from typing import Any, Dict, Optional, Callable, List, TypeVar, Generic
from sqlalchemy.orm import Session
from app.core.auth import CurrentUser

from app.serviceInput.base import ServiceInput
from app.serviceOutput.base import ServiceOutput

InputT = TypeVar("InputT")
OutputT = TypeVar("OutputT")

class Pipeline(Generic[InputT, OutputT]):
    """
    Pipeline base que unifica entrada, procesamiento y salida.
    """

    def __init__(self, db: Session, user: CurrentUser, operation: str):
        self.db = db
        self.user = user
        self.operation = operation
        self._steps: List[Callable] = []
        self._input: Optional[ServiceInput] = None
        self._output: Optional[ServiceOutput] = None
        self._input_data: Any = None
        self._schema = None
        self._permission: Optional[str] = None

    def set_input_data(self, data: Any) -> 'Pipeline':
        """Define los datos de entrada"""
        self._input_data = data
        return self

    def with_schema(self, schema: Any) -> 'Pipeline':
        """Define el schema de validación"""
        self._schema = schema
        return self

    def with_permission(self, permission: Optional[str]) -> 'Pipeline':
        """Define el permiso requerido"""
        self._permission = permission
        return self

    def add_step(self, name: str, func: Callable) -> 'Pipeline':
        """Agrega un paso al pipeline"""
        self._steps.append({"name": name, "func": func})
        return self

    async def execute(self, context: Dict = None) -> Dict:
        """
        Ejecuta el pipeline completo:
        1. Validación de entrada
        2. Verificación de permisos
        3. Ejecución de pasos
        4. Retorna resultado
        """
        if context is None:
            context = {}

        context["db"] = self.db
        context["user"] = self.user
        context["operation"] = self.operation
        context["input_data"] = self._input_data
        context["schema"] = self._schema
        context["permission"] = self._permission

        result = context

        for step in self._steps:
            result = await step["func"](result)
            if result.get("error"):
                return {"success": False, "error": result["error"]}

        return {"success": True, "data": result.get("output")}