Revert "Refactor current GAE abstraction library to be free of the SDK*"

go/src/infra/gae/libs/wrapper/memory/key.go

Index: go/src/infra/gae/libs/wrapper/memory/key.go
diff --git a/go/src/infra/gae/libs/wrapper/memory/key.go b/go/src/infra/gae/libs/wrapper/memory/key.go
new file mode 100644
index 0000000000000000000000000000000000000000..c6dd56fba8fb195207b06ff454cdd9d4fa576a8f
--- /dev/null
+++ b/go/src/infra/gae/libs/wrapper/memory/key.go
@@ -0,0 +1,236 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package memory
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+
+	"github.com/golang/protobuf/proto"
+	"github.com/luci/luci-go/common/cmpbin"
+	"github.com/mjibson/goon"
+
+	"appengine"
+	"appengine/datastore"
+	"appengine_internal"
+	basepb "appengine_internal/base"
+)
+
+const keyNumToksReasonableLimit = 50
+
+///////////////////////////// fakeGAECtxForNewKey //////////////////////////////
+
+type fakeGAECtxForNewKey string
+
+var _ = appengine.Context((fakeGAECtxForNewKey)(""))
+
+func (fakeGAECtxForNewKey) Debugf(format string, args ...interface{})    {}
+func (fakeGAECtxForNewKey) Infof(format string, args ...interface{})     {}
+func (fakeGAECtxForNewKey) Warningf(format string, args ...interface{})  {}
+func (fakeGAECtxForNewKey) Errorf(format string, args ...interface{})    {}
+func (fakeGAECtxForNewKey) Criticalf(format string, args ...interface{}) {}
+func (fakeGAECtxForNewKey) Request() interface{}                         { return nil }
+func (f fakeGAECtxForNewKey) Call(service, method string, in, out appengine_internal.ProtoMessage, opts *appengine_internal.CallOptions) error {
+	if service != "__go__" || method != "GetNamespace" {
+		panic(fmt.Errorf("fakeGAECtxForNewKey: cannot facilitate Call(%q, %q, ...)", service, method))
+	}
+	out.(*basepb.StringProto).Value = proto.String(string(f))
+	return nil
+}
+func (fakeGAECtxForNewKey) FullyQualifiedAppID() string { return "dev~my~app" }
+
+/////////////////////////////// Key construction ///////////////////////////////
+
+func newKey(ns, kind, stringID string, intID int64, parent *datastore.Key) *datastore.Key {
+	return datastore.NewKey(fakeGAECtxForNewKey(ns), kind, stringID, intID, parent)
+}
+func newKeyObjError(ns string, knr goon.KindNameResolver, src interface{}) (*datastore.Key, error) {
+	return (&goon.Goon{
+		Context:          fakeGAECtxForNewKey(ns),
+		KindNameResolver: knr}).KeyError(src)
+}
+func newKeyObj(ns string, knr goon.KindNameResolver, obj interface{}) *datastore.Key {
+	k, err := newKeyObjError(ns, knr, obj)
+	if err != nil {
+		panic(err)
+	}
+	return k
+}
+func kind(ns string, knr goon.KindNameResolver, src interface{}) string {
+	return newKeyObj(ns, knr, src).Kind()
+}
+
+/////////////////////////////// Binary Encoding ////////////////////////////////
+
+type keyTok struct {
+	kind     string
+	intID    uint64
+	stringID string
+}
+
+func keyToToks(key *datastore.Key) (namespace string, ret []*keyTok) {
+	var inner func(*datastore.Key)
+	inner = func(k *datastore.Key) {
+		if k.Parent() != nil {
+			inner(k.Parent())
+		}
+		ret = append(ret, &keyTok{k.Kind(), uint64(k.IntID()), k.StringID()})
+	}
+	inner(key)
+	namespace = key.Namespace()
+	return
+}
+
+func toksToKey(ns string, toks []*keyTok) (ret *datastore.Key) {
+	for _, t := range toks {
+		ret = newKey(ns, t.kind, t.stringID, int64(t.intID), ret)
+	}
+	return
+}
+
+type nsOption bool
+
+const (
+	withNS nsOption = true
+	noNS            = false
+)
+
+func keyBytes(nso nsOption, k *datastore.Key) []byte {
+	buf := &bytes.Buffer{}
+	writeKey(buf, nso, k)
+	return buf.Bytes()
+}
+
+func keyFromByteString(nso nsOption, d string, ns string) (*datastore.Key, error) {
+	return readKey(bytes.NewBufferString(d), nso, ns)
+}
+
+func writeKey(buf *bytes.Buffer, nso nsOption, k *datastore.Key) {
+	// namespace ++ #tokens ++ [tok.kind ++ tok.stringID ++ tok.intID?]*
+	namespace, toks := keyToToks(k)
+	if nso == withNS {
+		writeString(buf, namespace)
+	}
+	cmpbin.WriteUint(buf, uint64(len(toks)))
+	for _, tok := range toks {
+		writeString(buf, tok.kind)
+		writeString(buf, tok.stringID)
+		if tok.stringID == "" {
+			cmpbin.WriteUint(buf, tok.intID)
+		}
+	}
+}
+
+func readKey(buf *bytes.Buffer, nso nsOption, ns string) (*datastore.Key, error) {
+	namespace := ns
+	if nso == withNS {
+		err := error(nil)
+		if namespace, err = readString(buf); err != nil {
+			return nil, err
+		}
+	}
+
+	numToks, _, err := cmpbin.ReadUint(buf)
+	if err != nil {
+		return nil, err
+	}
+	if numToks > keyNumToksReasonableLimit {
+		return nil, fmt.Errorf("readKey: tried to decode huge key of length %d", numToks)
+	}
+
+	toks := make([]*keyTok, numToks)
+	for i := uint64(0); i < numToks; i++ {
+		tok := &keyTok{}
+		if tok.kind, err = readString(buf); err != nil {
+			return nil, err
+		}
+		if tok.stringID, err = readString(buf); err != nil {
+			return nil, err
+		}
+		if tok.stringID == "" {
+			if tok.intID, _, err = cmpbin.ReadUint(buf); err != nil {
+				return nil, err
+			}
+			if tok.intID == 0 {
+				return nil, errors.New("readKey: decoded key with empty stringID and empty intID")
+			}
+		}
+		toks[i] = tok
+	}
+
+	return toksToKey(namespace, toks), nil
+}
+
+//////////////////////////////// Key utilities /////////////////////////////////
+
+func rootKey(key *datastore.Key) *datastore.Key {
+	for key.Parent() != nil {
+		key = key.Parent()
+	}
+	return key
+}
+
+type keyValidOption bool
+
+const (
+	// userKeyOnly is used with keyValid, and ensures that the key is only one
+	// that's valid for a user program to write to.
+	userKeyOnly keyValidOption = false
+
+	// allowSpecialKeys is used with keyValid, and allows keys for special
+	// metadata objects (like "__entity_group__").
+	allowSpecialKeys = true
+)
+
+// keyValid checks to see if a key is valid by applying a bunch of constraint
+// rules to it (e.g. can't have StringID and IntID set at the same time, can't
+// have a parent key which is Incomplete(), etc.)
+//
+// It verifies that the key is also in the provided namespace. It can also
+// reject keys which are 'special' e.g. have a Kind starting with "__". This
+// behavior is controllable with opt.
+func keyValid(ns string, k *datastore.Key, opt keyValidOption) bool {
+	// copied from the appengine SDK because why would any user program need to
+	// see if a key is valid? /s
+	if k == nil {
+		return false
+	}
+	// since we do "client-side" validation of namespaces, check this here.
+	if k.Namespace() != ns {
+		return false
+	}
+	for ; k != nil; k = k.Parent() {
+		if opt == userKeyOnly && len(k.Kind()) >= 2 && k.Kind()[:2] == "__" { // reserve all Kinds starting with __
+			return false
+		}
+		if k.Kind() == "" || k.AppID() == "" {
+			return false
+		}
+		if k.StringID() != "" && k.IntID() != 0 {
+			return false
+		}
+		if k.Parent() != nil {
+			if k.Parent().Incomplete() {
+				return false
+			}
+			if k.Parent().AppID() != k.AppID() || k.Parent().Namespace() != k.Namespace() {
+				return false
+			}
+		}
+	}
+	return true
+}
+
+// keyCouldBeValid is like keyValid, but it allows for the possibility that the
+// last token of the key is Incomplete(). It returns true if the Key will become
+// valid once it recieves an automatically-assigned ID.
+func keyCouldBeValid(ns string, k *datastore.Key, opt keyValidOption) bool {
+	// adds an id to k if it's incomplete.
+	if k.Incomplete() {
+		k = newKey(ns, k.Kind(), "", 1, k.Parent())
+	}
+	return keyValid(ns, k, opt)
+}