from dataclasses import dataclass
from datetime import datetime

from anydi import singleton
from fansifter_common.auth.requests import AuthRequest
from fansifter_common.auth.services import AuthService
from fansifter_common.auth.types import Permission
from fansifter_common.utils import timezone

from email_campaigns.campaigns.enums import EmailCampaignStatus
from email_campaigns.campaigns.exceptions import EmailCampaignNotFoundError
from email_campaigns.campaigns.repositories.campaign import EmailCampaignRepository
from email_campaigns.campaigns.services.send_time_estimator import (
    SendTimeEstimatorService,
)


@dataclass(kw_only=True)
class EstimateSendTimeRequest(AuthRequest):
    campaign_id: str
    send_at: datetime | None = None


@dataclass(kw_only=True)
class EstimateSendTimeResponse:
    estimated_send_duration: int
    emails_to_send: int
    emails_count: int


@singleton
class EstimateSendTimeHandler:
    permission = Permission("email_campaign", "view")

    def __init__(
        self,
        auth_service: AuthService,
        campaign_repository: EmailCampaignRepository,
        estimator: SendTimeEstimatorService,
    ) -> None:
        self.auth_service = auth_service
        self.campaign_repository = campaign_repository
        self.estimator = estimator

    def handle(self, request: EstimateSendTimeRequest) -> EstimateSendTimeResponse:
        campaign = self.campaign_repository.get(request.campaign_id)
        if not campaign:
            raise EmailCampaignNotFoundError()

        self.auth_service.authorize_account(
            request.identity_id,
            account=campaign.account,
            permission=self.permission,
        )

        if campaign.status not in (
            EmailCampaignStatus.DRAFT,
            EmailCampaignStatus.SCHEDULED,
            EmailCampaignStatus.IN_PROGRESS,
        ):
            return EstimateSendTimeResponse(
                estimated_send_duration=0, emails_to_send=0, emails_count=0
            )

        if not campaign.audience_id or not campaign.email_domain_id:
            return EstimateSendTimeResponse(
                estimated_send_duration=0, emails_to_send=0, emails_count=0
            )

        if campaign.status == EmailCampaignStatus.IN_PROGRESS:
            send_at = timezone.now()
        elif campaign.status == EmailCampaignStatus.SCHEDULED:
            send_at = campaign.send_at or timezone.now()
        else:
            send_at = request.send_at or timezone.now()
            if campaign.status == EmailCampaignStatus.DRAFT:
                campaign.scheduled_at = timezone.now()

        estimated_duration, emails_to_send = self.estimator.estimate_send_duration(
            campaign=campaign,
            send_at=send_at,
        )

        return EstimateSendTimeResponse(
            estimated_send_duration=estimated_duration,
            emails_to_send=emails_to_send,
            emails_count=emails_to_send,
        )