import json
import urllib.parse
import urllib.request
import urllib.error

class PeiTariffApiError(Exception):
    def __init__(self, message, status=None, code="API_ERROR", request_id=None, details=None):
        super().__init__(message)
        self.status = status
        self.code = code
        self.request_id = request_id
        self.details = details

class PeiTariffApi:
    def __init__(self, api_key, base_url="https://powerexpertindia.com/v1", timeout=15):
        if not api_key:
            raise ValueError("api_key is required")
        self.api_key = api_key
        self.base_url = base_url.rstrip("/")
        self.timeout = timeout

    def request(self, path, method="GET", query=None, body=None):
        url = self.base_url + path
        if query:
            clean = {k: v for k, v in query.items() if v is not None and v != ""}
            if clean:
                url += "?" + urllib.parse.urlencode(clean)

        headers = {
            "Accept": "application/json",
            "X-API-Key": self.api_key,
        }

        data = None
        if body is not None:
            headers["Content-Type"] = "application/json"
            data = json.dumps(body).encode("utf-8")

        req = urllib.request.Request(url, data=data, headers=headers, method=method)

        try:
            with urllib.request.urlopen(req, timeout=self.timeout) as response:
                return json.loads(response.read().decode("utf-8"))
        except urllib.error.HTTPError as error:
            raw = error.read().decode("utf-8", errors="replace")
            try:
                payload = json.loads(raw)
            except Exception:
                payload = {}
            err = payload.get("error", {})
            raise PeiTariffApiError(
                err.get("message", f"API request failed with HTTP {error.code}"),
                error.code,
                err.get("code", "API_ERROR"),
                payload.get("request_id"),
                err.get("details"),
            ) from None

    def health(self):
        return self.request("/health")

    def states(self):
        return self.request("/states")

    def categories(self, **params):
        return self.request("/categories", query=params)

    def tariffs(self, **params):
        return self.request("/tariffs", query=params)

    def sources(self, **params):
        return self.request("/sources", query=params)

    def calculate(self, payload):
        return self.request("/calculate", method="POST", body=payload)

    def solar_savings(self, payload):
        return self.request("/solar-savings", method="POST", body=payload)