"""The scheduled send job (SPEC §6.5).

Fires ``UNDO_SECONDS`` after the user hits send. If the outbox row was cancelled
in the meantime, it does nothing (no SMTP traffic). Otherwise: SMTP send, append
to Sent (skipped for Gmail, which self-appends), harvest recipients into
``known_recipients`` (weight 3), and publish ``message.sent``.
"""

from __future__ import annotations

import logging
import uuid
from datetime import UTC, datetime
from typing import Any

from sqlalchemy import select
from sqlalchemy.dialects.postgresql import insert as pg_insert
from sqlalchemy.ext.asyncio import AsyncSession

from app.db import session_scope
from app.events import get_event_bus
from app.indexer import blobstore
from app.models import (
    Account,
    ComposeAttachment,
    Draft,
    KnownRecipient,
    Mailbox,
    Message,
    Outbox,
)
from app.outbox.mime_build import build_mime
from app.sync.provider_factory import build_provider

logger = logging.getLogger(__name__)


def _is_gmail(account: Account) -> bool:
    host = str(account.imap_config.get("host", "")).lower()
    return "gmail.com" in host or "googlemail.com" in host


async def _harvest_recipients(session: AsyncSession, user_id: uuid.UUID, emails: list[str]) -> None:
    now = datetime.now(UTC)
    for email in {e.lower() for e in emails if e}:
        stmt = pg_insert(KnownRecipient).values(
            user_id=user_id, email=email, name="", times_used=3, last_used_at=now
        )
        stmt = stmt.on_conflict_do_update(
            index_elements=[KnownRecipient.user_id, KnownRecipient.email],
            set_={
                "times_used": KnownRecipient.times_used + 3,  # sent-to weight (SPEC §4)
                "last_used_at": stmt.excluded.last_used_at,
            },
        )
        await session.execute(stmt)


async def _load_attachments(
    session: AsyncSession, user_id: uuid.UUID, draft: Draft
) -> list[tuple[str, str, bytes]]:
    """Resolve a draft's compose-attachment ids into (filename, mime, data) tuples."""
    raw_ids = draft.payload.get("attachment_ids") or []
    if not isinstance(raw_ids, list) or not raw_ids:
        return []
    ids: list[uuid.UUID] = []
    for value in raw_ids:
        try:
            ids.append(uuid.UUID(str(value)))
        except ValueError:
            continue
    if not ids:
        return []
    rows = await session.scalars(
        select(ComposeAttachment).where(
            ComposeAttachment.id.in_(ids), ComposeAttachment.user_id == user_id
        )
    )
    by_id = {r.id: r for r in rows}
    out: list[tuple[str, str, bytes]] = []
    for i in ids:
        att = by_id.get(i)
        if att is not None:
            out.append((att.filename, att.mime_type, blobstore.load(user_id, att.blob_sha256)))
    return out


async def send_job(ctx: dict[str, Any], outbox_id: str) -> None:
    """Send a queued message unless it was cancelled during the undo window."""
    oid = uuid.UUID(outbox_id)
    async with session_scope() as session:
        outbox = await session.get(Outbox, oid)
        if outbox is None or outbox.state != "undo_window":
            return  # cancelled, or already handled -> no SMTP traffic
        outbox.state = "sending"
        draft = await session.get(Draft, outbox.draft_id)
        if draft is None:
            outbox.state = "failed"
            outbox.error = "draft missing"
            return
        account = await session.get(Account, draft.account_id)
        reply_to = (
            await session.get(Message, draft.reply_to_message_id)
            if draft.reply_to_message_id
            else None
        )
        if account is None:
            outbox.state = "failed"
            outbox.error = "account missing"
            return
        user_id = outbox.user_id
        attachments = await _load_attachments(session, user_id, draft)
        raw, envelope_from, envelope_to = build_mime(account, draft, reply_to, attachments)
        sent_path = await session.scalar(
            select(Mailbox.path).where(
                Mailbox.account_id == account.id, Mailbox.special_use == "sent"
            )
        )
        gmail = _is_gmail(account)
        account_obj = account

    provider = build_provider(account_obj)
    try:
        await provider.send(raw, envelope_from, envelope_to)
        if sent_path and not gmail:
            await provider.append(sent_path, raw, frozenset({"\\Seen"}))
    except Exception as exc:  # noqa: BLE001 - record and notify, keep the draft
        async with session_scope() as session:
            ob = await session.get(Outbox, oid)
            if ob is not None:
                ob.state = "failed"
                ob.error = str(exc)[:500]
        await get_event_bus().publish(
            "outbox.state_changed",
            {"user_id": str(user_id), "outbox_id": str(oid), "state": "failed"},
        )
        logger.exception("send failed for outbox %s", oid)
        return
    finally:
        await provider.close()

    async with session_scope() as session:
        ob = await session.get(Outbox, oid)
        if ob is not None:
            ob.state = "sent"
        # The message left successfully: drop its draft so it no longer shows in
        # the Drafts folder (undo/cancel returns earlier, keeping the draft).
        draft_row = await session.get(Draft, draft.id)
        if draft_row is not None:
            await session.delete(draft_row)
        await _harvest_recipients(session, user_id, envelope_to)

    bus = get_event_bus()
    await bus.publish(
        "message.sent",
        {"user_id": str(user_id), "outbox_id": str(oid), "thread_id": str(draft.thread_id)},
    )
    await bus.publish(
        "outbox.state_changed",
        {"user_id": str(user_id), "outbox_id": str(oid), "state": "sent"},
    )