pama: implement the persistent store for projects

Implement the persistent store for models.Project structs.

Signed-off-by: Koni Marti <koni.marti@gmail.com>
Acked-by: Robin Jarry <robin@jarry.cc>

1 files changed, 244 insertions, 0 deletions

diff --git a/lib/pama/store/store.go b/lib/pama/store/store.go
new file mode 100644
index 00000000..8f93873d
--- /dev/null
+++ b/lib/pama/store/store.go
@@ -0,0 +1,244 @@
+package store
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"os"
+	"path"
+	"strings"
+
+	"git.sr.ht/~rjarry/aerc/lib/pama/models"
+	"git.sr.ht/~rjarry/aerc/lib/xdg"
+	"git.sr.ht/~rjarry/aerc/log"
+	"github.com/syndtr/goleveldb/leveldb"
+)
+
+const (
+	keyPrefix = "project."
+)
+
+var (
+	// versTag should be incremented when the underyling data structure
+	// changes.
+	versTag    = []byte("0001")
+	versTagKey = []byte("version.tag")
+	currentKey = []byte("current.project")
+)
+
+func createKey(name string) []byte {
+	return []byte(keyPrefix + name)
+}
+
+func parseKey(key []byte) string {
+	return strings.TrimPrefix(string(key), keyPrefix)
+}
+
+func isProjectKey(key []byte) bool {
+	return bytes.HasPrefix(key, []byte(keyPrefix))
+}
+
+func cacheDir() (string, error) {
+	dir, err := os.UserCacheDir()
+	if err != nil {
+		dir = xdg.ExpandHome("~/.cache")
+	}
+	return path.Join(dir, "aerc"), nil
+}
+
+func openStorage() (*leveldb.DB, error) {
+	cd, err := cacheDir()
+	if err != nil {
+		return nil, fmt.Errorf("Unable to find project store directory: %w", err)
+	}
+	p := path.Join(cd, "projects")
+
+	db, err := leveldb.OpenFile(p, nil)
+	if err != nil {
+		return nil, fmt.Errorf("Unable to open project store: %w", err)
+	}
+
+	has, err := db.Has(versTagKey, nil)
+	if err != nil {
+		return nil, err
+	}
+	setTag := !has
+	if has {
+		vers, err := db.Get(versTagKey, nil)
+		if err != nil {
+			return nil, err
+		}
+		if !bytes.Equal(vers, versTag) {
+			log.Warnf("patch store: version mismatch: wipe data")
+			iter := db.NewIterator(nil, nil)
+			for iter.Next() {
+				err := db.Delete(iter.Key(), nil)
+				if err != nil {
+					log.Errorf("delete: %v")
+				}
+			}
+			iter.Release()
+			setTag = true
+		}
+	}
+
+	if setTag {
+		err := db.Put(versTagKey, versTag, nil)
+		if err != nil {
+			return nil, err
+		}
+		log.Infof("patch store: set version: %s", string(versTag))
+	}
+
+	return db, nil
+}
+
+func encode(p models.Project) ([]byte, error) {
+	return json.Marshal(p)
+}
+
+func decode(data []byte) (p models.Project, err error) {
+	err = json.Unmarshal(data, &p)
+	return
+}
+
+func Store() models.PersistentStorer {
+	return &instance{}
+}
+
+type instance struct{}
+
+func (instance) StoreProject(p models.Project, overwrite bool) error {
+	db, err := openStorage()
+	if err != nil {
+		return err
+	}
+	defer db.Close()
+
+	key := createKey(p.Name)
+	has, err := db.Has(key, nil)
+	if err != nil {
+		return err
+	}
+	if has && !overwrite {
+		return fmt.Errorf("Project '%s' already exists.", p.Name)
+	}
+
+	log.Debugf("project data: %v", p)
+
+	encoded, err := encode(p)
+	if err != nil {
+		return err
+	}
+	return db.Put(key, encoded, nil)
+}
+
+func (instance) DeleteProject(name string) error {
+	db, err := openStorage()
+	if err != nil {
+		return err
+	}
+	defer db.Close()
+
+	key := createKey(name)
+	has, err := db.Has(key, nil)
+	if err != nil {
+		return err
+	}
+	if !has {
+		return fmt.Errorf("Project does not exist.")
+	}
+	return db.Delete(key, nil)
+}
+
+func (instance) CurrentName() (string, error) {
+	db, err := openStorage()
+	if err != nil {
+		return "", err
+	}
+	defer db.Close()
+	cur, err := db.Get(currentKey, nil)
+	if err != nil {
+		return "", err
+	}
+	return parseKey(cur), nil
+}
+
+func (instance) SetCurrent(name string) error {
+	db, err := openStorage()
+	if err != nil {
+		return err
+	}
+	defer db.Close()
+	key := createKey(name)
+	return db.Put(currentKey, key, nil)
+}
+
+func (instance) Current() (models.Project, error) {
+	db, err := openStorage()
+	if err != nil {
+		return models.Project{}, err
+	}
+	defer db.Close()
+
+	has, err := db.Has(currentKey, nil)
+	if err != nil {
+		return models.Project{}, err
+	}
+	if !has {
+		return models.Project{}, fmt.Errorf("No (current) project found; run 'project init' first.")
+	}
+	curProjectKey, err := db.Get(currentKey, nil)
+	if err != nil {
+		return models.Project{}, err
+	}
+	raw, err := db.Get(curProjectKey, nil)
+	if err != nil {
+		return models.Project{}, err
+	}
+	p, err := decode(raw)
+	if err != nil {
+		return models.Project{}, err
+	}
+	return p, nil
+}
+
+func (instance) Names() ([]string, error) {
+	db, err := openStorage()
+	if err != nil {
+		return nil, err
+	}
+	defer db.Close()
+	var names []string
+	iter := db.NewIterator(nil, nil)
+	for iter.Next() {
+		if !isProjectKey(iter.Key()) {
+			continue
+		}
+		names = append(names, parseKey(iter.Key()))
+	}
+	iter.Release()
+	return names, nil
+}
+
+func (instance) Projects() ([]models.Project, error) {
+	var projects []models.Project
+	db, err := openStorage()
+	if err != nil {
+		return nil, err
+	}
+	defer db.Close()
+	iter := db.NewIterator(nil, nil)
+	for iter.Next() {
+		if !isProjectKey(iter.Key()) {
+			continue
+		}
+		p, err := decode(iter.Value())
+		if err != nil {
+			return nil, err
+		}
+		projects = append(projects, p)
+	}
+	iter.Release()
+	return projects, nil
+}