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

import datetime, decimal
from sqlalchemy import sql, func

from ..model import db, Category, SingleExpense, CatExpense, MonthExpense

from ..forms import ExpenseForm

mod = Blueprint('expenses', __name__)

def expense_form(obj=None):
    form = ExpenseForm(obj=obj)
    form.category.query = Category.query.order_by("name")
    return form

def is_last(exp):
    return exp.date >= datetime.date.today().replace(day = 1)

def calc_month_exp(year, month):
    ssum = func.sum(SingleExpense.expense)
    query = SingleExpense.of_month(month, year)

    result = query.group_by(SingleExpense.category_id).\
             values(SingleExpense.category_id, ssum)

    exps = [CatExpense(Category.query.get(c), s, query.filter(SingleExpense.category_id == c)) for c,s in result]

    return MonthExpense(datetime.date(year, month, 1), exps)

def prev_date(exp):
    if exp.date.month == 1:
        return { "year": exp.date.year - 1, "month": 12 }
    else:
        return { "year": exp.date.year, "month": exp.date.month - 1 }

def next_date(exps):
    def _next_date(exp):
        if exp.date.month == 13 - len(exps):
            return { "year": exp.date.year + 1, "month": 1 }
        else:
            return { "year": exp.date.year, "month": exp.date.month + len(exps) }
    return _next_date

@mod.app_template_filter("date")
def format_date(s):
    if hasattr(s, "date"):
        return "%s/%s" % (s.date.year, s.date.month)
    else:
        return "%(year)s/%(month)s" % s

def render_show(exps, is_last):
    return render_template("pages/show.jinja", 
                            exps = exps, is_last = is_last,
                            prev_date = prev_date,
                            next_date = next_date(exps))


@mod.route("/<int(fixed_digits=4):year>/<int(fixed_digits=2):month>")
def show_date(year, month):
    c = calc_month_exp(year, month)
    return render_show([c], is_last(c))

@mod.route("/")
def show(year = None, month = None):
    d = datetime.date.today()
            
    first = calc_month_exp(d.year, d.month)
    if d.month == 1:
        second = calc_month_exp(d.year - 1, 12)
    else:
        second = calc_month_exp(d.year, d.month - 1)

    return render_show([first, second], is_last(first))

@mod.route("/edit/<int:id>", methods=("GET", "POST"))
def edit(id):
    exp = SingleExpense.get(id)
    form = expense_form(exp)

    ret = lambda: render_template("pages/edit.jinja", form=form)

    if request.method == "POST":
        if "deleteB" in request.form:
            db.session.delete(exp)

        elif form.validate(): # change
            form.populate_obj(exp)

        else:
            return ret()

        db.session.commit()
        return redirect(url_for("index"))

    return ret()

@mod.route("/add/", methods=("GET", "POST"))
def add():
    form = expense_form()

    if form.validate_on_submit():
        exp = SingleExpense()

        form.populate_obj(exp)

        db.session.add(exp)
        db.session.commit()

        return redirect(url_for("index"))

    return render_template("pages/add.jinja", form=form)