Index messages with attachments using a boolean

When indexing message attachment metadata using numeric indexes such as:

```javascript
{
  conversationId: '+12223334455',
  received_at: 123,
  attachments: […],
  numAttachments: 2,
},
{
  conversationId: '+12223334455',
  received_at: 456,
  attachments: [],
  numAttachments: 0,
}
{
  conversationId: '+12223334455',
  received_at: 789,
  attachments: [],
  numAttachments: 1,
}
```

It creates an index as follows:

```
[conversationId, received_at, numAttachments]
['+12223334455', 123, 2]
['+12223334455', 456, 0]
['+12223334455', 789, 1]
```

This means a query such as…

```
lowerBound: ['+12223334455', 0,                1               ]
upperBound: ['+12223334455', Number.MAX_VALUE, Number.MAX_VALUE]
```

…will return all three original entries because they span the `received_at`
from `0` through `Number.MAX_VALUE`. One workaround is to index booleans using
`1 | undefined` where `1` is included in the index and `undefined` is not, but
that way we lose the ability to query for the `false` value. Instead, we flip
adjust the index to `[conversationId, hasAttachments, received_at]` and can
then query messages with attachments using

```
[conversationId, 1 /* hasAttachments */, 0                /* received_at */]
[conversationId, 1 /* hasAttachments */, Number.MAX_VALUE /* received_at */]
```

js/modules/migrations/18/index.js

@@ -2,14 +2,14 @@ exports.run = (transaction) => {
   const messagesStore = transaction.objectStore('messages');
 
   [
-    'numAttachments',
-    'numVisualMediaAttachments',
-    'numFileAttachments',
+    'hasAttachments',
+    'hasVisualMediaAttachments',
+    'hasFileAttachments',
   ].forEach((name) => {
     console.log(`Create message attachment metadata index: '${name}'`);
     messagesStore.createIndex(
       name,
-      ['conversationId', 'received_at', name],
+      ['conversationId', name, 'received_at'],
       { unique: false }
     );
   });

js/modules/types/message.js

@@ -24,9 +24,9 @@ const PRIVATE = 'private';
 //   - Quotes: Write thumbnail data to disk and store relative path to it.
 // Version 5
 //   - Attachments: Track number and kind of attachments for media gallery
-//     - `numAttachments: Number`
-//     - `numVisualMediaAttachments: Number` (for media gallery ‘Media’ view)
-//     - `numFileAttachments: Number` (for media gallery ‘Documents’ view)
+//     - `hasAttachments?: 1 | undefined`
+//     - `hasVisualMediaAttachments?: 1 | undefined` (for media gallery ‘Media’ view)
+//     - `hasFileAttachments: ?1 | undefined` (for media gallery ‘Documents’ view)
 
 
 const INITIAL_SCHEMA_VERSION = 0;

test/modules/types/message_test.js

@@ -181,9 +181,9 @@ describe('Message', () => {
           fileName: 'test\uFFFDfig.exe',
           size: 1111,
         }],
-        numAttachments: 1,
-        numVisualMediaAttachments: 0,
-        numFileAttachments: 1,
+        hasAttachments: 1,
+        hasVisualMediaAttachments: undefined,
+        hasFileAttachments: 1,
         schemaVersion: Message.CURRENT_SCHEMA_VERSION,
       };
 

ts/test/types/message/initializeAttachmentMetadata_test.ts

@@ -38,9 +38,9 @@ describe('Message', () => {
           fileName: 'foo.jpg',
           size: 1111,
         }],
-        numAttachments: 1,
-        numVisualMediaAttachments: 1,
-        numFileAttachments: 0,
+        hasAttachments: 1,
+        hasVisualMediaAttachments: 1,
+        hasFileAttachments: undefined,
       };
 
       const actual = await Message.initializeAttachmentMetadata(input);

ts/types/IndexedDB.ts

@@ -0,0 +1,12 @@
+/**
+ * @prettier
+ */
+
+// IndexedDB doesn’t support boolean indexes so we map `true` to 1 and `false`
+// to `0`.
+// N.B. Using `undefined` allows excluding an entry from an index. Useful
+// when index size is a consideration or one only needs to query for `true`.
+export type IndexableBoolean = 1 | 0;
+
+export const toIndexableBoolean = (value: boolean): IndexableBoolean =>
+  value ? 1 : 0;

ts/types/Message.ts

@@ -2,6 +2,7 @@
  * @prettier
  */
 import { Attachment } from './Attachment';
+import { IndexableBoolean } from './IndexedDB';
 
 export type Message = IncomingMessage | OutgoingMessage | VerifiedChangeMessage;
 
@@ -73,8 +74,8 @@ type ExpirationTimerUpdate = Readonly<{
   }>;
 }>;
 
-type Message4 = Readonly<{
-  numAttachments?: number;
-  numVisualMediaAttachments?: number;
-  numFileAttachments?: number;
-}>;
+type Message4 = Partial<Readonly<{
+  hasAttachments: IndexableBoolean;
+  hasVisualMediaAttachments: IndexableBoolean;
+  hasFileAttachments: IndexableBoolean;
+}>>;

ts/types/message/initializeAttachmentMetadata.ts

@@ -4,25 +4,28 @@
 import { partition } from 'lodash';
 
 import * as Attachment from '../Attachment';
+import * as IndexedDB from '../IndexedDB';
 import { Message } from '../Message';
 
 export const initializeAttachmentMetadata = async (
-  message: Message
+  message: Message,
 ): Promise<Message> => {
   if (message.type === 'verified-change') {
     return message;
   }
 
-  const numAttachments = message.attachments.length;
-  const [numVisualMediaAttachments, numFileAttachments] = partition(
+  const hasAttachments = IndexedDB.toIndexableBoolean(message.attachments.length > 0);
+  const [hasVisualMediaAttachments, hasFileAttachments] = partition(
     message.attachments,
-    Attachment.isVisualMedia
-  ).map(attachments => attachments.length);
+    Attachment.isVisualMedia,
+  )
+    .map((attachments) => attachments.length > 0)
+    .map(IndexedDB.toIndexableBoolean);
 
   return {
     ...message,
-    numAttachments,
-    numVisualMediaAttachments,
-    numFileAttachments,
+    hasAttachments,
+    hasVisualMediaAttachments,
+    hasFileAttachments,
   };
 };