vendor: add github.com/diegomarangoni/gcscache

also include all transitive dependencies of gcscache, which seems to
bring in the entire world of Google Cloud Platform.

vendor/github.com/diegomarangoni/gcscache/README.md

@@ -0,0 +1,3 @@
+# GCS Cache
+
+Golang cache library that saves objects to Google Cloud Storage (GCS) for usage within [imageproxy](https://github.com/willnorris/imageproxy).

vendor/github.com/diegomarangoni/gcscache/gcscache.go

@@ -0,0 +1,112 @@
+package gcscache
+
+import (
+	"crypto/md5"
+	"encoding/hex"
+	"io"
+	"io/ioutil"
+	"log"
+	"net/http"
+	"os"
+	"regexp"
+	"strings"
+
+	"cloud.google.com/go/storage"
+	"golang.org/x/net/context"
+	"golang.org/x/oauth2/google"
+	"google.golang.org/api/option"
+)
+
+type Cache struct {
+	pathPrefix string
+	bucket     *storage.BucketHandle
+}
+
+func (c *Cache) Get(key string) (resp []byte, ok bool) {
+	obj := c.bucket.Object(c.url(key))
+
+	rdr, err := obj.NewReader(context.Background())
+	if err != nil {
+		return []byte{}, false
+	}
+	defer rdr.Close()
+
+	resp, err = ioutil.ReadAll(rdr)
+	if err != nil {
+		log.Printf("gcscache.Get failed: %s", err)
+	}
+
+	return resp, err == nil
+}
+
+func (c *Cache) Set(key string, resp []byte) {
+	obj := c.bucket.Object(c.url(key))
+
+	contentType := http.DetectContentType(resp)
+
+	w := obj.NewWriter(context.Background())
+	w.ContentType = contentType
+	w.ObjectAttrs.ContentType = contentType
+
+	_, err := w.Write(resp)
+	if err != nil {
+		log.Printf("gcscache.Set failed: %s", err)
+	}
+
+	err = w.Close()
+	if err != nil {
+		log.Printf("gcscache.Set failed: %s", err)
+	}
+}
+
+func (c *Cache) Delete(key string) {
+	obj := c.bucket.Object(c.url(key))
+
+	err := obj.Delete(context.Background())
+	if err != nil {
+		log.Printf("gcscache.Delete failed: %s", err)
+	}
+}
+
+func (c *Cache) url(key string) string {
+	key = cacheKeyToObjectKey(key)
+	if strings.HasSuffix(c.pathPrefix, "/") {
+		return c.pathPrefix + key
+	}
+	return c.pathPrefix + "/" + key
+}
+
+func cacheKeyToObjectKey(key string) string {
+	h := md5.New()
+	io.WriteString(h, key)
+	return hex.EncodeToString(h.Sum(nil))
+}
+
+func New(bucketURL string) *Cache {
+	cfg, err := google.JWTConfigFromJSON([]byte(os.Getenv("GCP_PRIVATE_KEY")), storage.ScopeReadWrite)
+	if err != nil {
+		panic(err)
+	}
+	ts := cfg.TokenSource(context.Background())
+	opt := option.WithTokenSource(ts)
+
+	client, err := storage.NewClient(context.Background(), opt)
+	if err != nil {
+		panic(err)
+	}
+
+	r := regexp.MustCompile("gcs://([^/]+)(/(.+)?)?$")
+	if !r.MatchString(bucketURL) {
+		panic("Invalid bucket string format. Must match: gcs://bucket-name/path/prefix")
+	}
+
+	match := r.FindStringSubmatch(bucketURL)
+
+	bucketName := match[1]
+	pathPrefix := match[3]
+
+	return &Cache{
+		pathPrefix: pathPrefix,
+		bucket:     client.Bucket(bucketName),
+	}
+}