"""notify-digest: once a rule's digest time has passed today (site time), send what it queued before then.

Recipients are resolved per event, then grouped per address: one message per address listing every event due for
it, across rules. One notifications_sent row per message (event_type 'digest'). An outbox row is marked sent once
every address it goes to has it; a failed send leaves it for the next run, and an address that already has an
event is not sent it again.
"""

from __future__ import annotations

import logging
from datetime import datetime, time, timedelta
from typing import Any
from zoneinfo import ZoneInfo

from psycopg.rows import dict_row

from ..settings import Settings
from . import smtp
from .routing import DIRECTORY_DOWN, DirectoryDown, NotifyDirectory, Recipient, Resolver, load_rules
from .send import deliver, event_lines, footer, record

log = logging.getLogger(__name__)

DEFAULT_TIME = time(7, 0)
BACKOFF = timedelta(minutes=30)


def _due_rows(conn: Any, settings: Settings, rules: dict[str, Any], now: datetime) -> list[dict[str, Any]]:
    tz = ZoneInfo(settings.site_tz)
    pending = [r[0] for r in conn.execute("SELECT DISTINCT event_type FROM notification_outbox WHERE sent_at IS NULL")]
    out: list[dict[str, Any]] = []
    for et in pending:
        rule = rules.get(et)
        at = rule.digest_time if rule is not None else DEFAULT_TIME
        cutoff = datetime.combine(now.astimezone(tz).date(), at, tzinfo=tz)
        if now < cutoff:
            continue
        with conn.cursor(row_factory=dict_row) as cur:
            out.extend(
                dict(r)
                for r in cur.execute(
                    "SELECT o.id AS outbox_id, o.queued_at, e.* FROM notification_outbox o"
                    " JOIN notification_events e ON e.id = o.event_id"
                    " WHERE o.sent_at IS NULL AND o.event_type = %s AND o.queued_at < %s ORDER BY o.id",
                    (et, cutoff),
                ).fetchall()
            )
    return out


def _already(conn: Any, event_ids: list[int]) -> set[tuple[int, str]]:
    """(event id, address) pairs a digest already carried, sent or recorded in dry run."""
    done: set[tuple[int, str]] = set()
    for ids, recips in conn.execute(
        "SELECT event_ids, recipients FROM notifications_sent WHERE digest AND result IN ('sent', 'dry_run')"
        " AND event_ids && %s::bigint[]",
        (event_ids,),
    ).fetchall():
        for rc in recips or []:
            addr = str(rc.get("address") or "").lower()
            done.update((int(i), addr) for i in ids or [])
    return done


def run_digest(
    conn: Any, settings: Settings, directory: NotifyDirectory | None, now: datetime | None = None
) -> dict[str, Any]:
    """Send the due digests. Returns counts."""
    tz = ZoneInfo(settings.site_tz)
    now = now or datetime.now(tz)
    last = conn.execute(
        "SELECT result, at FROM notifications_sent WHERE digest AND NOT test ORDER BY id DESC LIMIT 1"
    ).fetchone()
    rules = load_rules(conn)
    rows = _due_rows(conn, settings, rules, now)
    if not rows:
        return {"due": 0}
    if last is not None and last[0] == "failed" and now - last[1] < BACKOFF:
        return {"due": len(rows), "backoff": True}
    resolver = Resolver(conn, settings, directory)
    per_event: dict[int, list[Recipient]] = {}
    try:
        for r in rows:
            rule = rules.get(str(r["event_type"]))
            per_event[int(r["id"])] = resolver.resolve(rule, r.get("dept_code")) if rule and rule.enabled else []
    except DirectoryDown:
        ids = sorted({int(r["id"]) for r in rows})
        subject = smtp.full_subject(settings, "Daily digest")
        record(
            conn,
            event_type="digest",
            subject=subject,
            recipients=[],
            result="failed",
            error=DIRECTORY_DOWN,
            event_ids=ids,
            digest=True,
        )
        return {"due": len(rows), "failed": 1, "error": DIRECTORY_DOWN}
    done = _already(conn, sorted(per_event))
    by_addr: dict[str, tuple[Recipient, list[dict[str, Any]]]] = {}
    seen_event: dict[str, set[int]] = {}
    for r in rows:
        eid = int(r["id"])
        for rc in per_event[eid]:
            key = rc.address.lower()
            if (eid, key) in done or eid in seen_event.setdefault(key, set()):
                continue
            seen_event[key].add(eid)
            by_addr.setdefault(key, (rc, []))[1].append(r)
    failed_events: set[int] = set()
    sent_by_event: dict[int, int] = {}
    counts: dict[str, Any] = {"due": len(rows), "messages": 0}
    for _key, (rc, events) in sorted(by_addr.items()):
        n = len(events)
        subject = smtp.full_subject(settings, f"Daily digest: {n} notification{'s' if n != 1 else ''}")
        lines: list[str] = [f"{n} Packet Station notification{'s' if n != 1 else ''} since the last digest.", ""]
        for i, ev in enumerate(events, 1):
            block = event_lines(settings, ev)
            lines.append(f"{i}. {block[0]}")
            lines.extend(f"   {x}" if x else "" for x in block[1:])
            lines.append("")
        lines.extend(footer(settings))
        ids = [int(e["id"]) for e in events]
        result, error = deliver(settings, subject, "\n".join(lines), [rc])
        sid = record(
            conn,
            event_type="digest",
            subject=subject,
            recipients=[rc],
            result=result,
            error=error,
            event_ids=ids,
            digest=True,
        )
        counts["messages"] += 1
        counts[result] = counts.get(result, 0) + 1
        if result in ("sent", "dry_run"):
            for i in ids:
                sent_by_event[i] = sid
        else:
            failed_events.update(ids)
    with conn.transaction():
        for r in rows:
            eid = int(r["id"])
            if eid in failed_events:
                continue
            conn.execute(
                "UPDATE notification_outbox SET sent_at = now(), sent_id = %s WHERE id = %s AND sent_at IS NULL",
                (sent_by_event.get(eid), r["outbox_id"]),
            )
    counts["left"] = len({int(r["id"]) for r in rows if int(r["id"]) in failed_events})
    return counts