Imeplement PackageDatabase

Consume InMemoryDatabase for now, which act as a singleton in-memory db.

pkg/package/database_mem.go

@@ -0,0 +1,110 @@
+// Copyright © 2019 Ettore Di Giacinto <mudler@gentoo.org>
+//
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation; either version 2 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License along
+// with this program; if not, see <http://www.gnu.org/licenses/>.
+
+package pkg
+
+import (
+	"encoding/base64"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"hash/crc32"
+)
+
+var DBInMemoryInstance PackageDatabase
+
+type InMemoryDatabase struct {
+	Database map[string]string
+}
+
+func NewInMemoryDatabase() PackageDatabase {
+	// In memoryDB is a singleton
+	if DBInMemoryInstance == nil {
+		DBInMemoryInstance = &InMemoryDatabase{Database: map[string]string{}}
+	}
+	return DBInMemoryInstance
+}
+
+func (db *InMemoryDatabase) Get(s string) (string, error) {
+
+	pa, ok := db.Database[s]
+	if !ok {
+		return "", errors.New("No key found with that id")
+	}
+	return pa, nil
+}
+
+func (db *InMemoryDatabase) Set(k, v string) error {
+	db.Database[k] = v
+
+	return nil
+}
+
+func (db *InMemoryDatabase) Create(v []byte) (string, error) {
+	enc := base64.StdEncoding.EncodeToString(v)
+	crc32q := crc32.MakeTable(0xD5828281)
+	ID := fmt.Sprintf("%08x\n", crc32.Checksum([]byte(enc), crc32q))
+
+	return ID, db.Set(ID, enc)
+}
+
+func (db *InMemoryDatabase) Retrieve(ID string) ([]byte, error) {
+	pa, err := db.Get(ID)
+	if err != nil {
+		return nil, err
+	}
+
+	enc, err := base64.StdEncoding.DecodeString(pa)
+	if err != nil {
+		return nil, err
+	}
+	return enc, nil
+}
+
+func (db *InMemoryDatabase) GetPackage(ID string) (Package, error) {
+
+	enc, err := db.Retrieve(ID)
+	if err != nil {
+		return nil, err
+	}
+
+	p := &DefaultPackage{}
+
+	if err := json.Unmarshal(enc, &p); err != nil {
+		return nil, err
+	}
+	return p, nil
+}
+
+// Encode encodes the package to string.
+// It returns an ID which can be used to retrieve the package later on.
+func (db *InMemoryDatabase) CreatePackage(p Package) (string, error) {
+
+	pd, ok := p.(*DefaultPackage)
+	if !ok {
+		return "", errors.New("InMemoryDatabase suports only DefaultPackage")
+	}
+
+	res, err := json.Marshal(pd)
+	if err != nil {
+		return "", err
+	}
+
+	ID, err := db.Create(res)
+	if err != nil {
+		return "", err
+	}
+	return ID, nil
+}