Initial commit: doujinshi-dl generic plugin framework

History reset as part of DMCA compliance. The project has been
refactored into a generic, site-agnostic download framework.
Site-specific logic lives in separate plugin packages.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

doujinshi_dl/core/utils/db.py

@@ -0,0 +1,50 @@
+# coding: utf-8
+"""DB and Singleton utilities."""
+import os
+import sqlite3
+
+
+class _Singleton(type):
+    """ A metaclass that creates a Singleton base class when called. """
+    _instances = {}
+
+    def __call__(cls, *args, **kwargs):
+        if cls not in cls._instances:
+            cls._instances[cls] = super(_Singleton, cls).__call__(*args, **kwargs)
+        return cls._instances[cls]
+
+
+class Singleton(_Singleton(str('SingletonMeta'), (object,), {})):
+    pass
+
+
+class DB(object):
+    conn = None
+    cur = None
+
+    def __enter__(self):
+        from doujinshi_dl.core import config
+        history_path = config.get(
+            'history_path',
+            os.path.expanduser('~/.doujinshi-dl/history.sqlite3'),
+        )
+        self.conn = sqlite3.connect(history_path)
+        self.cur = self.conn.cursor()
+        self.cur.execute('CREATE TABLE IF NOT EXISTS download_history (id text)')
+        self.conn.commit()
+        return self
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        self.conn.close()
+
+    def clean_all(self):
+        self.cur.execute('DELETE FROM download_history WHERE 1')
+        self.conn.commit()
+
+    def add_one(self, data):
+        self.cur.execute('INSERT INTO download_history VALUES (?)', [data])
+        self.conn.commit()
+
+    def get_all(self):
+        data = self.cur.execute('SELECT id FROM download_history')
+        return [i[0] for i in data]