import sqlite3
import json
from typing import Any, Dict, List
from core.config import Env

class SqliteQueue:
    """
    """

    def __init__(self, db_path: str = Env.SQLITE_PATH):
        self.db_path = db_path
        self._init_schema()

    def _conn(self):
        conn = sqlite3.connect(self.db_path)
        conn.row_factory = sqlite3.Row
        conn.execute("PRAGMA journal_mode=WAL;")
        conn.execute("PRAGMA synchronous=NORMAL;")
        return conn

    def _init_schema(self):
        with self._conn() as con:
            con.executescript("""
            CREATE TABLE IF NOT EXISTS tasks(
                task_id TEXT PRIMARY KEY,
                queue   TEXT NOT NULL,
                type    TEXT NOT NULL,
                payload_json TEXT NOT NULL,
                created_at INTEGER NOT NULL,
                status TEXT DEFAULT 'pending',
                attempts INTEGER DEFAULT 0,
                last_error TEXT
            );
            CREATE INDEX IF NOT EXISTS idx_tasks_queue_status ON tasks(queue, status);
            """)

    def add_task(self, task: Dict[str, Any]) -> None:
        with self._conn() as con:
            con.execute("""
            INSERT OR REPLACE INTO tasks(task_id, queue, type, payload_json, created_at, status, attempts)
            VALUES(?,?,?,?,?,'pending',?)
            """, (task["task_id"], task["queue"], task["type"], json.dumps(task["payload"]), task["created_at"], task.get("_attempts", 0)))

    def update_task(self, task_id: str, status: str, error: str | None = None, attempts: int | None = None) -> None:
        with self._conn() as con:
            con.execute("""UPDATE tasks SET status=?, last_error=?, attempts=COALESCE(?, attempts) WHERE task_id=? """, (status, error, attempts, task_id))

    def pending_for_queue(self, queue: str) -> List[Dict[str, Any]]:
        with self._conn() as con:
            rows = con.execute("SELECT * FROM tasks WHERE queue=? AND status='pending'", (queue,)).fetchall()
            return [dict(r) for r in rows]