from dataclasses import dataclass
from typing import Optional
import json
import os

@dataclass
class HanaConfig:
    company: str
    server: str
    port: int
    user: str
    password: str

@dataclass
class ServiceLayerConfig:
    url: str
    username: str
    password: str
    maxpagesize: int
    b1s_replacecollectionsonpatch: bool

@dataclass
class Config:
    hana: HanaConfig
    service_layer: ServiceLayerConfig

    @staticmethod
    def load(path: str = "config.json") -> 'Config':
        if not os.path.exists(path):
            raise FileNotFoundError(f"No se encontró el archivo de configuración: {path}")
            
        with open(path, 'r', encoding='utf-8') as f:
            data = json.load(f)
        
        hana_data = data.get('hana', {})
        service_layer_data = data.get('service_layer', {})
        
        # Validar campos requeridos para HANA
        required_hana = ['company', 'server', 'port', 'user', 'password']
        for field in required_hana:
            if field not in hana_data:
                raise KeyError(f"Falta el campo requerido '{field}' en la sección 'hana' de {path}")

        # Validar campos requeridos para Service Layer
        required_service_layer = ['url', 'username', 'password', 'maxpagesize', 'b1s_replacecollectionsonpatch']
        for field in required_service_layer:
            if field not in service_layer_data:
                raise KeyError(f"Falta el campo requerido '{field}' en la sección 'service_layer' de {path}")

        hana = HanaConfig(**hana_data)
        service_layer = ServiceLayerConfig(**service_layer_data)
        
        return Config(hana=hana, service_layer=service_layer)