from datetime import datetime, timedelta

from fastapi import APIRouter, HTTPException, Query, Request
from fastapi.responses import HTMLResponse

from app.broker_store import expire_user_broker_session
from app.services.auth_service import get_user_for_session
from app.services.email_service import send_email_async
from app.services.live_equity_service import (
    capture_live_equity_snapshot,
    get_live_equity_curve,
)
from app.services.zerodha_service import (
    KiteApiError,
    KiteTokenError,
    build_login_url,
    exchange_request_token,
    fetch_funds,
    fetch_holdings,
    normalize_holding,
)
from app.services.zerodha_storage import (
    clear_session,
    consume_request_token,
    get_session,
    set_session,
    store_request_token,
)

router = APIRouter(prefix="/api/zerodha")
public_router = APIRouter()


def _require_user(request: Request):
    session_id = request.cookies.get("session_id")
    if not session_id:
        raise HTTPException(status_code=401, detail="Not authenticated")
    user = get_user_for_session(session_id)
    if not user:
        raise HTTPException(status_code=401, detail="Not authenticated")
    return user


def _capture_request_token(request: Request, request_token: str):
    user = _require_user(request)
    token = request_token.strip()
    if not token:
        raise HTTPException(status_code=400, detail="Missing request_token")
    store_request_token(user["id"], token)


def _clear_broker_session(user_id: str, email: str | None = None):
    expire_user_broker_session(user_id)
    clear_session(user_id)
    if email:
        try:
            body = (
                "Your Zerodha session has expired and your broker connection has been disconnected.\n\n"
                "Please log in to QuantFortune and reconnect your Zerodha account to resume your strategy.\n\n"
                "If your strategy was running, it has been paused until you reconnect."
            )
            send_email_async(email, "Action required: Zerodha session expired", body)
        except Exception:
            pass


def _raise_kite_error(user_id: str, exc: KiteApiError, email: str | None = None):
    if isinstance(exc, KiteTokenError):
        _clear_broker_session(user_id, email=email)
        raise HTTPException(
            status_code=401, detail="Zerodha session expired. Please reconnect."
        ) from exc
    raise HTTPException(status_code=502, detail=str(exc)) from exc


@router.post("/login-url")
async def login_url(payload: dict, request: Request):
    _require_user(request)
    api_key = (payload.get("apiKey") or "").strip()
    if not api_key:
        raise HTTPException(status_code=400, detail="API key is required")
    return {"loginUrl": build_login_url(api_key)}


@router.post("/session")
async def create_session(payload: dict, request: Request):
    user = _require_user(request)
    api_key = (payload.get("apiKey") or "").strip()
    api_secret = (payload.get("apiSecret") or "").strip()
    request_token = (payload.get("requestToken") or "").strip()
    if not api_key or not api_secret or not request_token:
        raise HTTPException(
            status_code=400, detail="API key, secret, and request token are required"
        )

    try:
        session_data = exchange_request_token(api_key, api_secret, request_token)
    except Exception as exc:
        raise HTTPException(status_code=400, detail=str(exc)) from exc

    saved = set_session(
        user["id"],
        {
            "api_key": api_key,
            "access_token": session_data.get("access_token"),
            "request_token": session_data.get("request_token", request_token),
            "user_name": session_data.get("user_name"),
            "broker_user_id": session_data.get("user_id"),
        },
    )

    return {
        "connected": True,
        "userName": saved.get("user_name"),
        "brokerUserId": saved.get("broker_user_id"),
        "accessToken": saved.get("access_token"),
    }


@router.get("/status")
async def status(request: Request):
    user = _require_user(request)
    session = get_session(user["id"])
    if not session:
        return {"connected": False}

    return {
        "connected": True,
        "broker": "zerodha",
        "userName": session.get("user_name"),
        "linkedAt": session.get("linked_at"),
    }


@router.get("/request-token")
async def request_token(request: Request):
    user = _require_user(request)
    token = consume_request_token(user["id"])
    if not token:
        raise HTTPException(status_code=404, detail="No request token available.")
    return {"requestToken": token}


@router.get("/holdings")
async def holdings(request: Request):
    user = _require_user(request)
    session = get_session(user["id"])
    if not session:
        raise HTTPException(status_code=400, detail="Zerodha is not connected")
    try:
        data = fetch_holdings(session["api_key"], session["access_token"])
    except KiteApiError as exc:
        _raise_kite_error(user["id"], exc, email=user["username"])
    return {"holdings": [normalize_holding(item) for item in data]}


@router.get("/funds")
async def funds(request: Request):
    user = _require_user(request)
    session = get_session(user["id"])
    if not session:
        raise HTTPException(status_code=400, detail="Zerodha is not connected")
    try:
        data = fetch_funds(session["api_key"], session["access_token"])
    except KiteApiError as exc:
        _raise_kite_error(user["id"], exc, email=user["username"])
    equity = data.get("equity", {}) if isinstance(data, dict) else {}
    return {"funds": {**equity, "raw": data}}


@router.get("/equity-curve")
async def equity_curve(request: Request, from_: str = Query("", alias="from")):
    user = _require_user(request)
    session = get_session(user["id"])
    if not session:
        raise HTTPException(status_code=400, detail="Zerodha is not connected")

    try:
        holdings = fetch_holdings(session["api_key"], session["access_token"])
        funds_data = fetch_funds(session["api_key"], session["access_token"])
    except KiteApiError as exc:
        _raise_kite_error(user["id"], exc, email=user["username"])

    try:
        capture_live_equity_snapshot(
            user["id"],
            holdings=holdings,
            funds_data=funds_data,
        )
    except KiteApiError as exc:
        _raise_kite_error(user["id"], exc, email=user["username"])

    now = datetime.utcnow()
    default_start = (now - timedelta(days=90)).date()
    if from_:
        try:
            start_date = datetime.fromisoformat(from_).date()
        except ValueError:
            start_date = default_start
    else:
        start_date = default_start
    if start_date > now.date():
        start_date = now.date()
    return get_live_equity_curve(user["id"], start_date=start_date)


@router.get("/callback")
async def callback(request: Request, request_token: str = ""):
    _capture_request_token(request, request_token)
    return {
        "status": "ok",
        "message": "Request token captured. You can close this tab.",
    }


@router.get("/login")
async def login_redirect(request: Request, request_token: str = ""):
    return await callback(request, request_token=request_token)


@public_router.get("/login", response_class=HTMLResponse)
async def login_capture(request: Request, request_token: str = ""):
    _capture_request_token(request, request_token)
    return (
        "<html><body style=\"font-family:sans-serif;padding:24px;\">"
        "<h3>Request token captured</h3>"
        "<p>You can close this tab and return to QuantFortune.</p>"
        "</body></html>"
    )