[Improvement] Use SQLite for chat memory (#910)

Co-authored-by: Deven Patel <deven298@yahoo.com>

embedchain/memory/base.py

@@ -0,0 +1,112 @@
+import json
+import logging
+import sqlite3
+import uuid
+from typing import Any, Dict, List, Optional
+
+from embedchain.constants import SQLITE_PATH
+from embedchain.memory.message import ChatMessage
+from embedchain.memory.utils import merge_metadata_dict
+
+CHAT_MESSAGE_CREATE_TABLE_QUERY = """
+            CREATE TABLE IF NOT EXISTS chat_history (
+                app_id TEXT,
+                id TEXT,
+                question TEXT,
+                answer TEXT,
+                metadata TEXT,
+                created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
+                PRIMARY KEY (id, app_id)
+            )
+            """
+
+
+class ECChatMemory:
+    def __init__(self) -> None:
+        with sqlite3.connect(SQLITE_PATH) as self.connection:
+            self.cursor = self.connection.cursor()
+
+            self.cursor.execute(CHAT_MESSAGE_CREATE_TABLE_QUERY)
+            self.connection.commit()
+
+    def add(self, app_id, chat_message: ChatMessage) -> Optional[str]:
+        memory_id = str(uuid.uuid4())
+        metadata_dict = merge_metadata_dict(chat_message.human_message.metadata, chat_message.ai_message.metadata)
+        if metadata_dict:
+            metadata = self._serialize_json(metadata_dict)
+        ADD_CHAT_MESSAGE_QUERY = """
+            INSERT INTO chat_history (app_id, id, question, answer, metadata)
+            VALUES (?, ?, ?, ?, ?)
+        """
+        self.cursor.execute(
+            ADD_CHAT_MESSAGE_QUERY,
+            (
+                app_id,
+                memory_id,
+                chat_message.human_message.content,
+                chat_message.ai_message.content,
+                metadata if metadata_dict else "{}",
+            ),
+        )
+        self.connection.commit()
+        logging.info(f"Added chat memory to db with id: {memory_id}")
+        return memory_id
+
+    def delete_chat_history(self, app_id: str):
+        DELETE_CHAT_HISTORY_QUERY = """
+            DELETE FROM chat_history WHERE app_id=?
+        """
+        self.cursor.execute(
+            DELETE_CHAT_HISTORY_QUERY,
+            (app_id,),
+        )
+        self.connection.commit()
+
+    def get_recent_memories(self, app_id, num_rounds=10) -> List[ChatMessage]:
+        """
+        Get the most recent num_rounds rounds of conversations
+        between human and AI, for a given app_id.
+        """
+
+        QUERY = """
+            SELECT * FROM chat_history
+            WHERE app_id=?
+            ORDER BY created_at DESC
+            LIMIT ?
+        """
+        self.cursor.execute(
+            QUERY,
+            (app_id, num_rounds),
+        )
+
+        results = self.cursor.fetchall()
+        history = []
+        for result in results:
+            app_id, id, question, answer, metadata, timestamp = result
+            metadata = self._deserialize_json(metadata=metadata)
+            memory = ChatMessage()
+            memory.add_user_message(question, metadata=metadata)
+            memory.add_ai_message(answer, metadata=metadata)
+            history.append(memory)
+        return history
+
+    def _serialize_json(self, metadata: Dict[str, Any]):
+        return json.dumps(metadata)
+
+    def _deserialize_json(self, metadata: str):
+        return json.loads(metadata)
+
+    def close_connection(self):
+        self.connection.close()
+
+    def count_history_messages(self, app_id: str):
+        QUERY = """
+        SELECT COUNT(*) FROM chat_history
+        WHERE app_id=?
+        """
+        self.cursor.execute(
+            QUERY,
+            (app_id,),
+        )
+        count = self.cursor.fetchone()[0]
+        return count