*: add the ability to define passwords statically

storage/static.go

@@ -1,6 +1,9 @@
 package storage
 
-import "errors"
+import (
+	"errors"
+	"strings"
+)
 
 // Tests for this code are in the "memory" package, since this package doesn't
 // define a concrete storage implementation.
@@ -53,3 +56,39 @@ func (s staticClientsStorage) DeleteClient(id string) error {
 func (s staticClientsStorage) UpdateClient(id string, updater func(old Client) (Client, error)) error {
 	return errors.New("static clients: read-only cannot update client")
 }
+
+type staticPasswordsStorage struct {
+	Storage
+
+	passwordsByEmail map[string]Password
+}
+
+// WithStaticPasswords returns a storage with a read-only set of passwords. Write actions,
+// such as creating other passwords, will fail.
+func WithStaticPasswords(s Storage, staticPasswords []Password) Storage {
+	passwordsByEmail := make(map[string]Password, len(staticPasswords))
+	for _, p := range staticPasswords {
+		p.Email = strings.ToLower(p.Email)
+		passwordsByEmail[p.Email] = p
+	}
+	return staticPasswordsStorage{s, passwordsByEmail}
+}
+
+func (s staticPasswordsStorage) GetPassword(email string) (Password, error) {
+	if password, ok := s.passwordsByEmail[strings.ToLower(email)]; ok {
+		return password, nil
+	}
+	return Password{}, ErrNotFound
+}
+
+func (s staticPasswordsStorage) CreatePassword(p Password) error {
+	return errors.New("static passwords: read-only cannot create password")
+}
+
+func (s staticPasswordsStorage) DeletePassword(id string) error {
+	return errors.New("static passwords: read-only cannot create password")
+}
+
+func (s staticPasswordsStorage) UpdatePassword(id string, updater func(old Password) (Password, error)) error {
+	return errors.New("static passwords: read-only cannot update password")
+}