From 5abe27f423e19e73665bf7f069820b9e9bd6f1ef Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Sat, 19 Mar 2016 21:40:29 +0530
Subject: [PATCH] Detect support for storing blobs in IndexedDB

---
 src/pyj/read_book/db.pyj | 36 +++++++++++++++++++++++++++---------
 src/pyj/read_book/ui.pyj |  8 ++++++--
 2 files changed, 33 insertions(+), 11 deletions(-)

diff --git a/src/pyj/read_book/db.pyj b/src/pyj/read_book/db.pyj
index bfd67d0660..9f4b94b86e 100644
--- a/src/pyj/read_book/db.pyj
+++ b/src/pyj/read_book/db.pyj
@@ -15,9 +15,12 @@ DB_NAME = 'calibre-books-db-test'  # TODO: Remove test suffix
 
 class DB:
 
-    def __init__(self, idb, interface_data):
-        self.interface_data = interface_data
+    def __init__(self, idb, ui, supports_blobs):
+        self.interface_data = ui.interface_data
         self.idb = idb
+        self.supports_blobs = supports_blobs
+        if not supports_blobs:
+            print('IndexedDB does not support Blob storage, using base64 encoding instead')
 
         idb.onerror = def(event):
             self.display_error(None, event)
@@ -80,6 +83,8 @@ class DB:
         book.manifest = manifest
         book.metadata = manifest.metadata
         book.book_hash = manifest.book_hash.hash
+        book.is_complete = False
+        book.stores_blobs = True
         v'delete manifest["metadata"]'
         self.do_op(['books'], book, _('Failed to write to the books database'), proceed, op='put')
 
@@ -88,12 +93,25 @@ def create_db(ui, interface_data):
         ui.db = _('Your browser does not support IndexedDB. Cannot read books. Consider using a modern browser, such as Firefox, Chrome or Edge.')
         return
     request = window.indexedDB.open(DB_NAME, 1)
-    request.onblocked = def(event):
-        alert(_('Please close all other tabs with a calibre book open'))
-    request.onerror = def(event):
-        ui.db = _('You must allow calibre to use IndexedDB storage in your browser to read books')
-    request.onsuccess = def(event):
-        ui.db = DB(event.target.result, interface_data)
-        ui.db_initialized()
+
     request.onupgradeneeded = def(event):
         upgrade_schema(event.target.result, event.oldVersion, event.newVersion)
+
+    request.onblocked = def(event):
+        alert(_('Please close all other tabs with a calibre book open'))
+
+    request.onerror = def(event):
+        ui.db = _('You must allow calibre to use IndexedDB storage in your browser to read books')
+
+    request.onsuccess = def(event):
+        blob = Blob(['test'], {'type':"text/plain"})
+        idb = event.target.result
+        try:
+            req = idb.transaction(['files'], 'readwrite').objectStore('files').put(blob, ':-test-blob-:')
+        except Exception:
+            ui.db_initialized(DB(idb, ui, False))
+            return
+        req.onsuccess = def(event):
+            ui.db_initialized(DB(idb, ui, True))
+        req.onerror = def(event):
+            ui.db_initialized(DB(idb, ui, False))
diff --git a/src/pyj/read_book/ui.pyj b/src/pyj/read_book/ui.pyj
index 4251246030..b3a23e285f 100644
--- a/src/pyj/read_book/ui.pyj
+++ b/src/pyj/read_book/ui.pyj
@@ -24,7 +24,8 @@ class ReadUI:
             return
         self.start_load(book_id, fmt, metadata)
 
-    def db_initialized(self):
+    def db_initialized(self, db):
+        self.db = db
         if self.pending_load is not None:
             pl, self.pending_load = self.pending_load, None
             self.start_load(*pl)
@@ -41,7 +42,7 @@ class ReadUI:
         if not book.manifest or book.manifest.version != RENDER_VERSION:
             self.get_manifest(book)
             return
-        self.download_book(book)
+        self.display_book(book) if book.is_complete else self.download_book(book)
 
     def get_manifest(self, book):
         library_id, book_id, fmt = book.key
@@ -74,3 +75,6 @@ class ReadUI:
 
     def download_book(self, book):
         pass
+
+    def display_book(self, book):
+        pass