package builder
 
 import (
 	"os"
 

 	"github.com/docker/docker/builder/dockerignore"

 	"github.com/docker/docker/pkg/fileutils"
 )
 
 // DockerIgnoreContext wraps a ModifiableContext to add a method
 // for handling the .dockerignore file at the root of the context.
 type DockerIgnoreContext struct {
 	ModifiableContext
 }
 
 // Process reads the .dockerignore file at the root of the embedded context.
 // If .dockerignore does not exist in the context, then nil is returned.
 //
 // It can take a list of files to be removed after .dockerignore is removed.
 // This is used for server-side implementations of builders that need to send
 // the .dockerignore file as well as the special files specified in filesToRemove,
 // but expect them to be excluded from the context after they were processed.
 //
 // For example, server-side Dockerfile builders are expected to pass in the name
 // of the Dockerfile to be removed after it was parsed.
 //
 // TODO: Don't require a ModifiableContext (use Context instead) and don't remove
 // files, instead handle a list of files to be excluded from the context.
 func (c DockerIgnoreContext) Process(filesToRemove []string) error {

 	f, err := c.Open(".dockerignore")

 	// Note that a missing .dockerignore file isn't treated as an error
 	if err != nil {
 		if os.IsNotExist(err) {
 			return nil
 		}
 		return err
 	}

 	excludes, _ := dockerignore.ReadAll(f)

 	filesToRemove = append([]string{".dockerignore"}, filesToRemove...)
 	for _, fileToRemove := range filesToRemove {
 		rm, _ := fileutils.Matches(fileToRemove, excludes)
 		if rm {
 			c.Remove(fileToRemove)
 		}
 	}
 	return nil
 }