"""Author RAG Chatbot SaaS — Email Celery Tasks.

All email sending is done here as background tasks — never blocks API.
"""

from datetime import datetime, timedelta, timezone

import structlog
from app.tasks.celery_app import celery_app

logger = structlog.get_logger(__name__)


@celery_app.task(name="app.tasks.email_task.send_weekly_digests")
def send_weekly_digests():
    """Send weekly digest emails to all authors who opted in."""
    import asyncio
    asyncio.run(_run_weekly_digests())


async def _run_weekly_digests():
    from sqlalchemy import select
    from app.dependencies import _get_session_factory
    from app.models.user import User
    from app.repositories.analytics_repo import AnalyticsRepository
    from app.repositories.access_repo import AccessRepository
    from app.services.email_service import EmailService
    from app.services.token_budget import percent_used

    email = EmailService()
    since = datetime.now(timezone.utc) - timedelta(days=7)
    async with _get_session_factory()() as db:
        result = await db.execute(
            select(User).where(
                User.role == "author",
                User.is_active == True,
                User.notify_weekly_digest == True,
            )
        )
        authors = result.scalars().all()
        analytics = AnalyticsRepository(db)
        access_repo = AccessRepository(db)
        sent = 0
        for author in authors:
            try:
                stats = await analytics.weekly_digest_stats(author.id, since)
                access = await access_repo.get_active_for_author(author.id)
                token_pct = int(round(percent_used(access), 0)) if access else 0
                email.send_weekly_digest(
                    to=author.email,
                    name=author.full_name or author.email,
                    chat_count=stats["chat_count"],
                    top_book=stats["top_book"],
                    token_pct=token_pct,
                    top_country=stats["top_country"],
                )
                sent += 1
            except Exception as e:
                logger.warning("Weekly digest email failed", author_id=author.id, error=str(e))
    logger.info("Weekly digests sent", count=sent)


@celery_app.task(name="app.tasks.email_task.send_token_warning")
def send_token_warning(author_id: str, pct_used: int):
    """Send token budget warning email to an author."""
    import asyncio
    asyncio.run(_send_token_warning(author_id, pct_used))


async def _send_token_warning(author_id: str, pct_used: int):
    from app.dependencies import _get_session_factory
    from app.repositories.access_repo import AccessRepository
    from app.repositories.user_repo import UserRepository
    from app.services.email_service import EmailService
    from app.services.token_budget import total_budget, tokens_remaining

    email = EmailService()
    async with _get_session_factory()() as db:
        user = await UserRepository(db).get_by_id(author_id)
        access = await AccessRepository(db).get_active_for_author(author_id)
        if user and user.notify_token_alerts and access:
            budget = total_budget(access)
            used = access.tokens_used or 0
            remaining = tokens_remaining(access)
            days_left = 30
            if access.expires_at:
                delta = (access.expires_at - datetime.now(timezone.utc)).days
                days_left = max(delta, 1)
            daily = used / max(30 - days_left, 1) if used else 0
            forecast = "soon" if daily > 0 and remaining / daily < 7 else f"in ~{days_left} days"
            email.send_token_budget_warning(
                to=user.email,
                name=user.full_name or user.email,
                pct_used=pct_used,
                tokens_used=used,
                tokens_total=budget,
                forecast_date=forecast,
            )


@celery_app.task(name="app.tasks.email_task.send_publish_help_request")
def send_publish_help_request(payload: dict):
    """Send publish-help request to support and optional author confirmation."""
    from app.services.email_service import EmailService

    email = EmailService()
    try:
        email.send_publish_help_request(**payload)
        author_email = payload.get("author_email")
        if author_email:
            email.send_publish_help_confirmation(
                to=author_email,
                name=payload.get("author_name", author_email),
                book_title=payload.get("book_title", "your book"),
                platform_names=payload.get("platform_names", []),
            )
        logger.info("Publish help emails sent", author_email=author_email)
    except Exception as exc:
        logger.error("Publish help email failed", error=str(exc))
        raise


@celery_app.task(name="app.tasks.email_task.send_contact_request")
def send_contact_request(payload: dict):
    """Send general contact message to support."""
    from app.services.email_service import EmailService

    email = EmailService()
    try:
        email.send_contact_request(**payload)
        logger.info("Contact email sent", author_email=payload.get("author_email"))
    except Exception as exc:
        logger.error("Contact email failed", error=str(exc))
        raise