import datetime
from dataclasses import dataclass

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.adapters.db.decorators import transactional
from email_campaigns.audiences.exceptions import InvalidAudienceIdError
from email_campaigns.audiences.repositories import AudienceRepository
from email_campaigns.campaigns.enums import EmailCampaignStatus
from email_campaigns.campaigns.exceptions import (
    CampaignAlreadyQueuedError,
    EmailCampaignMustBeScheduledError,
    EmailCampaignSendAtMustBeFutureError,
)
from email_campaigns.campaigns.services import EmailCampaignService
from email_campaigns.campaigns.validators import CampaignValidator


@dataclass(kw_only=True)
class EditScheduleCampaignRequest(AuthRequest):
    campaign_id: str
    send_at: datetime.datetime
    timezone: str


@singleton
class EditScheduleCampaignHandler:
    permission = Permission("email_campaign", "schedule")

    def __init__(
        self,
        auth_service: AuthService,
        campaign_validator: CampaignValidator,
        campaign_service: EmailCampaignService,
        audience_repository: AudienceRepository,
    ) -> None:
        self.auth_service = auth_service
        self.campaign_validator = campaign_validator
        self.campaign_service = campaign_service
        self.audience_repository = audience_repository

    @transactional
    def handle(self, request: EditScheduleCampaignRequest) -> None:
        campaign = self.campaign_service.get_campaign(request.campaign_id)

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

        # Do not allow edit schedule of non-scheduled campaigns
        if not campaign.is_scheduled:
            raise EmailCampaignMustBeScheduledError

        # Do not allow edit schedule of campaigns
        # that are already in the send queue
        if self.campaign_service.should_enqueue_campaign(campaign):
            raise CampaignAlreadyQueuedError

        # Validate send date
        if request.send_at < timezone.now():
            raise EmailCampaignSendAtMustBeFutureError

        # Validate required fields
        self.campaign_validator.validate_required_fields(campaign, raise_on_error=True)

        # Ensure that the audience is set and correct
        audience = self.audience_repository.get(campaign.audience_id)
        if audience is None:
            raise InvalidAudienceIdError

        self.campaign_validator.validate_audience(audience)

        campaign.status = EmailCampaignStatus.SCHEDULED
        campaign.send_at = request.send_at
        campaign.scheduled_at = timezone.now()
        campaign.recipients_count = audience.fan_count
        campaign.updated_by = request.identity_id
        campaign.send_at_timezone = request.timezone

        # Save the email campaign
        self.campaign_service.save_campaign(campaign)