WSLC: Refactor ParseImage and ParseRepository (PR Feedback followup)

[David Bennett (dkbennett)]

Summary of the Pull Request

This is a follow-up from some PR commentary that had a fairly large blast radius to do it cleanly so it is a separate PR.

Replaces the free functions ParseImage, GetCanonicalImageReference, and
NormalizeRepo in wslutil with two composable, immutable value types:
RepositoryReference and ImageReference. A reference is now parsed once
into a single source of truth, and all derived forms (normalized server/path,
canonical strings, tag-or-digest collapsing) are available on demand via
accessors — instead of being recomputed by callers or threaded through helper
functions as loose std::pair/std::string values.

Cleanup is entirely client-side:
no IDL, COM, or service-ABI changes.

PR Checklist

• Closes: Link to issue #xxx
• Communication: I've discussed this with core contributors already. If work hasn't been agreed, this work might be rejected
• Tests: Added/updated if needed and all pass
• Localization: All end user facing strings can be localized
• Dev docs: Added/updated if needed
• Documentation updated: If checked, please file a pull request on our docs repo and link it here: #xxx

Detailed Description of the Pull Request / Additional comments

New types

RepositoryReference — an immutable container-repository reference.

• const std::string Name — the verbatim repository token as written.
• const std::string Server / const std::string Path — the normalized
  registry server and path (Docker client-side normalization,
  e.g. ubuntu → {docker.io, library/ubuntu}).
• static Parse(repository) — splits and normalizes (folds in the old
  NormalizeRepo).
• GetCanonical() — the fully-qualified server/path form.

ImageReference — an immutable image reference such as
ubuntu:22.04@sha256:....

• const RepositoryReference Repository — composed, not a raw string.
• const std::optional<std::string> Tag / Digest — kept as distinct fields.
• const EnumReferenceFormat Format — None / Tag / Digest classification.
• static Parse(input) — throws E_INVALIDARG (with a user-facing message)
  on a malformed reference.
• TagOrDigest() — collapses to a single field, digest taking precedence.
• GetCanonical() — the canonical string matching docker pull output
  (keeps both a tag and a digest when both are present).

Implementation details

• Composition / single source of truth. ImageReference embeds a
  RepositoryReference; every part is const, so a reference is fixed once
  created. Consumers that need repository parts use accessors
  (.Repository.Server, .Repository.Name, .Repository.GetCanonical())
  rather than re-parsing.
• Why Name is retained. Normalization is lossy — ubuntu,
  docker.io/ubuntu, and index.docker.io/library/ubuntu all normalize to the
  same server/path. Consumers that must echo the repository exactly as written
  (wslc image list display, wslc tag's C-API Repo) read Name.
• Removed a redundant parse. EnforceRegistryAllowlist now takes a
  const RepositoryReference& instead of a raw string, eliminating a second
  normalization/regex pass on the pull/push paths.
• Quiet-pull tidy-up. wslc image pull --quiet now only constructs the
  progress callback when it is actually needed
  (std::optional<ImageProgressCallback>).

Validation Steps Performed

• Debug build clean (no errors).
• Unit tests pass: WSLCTests::ImageParsing, RepoParsing,
  CanonicalImageReference (converted/expanded to cover the new types,
  including Name/Server/Path, TagOrDigest(), Format, and
  GetCanonical()).
• E2E image tests pass: 87 passed, 0 failed, 3 skipped (the skips are
  intentional — stdin/terminal/build cases). Includes
  WSLCE2E_Image_Pull_QuietOption and WSLCE2E_Image_Pull_NameOnlyDefaultsTag,
  which exercise the quiet-callback and default-tag paths.

[Copilot]

Pull request overview

Refactors container image/repository parsing in the WSLC client-side code by replacing the legacy free functions with immutable parsed reference types, reducing repeated parsing and making derived forms (canonical, normalized server/path, tag vs digest) available via accessors.

Changes:

• Introduces wslutil::RepositoryReference and wslutil::ImageReference (parse-once, immutable) and migrates callers off ParseImage/NormalizeRepo/GetCanonicalImageReference.
• Updates allowlist enforcement to accept a parsed RepositoryReference to avoid redundant parsing on pull/push paths.
• Tightens CLI pull behavior by only constructing the progress callback when not in --quiet, and uses the parsed reference for canonical output.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
test/windows/WSLCTests.cpp	Updates/expands unit tests to validate the new parsed reference types (Name/Server/Path, Tag/Digest, TagOrDigest, Format, canonical).
src/windows/wslcsession/WSLCSession.cpp	Switches pull/push/import/tag-related codepaths to ImageReference/RepositoryReference and updates allowlist enforcement signature.
src/windows/wslcsession/DockerHTTPClient.cpp	Uses RepositoryReference::Parse(...).GetCanonical() when building Docker pull URL parameters.
src/windows/wslc/tasks/ImageTasks.cpp	Parses once for default-tag messaging + canonical output; avoids constructing progress callback in --quiet.
src/windows/wslc/services/ImageService.cpp	Uses ImageReference for server extraction, list parsing, and tag validation.
src/windows/common/wslutil.h	Removes old free-function APIs and adds the new RepositoryReference / ImageReference public types.
src/windows/common/wslutil.cpp	Implements the new Parse()/GetCanonical() methods and refactors the old logic into the new types.