from __future__ import annotations

import re

from django.core.exceptions import ImproperlyConfigured
from rest_framework.settings import api_settings
from rest_framework.throttling import SimpleRateThrottle


class ScopedMobileThrottle(SimpleRateThrottle):
    scope = ""

    def get_rate(self):
        if not self.scope:
            raise ImproperlyConfigured(
                f"{self.__class__.__name__} must define a scope or rate."
            )

        try:
            return api_settings.DEFAULT_THROTTLE_RATES[self.scope]
        except KeyError as exc:
            raise ImproperlyConfigured(
                f'No default throttle rate set for scope "{self.scope}".'
            ) from exc

    def parse_rate(self, rate):
        if rate is None:
            return (None, None)

        num_requests, period = rate.split("/")
        match = re.fullmatch(r"(?:(\d+)\s*)?([smhd]|sec|second|min|minute|hour|day)s?", period.strip(), re.IGNORECASE)
        if not match:
            return super().parse_rate(rate)

        multiplier = int(match.group(1) or "1")
        unit = match.group(2).lower()
        unit_seconds = {
            "s": 1,
            "sec": 1,
            "second": 1,
            "m": 60,
            "min": 60,
            "minute": 60,
            "h": 3600,
            "hour": 3600,
            "d": 86400,
            "day": 86400,
        }[unit]

        return int(num_requests), multiplier * unit_seconds

    def get_mobile_identifier(self, request) -> str | None:
        mobile = None
        try:
            mobile = request.data.get("mobile")
        except Exception:
            mobile = None

        if not isinstance(mobile, str):
            return None

        normalized = "".join(ch for ch in mobile if ch.isdigit())
        return normalized or None

    def get_cache_key(self, request, view):
        ident = self.get_ident(request)
        mobile = self.get_mobile_identifier(request)
        if mobile:
            return self.cache_format % {
                "scope": self.scope,
                "ident": f"{ident}:{mobile}",
            }
        return self.cache_format % {
            "scope": self.scope,
            "ident": ident,
        }

    def allow_request(self, request, view):
        allowed = super().allow_request(request, view)
        if not allowed:
            request._throttle_scope = self.scope
            request._retry_after_seconds = self.wait()
        return allowed


class OTPSendBurstThrottle(ScopedMobileThrottle):
    scope = "otp_send_burst"


class OTPSendSustainedThrottle(ScopedMobileThrottle):
    scope = "otp_send_sustained"


class PasswordLoginThrottle(ScopedMobileThrottle):
    scope = "login_password"


class OTPLoginThrottle(ScopedMobileThrottle):
    scope = "login_otp"