from __future__ import annotations

from functools import lru_cache
from pathlib import Path
from typing import Literal

from dotenv import load_dotenv
from pydantic import AliasChoices, Field, field_validator
from pydantic_settings import BaseSettings, SettingsConfigDict

# Carrega o .env do projeto backoffice. Variáveis já exportadas no shell continuam com prioridade.
_PROJECT_ROOT = Path(__file__).resolve().parents[2]
load_dotenv(_PROJECT_ROOT / ".env", override=False)
load_dotenv(_PROJECT_ROOT / ".env.backoffice_mcp", override=False)


class BackofficeMCPSettings(BaseSettings):
    """Configurações do MCP Server de Backoffice.

    Suporta dois estilos de configuração:
    - novo/padronizado: BACKOFFICE_MCP_*
    - original develop TIM: PMID_*, SIEBEL_*, SPEECH_*, TAIS_*, ABRT_*, PORTABILITY_*

    O default agora é usar os clients TIM originais quando não for explicitado mock,
    para não mascarar erro de configuração com resposta simulada.
    """

    model_config = SettingsConfigDict(
        env_file=str(_PROJECT_ROOT / ".env"),
        extra="ignore",
        case_sensitive=False,
    )

    host: str = Field(default="0.0.0.0", validation_alias=AliasChoices("BACKOFFICE_MCP_HOST", "MCP_HOST"))
    port: int = Field(default=8010, validation_alias=AliasChoices("BACKOFFICE_MCP_PORT", "MCP_PORT"))
    log_level: str = Field(default="info", validation_alias=AliasChoices("BACKOFFICE_MCP_LOG_LEVEL", "LOG_LEVEL"))

    use_mock: bool = Field(default=True, validation_alias=AliasChoices("BACKOFFICE_MCP_USE_MOCK", "MCP_USE_MOCK", "USE_MOCK"))
    backend_type: Literal["mock", "tim_clients", "rest", "oracle"] = Field(
        default="mock",
        validation_alias=AliasChoices("BACKOFFICE_MCP_BACKEND_TYPE", "MCP_BACKEND_TYPE"),
    )

    # REST genérico opcional. Não é usado quando backend_type=tim_clients.
    rest_base_url: str = Field(default="", validation_alias=AliasChoices("BACKOFFICE_MCP_REST_BASE_URL", "BACKOFFICE_REST_BASE_URL"))
    rest_timeout_seconds: float = Field(default=20.0, validation_alias=AliasChoices("BACKOFFICE_MCP_REST_TIMEOUT_SECONDS", "BACKOFFICE_REST_TIMEOUT_SECONDS"))
    rest_api_key: str = Field(default="", validation_alias=AliasChoices("BACKOFFICE_MCP_REST_API_KEY", "BACKOFFICE_REST_API_KEY"))
    rest_auth_header: str = Field(default="Authorization", validation_alias=AliasChoices("BACKOFFICE_MCP_REST_AUTH_HEADER", "BACKOFFICE_REST_AUTH_HEADER"))

    # Oracle backend opcional.
    oracle_user: str = Field(default="", validation_alias=AliasChoices("BACKOFFICE_MCP_ORACLE_USER", "ORACLE_USER"))
    oracle_password: str = Field(default="", validation_alias=AliasChoices("BACKOFFICE_MCP_ORACLE_PASSWORD", "ORACLE_PASSWORD"))
    oracle_dsn: str = Field(default="", validation_alias=AliasChoices("BACKOFFICE_MCP_ORACLE_DSN", "ORACLE_DSN"))
    oracle_wallet_location: str = Field(default="", validation_alias=AliasChoices("BACKOFFICE_MCP_ORACLE_WALLET_LOCATION", "ORACLE_WALLET_LOCATION"))
    oracle_wallet_password: str = Field(default="", validation_alias=AliasChoices("BACKOFFICE_MCP_ORACLE_WALLET_PASSWORD", "ORACLE_WALLET_PASSWORD"))

    # TIM/develop original. Esses campos existem para health/debug e validação rápida.
    pmid_api_host: str | None = Field(default=None, validation_alias=AliasChoices("PMID_API_HOST"))
    siebel_api_host: str | None = Field(default=None, validation_alias=AliasChoices("SIEBEL_API_HOST"))
    speech_prediction_base_url: str | None = Field(default=None, validation_alias=AliasChoices("SPEECH_PREDICTION_BASE_URL"))
    speech_history_base_url: str | None = Field(default=None, validation_alias=AliasChoices("SPEECH_HISTORY_BASE_URL"))
    tais_db_dsn: str | None = Field(default=None, validation_alias=AliasChoices("TAIS_DB_DSN"))
    tais_genai_endpoint: str | None = Field(default=None, validation_alias=AliasChoices("TAIS_GENAI_ENDPOINT"))

    fail_open_on_backend_error: bool = Field(default=True, validation_alias=AliasChoices("BACKOFFICE_MCP_FAIL_OPEN_ON_BACKEND_ERROR", "MCP_FAIL_OPEN_ON_BACKEND_ERROR"))

    @field_validator("rest_base_url")
    @classmethod
    def validate_rest_base_url(cls, v: str) -> str:
        value = (v or "").strip()
        if value and not value.startswith(("http://", "https://")):
            raise ValueError("BACKOFFICE_MCP_REST_BASE_URL precisa começar com http:// ou https://")
        return value

    def tim_clients_configured(self) -> bool:
        return bool(self.pmid_api_host or self.siebel_api_host or self.speech_prediction_base_url or self.tais_db_dsn)


@lru_cache(maxsize=1)
def get_settings() -> BackofficeMCPSettings:
    return BackofficeMCPSettings()