"""Minimal {{APP_NAME}} API client for Python 3.10+ (pip install requests).

    gw = GatewayClient(os.environ["GATEWAY_API_KEY"])
    user = gw.create_user("10025", "Asha Patel", "asha@example.com")
    print(user["deposit_wallet"]["deposit_address"])

Amounts are strings: convert with decimal.Decimal, never float().
"""
import time
from decimal import Decimal
from urllib.parse import quote

import requests


class GatewayError(Exception):
    pass


class GatewayClient:
    def __init__(self, api_key: str, base_url: str = "{{BASE_URL}}"):
        self.base_url = base_url
        self.session = requests.Session()
        self.session.headers.update({"Authorization": f"Bearer {api_key}", "Accept": "application/json"})

    def create_user(self, external_id: str, name: str, email: str | None = None) -> dict:
        """Idempotent per external_id: safe to call every time the customer opens your payment page."""
        body = {"external_id": external_id, "name": name}
        if email:
            body["email"] = email
        return self._request("POST", "/api/v1/users", body, idempotency_key=f"user-{external_id}")

    def deposit_address(self, external_id: str) -> str:
        return self._request("POST", f"/api/v1/users/{quote(external_id)}/deposit-wallet")["deposit_address"]

    def portal_link(self, external_id: str) -> str:
        return self._request("POST", f"/api/v1/users/{quote(external_id)}/portal-link")["url"]

    def deposits(self, since_id: int = 0, status: str = "CONFIRMED", limit: int = 100) -> dict:
        return self._request("GET", f"/api/v1/deposits?since_id={since_id}&status={status}&limit={limit}")

    def balance(self) -> Decimal:
        return Decimal(self._request("GET", "/api/v1/balance")["balance"])

    def _request(self, method: str, path: str, body: dict | None = None, idempotency_key: str | None = None) -> dict:
        headers = {"Idempotency-Key": idempotency_key} if idempotency_key else {}
        for attempt in range(1, 5):
            try:
                r = self.session.request(method, self.base_url + path, json=body, headers=headers, timeout=20)
            except requests.RequestException:
                if attempt == 4:
                    raise
                time.sleep(2 ** attempt)
                continue
            data = r.json() if r.content else {}
            # retry 429 / 5xx (POSTs are safe to retry thanks to the Idempotency-Key)
            if (r.status_code == 429 or r.status_code >= 500) and attempt < 4:
                time.sleep(data.get("error", {}).get("retry_after", 2 ** attempt))
                continue
            if not r.ok:
                raise GatewayError(f"{r.status_code}: {data.get('error', {}).get('message', 'no response')}")
            return data
        raise GatewayError("unreachable")