"""User settings + per-sender image allowlist (SPEC §9.1 Settings, §9.4)."""

from __future__ import annotations

import re
from typing import Annotated

from fastapi import APIRouter, Depends
from pydantic import BaseModel
from sqlalchemy import func, select
from sqlalchemy.ext.asyncio import AsyncSession

from app.db import get_session
from app.identity.deps import CurrentUser, require_csrf
from app.models import Message, User

router = APIRouter(prefix="/settings", tags=["settings"])

DbSession = Annotated[AsyncSession, Depends(get_session)]

_ALLOWED_ORDER = {"asc", "desc"}
_ALLOWED_TIME_FORMAT = {"12", "24"}
_ALLOWED_REMINDER_METHOD = {"alert", "email"}
_ALLOWED_INVITE_POLICY = {"add_update", "update_only", "none"}
_ALLOWED_INVITE_FROM = {"contacts", "anyone"}


# "auto", or a LanguageTool language code such as "pl-PL", "en-GB", "de".
_LANG_CODE = re.compile(r"auto|[a-z]{2,3}(-[A-Za-z0-9]{2,8})*")


class ReminderPref(BaseModel):
    method: str = "alert"  # alert = in-app notification, email = email me
    minutes: int = 0  # minutes before the event start (0 = at time of event)


class SettingsOut(BaseModel):
    thread_order: str = "asc"
    tz: str = "UTC"
    time_format: str = "24"  # 12 = AM/PM, 24 = 24-hour (default); applies app-wide
    jitsi_server: str = ""  # blank => https://meet.jit.si/
    default_calendar: str = ""  # calendar id new events default to (blank => first)
    default_reminders_timed: list[ReminderPref] = []  # defaults for timed events
    default_reminders_allday: list[ReminderPref] = []  # defaults for all-day events
    # How emailed events update the calendar: none | update_only | add_update.
    invitation_policy: str = "none"
    invitation_from: str = "contacts"  # whose emailed events auto-add (contacts|anyone)
    invitation_calendar: str = ""  # calendar id emailed events land in (blank => default)
    invitation_file: bool = False  # also mark the invite message read + filed
    allowed_image_senders: list[str] = []
    # Spelling and grammar check in the compose window, and its language
    # ("auto" detects it per message).
    spellcheck_enabled: bool = True
    spellcheck_language: str = "auto"


class SettingsPatch(BaseModel):
    thread_order: str | None = None
    tz: str | None = None
    time_format: str | None = None
    jitsi_server: str | None = None
    default_calendar: str | None = None
    default_reminders_timed: list[ReminderPref] | None = None
    default_reminders_allday: list[ReminderPref] | None = None
    invitation_policy: str | None = None
    invitation_from: str | None = None
    invitation_calendar: str | None = None
    invitation_file: bool | None = None
    spellcheck_enabled: bool | None = None
    spellcheck_language: str | None = None


class QuotaOut(BaseModel):
    used_bytes: int
    quota_bytes: int


def allowed_image_senders(user: User) -> set[str]:
    value = user.settings.get("allowed_image_senders", [])
    if isinstance(value, list):
        return {str(e).lower() for e in value}
    return set()


def add_allowed_image_sender(user: User, email: str) -> None:
    current = sorted(allowed_image_senders(user))
    if email.lower() not in current:
        current.append(email.lower())
    # Reassign the whole dict so SQLAlchemy detects the JSONB change.
    user.settings = {**user.settings, "allowed_image_senders": current}


def _reminder_list(value: object) -> list[ReminderPref]:
    """Normalize stored reminders. Accepts the legacy ``list[int]`` (minutes only,
    method defaults to alert) as well as the ``{method, minutes}`` object form."""
    if not isinstance(value, list):
        return []
    out: list[ReminderPref] = []
    for x in value:
        if isinstance(x, dict):
            method = str(x.get("method", "alert"))
            out.append(
                ReminderPref(
                    method=method if method in _ALLOWED_REMINDER_METHOD else "alert",
                    minutes=int(x.get("minutes", 0)),
                )
            )
        else:
            out.append(ReminderPref(method="alert", minutes=int(x)))
    return out


def _settings_out(user: User) -> SettingsOut:
    s = user.settings
    return SettingsOut(
        thread_order=str(s.get("thread_order", "asc")),
        tz=str(s.get("tz", "UTC")),
        time_format=str(s.get("time_format", "24")),
        jitsi_server=str(s.get("jitsi_server", "")),
        default_calendar=str(s.get("default_calendar", "")),
        default_reminders_timed=_reminder_list(s.get("default_reminders_timed")),
        default_reminders_allday=_reminder_list(s.get("default_reminders_allday")),
        invitation_policy=str(s.get("invitation_policy", "none")),
        invitation_from=str(s.get("invitation_from", "contacts")),
        invitation_calendar=str(s.get("invitation_calendar", "")),
        invitation_file=bool(s.get("invitation_file", False)),
        allowed_image_senders=sorted(allowed_image_senders(user)),
        spellcheck_enabled=bool(s.get("spellcheck_enabled", True)),
        spellcheck_language=str(s.get("spellcheck_language", "auto")),
    )


@router.get("", response_model=SettingsOut)
async def get_settings_endpoint(user: CurrentUser) -> SettingsOut:
    return _settings_out(user)


@router.get("/quota", response_model=QuotaOut)
async def get_quota(user: CurrentUser, db: DbSession) -> QuotaOut:
    """Storage quota and current usage (sum of stored message sizes)."""
    used = await db.scalar(
        select(func.coalesce(func.sum(Message.size_bytes), 0)).where(Message.user_id == user.id)
    )
    return QuotaOut(used_bytes=int(used or 0), quota_bytes=user.quota_bytes)


@router.patch("", response_model=SettingsOut, dependencies=[Depends(require_csrf)])
async def patch_settings(body: SettingsPatch, user: CurrentUser, db: DbSession) -> SettingsOut:
    updates = dict(user.settings)
    if body.thread_order is not None and body.thread_order in _ALLOWED_ORDER:
        updates["thread_order"] = body.thread_order
    if body.tz is not None:
        updates["tz"] = body.tz
    if body.time_format is not None and body.time_format in _ALLOWED_TIME_FORMAT:
        updates["time_format"] = body.time_format
    if body.jitsi_server is not None:
        updates["jitsi_server"] = body.jitsi_server.strip()
    if body.default_calendar is not None:
        updates["default_calendar"] = body.default_calendar
    if body.default_reminders_timed is not None:
        updates["default_reminders_timed"] = [r.model_dump() for r in body.default_reminders_timed]
    if body.default_reminders_allday is not None:
        updates["default_reminders_allday"] = [
            r.model_dump() for r in body.default_reminders_allday
        ]
    if body.invitation_policy is not None and body.invitation_policy in _ALLOWED_INVITE_POLICY:
        updates["invitation_policy"] = body.invitation_policy
    if body.invitation_from is not None and body.invitation_from in _ALLOWED_INVITE_FROM:
        updates["invitation_from"] = body.invitation_from
    if body.invitation_calendar is not None:
        updates["invitation_calendar"] = body.invitation_calendar
    if body.invitation_file is not None:
        updates["invitation_file"] = body.invitation_file
    if body.spellcheck_enabled is not None:
        updates["spellcheck_enabled"] = body.spellcheck_enabled
    if body.spellcheck_language is not None and _LANG_CODE.fullmatch(body.spellcheck_language):
        updates["spellcheck_language"] = body.spellcheck_language
    user.settings = updates
    await db.commit()
    return _settings_out(user)