2 files changed, 36 insertions, 10 deletions

diff --git a/ext/bg/js/dictionary.js b/ext/bg/js/dictionary.js
index 20a94f8f..936dc3c1 100644
--- a/ext/bg/js/dictionary.js
+++ b/ext/bg/js/dictionary.js
@@ -20,26 +20,53 @@
 class Dictionary {
     constructor() {
         this.db = null;
+        this.dbVer = 1;
         this.entities = null;
     }
 
     initDb() {
+        if (this.db !== null) {
+            return Promise.reject('database already initialized');
+        }
+
         this.db = new Dexie('dict');
         this.db.version(1).stores({
             terms: '++id,expression,reading',
             entities: '++,name',
-            kanji: '++,character'
+            kanji: '++,character',
+            meta: 'name,value',
         });
-
-        this.entities = null;
     }
 
-    deleteDb() {
-        return this.db === null ? Promise.resolve() : this.db.delete();
+    prepareDb() {
+        this.initDb();
+
+        return this.db.meta.get('version').then(row => {
+            return row ? row.value : 0;
+        }).catch(() => {
+            return 0;
+        }).then(version => {
+            if (this.dbVer === version) {
+                return true;
+            }
+
+            const db = this.db;
+            this.db.close();
+            this.db = null;
+
+            return db.delete().then(() => {
+                this.initDb();
+                return false;
+            });
+        });
     }
 
-    existsDb() {
-        return Dexie.exists('dict');
+    sealDb() {
+        if (this.db === null) {
+            return Promise.reject('database not initialized');
+        }
+
+        return this.db.meta.put({name: 'version', value: this.dbVer});
     }
 
     findTerm(term) {
diff --git a/ext/bg/js/translator.js b/ext/bg/js/translator.js
index b8cad6de..2cc97e1c 100644
--- a/ext/bg/js/translator.js
+++ b/ext/bg/js/translator.js
@@ -35,15 +35,14 @@ class Translator {
             return loadJson('bg/data/tags.json');
         }).then(tagMeta => {
             this.tagMeta = tagMeta;
-            return this.dictionary.existsDb();
+            return this.dictionary.prepareDb();
         }).then(exists => {
-            this.dictionary.initDb();
             if (!exists) {
                 return Promise.all([
                     this.dictionary.importKanjiDict('bg/data/kanjidic/index.json'),
                     this.dictionary.importTermDict('bg/data/edict/index.json'),
                     this.dictionary.importTermDict('bg/data/enamdict/index.json')
-                ]);
+                ]).then(() => this.dictionary.sealDb());
             }
         }).then(() => {
             this.loaded = true;