Added database

updates_notifier/__init__.py

+from .database import EntriesDatabase
 from .entry import Entry

updates_notifier/database.py

+import sqlite3
+from typing import Any, Iterable, Optional
+
+from .entry import Entry
+
+CREATE_ENTRIES_TABLE_SQL = """\
+CREATE TABLE IF NOT EXISTS {table_name} (
+    feed_id integer,
+    tag_id text,
+    name text,
+    version text,
+    url text
+)
+"""
+
+SEARCH_FOR_ENTRY_SQL = """\
+SELECT
+    tag_id
+FROM {table_name}
+WHERE feed_id=?
+    AND tag_id=?
+"""
+
+INSERT_ENTRY_SQL = """\
+INSERT INTO {table_name}
+    (feed_id, tag_id, name, version, url)
+VALUES (?, ?, ?, ?, ?)
+"""
+
+
+class EntriesDatabase:
+    def __init__(self, db_path: str, table_name: str = "entries"):
+        self.table_name = table_name
+
+        self._conn = sqlite3.connect(db_path)
+        self._cursor: Optional[sqlite3.Cursor] = None
+
+        self._execute(CREATE_ENTRIES_TABLE_SQL)
+        self._conn.commit()
+
+    def _execute(
+        self, query: str, params: Iterable[Any] = None, no_cursor=False
+    ) -> sqlite3.Cursor:
+        if params is None:
+            params = []
+        if no_cursor or self._cursor is None:
+            execute_func = self._conn.execute
+        else:
+            execute_func = self._cursor.execute
+
+        return execute_func(query.format(table_name=self.table_name), params)
+
+    def contains(self, entry: Entry) -> bool:
+        if not isinstance(entry, Entry):
+            raise TypeError("Element must be of type Entry")
+
+        cursor = self._execute(
+            SEARCH_FOR_ENTRY_SQL, (entry.feed_id, entry.tag_id), True
+        )
+        return cursor.fetchone() is not None
+
+    def insert(self, entry: Entry) -> None:
+        self._execute(
+            INSERT_ENTRY_SQL,
+            (entry.feed_id, entry.tag_id, entry.name, entry.version, entry.url),
+        )
+
+    def __contains__(self, entry: Entry) -> bool:
+        return self.contains(entry)
+
+    def __enter__(self) -> None:
+        if self._cursor is not None:
+            raise RuntimeError("Global cursor already activated.")
+        self._cursor = self._conn.cursor()
+
+    def __exit__(self, *_) -> None:
+        # TODO decide wether all transactions are committed when an exception is raised
+        if self._cursor is None:
+            raise RuntimeError("Global cursor not activated")
+        self._conn.commit()
+        self._cursor = None
+
+    def __iadd__(self, entry: Entry) -> None:
+        self.insert(entry)