Returns the expected path to the AppRun executable.

@spec bin_version() :: {:ok, String.t()} | :error

Returns the version of the installed qpdf executable.

Returns {:ok, version_string} on success or :error when the executable is not available or cannot be run.

Returns the default qpdf version.

Detects the current OS and CPU architecture.

@spec ensure_executable() :: {:ok, String.t()} | {:error, any()}

Finds or installs qpdf, returning installation failures as error tuples.

@spec ensure_executable!() :: String.t()

Ensures that the qpdf executable is available. Returns the path to the executable, downloading and installing it if not present.

@spec find_executable() :: {:ok, String.t()} | {:error, :not_found}

Finds the configured or existing qpdf executable without attempting to download.

@spec install(keyword()) :: {:ok, String.t()} | {:error, any()}

Downloads, verifies, and extracts the qpdf AppImage into priv/native or _build.

Options include :version, :force, :url, and :sha256. The default release has a pinned SHA-256. Other releases require a trusted 64-character hex digest via :sha256 or the :appimage_sha256 application setting. Verification occurs before making the download executable. Existing installations are reused unless force: true is given.

Returns the priv directory for the :qpdf application.

Returns the directory where the qpdf native files are stored. Uses _build/qpdf-<version> when running under Mix to keep priv/ in the source repository clean, and falls back to priv/native in releases for the default version. Set config :qpdf, storage_dir: "/path/to/cache" to use a custom base directory; each version is stored in its own qpdf-<version> subdirectory.

Returns the configured qpdf version.