func createMainGoModVendored()

in cmd/go/functions_framework/main.go [226:293]
51 lines of code
11 McCabe index (conditional complexity)

func createMainGoModVendored(ctx *gcp.Context, fn fnInfo) error {
	l, err := ctx.Layer(gopathLayerName, gcp.BuildLayer)
	if err != nil {
		return fmt.Errorf("creating %v layer: %w", gopathLayerName, err)
	}
	l.BuildEnvironment.Override("GOPATH", l.Path)
	if err := ctx.Setenv("GOPATH", l.Path); err != nil {
		return err
	}

	_, fnPackage, err := moduleAndPackageNames(ctx, fn)
	if err != nil {
		return fmt.Errorf("extracting module and package names: %w", err)
	}
	fn.Package = fnPackage

	fnFrameworkVendoredPathExists, err := ctx.FileExists(fn.Source, "vendor", functionsFrameworkPackage)
	if err != nil {
		return err
	}

	version, err := frameworkSpecifiedVersion(ctx, fn.Source)
	if err != nil {
		return fmt.Errorf("checking for functions framework dependency in go.mod: %w", err)
	}

	// The function must declare functions framework as a dependency.
	if version == "" || !fnFrameworkVendoredPathExists {
		// Vendored dependencies must include the functions framework. Modifying vendored dependencies
		// and adding the framework ourselves by merging two vendor directories is brittle and likely
		// to cause conflicts among the function's and the framework's dependencies.
		return gcp.UserErrorf("vendored dependencies must include %q; if your function does not depend on the module, please add a blank import: `_ %q`", functionsFrameworkModule, functionsFrameworkPackage)
	}

	cloudfunctions.AddFrameworkVersionLabel(ctx, &cloudfunctions.FrameworkVersionInfo{
		Runtime:  "go",
		Version:  version,
		Injected: false,
	})

	var buildablePackagePath string
	var appDir string

	supportsVendorModification, err := golang.SupportsVendorModificaton(ctx)
	if err != nil {
		return fmt.Errorf("checking if vendor modification is supported: %w", err)
	}

	if !supportsVendorModification {
		appDir = filepath.Join(fn.Source, appModule)
		buildablePackagePath = appDir

	} else {
		appDir = filepath.Join(fn.Source, "vendor", appModule)
		buildablePackagePath = appModule
	}

	if err := ctx.MkdirAll(appDir, 0755); err != nil {
		return err
	}

	appMainPath := filepath.Join(appDir, "main.go")

	l.BuildEnvironment.Override(env.Buildable, buildablePackagePath)
	l.BuildEnvironment.Override(golang.BuildDirEnv, fn.Source)

	return createMainGoFile(ctx, fn, appMainPath, version)
}