# -*- coding: utf-8 -*-
from . import Blueprint, flash, db, \
        current_user, login_required, \
        assert_authorisation, templated, redirect, request, \
        today

from ..model import Category, ConstExpense
from .. import forms as F

from sqlalchemy import sql
from functools import partial

mod = Blueprint('consts', __name__)
assert_authorisation = partial(assert_authorisation, ConstExpense.get)

def one_year(d):
    """Returns the date d', such that [d, d'] spans exactly one year.
    In effect, this is d + 11 months (NB: not 12!)"""
    if d.month == 1:
        return d.replace(month = 12)
    else:
        return d.replace(month = d.month - 1, year = d.year + 1)

#
# Form
#
class ConstForm(F.Form):
    start = F.DateField('Beginn', F.req,
            format='%m.%Y',
            default=lambda: today())

    end = F.DateField('Ende', F.req,
            format='%m.%Y',
            default=lambda: one_year(today()),
            description='(einschließlich)')

    months = F.IntegerField('Zahlungsrythmus', F.req,
            description='Monate')

    expense = F.DecimalField('Betrag', F.req,
            description='EUR',
            places=2)

    description = F.StringField('Beschreibung', F.req)

    category = F.QuerySelectField('Kategorie',
            get_label='name')

    prev = F.QuerySelectField('Vorgänger',
            get_label='description',
            allow_blank=True)

    def __init__(self, cur=None, obj=None):
        obj = cur if obj is None else obj
        super().__init__(obj=obj)
        self.category.query = Category.of(current_user).order_by(Category.name)

        # init prev_list
        CE = ConstExpense

        filter = (CE.next == None)

        if cur and cur.id is not None: # not empty
            filter = sql.or_(CE.next == cur, filter)
            filter = sql.and_(filter, CE.id != cur.id)

        self.prev.query = CE.of(current_user).filter(filter).order_by(CE.description)

#
# Views
#
@mod.route('/')
@login_required
@templated
def list ():
    """List all constant expenses."""
    d = today().replace(day = 1)

    expenses = ConstExpense.of(current_user).order_by(ConstExpense.description).all()

    current = []
    old = []
    future = []
    last_month = []

    for e in expenses:
        if e.start <= d:
            if e.end >= d:
                current.append(e)
            else:
                if (d.month == 1 and e.end.month == 12 and e.end.year == d.year - 1) \
                    or (e.end.year == d.year and e.end.month == d.month - 1):
                        last_month.append(e)
                else:
                    old.append(e)
        else:
            future.append(e)

    return { 'current': current, 'old': old, 'future': future, 'last_month': last_month }


@mod.route('/<int:id>')
@login_required
@assert_authorisation('id')
@templated
def show(id):
    """Show a specific constant expense."""
    return { 'exp': ConstExpense.get(id) }


@mod.route('/edit/<int:id>', methods=('GET', 'POST'))
@login_required
@assert_authorisation('id')
@templated
def edit(id):
    """Edit a specific constant expense. This includes deletion."""
    exp = ConstExpense.get(id)
    form = ConstForm(exp)

    if form.is_submitted():
        if 'deleteB' in request.form:
            db.session.delete(exp)
            db.session.commit()
            return redirect('.list')

        elif form.flash_validate(): # change
            form.populate_obj(exp)
            db.session.commit()
            flash("Eintrag geändert.")
            return redirect('.show', id = id)

    return { 'form': form }


@mod.route('/add/', methods=('GET', 'POST'))
@login_required
@templated
def add():
    """Add a new constant expense."""
    exp = ConstExpense()

    form = ConstForm()

    if form.validate_on_submit():
        form.populate_obj(exp)
        exp.user = current_user
        db.session.add(exp)
        db.session.commit()
        flash("Eintrag hinzugefügt.")
        return redirect('.show', id = exp.id)

    return { 'form': form }


@mod.route('/add/from/<int:other>')
@login_required
@assert_authorisation('other')
@templated('.add')
def add_from(other):
    """Copy `other` and create a new expense based on it."""
    exp = ConstExpense() # needed to initialize 'CE.next'

    other = ConstExpense.get(other)

    # get form with data from other
    form = ConstForm(obj = other)

    # replace some fields to be more meaningful
    start = max(form.end.data, today())
    form.start.data = start
    form.end.data = one_year(start)
    if not other.next: form.prev.data = other

    return { 'form': form }