import logging
from pathlib import Path

from fastapi import APIRouter, Depends, Request, status
from fastapi.responses import HTMLResponse, RedirectResponse, Response
from fastapi.templating import Jinja2Templates

from app.config import Settings, get_settings
from app.dependencies import get_app_settings, get_auth_db, get_current_auth_session
from app.services.auth import AuthenticatedSession
from app.services.config_page import (
    ConfigSaveError,
    build_config_sections,
    is_ticktick_oauth_ready,
    save_config_updates,
)
from app.services.email import EmailConfigurationError, EmailDeliveryError, is_smtp_ready, send_smtp_test_email
from sqlalchemy.orm import Session

templates = Jinja2Templates(directory=str(Path(__file__).resolve().parents[2] / "templates"))
router = APIRouter(tags=["pages"])
logger = logging.getLogger(__name__)


def _ticktick_oauth_notice(status_value: str | None) -> tuple[str | None, str | None]:
    if status_value == "success":
        return "TickTick authorization completed successfully.", None
    if status_value == "invalid-state":
        return None, "TickTick authorization failed due to invalid OAuth state. Start the flow again."
    if status_value == "invalid-callback":
        return None, "TickTick authorization callback was missing required parameters."
    if status_value == "failed":
        return None, "TickTick authorization failed. Check server logs for the provider response and verify TickTick app credentials and redirect URI."
    return None, None


def _smtp_test_notice(status_value: str | None) -> tuple[str | None, str | None]:
    if status_value == "success":
        return "SMTP test email sent successfully.", None
    if status_value == "config-error":
        return None, "SMTP test failed. Check required SMTP settings before sending a test email."
    if status_value == "failed":
        return None, "SMTP test failed. Check saved SMTP settings and server reachability."
    return None, None


def _build_config_context(
    *,
    auth_db_session: Session,
    settings: Settings,
    current_auth: AuthenticatedSession,
    config_saved: bool,
    config_error: str | None,
    password_change_error: str | None,
    ticktick_oauth_notice: str | None,
    ticktick_oauth_error: str | None,
    smtp_test_notice: str | None,
    smtp_test_error: str | None,
) -> dict[str, object]:
    return {
        "app_name": settings.app_name,
        "app_env": settings.app_env,
        "current_username": current_auth.user.username,
        "csrf_token": current_auth.session.csrf_token,
        "force_password_change": current_auth.user.force_password_change,
        "password_change_error": password_change_error,
        "config_error": config_error,
        "config_saved": config_saved,
        "config_sections": build_config_sections(auth_db_session, settings),
        "ticktick_oauth_ready": is_ticktick_oauth_ready(settings),
        "ticktick_redirect_uri": settings.ticktick_redirect_uri,
        "ticktick_oauth_notice": ticktick_oauth_notice,
        "ticktick_oauth_error": ticktick_oauth_error,
        "smtp_test_ready": is_smtp_ready(settings),
        "smtp_test_notice": smtp_test_notice,
        "smtp_test_error": smtp_test_error,
    }


@router.get("/", response_class=HTMLResponse)
def home(
    request: Request,
    current_auth: AuthenticatedSession | None = Depends(get_current_auth_session),
) -> RedirectResponse:
    if current_auth is None:
        return RedirectResponse(url="/login", status_code=status.HTTP_303_SEE_OTHER)
    return RedirectResponse(url="/config", status_code=status.HTTP_303_SEE_OTHER)


@router.get("/admin", response_class=HTMLResponse)
def admin_redirect(
    request: Request,
    current_auth: AuthenticatedSession | None = Depends(get_current_auth_session),
) -> RedirectResponse:
    if current_auth is None:
        return RedirectResponse(url="/login", status_code=status.HTTP_303_SEE_OTHER)
    return RedirectResponse(url="/config", status_code=status.HTTP_303_SEE_OTHER)


@router.get("/config", response_class=HTMLResponse)
def config_page(
    request: Request,
    auth_db_session: Session = Depends(get_auth_db),
    settings: Settings = Depends(get_app_settings),
    current_auth: AuthenticatedSession | None = Depends(get_current_auth_session),
) -> Response:
    if current_auth is None:
        return RedirectResponse(url="/login", status_code=status.HTTP_303_SEE_OTHER)

    ticktick_oauth_notice, ticktick_oauth_error = _ticktick_oauth_notice(
        request.query_params.get("ticktick_oauth")
    )
    smtp_test_notice, smtp_test_error = _smtp_test_notice(request.query_params.get("smtp_test"))
    context = _build_config_context(
        auth_db_session=auth_db_session,
        settings=settings,
        current_auth=current_auth,
        config_saved=request.query_params.get("saved") == "1",
        config_error=None,
        password_change_error=None,
        ticktick_oauth_notice=ticktick_oauth_notice,
        ticktick_oauth_error=ticktick_oauth_error,
        smtp_test_notice=smtp_test_notice,
        smtp_test_error=smtp_test_error,
    )
    return templates.TemplateResponse(request, "config.html", context)


@router.post("/config", response_class=HTMLResponse)
async def config_submit(
    request: Request,
    auth_db_session: Session = Depends(get_auth_db),
    settings: Settings = Depends(get_app_settings),
    current_auth: AuthenticatedSession | None = Depends(get_current_auth_session),
) -> Response:
    if current_auth is None:
        return RedirectResponse(url="/login", status_code=status.HTTP_303_SEE_OTHER)

    form = await request.form()
    csrf_token = form.get("csrf_token")
    if csrf_token != current_auth.session.csrf_token:
        logger.warning("Rejected config update due to CSRF validation failure")
        context = _build_config_context(
            auth_db_session=auth_db_session,
            settings=settings,
            current_auth=current_auth,
            config_saved=False,
            config_error="invalid config update request",
            password_change_error=None,
            ticktick_oauth_notice=None,
            ticktick_oauth_error=None,
            smtp_test_notice=None,
            smtp_test_error=None,
        )
        return templates.TemplateResponse(
            request,
            "config.html",
            context,
            status_code=status.HTTP_400_BAD_REQUEST,
        )

    try:
        save_config_updates(auth_db_session, dict(form), settings)
    except ConfigSaveError:
        logger.warning("Rejected config update due to invalid submitted values")
        refreshed_settings = get_settings()
        context = _build_config_context(
            auth_db_session=auth_db_session,
            settings=refreshed_settings,
            current_auth=current_auth,
            config_saved=False,
            config_error="invalid config submission",
            password_change_error=None,
            ticktick_oauth_notice=None,
            ticktick_oauth_error=None,
            smtp_test_notice=None,
            smtp_test_error=None,
        )
        return templates.TemplateResponse(
            request,
            "config.html",
            context,
            status_code=status.HTTP_400_BAD_REQUEST,
        )

    return RedirectResponse(url="/config?saved=1", status_code=status.HTTP_303_SEE_OTHER)


@router.post("/config/smtp/test", response_class=HTMLResponse)
async def smtp_test_submit(
    request: Request,
    auth_db_session: Session = Depends(get_auth_db),
    settings: Settings = Depends(get_app_settings),
    current_auth: AuthenticatedSession | None = Depends(get_current_auth_session),
) -> Response:
    if current_auth is None:
        return RedirectResponse(url="/login", status_code=status.HTTP_303_SEE_OTHER)

    form = await request.form()
    csrf_token = form.get("csrf_token")
    if csrf_token != current_auth.session.csrf_token:
        logger.warning("Rejected SMTP test due to CSRF validation failure")
        context = _build_config_context(
            auth_db_session=auth_db_session,
            settings=settings,
            current_auth=current_auth,
            config_saved=False,
            config_error=None,
            password_change_error=None,
            ticktick_oauth_notice=None,
            ticktick_oauth_error=None,
            smtp_test_notice=None,
            smtp_test_error="invalid SMTP test request",
        )
        return templates.TemplateResponse(
            request,
            "config.html",
            context,
            status_code=status.HTTP_400_BAD_REQUEST,
        )

    try:
        send_smtp_test_email(settings)
    except EmailConfigurationError as exc:
        logger.warning("SMTP test email rejected due to configuration: %s", exc)
        return RedirectResponse(
            url="/config?smtp_test=config-error",
            status_code=status.HTTP_303_SEE_OTHER,
        )
    except EmailDeliveryError as exc:
        logger.warning("SMTP test email failed: %s", exc)
        return RedirectResponse(
            url="/config?smtp_test=failed",
            status_code=status.HTTP_303_SEE_OTHER,
        )

    return RedirectResponse(
        url="/config?smtp_test=success",
        status_code=status.HTTP_303_SEE_OTHER,
    )