Attempt to fix the perf issue in selectattr | first filter (#209)

Replace O(n²) Jinja2 filter searches with an O(1) dictionary lookup.

README.md

@@ -113,7 +113,7 @@ Do an iPhone/iPad Backup with iTunes/Finder first.
 > [!NOTE]
 > If you are working on unencrypted iOS/iPadOS backup, skip this.
 
-If you want to work on an encrypted iOS/iPadOS Backup, you should install `iphone_backup_decrypt` from [KnugiHK/iphone_backup_decrypt](https://github.com/KnugiHK/iphone_backup_decrypt) before you run the `ios_media_handler.py`.
+If you want to work on an encrypted iOS/iPadOS Backup, you should install `iphone_backup_decrypt` from [KnugiHK/iphone_backup_decrypt](https://github.com/KnugiHK/iphone_backup_decrypt) before you run the extract_iphone_media.py.
 ```sh
 pip install git+https://github.com/KnugiHK/iphone_backup_decrypt
 ```

Whatsapp_Chat_Exporter/utility.py

@@ -213,6 +213,9 @@ def rendering(
     if "??" not in headline:
         raise ValueError("Headline must contain '??' to replace with name")
     headline = headline.replace("??", name)
+    # Create a temporary lookup map only at render-time;
+    # media preview in reply is a UI-specific concern and
+    # is ignored by the core database processing
     with open(output_file_name, "w", encoding="utf-8") as f:
         f.write(
             template.render(
@@ -226,7 +229,8 @@ def rendering(
                 previous=previous,
                 status=chat.status,
                 media_base=chat.media_base,
-                headline=headline
+                headline=headline,
+                msg_map={m.key_id: m for m in msgs}.get
             )
         )
 

Whatsapp_Chat_Exporter/whatsapp.html

@@ -355,7 +355,7 @@
                                                     {% endif %}
                                                 </p>
                                             </div>
-                                            {% set replied_msg = msgs | selectattr('key_id', 'equalto', msg.reply) | first %}
+                                            {% set replied_msg = msg_map(msg.reply) %}
                                             {% if replied_msg and replied_msg.media == true %}
                                             <div class="flex-shrink-0">
                                                 {% if "image/" in replied_msg.mime %}
@@ -461,7 +461,7 @@
                                                     {% endif %}
                                                 </p>
                                             </div>
-                                            {% set replied_msg = msgs | selectattr('key_id', 'equalto', msg.reply) | first %}
+                                            {% set replied_msg = msg_map(msg.reply) %}
                                             {% if replied_msg and replied_msg.media == true %}
                                             <div class="flex-shrink-0">
                                                 {% if "image/" in replied_msg.mime %}