# Copyright (c) 2015, Frappe Technologies Pvt. Ltd. and Contributors
# License: GNU General Public License v3. See license.txt

from __future__ import unicode_literals
from itertools import groupby
from operator import itemgetter
import frappe
from frappe.utils import add_to_date, date_diff, getdate, nowdate
from erpnext.accounts.report.general_ledger.general_ledger import execute


def get(filters= None):
    print(filters)
    timespan = filters.get("timespan")
    timegrain = filters.get("timegrain")
    from_date = get_from_date_from_timespan(timespan)
    to_date = nowdate()
    filters = frappe._dict({
        "company": "Gadget Technologies Pvt. Ltd.",
        "from_date": from_date,
        "to_date": to_date,
        "account": "Cash - GTPL",
        "group_by": "Group by Voucher (Consolidated)"
    })
    report_columns, report_results = execute(filters=filters)

    interesting_fields = ["posting_date", "balance"]

    columns = [column for column in report_columns if column["fieldname"] in interesting_fields]

    _results = []
    for row in report_results[1:-2]:
        _results.append([row[key] for key in interesting_fields])

    _results = add_opening_balance(from_date, _results, report_results[0])

    grouped_results = groupby(_results, key=itemgetter(0))

    results = [list(values)[-1] for key, values in grouped_results]

    results = add_missing_dates(results, from_date, to_date)

    results = granulate_results(results, from_date, to_date, timegrain)

    return {
        "labels": [result[0] for result in results],
        "datasets": [{
            "name": "Cash - GTPL",
            "values": [result[1] for result in results]
        }]
    }

def get_from_date_from_timespan(timespan):
    days = months = years = 0
    if "Last Week" == timespan:
        days = -7
    if "Last Month" == timespan:
        months = -1
    elif "Last Quarter" == timespan:
        months = -3
    elif "Last Year" == timespan:
        years = -1
    return add_to_date(None, years=years, months=months, days=days,
        as_string=True, as_datetime=True)


def add_opening_balance(from_date, _results, opening):
    if not _results or (_results[0][0] != getdate(from_date)):
        _results.insert(0, [from_date, opening.balance])
    return _results

def add_missing_dates(incomplete_results, from_date, to_date):
    dates = [r[0] for r in incomplete_results]
    day_count = date_diff(to_date, from_date)

    results_dict = dict(incomplete_results)
    last_date, last_balance = incomplete_results[0]
    results = []
    for date in (add_to_date(getdate(from_date), days=n) for n in range(day_count + 1)):
        if date in results_dict:
            last_date = date
            last_balance = results_dict[date]
        results.append([date, last_balance])
    return results

def get_dates_from_timegrain(from_date, to_date, timegrain):
    days = months = years = 0
    if "Daily" == timegrain:
        days = 1
    elif "Weekly" == timegrain:
        days = 7
    elif "Monthly" == timegrain:
        months = 1
    elif "Quarterly" == timegrain:
        months = 3

    dates = [from_date]
    while dates[-1] <= to_date:
        dates.append(add_to_date(dates[-1], years=years, months=months, days=days))
    return dates

def granulate_results(incomplete_results, from_date, to_date, timegrain):
    dates = set(get_dates_from_timegrain(getdate(from_date), getdate(to_date), timegrain))
    return list(filter(lambda x: x[0] in dates,incomplete_results))