Refactor packages and add docs (#15)

This is a large refactor of the library. Packages
have been organized based on dependencies. A Streamer
interface has been added as an abstraction for converting
urls to streams. Some interfaces have been removed since
they were not being used. All packages now have
descriptions and relevant usage documentation.

Author: murphm8

README.md

@@ -1,3 +1,4 @@
+[![Build Status](https://travis-ci.org/aws-robotics/aws-robomaker-bundle-support-library.svg?branch=development)](https://travis-ci.org/aws-robotics/aws-robomaker-bundle-support-library) [![Go Report Card](https://goreportcard.com/badge/github.com/aws-robotics/aws-robomaker-bundle-support-library)](https://goreportcard.com/report/github.com/aws-robotics/aws-robomaker-bundle-support-library)
 ## AWS Robomaker Bundle Support Library
 
 **This API is currently under active development and should not be considered stable.**

cmd/cli/main.go

@@ -1,34 +1,56 @@
+// Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+/*
+Package cli provides a basic command line application to interact with bundles.
+
+It will extract the bundle to the cache directory and then print the
+command that can be used to source the bundle into the environment.
+
+Usage:
+  go run github.com/aws-robotics/aws-robomaker-bundle-support-library \
+		--bundle <path to bundle> \
+		--cache (optional) <path to cache directory (default: cache)> \
+		--prefix (optional) <prefix for source command paths (must include cache directory)>
+*/
 package main
 
 import (
 	"fmt"
+	"github.com/aws-robotics/aws-robomaker-bundle-support-library/pkg/stream/local"
 	"io/ioutil"
 	"log"
 	"os"
 
 	"github.com/aws-robotics/aws-robomaker-bundle-support-library/pkg/bundle"
-	"github.com/aws-robotics/aws-robomaker-bundle-support-library/pkg/file_system"
 	"github.com/aws-robotics/aws-robomaker-bundle-support-library/pkg/store"
+	"github.com/aws-robotics/aws-robomaker-bundle-support-library/pkg/stream"
 	"github.com/urfave/cli"
 )
 
 func main() {
 	app := cli.NewApp()
-	app.Name = "Bundle Info"
-	app.Usage = "Get source command for bundle"
+	app.Name = "Bundle Helper"
+	app.Usage = "Extracts a bundle and prints the command to source the bundle into a shell environment. " +
+		"Will intelligently cache in the cache directory."
 	app.Flags = []cli.Flag{
 		cli.StringFlag{Name: "bundle", Value: "", Usage: "Path to bundle file"},
 		cli.StringFlag{Name: "prefix", Value: "", Usage: "Prefix to put onto the source command"},
+		cli.StringFlag{Name: "cache", Value: "cache", Usage: "Folder to be used as the cache " +
+			"directory for extracted bundles."},
 	}
+
+	local := local.NewStreamer()
+	stream.RegisterStreamer(local)
+
 	app.Action = func(c *cli.Context) error {
-		fmt.Println("Opening ", c.String("bundle"))
-		cache_path := "./cache"
-		bundle_store := store.NewSimpleStore(cache_path, file_system.NewLocalFS())
+		cachePath := c.String("cache")
+		bundleStore := store.NewSimpleStore(cachePath)
 
-		bundle_path := c.String("bundle")
-		prefix_path := c.String("prefix")
+		bundlePath := c.String("bundle")
+		prefixPath := c.String("prefix")
 
-		files, err := ioutil.ReadDir(cache_path)
+		files, err := ioutil.ReadDir(cachePath)
 		if err != nil {
 			log.Fatal(err)
 		}
@@ -40,20 +62,20 @@ func main() {
 			}
 		}
 
-		err = bundle_store.Load(keys)
+		err = bundleStore.Load(keys)
 		if err != nil {
 			log.Fatal(err)
 			return err
 		}
 
-		bundle_provider := bundle.NewBundleProvider(bundle_store)
-		b, err := bundle_provider.GetBundle(bundle_path)
+		bundleProvider := bundle.NewProvider(bundleStore)
+		b, err := bundleProvider.GetBundle(bundlePath)
 		if err != nil {
 			log.Fatal(err)
 			return err
 		}
 		for i := 0; i < len(b.PosixSourceCommands()); i++ {
-			fmt.Print(b.PosixSourceCommandsUsingLocation(prefix_path)[i])
+			fmt.Print(b.PosixSourceCommandsUsingLocation(prefixPath)[i])
 		}
 
 		return nil

example/s3_download/main.go

@@ -0,0 +1,101 @@
+// Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+package bundle
+
+//go:generate mockgen -destination=mock_archiver.go -package=bundle github.com/aws-robotics/aws-robomaker-bundle-support-library/pkg/3p/archiver Archiver
+
+import (
+	"archive/tar"
+	"compress/gzip"
+	"errors"
+	"fmt"
+	"github.com/aws-robotics/aws-robomaker-bundle-support-library/pkg/fs"
+	"io"
+)
+
+const (
+	versionFileName             = "version"
+	defaultFileMode fs.FileMode = 0755
+)
+
+// archive's responsibility is to be able to Extract bundles of all versions, v1, v2, etc.
+type archive struct {
+	version         string
+	inputStream     io.ReadSeeker
+	bundleProcessor bundleProcessor
+}
+
+func newBundleArchive(inputStream io.ReadSeeker) (*archive, error) {
+	// read version to determine bundle version
+	tarReader := tarReaderFromStream(inputStream)
+	version, versionErr := readVersionFromBundle(tarReader)
+
+	if versionErr != nil {
+		return nil, fmt.Errorf("unable to read version from bundle: %v", versionErr)
+	}
+
+	// get the appropriate bundle processor for the version
+	bundleProcessor := processorForVersion(version)
+	if bundleProcessor == nil {
+		return nil, fmt.Errorf("unsuppported bundle processor version: %s", version)
+	}
+
+	// reset seek position to start of the stream and init with the stream
+	inputStream.Seek(0, io.SeekStart)
+	return &archive{
+		version:         version,
+		inputStream:     inputStream,
+		bundleProcessor: bundleProcessor,
+	}, nil
+}
+
+// What version is this bundle?
+func (b *archive) Version() string {
+	return b.version
+}
+
+// Extract everything into the cache
+func (b *archive) Extract(bundleStore Cache) (Bundle, error) {
+	return b.bundleProcessor.extract(b.inputStream, bundleStore)
+}
+
+func readVersionFromBundle(tarReader *tar.Reader) (string, error) {
+	header, headerErr := tarReader.Next()
+	if headerErr != nil {
+		fmt.Printf("bundleError parsing tar: %v", headerErr)
+		return "", headerErr
+	}
+
+	if header.Name != versionFileName {
+		err := errors.New("invalid bundle format, first file should be a version file")
+		return "", err
+	}
+
+	versionData := make([]byte, header.Size)
+	_, readVersionErr := tarReader.Read(versionData)
+	// We need to read a second time to get the io.EOF message
+	_, readVersionErr = tarReader.Read(nil)
+	if readVersionErr != io.EOF {
+		return "", fmt.Errorf("unable to read version: %v", readVersionErr)
+	}
+
+	return string(versionData), nil
+}
+
+func tarReaderFromStream(inputStream io.ReadSeeker) *tar.Reader {
+	var tarReader *tar.Reader
+
+	// try as a gzReader
+	gzReader, gzErr := gzip.NewReader(inputStream)
+	if gzErr == nil {
+		// this is a valid gz file
+		// create the tar reader from the gzReader
+		tarReader = tar.NewReader(gzReader)
+	} else {
+		// it wasn't a gz file, let's try to create the tar reader from the input stream
+		inputStream.Seek(0, io.SeekStart)
+		tarReader = tar.NewReader(inputStream)
+	}
+	return tarReader
+}