import os
import subprocess
import tempfile
from typing import List, AsyncIterator, Dict, Any
from .base import SourceAdapter, FileInfo


class DatabaseAdapter(SourceAdapter):
    async def connect(self) -> None:
        pass

    async def disconnect(self) -> None:
        pass

    async def list_files(self, path: str = "") -> List[FileInfo]:
        return []

    async def read_file(self, path: str) -> AsyncIterator[bytes]:
        raise NotImplementedError("Database adapter does not support file reading")

    async def get_database_dump(self, config: Dict[str, Any]) -> AsyncIterator[bytes]:
        db_type = config.get("db_type", "postgresql")
        host = config.get("host", "localhost")
        port = config.get("port", 5432 if db_type == "postgresql" else 3306)
        database = config.get("database")
        username = config.get("username")
        password = config.get("password")

        if not database:
            raise ValueError("Database name is required")

        with tempfile.NamedTemporaryFile(suffix=".sql", delete=False) as tmp:
            tmp_path = tmp.name

        try:
            if db_type == "postgresql":
                env = os.environ.copy()
                if password:
                    env["PGPASSWORD"] = password

                cmd = [
                    "pg_dump",
                    "-h", host,
                    "-p", str(port),
                    "-U", username or "postgres",
                    "-f", tmp_path,
                    database
                ]
            elif db_type == "mysql":
                env = os.environ.copy()
                if password:
                    env["MYSQL_PWD"] = password

                cmd = [
                    "mysqldump",
                    "-h", host,
                    "-P", str(port),
                    "-u", username or "root",
                    "--result-file", tmp_path,
                    database
                ]
            else:
                raise ValueError(f"Unsupported database type: {db_type}")

            result = subprocess.run(cmd, env=env, capture_output=True, text=True)
            if result.returncode != 0:
                raise RuntimeError(f"Database dump failed: {result.stderr}")

            with open(tmp_path, "rb") as f:
                while chunk := f.read(8192):
                    yield chunk
        finally:
            if os.path.exists(tmp_path):
                os.unlink(tmp_path)