"""Owner agenda: server-rendered week view, manual walk-in/phone bookings,
and owner-initiated cancel/reschedule (#20).

All routes are session-authenticated via owner_auth.login_required and
reuse booking_api.py's create/cancel/reschedule helpers, so the EXCLUDE
constraint (#16) and confirmation email (#18) stay on the single code path
those tickets already established -- this module never calls booking_db.py
directly for a mutation, only for the read-side agenda listing.

Manual creation passes skip_availability_check=True (the "override flag"
#20 asks for): it bypasses opening-hours/min-notice/max-advance/buffer, but
booking_api.create_booking_row still always goes through
booking_db.create_booking, so the Postgres EXCLUDE constraint -- the actual
double-booking guard -- is never bypassable, owner included.
"""
from datetime import datetime, timedelta, timezone
from zoneinfo import ZoneInfo

from flask import Blueprint, redirect, render_template, request, session, url_for

import booking_api as bapi
import booking_db as bdb
from owner_auth import login_required

bp = Blueprint("owner_booking", __name__, url_prefix="/owner")


def _tz(client):
    return ZoneInfo((client or {}).get("timezone") or "Europe/Berlin")


def _week_start(value):
    """Monday (a date) of the week containing value (an ISO date string),
    or of the current week if value is missing/unparseable."""
    try:
        d = datetime.fromisoformat(value).date() if value else datetime.now().date()
    except ValueError:
        d = datetime.now().date()
    return d - timedelta(days=d.weekday())


def _parse_local_start(value, tz):
    """value is a <input type=datetime-local> string (e.g.
    "2026-08-10T14:30"), naive and meant in the client's own timezone --
    never UTC, since that's what an owner typing a time means."""
    try:
        naive = datetime.fromisoformat(value)
    except (TypeError, ValueError):
        return None
    return naive.replace(tzinfo=tz).astimezone(timezone.utc)


def _agenda_redirect(monday, error=None):
    return redirect(url_for("owner_booking.agenda", week=monday.isoformat(), error=error))


def _agenda_days(client_id, client, monday):
    """[(date, [booking, ...]), ...] for the 7 days starting at monday, each
    booking augmented with resource_name/start_local for display."""
    tz = _tz(client)
    start_utc = datetime.combine(monday, datetime.min.time(), tzinfo=tz).astimezone(timezone.utc)
    end_utc = datetime.combine(monday + timedelta(days=7), datetime.min.time(),
                                tzinfo=tz).astimezone(timezone.utc)
    rows = bdb.list_bookings_between(client_id, start_utc, end_utc)
    resource_names = {r["resource_id"]: r["name"] for r in bdb.list_resources(client_id)}

    by_date = {monday + timedelta(days=i): [] for i in range(7)}
    for row in rows:
        local_date = row["start_time"].astimezone(tz).date()
        if local_date not in by_date:
            continue  # a booking straddling the window edge in another tz
        row = dict(row)
        row["resource_name"] = resource_names.get(row["resource_id"], row["resource_id"])
        row["start_local"] = row["start_time"].astimezone(tz)
        by_date[local_date].append(row)
    return sorted(by_date.items())


@bp.get("/agenda")
@login_required
def agenda():
    client_id = session["client_id"]
    client = bdb.get_client(client_id)
    monday = _week_start(request.args.get("week"))
    today = datetime.now(_tz(client)).date()
    return render_template(
        "owner/agenda.html", client=client, days=_agenda_days(client_id, client, monday),
        week_start=monday, today=today,
        prev_week=(monday - timedelta(days=7)).isoformat(),
        next_week=(monday + timedelta(days=7)).isoformat(),
        this_week=_week_start(None).isoformat(),
        resources=bdb.list_active_resources(client_id),
        services=bdb.list_active_services(client_id),
        error=request.args.get("error"))


@bp.post("/bookings")
@login_required
def create_manual_booking():
    client_id = session["client_id"]
    client = bdb.get_client(client_id)
    monday = _week_start(request.form.get("week"))
    start_time = _parse_local_start(request.form.get("start_time"), _tz(client))
    resource_id = request.form.get("resource_id")
    service_id = request.form.get("service_id")
    customer_name = (request.form.get("customer_name") or "").strip()
    customer_contact = (request.form.get("customer_contact") or "").strip()

    if not (start_time and resource_id and service_id and customer_name and customer_contact):
        return _agenda_redirect(monday, error="missing_fields")
    try:
        bapi.create_booking_row(
            client_id, resource_id, service_id, start_time, customer_name,
            customer_contact, source="owner", skip_availability_check=True)
    except bapi.NotFound:
        return _agenda_redirect(monday, error="not_found")
    except bapi.SlotTaken:
        return _agenda_redirect(monday, error="slot_taken")
    return _agenda_redirect(monday)


@bp.post("/bookings/<booking_id>/cancel")
@login_required
def cancel_manual_booking(booking_id):
    client_id = session["client_id"]
    monday = _week_start(request.form.get("week"))
    try:
        bapi.cancel_booking_row(client_id, booking_id)
    except bapi.NotFound:
        return _agenda_redirect(monday, error="not_found")
    except bapi.AlreadyCancelled:
        return _agenda_redirect(monday, error="already_cancelled")
    return _agenda_redirect(monday)


@bp.post("/bookings/<booking_id>/reschedule")
@login_required
def reschedule_manual_booking(booking_id):
    client_id = session["client_id"]
    client = bdb.get_client(client_id)
    monday = _week_start(request.form.get("week"))
    new_start = _parse_local_start(request.form.get("start_time"), _tz(client))
    if new_start is None:
        return _agenda_redirect(monday, error="bad_time")
    try:
        bapi.reschedule_booking_row(client_id, booking_id, new_start)
    except bapi.NotFound:
        return _agenda_redirect(monday, error="not_found")
    except bapi.AlreadyCancelled:
        return _agenda_redirect(monday, error="already_cancelled")
    except bapi.SlotUnavailable:
        return _agenda_redirect(monday, error="unavailable")
    except bapi.SlotTaken:
        return _agenda_redirect(monday, error="slot_taken")
    return _agenda_redirect(monday)