import hashlib
import json
import os
import urllib.error
import urllib.parse
import urllib.request


KITE_API_BASE = os.getenv("KITE_API_BASE", "https://api.kite.trade")
KITE_LOGIN_URL = os.getenv("KITE_LOGIN_URL", "https://kite.trade/connect/login")
KITE_VERSION = "3"


class KiteApiError(Exception):
    def __init__(self, status_code: int, error_type: str, message: str):
        super().__init__(f"Kite API error {status_code}: {error_type} - {message}")
        self.status_code = status_code
        self.error_type = error_type
        self.message = message


class KiteTokenError(KiteApiError):
    pass


class KitePermissionError(KiteApiError):
    pass


def build_login_url(api_key: str, redirect_url: str | None = None) -> str:
    params = {"api_key": api_key, "v": KITE_VERSION}
    redirect_url = (redirect_url or os.getenv("ZERODHA_REDIRECT_URL") or "").strip()
    if redirect_url:
        params["redirect_url"] = redirect_url
    query = urllib.parse.urlencode(params)
    return f"{KITE_LOGIN_URL}?{query}"


def _request(method: str, url: str, data: dict | None = None, headers: dict | None = None):
    payload = None
    if data is not None:
        payload = urllib.parse.urlencode(data).encode("utf-8")
    req = urllib.request.Request(url, data=payload, headers=headers or {}, method=method)
    try:
        with urllib.request.urlopen(req, timeout=20) as resp:
            body = resp.read().decode("utf-8")
    except urllib.error.HTTPError as err:
        error_body = err.read().decode("utf-8") if err.fp else ""
        try:
            payload = json.loads(error_body) if error_body else {}
        except json.JSONDecodeError:
            payload = {}
        error_type = payload.get("error_type") or payload.get("status") or "unknown_error"
        message = payload.get("message") or error_body or err.reason
        if error_type == "TokenException":
            exc_cls = KiteTokenError
        elif error_type == "PermissionException":
            exc_cls = KitePermissionError
        else:
            exc_cls = KiteApiError
        raise exc_cls(err.code, error_type, message) from err
    return json.loads(body)


def _auth_headers(api_key: str, access_token: str) -> dict:
    return {
        "X-Kite-Version": KITE_VERSION,
        "Authorization": f"token {api_key}:{access_token}",
    }


def exchange_request_token(api_key: str, api_secret: str, request_token: str) -> dict:
    checksum = hashlib.sha256(
        f"{api_key}{request_token}{api_secret}".encode("utf-8")
    ).hexdigest()
    url = f"{KITE_API_BASE}/session/token"
    response = _request(
        "POST",
        url,
        data={
            "api_key": api_key,
            "request_token": request_token,
            "checksum": checksum,
        },
    )
    return response.get("data", {})


def fetch_holdings(api_key: str, access_token: str) -> list:
    url = f"{KITE_API_BASE}/portfolio/holdings"
    response = _request("GET", url, headers=_auth_headers(api_key, access_token))
    return response.get("data", [])


def fetch_funds(api_key: str, access_token: str) -> dict:
    url = f"{KITE_API_BASE}/user/margins"
    response = _request("GET", url, headers=_auth_headers(api_key, access_token))
    return response.get("data", {})


def fetch_ltp_quotes(api_key: str, access_token: str, instruments: list[str]) -> dict:
    symbols = [str(item).strip() for item in instruments if str(item).strip()]
    if not symbols:
        return {}
    query = urllib.parse.urlencode([("i", symbol) for symbol in symbols])
    url = f"{KITE_API_BASE}/quote/ltp?{query}"
    response = _request("GET", url, headers=_auth_headers(api_key, access_token))
    return response.get("data", {})


def fetch_ohlc_quotes(api_key: str, access_token: str, instruments: list[str]) -> dict:
    symbols = [str(item).strip() for item in instruments if str(item).strip()]
    if not symbols:
        return {}
    query = urllib.parse.urlencode([("i", symbol) for symbol in symbols])
    url = f"{KITE_API_BASE}/quote/ohlc?{query}"
    response = _request("GET", url, headers=_auth_headers(api_key, access_token))
    return response.get("data", {})


def fetch_historical_candles(
    api_key: str,
    access_token: str,
    instrument_token: int | str,
    interval: str,
    *,
    from_dt,
    to_dt,
    continuous: bool = False,
    oi: bool = False,
) -> list:
    params = {
        "from": from_dt.strftime("%Y-%m-%d %H:%M:%S"),
        "to": to_dt.strftime("%Y-%m-%d %H:%M:%S"),
        "continuous": 1 if continuous else 0,
        "oi": 1 if oi else 0,
    }
    query = urllib.parse.urlencode(params)
    url = f"{KITE_API_BASE}/instruments/historical/{instrument_token}/{interval}?{query}"
    response = _request("GET", url, headers=_auth_headers(api_key, access_token))
    return response.get("data", {}).get("candles", [])


def place_order(
    api_key: str,
    access_token: str,
    *,
    tradingsymbol: str,
    exchange: str,
    transaction_type: str,
    order_type: str,
    quantity: int,
    product: str,
    price: float | None = None,
    validity: str = "DAY",
    variety: str = "regular",
    market_protection: int | None = None,
    tag: str | None = None,
) -> dict:
    payload = {
        "tradingsymbol": tradingsymbol,
        "exchange": exchange,
        "transaction_type": transaction_type,
        "order_type": order_type,
        "quantity": int(quantity),
        "product": product,
        "validity": validity,
    }
    if price is not None:
        payload["price"] = price
    if market_protection is not None:
        payload["market_protection"] = market_protection
    if tag:
        payload["tag"] = tag

    url = f"{KITE_API_BASE}/orders/{variety}"
    response = _request(
        "POST",
        url,
        data=payload,
        headers=_auth_headers(api_key, access_token),
    )
    return response.get("data", {})


def fetch_orders(api_key: str, access_token: str) -> list:
    url = f"{KITE_API_BASE}/orders"
    response = _request("GET", url, headers=_auth_headers(api_key, access_token))
    return response.get("data", [])


def fetch_order_history(api_key: str, access_token: str, order_id: str) -> list:
    url = f"{KITE_API_BASE}/orders/{order_id}"
    response = _request("GET", url, headers=_auth_headers(api_key, access_token))
    return response.get("data", [])


def cancel_order(
    api_key: str,
    access_token: str,
    *,
    order_id: str,
    variety: str = "regular",
) -> dict:
    url = f"{KITE_API_BASE}/orders/{variety}/{order_id}"
    response = _request("DELETE", url, headers=_auth_headers(api_key, access_token))
    return response.get("data", {})