"""Implements various support classes and functions used in a number of
places in Roundup code.
"""

from __future__ import print_function
__docformat__ = 'restructuredtext'

import os, time, sys


class TruthDict:
    '''Returns True for valid keys, False for others.
    '''

    __slots__ = ('keys',)

    def __init__(self, keys):
        if keys:
            self.keys = {}
            for col in keys:
                self.keys[col] = 1

    def __getitem__(self, name):
        if hasattr(self, 'keys'):
            return name in self.keys
        else:
            return True


def ensureParentsExist(dest):
    if not os.path.exists(os.path.dirname(dest)):
        os.makedirs(os.path.dirname(dest))


class PrioList:
    '''Manages a sorted list.

    Currently only implements method 'append' and iteration from a
    full list interface.
    Implementation: We manage a "sorted" status and sort on demand.
    Appending to the list will require re-sorting before use.
    >>> p = PrioList()
    >>> for i in 5,7,1,-1:
    ...  p.append(i)
    ...
    >>> for k in p:
    ...  print (k)
    ...
    -1
    1
    5
    7

    '''

    __slots__ = ('key', 'list', 'sorted')

    def __init__(self, key=None):
        self.list = []
        self.key = key
        self.sorted = True

    def append(self, item):
        self.list.append(item)
        self.sorted = False

    def __iter__(self):
        if not self.sorted:
            self.list.sort(key=self.key)
            self.sorted = True
        return iter(self.list)


class Progress:
    '''Progress display for console applications.

    '''
    def __init__(self, info, sequence):
        self.info = info
        self.sequence = iter(sequence)
        self.total = len(sequence)
        self.start = self.now = time.time()
        self.num = 0
        self.stepsize = self.total // 100 or 1
        self.steptimes = []
        self.display()

    def __iter__(self): return self

    def __next__(self):
        self.num += 1

        if self.num > self.total:
            print(self.info, 'done', ' '*(75-len(self.info)-6))
            sys.stdout.flush()
            return next(self.sequence)

        if self.num % self.stepsize:
            return next(self.sequence)

        self.display()
        return next(self.sequence)
    # Python 2 compatibility:
    next = __next__

    def display(self):
        # figure how long we've spent - guess how long to go
        now = time.time()
        steptime = now - self.now
        self.steptimes.insert(0, steptime)
        if len(self.steptimes) > 5:
            self.steptimes.pop()
        steptime = sum(self.steptimes) / len(self.steptimes)
        self.now = now
        eta = steptime * ((self.total - self.num)/self.stepsize)

        # tell it like it is (or might be)
        if now - self.start > 3:
            M = eta / 60
            H = M / 60
            M = M % 60
            S = eta % 60
            if self.total:
                s = '%s %2d%% (ETA %02d:%02d:%02d)' % (self.info,
                    self.num * 100. / self.total, H, M, S)
            else:
                s = '%s 0%% (ETA %02d:%02d:%02d)' % (self.info, H, M, S)
        elif self.total:
            s = '%s %2d%%' % (self.info, self.num * 100. / self.total)
        else:
            s = '%s %d done' % (self.info, self.num)
        sys.stdout.write(s + ' '*(75-len(s)) + '\r')
        sys.stdout.flush()

# vim: set et sts=4 sw=4 :