import datetime
import os
import re
import logging

_logger = 'rotator'

def parse_filename(name, regex, timeformat):
    log = logging.getLogger(_logger)
    match = regex.search(name)
    if match:
        prefix, date = match.groups()
        log.debug('successfully parsed filename: {}'.format(name))
        return (prefix, datetime.datetime.strptime(date, timeformat))
    return (None, None)

def get_files_in_dir(path, regex, timeformat, recurse=False):
    res = {}
    for root,dirs,files in os.walk(path, topdown=False):
        for f in files:
            prefix, timestamp = parse_filename(f, regex, timeformat)
            if not prefix:
                continue
            if prefix not in res:
                res[prefix] = set()
            res[prefix].add((os.path.join(root,f), timestamp))
        if not recurse:
            return res
    return res

def rotate(
        dirs,
        regex,
        timeformat,
        recurse = False,
        keep_yearly = 0,
        keep_monthly = 0,
        keep_weekly = 0,
        keep_daily = 0,
        keep_hourly = 0,
        keep_30min = 0,
        keep_15min = 0,
        keep_5min = 0,
        keep_1min = 0):

    log = logging.getLogger(_logger)

    merged_filelist = {}
    for d in dirs:
        files = get_files_in_dir(d, regex, timeformat, recurse)
        for prefix in files.keys():
            if prefix not in merged_filelist:
                merged_filelist[prefix] = set()
            merged_filelist[prefix].update(files[prefix])

    for prefix, filelist in merged_filelist.items():
        to_remove = get_deprecated_files(
                filelist,
                keep_yearly,
                keep_monthly,
                keep_weekly,
                keep_daily,
                keep_hourly,
                keep_30min,
                keep_15min,
                keep_5min,
                keep_1min)
        for f in to_remove:
            log.info("removing: {}".format(f))
            os.remove(f)

def get_deprecated_files(
                filelist,
                keep_yearly,
                keep_monthly,
                keep_weekly,
                keep_daily,
                keep_hourly,
                keep_30min,
                keep_15min,
                keep_5min,
                keep_1min):

    dates = [date for path,date in filelist]

    keep = {
            'year' : [],
            'month' : [],
            'week' : [],
            'day' : [],
            'hour' : [],
            'min30' : [],
            'min15' : [],
            'min5' : [],
            'min1' : []
            }
    saved = {
            'year' : [],
            'month' : [],
            'week' : [],
            'day' : [],
            'hour' : [],
            'min30' : [],
            'min15' : [],
            'min5' : [],
            'min1' : []
            }

    for date in sorted(dates):
        min1 = date-datetime.timedelta(seconds=date.second, microseconds=date.microsecond)
        min5 = date-datetime.timedelta(minutes=date.minute%5, seconds=date.second, microseconds=date.microsecond)
        min15 = date-datetime.timedelta(minutes=date.minute%15, seconds=date.second, microseconds=date.microsecond)
        min30 = date-datetime.timedelta(minutes=date.minute%30, seconds=date.second, microseconds=date.microsecond)
        hour = date-datetime.timedelta(minutes=date.minute, seconds=date.second, microseconds=date.microsecond)
        day = datetime.datetime.combine(date.date(), datetime.time.min)
        week = datetime.datetime.combine(date.date()-datetime.timedelta(days=date.weekday()), datetime.time.min)
        month = datetime.datetime(year=date.year, month=date.month, day=1)
        year = datetime.datetime(year=date.year, month=1, day=1)

        if year not in saved['year']:
            saved['year'].append(year)
            keep['year'].append(date)
        if month not in saved['month']:
            saved['month'].append(month)
            keep['month'].append(date)
        if week not in saved['week']:
            saved['week'].append(week)
            keep['week'].append(date)
        if day not in saved['day']:
            saved['day'].append(day)
            keep['day'].append(date)
        if hour not in saved['hour']:
            saved['hour'].append(hour)
            keep['hour'].append(date)
        if min30 not in saved['min30']:
            saved['min30'].append(min30)
            keep['min30'].append(date)
        if min15 not in saved['min15']:
            saved['min15'].append(min15)
            keep['min15'].append(date)
        if min5 not in saved['min5']:
            saved['min5'].append(min5)
            keep['min5'].append(date)
        if min1 not in saved['min1']:
            saved['min1'].append(min1)
            keep['min1'].append(date)

    if keep_yearly:
        keep['year'] = keep['year'][-keep_yearly:]
    else:
        keep['year'] = []
    
    if keep_monthly:
        keep['month'] = keep['month'][-keep_monthly:]
    else:
        keep['month'] = []

    if keep_weekly:
        keep['week'] = keep['week'][-keep_weekly:]
    else:
        keep['week'] = []

    if keep_daily:
        keep['day'] = keep['day'][-keep_daily:]
    else:
        keep['day'] = []

    if keep_hourly:
        keep['hour'] = keep['hour'][-keep_hourly:]
    else:
        keep['hour'] = []

    if keep_30min:
        keep['min30'] = keep['min30'][-keep_30min:]
    else:
        keep['min30'] = []

    if keep_15min:
        keep['min15'] = keep['min15'][-keep_15min:]
    else:
        keep['min15'] = []

    if keep_5min:
        keep['min5'] = keep['min5'][-keep_5min:]
    else:
        keep['min5'] = []

    if keep_1min:
        keep['min1'] = keep['min1'][-keep_1min:]
    else:
        keep['min1'] = []

    all_keep = []
    all_keep.extend(keep['year'])
    all_keep.extend(keep['month'])
    all_keep.extend(keep['week'])
    all_keep.extend(keep['day'])
    all_keep.extend(keep['hour'])
    all_keep.extend(keep['min30'])
    all_keep.extend(keep['min15'])
    all_keep.extend(keep['min5'])
    all_keep.extend(keep['min1'])
    all_keep = set(all_keep)

    to_remove = [date for date in dates if date not in all_keep]
    return [path for path,date in filelist if date not in all_keep]