protoc

type CompileResult struct {
	// The failures from all calls.
	Failures []*text.Failure
	// Will not be set if there are any failures.
	FileDescriptorSets []*descriptor.FileDescriptorSet
}

type Compiler interface {
	// Compile the protobuf files with protoc.
	//
	// If there are compile failures, they will be returned in the slice
	// and there will be no error. The caller can determine if this is
	// an error case. If there is any other type of error, or some output
	// from protoc cannot be interpreted, an error will be returned.
	//
	// FileDescriptorSet will only be set if the CompilerWithFileDescriptorSet
	// option is used.
	Compile(...*file.ProtoSet) (*CompileResult, error)

	// Return the protoc commands that would be run on Compile.
	//
	// This will ignore the CompilerWithFileDescriptorSet option.
	ProtocCommands(...*file.ProtoSet) ([]string, error)
}

type CompilerOption func(*compiler)

type Downloader interface {
	// Download protobuf.
	//
	// If already downloaded, this has no effect. This is thread-safe.
	// This will download to ${XDG_CACHE_HOME}/prototool/$(uname -s)/$(uname -m)
	// unless overridden by a DownloaderOption.
	// If ${XDG_CACHE_HOME} is not set, it defaults to ${HOME}/Library/Caches on
	// Darwin, and ${HOME}/.cache on Linux.
	// If ${HOME} is not set, an error will be returned.
	//
	// Returns the path to the downloaded protobuf artifacts.
	//
	// ProtocPath and WellKnownTypesIncludePath implicitly call this.
	Download() (string, error)

	// Get the path to protoc.
	//
	// If not downloaded, this downloads and caches protobuf. This is thread-safe.
	ProtocPath() (string, error)

	// Get the path to include for the well-known types.
	//
	// Inside this directory will be the subdirectories google/protobuf.
	//
	// If not downloaded, this downloads and caches protobuf. This is thread-safe.
	WellKnownTypesIncludePath() (string, error)

	// Delete any downloaded artifacts.
	//
	// This is not thread-safe and no calls to other functions can be reliably
	// made simultaneously.
	Delete() error
}

type DownloaderOption func(*downloader)