Add optional property for currentVersion (loaded version from file)
+//       and rename version to nextVersion.
+
+/// An internal type that holds onto the loaded version from a file (if found),
+/// the computed next version, and the target file url.
+///
+@_spi(Internal)
+public struct CurrentVersionContainer: Sendable {
+
+  let targetUrl: URL
+  let currentVersion: CurrentVersion?
+  let version: Version
+
+  // TODO: Derive from current version.
+  var usesOptionalType: Bool {
+    switch version {
+    case .string: return false
+    case let .semvar(_, usesOptionalType, _): return usesOptionalType
+    }
+  }
+
+  var hasChanges: Bool {
+    guard let currentVersion else { return false }
+    switch (currentVersion, version) {
+    case let (.branch(currentString, _), .string(nextString)):
+      return currentString == nextString
+    case let (.semvar(currentSemvar, _), .semvar(nextSemvar, _, _)):
+      return currentSemvar == nextSemvar
+    // TODO: What to do with mis-matched values.
+    case (.branch, .semvar),
+         (.semvar, .string):
+      return true
+    }
+  }
+
+  public enum CurrentVersion: Sendable {
+    case branch(String, usesOptionalType: Bool)
+    case semvar(SemVar, usesOptionalType: Bool)
+  }
+
+  public enum Version: Sendable {
+    // TODO: Call this branch for consistency.
+    case string(String)
+    // TODO: Remove has changes when currentVersion/nextVersion is implemented.
+    case semvar(SemVar, usesOptionalType: Bool = true, hasChanges: Bool)
+
+    func string(allowPreReleaseTag: Bool) throws -> String {
+      switch self {
+      case let .string(string):
+        return string
+      case let .semvar(semvar, usesOptionalType: _, hasChanges: _):
+        return semvar.versionString(withPreReleaseTag: allowPreReleaseTag)
+      }
+    }
+  }
+}
+
+extension CurrentVersionContainer {
+
+  static func load(
+    configuration: Configuration,
+    sharedOptions: CliClient.SharedOptions
+  ) async throws -> Self {
+    @Dependency(\.fileClient) var fileClient
+    @Dependency(\.logger) var logger
+
+    let targetUrl = try configuration.targetUrl(gitDirectory: sharedOptions.projectDirectory)
+    logger.trace("Begin loading current version from: \(targetUrl.cleanFilePath)")
+
+    let currentVersion = try await fileClient.loadCurrentVersion(
+      url: targetUrl,
+      gitDirectory: sharedOptions.projectDirectory,
+      expectsBranch: configuration.strategy?.branch != nil
+    )
+    var currentVersionString = ""
+    customDump(currentVersion, to: &currentVersionString)
+    logger.trace("Loaded current version:\n\(currentVersionString)")
+
+    if configuration.strategy?.semvar?.requireExistingFile == true {
+      guard currentVersion != nil else {
+        // TODO: Better error.
+        throw CliClientError.semVarNotFound
+      }
+    }
+
+    // Check that there's a valid strategy to get the next version.
+    guard let strategy = configuration.strategy else {
+      // TODO: Return without a next version here when nextVersion is optional.
+      fatalError()
+    }
+
+    // TODO: make optional?
+    let next = try await strategy.loadNextVersion(gitDirectory: sharedOptions.projectDirectory)
+
+    fatalError()
+  }
+}