"""notify-send: deliver the events nobody has handled yet, and the Admin's test send.

Per event: rule off -> dispatched `rule_off`; immediate -> one message to the resolved recipients, one
notifications_sent row, dispatched with the result; digest -> an outbox row, dispatched `queued`.
NOTIFY_DRY_RUN records `dry_run` and sends nothing, except a test send, which always goes.
"""

from __future__ import annotations

import logging
from collections.abc import Sequence
from datetime import datetime
from typing import Any
from zoneinfo import ZoneInfo

from psycopg.rows import dict_row
from psycopg.types.json import Jsonb

from ..settings import Settings
from . import smtp
from .catalog import EVENT_TYPES
from .routing import DIRECTORY_DOWN, DirectoryDown, NotifyDirectory, Recipient, Resolver, load_rules

log = logging.getLogger(__name__)

MAX_DIRECTORY_TRIES = 3
RETRY_PREFIX = "directory_retry:"
BATCH = 200
FOOTER = "Sent by Packet Station. Who gets this is set on the Admin page, Notifications tab."


def record(
    conn: Any,
    *,
    event_type: str,
    subject: str,
    recipients: Sequence[Recipient],
    result: str,
    error: str | None = None,
    event_ids: Sequence[int] = (),
    digest: bool = False,
    test: bool = False,
    requested_by: Any = None,
) -> int:
    row = conn.execute(
        "INSERT INTO notifications_sent (event_type, event_ids, digest, test, subject, recipients, result, error,"
        " requested_by) VALUES (%s, %s, %s, %s, %s, %s, %s, %s, %s) RETURNING id",
        (
            event_type,
            list(event_ids),
            digest,
            test,
            subject,
            Jsonb([r.as_json() for r in recipients]),
            result,
            (error or None) and str(error)[:1000],
            requested_by,
        ),
    ).fetchone()
    return int(row[0])


def deliver(
    settings: Settings, subject: str, body: str, recipients: Sequence[Recipient], *, test: bool = False
) -> tuple[str, str | None]:
    """(result, error) for one message. No recipients -> no_recipients; dry run (not a test) -> dry_run."""
    if not recipients:
        return "no_recipients", None
    if settings.notify_dry_run and not test:
        return "dry_run", None
    try:
        note = smtp.send(settings, subject, body, [r.address for r in recipients])
    except smtp.MailError as e:
        log.warning("notify: mail not sent: %s", e)
        return "failed", str(e)
    return "sent", note


def site_time(settings: Settings, at: datetime | None) -> str:
    if at is None:
        return ""
    return at.astimezone(ZoneInfo(settings.site_tz)).strftime("%Y-%m-%d %H:%M")


def label_of(event_type: str) -> str:
    et = EVENT_TYPES.get(event_type)
    return et.label if et else event_type


def event_title(ev: dict[str, Any]) -> str:
    return str(ev.get("title") or label_of(str(ev.get("event_type"))))


def event_lines(settings: Settings, ev: dict[str, Any]) -> list[str]:
    """The plain-text block for one event (a whole immediate message, or one entry in a digest)."""
    lines = [event_title(ev)]
    if ev.get("body"):
        lines += ["", str(ev["body"]).rstrip()]
    lines.append("")
    lines.append(f"Event: {label_of(str(ev.get('event_type')))}")
    if ev.get("subject"):
        lines.append(f"About: {ev['subject']}")
    if ev.get("dept_code"):
        lines.append(f"Department: {ev['dept_code']}")
    lines.append(f"When: {site_time(settings, ev.get('created_at'))} ({settings.site_tz})")
    if int(ev.get("raised_count") or 1) > 1:
        lines.append(f"Seen {ev['raised_count']} times, last {site_time(settings, ev.get('last_raised_at'))}")
    return lines


def footer(settings: Settings) -> list[str]:
    return ["", "--", f"{FOOTER} Stack {settings.stack}, build {settings.ps_build}."]


def immediate_text(settings: Settings, ev: dict[str, Any]) -> tuple[str, str]:
    return smtp.full_subject(settings, event_title(ev)), "\n".join(event_lines(settings, ev) + footer(settings))


def _tries(result: Any) -> int:
    text = str(result or "")
    if text.startswith(RETRY_PREFIX):
        try:
            return int(text[len(RETRY_PREFIX) :])
        except ValueError:
            return 0
    return 0


def dispatch_pending(conn: Any, settings: Settings, directory: NotifyDirectory | None) -> dict[str, int]:
    """Handle every undispatched event once. Returns counts by outcome."""
    counts: dict[str, int] = {}
    ids = [
        int(r[0])
        for r in conn.execute(
            "SELECT id FROM notification_events WHERE dispatched_at IS NULL AND event_type IS NOT NULL"
            " ORDER BY id LIMIT %s",
            (BATCH,),
        ).fetchall()
    ]
    if not ids:
        return counts
    rules = load_rules(conn)
    resolver = Resolver(conn, settings, directory)
    for eid in ids:
        with conn.transaction(), conn.cursor(row_factory=dict_row) as cur:
            ev = cur.execute(
                "SELECT * FROM notification_events WHERE id = %s AND dispatched_at IS NULL FOR UPDATE SKIP LOCKED",
                (eid,),
            ).fetchone()
            if ev is None:
                continue
            outcome = _dispatch_one(conn, settings, resolver, rules.get(str(ev["event_type"])), dict(ev))
        counts[outcome] = counts.get(outcome, 0) + 1
    return counts


def _done(conn: Any, eid: int, result: str) -> None:
    conn.execute(
        "UPDATE notification_events SET dispatched_at = now(), dispatch_result = %s WHERE id = %s", (result, eid)
    )


def _dispatch_one(conn: Any, settings: Settings, resolver: Resolver, rule: Any, ev: dict[str, Any]) -> str:
    eid = int(ev["id"])
    if rule is None:
        _done(conn, eid, "no_rule")
        return "no_rule"
    if not rule.enabled:
        _done(conn, eid, "rule_off")
        return "rule_off"
    if rule.delivery == "digest":
        conn.execute("INSERT INTO notification_outbox (event_id, event_type) VALUES (%s, %s)", (eid, ev["event_type"]))
        _done(conn, eid, "queued")
        return "queued"
    subject, body = immediate_text(settings, ev)
    try:
        recipients = resolver.resolve(rule, ev.get("dept_code"))
    except DirectoryDown:
        tries = _tries(ev.get("dispatch_result")) + 1
        record(
            conn,
            event_type=ev["event_type"],
            subject=subject,
            recipients=[],
            result="failed",
            error=DIRECTORY_DOWN,
            event_ids=[eid],
        )
        if tries >= MAX_DIRECTORY_TRIES:
            _done(conn, eid, "failed")
            return "failed"
        conn.execute(
            "UPDATE notification_events SET dispatch_result = %s WHERE id = %s", (f"{RETRY_PREFIX}{tries}", eid)
        )
        return "retry"
    result, error = deliver(settings, subject, body, recipients)
    record(
        conn,
        event_type=ev["event_type"],
        subject=subject,
        recipients=recipients,
        result=result,
        error=error,
        event_ids=[eid],
    )
    _done(conn, eid, result)
    return result


# ---------------------------------------------------------------- test send


def send_test(
    conn: Any,
    settings: Settings,
    directory: NotifyDirectory | None,
    event_type: str,
    *,
    to: str | None = None,
    requested_by: Any = None,
) -> dict[str, Any]:
    """Send a test of one event type now, even in dry run. With `to`, only to that address."""
    et = EVENT_TYPES[event_type]
    subject = smtp.full_subject(settings, f"Test: {et.label}")
    body = "\n".join(
        [
            f'This is a test of the Packet Station notification "{et.label}".',
            "",
            et.description,
            "",
            "Nothing has happened. An Admin sent this from the Notifications tab.",
            *footer(settings),
        ]
    )
    recipients: list[Recipient] = []
    error: str | None = None
    result: str | None = None
    if to:
        recipients = [Recipient(to.strip(), None, "test address")]
    else:
        rule = load_rules(conn, event_type).get(event_type)
        try:
            recipients = Resolver(conn, settings, directory).resolve(rule, None) if rule else []
        except DirectoryDown:
            result, error = "failed", DIRECTORY_DOWN
    if result is None:
        result, error = deliver(settings, subject, body, recipients, test=True)
    sent_id = record(
        conn,
        event_type=event_type,
        subject=subject,
        recipients=recipients,
        result=result,
        error=error,
        test=True,
        requested_by=requested_by,
    )
    return {
        "result": result,
        "subject": subject,
        "recipients": [r.as_json() for r in recipients],
        "error": error,
        "sent_id": sent_id,
    }