"""Envoi d'emails d'information aux bénévoles (récapitulatif de planning)."""

import datetime as dt
import logging
import uuid
from collections import defaultdict
from dataclasses import dataclass
from email.message import EmailMessage

from fastapi import APIRouter, BackgroundTasks, Depends, HTTPException
from sqlmodel import Session, select

from app.api.deps import get_edition
from app.api.schemas import (
    PlanningNotificationRequest,
    PlanningNotificationResult,
    TestEmailRequest,
    TestEmailResult,
)
from app.auth.deps import require_coordinator
from app.auth.magic_link import build_magic_link_url, issue_magic_link_token
from app.config import get_settings
from app.db import get_session
from app.email import edition_logo, render_planning
from app.email.html import render_planning_table
from app.email.sender import build_message, deliver_test, send_messages
from app.i18n import t
from app.models import Account, Assignment, DayPart, Edition, Position, Shift, Volunteer
from app.validation.engine import day_boundary, festival_day

logger = logging.getLogger("app.notifications")

router = APIRouter(
    prefix="/editions/{edition_id}/notifications", tags=["notifications"]
)

_LOGIN_PLACEHOLDER = "{lien_connexion}"


def _login_link(session: Session, edition: Edition, volunteer: Volunteer) -> str:
    """Lien magique personnel si le bénévole a un compte, sinon l'accueil."""
    account = session.exec(
        select(Account)
        .where(Account.edition_id == edition.id)
        .where(Account.volunteer_id == volunteer.id)
        .where(Account.password_hash.is_(None))
    ).first()
    if account is None:
        return build_magic_link_url("").split("?")[0]
    return build_magic_link_url(issue_magic_link_token(session, account))


# Repère du tableau des créneaux dans la version HTML (caractère d'usage
# privé : jamais saisi dans un modèle), remplacé par le vrai tableau.
_SHIFTS_MARKER = "\ue000creneaux\ue000"


@dataclass(frozen=True)
class _PlanningContext:
    """Ce qui sert à composer le récapitulatif de chaque bénévole, chargé
    une fois par envoi."""

    positions: dict[uuid.UUID, Position]
    # Nom + téléphone du référent de chaque poste qui en a un.
    referents: dict[uuid.UUID, str]
    shifts_by_volunteer: dict[uuid.UUID, list[Shift]]
    boundary: dt.time


def _load_context(session: Session, edition: Edition) -> _PlanningContext:
    positions = {
        p.id: p for p in session.exec(select(Position).where(Position.edition_id == edition.id))
    }
    referents: dict[uuid.UUID, str] = {}
    for position_id, referent in session.exec(
        select(Position.id, Volunteer)
        .join(Account, Account.id == Position.lead_account_id)
        .join(Volunteer, Volunteer.id == Account.volunteer_id)
        .where(Position.edition_id == edition.id)
    ):
        name = f"{referent.first_name} {referent.last_name}".strip()
        referents[position_id] = f"{name} · {referent.phone}" if referent.phone else name
    shifts_by_volunteer: dict[uuid.UUID, list[Shift]] = defaultdict(list)
    for volunteer_id, shift in session.exec(
        select(Assignment.volunteer_id, Shift)
        .join(Shift, Shift.id == Assignment.shift_id)
        .where(Assignment.edition_id == edition.id)
    ):
        shifts_by_volunteer[volunteer_id].append(shift)
    boundary = day_boundary(session.exec(select(DayPart).where(DayPart.edition_id == edition.id)))
    return _PlanningContext(positions, referents, shifts_by_volunteer, boundary)


def _day_label(day: dt.date) -> str:
    """« Samedi 11 » — même en-tête de jour que le tableau des badges."""
    return t("badge.table.day_label", weekday=t(f"badge.weekday.{day.weekday()}"), day=day.day)


def _shift_sections(
    shifts: list[Shift], ctx: _PlanningContext
) -> list[tuple[str, list[tuple[str, str, str]]]]:
    """Créneaux regroupés par journée de festival (une nuit reste sur le
    jour où elle a commencé), comme le tableau des badges :
    `[(jour, [(horaire, poste, référent)])]`."""
    by_day: dict[dt.date, list[tuple[str, str, str]]] = defaultdict(list)
    for s in sorted(shifts, key=lambda s: s.starts_at):
        by_day[festival_day(s.starts_at, ctx.boundary)].append(
            (
                f"{s.starts_at:%H:%M}–{s.ends_at:%H:%M}",
                ctx.positions[s.position_id].name,
                ctx.referents.get(s.position_id) or t("email.planning.table.no_referent"),
            )
        )
    return [(_day_label(day), rows) for day, rows in sorted(by_day.items())]


def _shifts_text(sections: list[tuple[str, list[tuple[str, str, str]]]]) -> str:
    """Version texte du tableau (clients mail sans HTML) : le jour, puis
    une ligne par créneau."""
    if not sections:
        return t("email.planning.no_shifts")
    return "\n\n".join(
        day
        + "\n"
        + "\n".join(
            t("email.planning.table.text_line", time=time, position=position, referent=referent)
            for time, position, referent in rows
        )
        for day, rows in sections
    )


@dataclass(frozen=True)
class _PlanningEmail:
    subject: str
    body: str
    # Corps de la version HTML : `{creneaux}` y devient un vrai tableau.
    html_body: str
    html_blocks: dict[str, str]


def _planning_email(
    *,
    ctx: _PlanningContext,
    subject_template: str,
    body_template: str,
    first_name: str,
    last_name: str,
    shifts: list[Shift],
    login_link: str,
) -> _PlanningEmail:
    """Récapitulatif de planning d'un bénévole — partagé par l'envoi réel
    et l'email de test. `{creneaux}` : tableau par jour (horaire, poste,
    référent avec son téléphone), en HTML et en texte."""
    minutes = sum((s.ends_at - s.starts_at).total_seconds() / 60 for s in shifts)
    sections = _shift_sections(shifts, ctx)

    def render(shifts_text: str) -> tuple[str, str]:
        return render_planning(
            subject_template=subject_template,
            body_template=body_template,
            first_name=first_name,
            last_name=last_name,
            shift_count=len(shifts),
            hours=round(minutes / 60, 1),
            shifts_text=shifts_text,
            login_link=login_link,
        )

    subject, body = render(_shifts_text(sections))
    if not sections:
        return _PlanningEmail(subject, body, body, {})
    _, html_body = render(_SHIFTS_MARKER)
    table = render_planning_table(
        sections,
        (
            t("email.planning.table.time"),
            t("email.planning.table.position"),
            t("email.planning.table.referent"),
        ),
    )
    return _PlanningEmail(subject, body, html_body, {_SHIFTS_MARKER: table})


@router.post("/test", response_model=TestEmailResult)
def send_test_email(
    payload: TestEmailRequest,
    edition: Edition = Depends(get_edition),
    _guard: Account = Depends(require_coordinator),
    session: Session = Depends(get_session),
) -> TestEmailResult:
    """Envoie tout de suite à l'adresse saisie le récapitulatif de planning
    **tel que les bénévoles le recevront** : le modèle en cours d'édition
    (`subject`/`body`), variables remplies avec les données d'un vrai
    bénévole, même mise en forme et même logo — sujet préfixé « [Test] ».
    Renvoie le résultat réel du serveur SMTP, pour vérifier à la fois le
    contenu et la configuration d'envoi depuis l'écran « Messages ».
    `{lien_connexion}` y est remplacé par l'adresse de la page de connexion,
    **sans jeton** : un vrai lien magique ouvrirait le compte du bénévole à
    quiconque lit la boîte de test."""
    email = payload.email.strip()
    if "@" not in email or email.startswith("@") or email.endswith("@") or " " in email:
        raise HTTPException(status_code=422, detail={"code": "notifications.invalid_email"})

    ctx = _load_context(session, edition)
    shifts_by_volunteer = ctx.shifts_by_volunteer
    volunteers = list(
        session.exec(
            select(Volunteer)
            .where(Volunteer.edition_id == edition.id)
            .order_by(Volunteer.last_name, Volunteer.first_name)
        )
    )
    example = next((v for v in volunteers if v.id == payload.volunteer_id), None) or next(
        (v for v in volunteers if shifts_by_volunteer.get(v.id)),
        volunteers[0] if volunteers else None,
    )
    composed = _planning_email(
        ctx=ctx,
        subject_template=payload.subject or t("email.planning.default_subject"),
        body_template=payload.body or t("email.planning.default_body"),
        first_name=example.first_name if example else t("email.test.example_first_name"),
        last_name=example.last_name if example else t("email.test.example_last_name"),
        shifts=shifts_by_volunteer.get(example.id, []) if example else [],
        login_link=build_magic_link_url("").split("?")[0],
    )
    message = build_message(
        email,
        t("email.test.subject_prefix", subject=composed.subject),
        composed.body,
        logo=edition_logo(session, edition.id),
        html_body=composed.html_body,
        html_blocks=composed.html_blocks,
    )
    status, detail = deliver_test(message)
    settings = get_settings()
    return TestEmailResult(
        status=status,
        detail=detail,
        smtp_host=f"{settings.smtp_host}:{settings.smtp_port}",
        smtp_from=settings.smtp_from,
        example_volunteer_id=example.id if example else None,
        example_volunteer_name=(
            f"{example.first_name} {example.last_name}".strip() if example else ""
        ),
    )


@router.post("/planning", response_model=PlanningNotificationResult)
def send_planning_notification(
    payload: PlanningNotificationRequest,
    background: BackgroundTasks,
    edition: Edition = Depends(get_edition),
    _guard: Account = Depends(require_coordinator),
    session: Session = Depends(get_session),
) -> PlanningNotificationResult:
    subject_template = payload.subject or t("email.planning.default_subject")
    body_template = payload.body or t("email.planning.default_body")
    wants_login_link = _LOGIN_PLACEHOLDER in subject_template or (
        _LOGIN_PLACEHOLDER in body_template
    )

    stmt = select(Volunteer).where(Volunteer.edition_id == edition.id)
    if payload.volunteer_ids is not None:
        stmt = stmt.where(Volunteer.id.in_(payload.volunteer_ids))
    volunteers = list(session.exec(stmt.order_by(Volunteer.last_name)))

    ctx = _load_context(session, edition)
    logo = edition_logo(session, edition.id)

    messages: list[EmailMessage] = []
    recipients: list[uuid.UUID] = []
    skipped_no_email = 0
    for volunteer in volunteers:
        if not volunteer.email:
            skipped_no_email += 1
            continue
        composed = _planning_email(
            ctx=ctx,
            subject_template=subject_template,
            body_template=body_template,
            first_name=volunteer.first_name,
            last_name=volunteer.last_name,
            shifts=ctx.shifts_by_volunteer.get(volunteer.id, []),
            login_link=(
                _login_link(session, edition, volunteer)
                if wants_login_link
                else ""
            ),
        )
        messages.append(
            build_message(
                volunteer.email,
                composed.subject,
                composed.body,
                logo=logo,
                html_body=composed.html_body,
                html_blocks=composed.html_blocks,
            )
        )
        recipients.append(volunteer.id)

    session.commit()  # persiste les éventuels MagicLinkToken émis
    logger.info(
        "Récapitulatif de planning (édition %s) : %d emails en file, %d bénévoles sans email",
        edition.id,
        len(messages),
        skipped_no_email,
    )
    background.add_task(send_messages, messages)
    return PlanningNotificationResult(
        queued=len(messages),
        skipped_no_email=skipped_no_email,
        recipients=recipients,
    )