agent/memory.py

from langgraph.checkpoint.sqlite import SqliteSaver

class extended_sqliteSaver(SqliteSaver):
    def __init__(self, conn_string):
        super().__init__(conn_string)
        self.create_table("chat_history", {"thread_id": "TEXT", "message": "TEXT", "response": "TEXT"})

    @classmethod
    def from_conn_string(cls, conn_string: str) -> "SqliteSaver":
        import sqlite3
        return SqliteSaver(conn=sqlite3.connect(conn_string, check_same_thread=False))

class Memory: 

    def __init__(self, payload):
        self.checkpoints = extended_sqliteSaver.from_conn_string("_chat_history.sqlite")

        if(payload.get("thread_id")):
            self.thread_id = payload.get("thread_id")
            self.isNew = 0
        else:
            self.thread_id = "1"
            self.isNew = 1

            try:

                cursor = self.checkpoints.conn.cursor()

                ## IF THERE ARE MORE THAN N THREADS, DELETE THE OLDEST ONES TO MAKE N THREADS
                n=20
                cursor.execute(f"DELETE FROM checkpoints WHERE thread_id NOT IN (SELECT thread_id FROM checkpoints ORDER BY thread_id DESC LIMIT {n})")
        
                ## GET THE HIGHEST THREAD VALUE AND ADD ONE TO CREATE THE NEW THREAD_ID
                self.thread_id=cursor.execute("SELECT thread_id FROM checkpoints ORDER BY thread_id DESC LIMIT 1").fetchone()[0] or 0
                self.thread_id=int(self.thread_id)+1
            except:
                self.thread_id=1

            print("New thread created with id #", self.thread_id)