Wrap resourceStore for Functions, HTTPTriggers and Environments

FunctionStore uses fileStore for function code and resourceStore for
the Function's metadata.  Environment- and HTTPTrigger- Store are just
thin wrappers on resourceStore.

There is probably a better way to organize this code, maybe with
reflection.

controller/functionStore.go

@@ -0,0 +1,137 @@
+/*
+Copyright 2016 The Fission Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package controller
+
+import (
+	log "github.com/Sirupsen/logrus"
+
+	"github.com/platform9/fission"
+)
+
+type FunctionStore struct {
+	resourceStore
+}
+
+func (fs *FunctionStore) Create(f *fission.Function) (string, error) {
+	code := []byte(f.Code)
+	_, uid, err := fs.resourceStore.writeFile(f.Key(), code)
+	if err != nil {
+		return "", err
+	}
+
+	f.Metadata.Uid = uid
+	f.Code = ""
+
+	err = fs.resourceStore.create(f)
+	if err != nil {
+		fs.resourceStore.deleteFile(f.Key(), uid) // ignore errors
+		return "", err
+	}
+	return f.Metadata.Uid, nil
+}
+
+func (fs *FunctionStore) Get(m *fission.Metadata) (*fission.Function, error) {
+	var f fission.Function
+	err := fs.resourceStore.read(m.Name, &f)
+	if err != nil {
+		return nil, err
+	}
+
+	var code []byte
+	if len(m.Uid) > 0 {
+		log.WithFields(log.Fields{"Uid": m.Uid}).Info("fetching by uid")
+		code, err = fs.resourceStore.readFile(m.Name, &m.Uid)
+		f.Metadata = *m
+	} else {
+		code, err = fs.resourceStore.readFile(m.Name, nil)
+	}
+	if err != nil {
+		return nil, err
+	}
+
+	f.Code = string(code)
+	return &f, nil
+}
+
+func (fs *FunctionStore) Update(f *fission.Function) (string, error) {
+	code := []byte(f.Code)
+	_, uid, err := fs.resourceStore.writeFile(f.Key(), code)
+	if err != nil {
+		return "", err
+	}
+
+	var fnew fission.Function
+	err = fs.resourceStore.read(f.Metadata.Name, &fnew)
+	if err != nil {
+		fs.resourceStore.deleteFile(f.Key(), uid) // ignore err
+		return "", err
+	}
+
+	fnew.Metadata.Uid = uid
+	fnew.Environment = f.Environment
+
+	err = fs.resourceStore.update(fnew)
+	if err != nil {
+		fs.resourceStore.deleteFile(f.Key(), uid) // ignore err
+		return "", err
+	}
+	return uid, err
+}
+
+func (fs *FunctionStore) Delete(m fission.Metadata) error {
+	if len(m.Uid) == 0 {
+		err := fs.resourceStore.deleteAllFiles(m.Name)
+		if err != nil {
+			return err
+		}
+	} else {
+		err := fs.resourceStore.deleteFile(m.Name, m.Uid)
+		if err != nil {
+			return err
+		}
+	}
+	typeName, err := getTypeName(fission.Function{})
+	if err != nil {
+		return err
+	}
+	return fs.resourceStore.delete(typeName, m.Name)
+}
+
+func (fs *FunctionStore) List() ([]fission.Function, error) {
+	typeName, err := getTypeName(fission.Function{})
+	if err != nil {
+		return nil, err
+	}
+
+	bufs, err := fs.resourceStore.getAll(typeName)
+	if err != nil {
+		return nil, err
+	}
+
+	js := JsonSerializer{}
+	functions := make([]fission.Function, 0, len(bufs))
+	for _, buf := range bufs {
+		var f fission.Function
+		err = js.deserialize([]byte(buf), &f)
+		if err != nil {
+			return nil, err
+		}
+		functions = append(functions, f)
+	}
+
+	return functions, nil
+}