import secrets
from datetime import datetime

import httpx

from fastapi import APIRouter, Request, Depends
from fastapi.responses import RedirectResponse
from web.templates_env import templates
from sqlalchemy.orm import Session

from web.auth import get_current_user
from web.config import settings
from web.database import get_db
from web.models import User, VkConnection

router = APIRouter(prefix="/vk")

VK_AUTHORIZE_URL = "https://oauth.vk.com/authorize"
VK_TOKEN_URL = "https://oauth.vk.com/access_token"
VK_API_URL = "https://api.vk.com/method"


def _redirect_uri() -> str:
    return f"{settings.BASE_URL}/vk/callback"


@router.get("")
def vk_page(
    request: Request,
    db: Session = Depends(get_db),
    user: User | None = Depends(get_current_user),
):
    if not user:
        return RedirectResponse("/login", 303)

    connection = db.query(VkConnection).filter(VkConnection.user_id == user.id).first()
    error = request.query_params.get("error")
    return templates.TemplateResponse("vk.html", {
        "request": request,
        "user": user,
        "connection": connection,
        "error": error,
    })


@router.get("/connect")
def vk_connect(request: Request, user: User | None = Depends(get_current_user)):
    if not user:
        return RedirectResponse("/login", 303)

    state = secrets.token_urlsafe(32)
    request.session["vk_oauth_state"] = state

    params = (
        f"?client_id={settings.VK_CLIENT_ID}"
        f"&response_type=code"
        f"&redirect_uri={_redirect_uri()}"
        f"&scope={settings.VK_SCOPES.replace(' ', '%20')}"
        f"&state={state}"
        f"&display=page"
        f"&v={settings.VK_API_VERSION}"
    )
    return RedirectResponse(VK_AUTHORIZE_URL + params, 302)


@router.get("/callback")
async def vk_callback(
    request: Request,
    db: Session = Depends(get_db),
    user: User | None = Depends(get_current_user),
):
    if not user:
        return RedirectResponse("/login", 303)

    code = request.query_params.get("code")
    state = request.query_params.get("state")
    saved_state = request.session.pop("vk_oauth_state", None)

    if not code or not state or state != saved_state:
        return RedirectResponse("/vk?error=invalid_state", 303)

    # Exchange code for token (VK uses GET with query params)
    try:
        async with httpx.AsyncClient() as client:
            token_response = await client.get(
                VK_TOKEN_URL,
                params={
                    "client_id": settings.VK_CLIENT_ID,
                    "client_secret": settings.VK_CLIENT_SECRET,
                    "code": code,
                    "redirect_uri": _redirect_uri(),
                },
                timeout=15,
            )
            token_response.raise_for_status()
            token_data = token_response.json()
    except Exception:
        return RedirectResponse("/vk?error=token_exchange", 303)

    access_token = token_data.get("access_token")
    vk_user_id = str(token_data.get("user_id", "")) or None
    if not access_token:
        return RedirectResponse("/vk?error=no_token", 303)

    # Fetch VK profile info
    first_name = None
    last_name = None
    try:
        async with httpx.AsyncClient() as client:
            profile_response = await client.get(
                f"{VK_API_URL}/users.get",
                params={"access_token": access_token, "v": settings.VK_API_VERSION},
                timeout=15,
            )
            if profile_response.status_code == 200:
                profile_data = profile_response.json()
                items = profile_data.get("response", [])
                if items:
                    first_name = items[0].get("first_name")
                    last_name = items[0].get("last_name")
    except Exception:
        pass

    # Save or update connection
    connection = db.query(VkConnection).filter(VkConnection.user_id == user.id).first()
    if connection:
        connection.access_token = access_token
        connection.vk_user_id = vk_user_id
        connection.first_name = first_name
        connection.last_name = last_name
        connection.is_online = True
        connection.last_checked_at = datetime.utcnow()
    else:
        connection = VkConnection(
            user_id=user.id,
            access_token=access_token,
            vk_user_id=vk_user_id,
            first_name=first_name,
            last_name=last_name,
            is_online=True,
            last_checked_at=datetime.utcnow(),
        )
        db.add(connection)
    db.commit()

    return RedirectResponse("/connections", 303)


@router.post("/disconnect")
async def vk_disconnect(
    request: Request,
    db: Session = Depends(get_db),
    user: User | None = Depends(get_current_user),
):
    if not user:
        return RedirectResponse("/login", 303)

    connection = db.query(VkConnection).filter(VkConnection.user_id == user.id).first()
    if connection:
        db.delete(connection)
        db.commit()

    return RedirectResponse("/connections", 303)