# -*- coding: utf-8 -*-
#
# Picard, the next-generation MusicBrainz tagger
#
# Copyright (C) 2021 Gabriel Ferreira
# Copyright (C) 2021 Philipp Wolfer
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.


from collections import deque

from test.picardtestcase import PicardTestCase

from picard.log import _calculate_bounds


class MockLogItem:
    def __init__(self, pos=0):
        self.pos = pos


class MockLogItemQueue:
    def __init__(self):
        self._log_queue = deque(maxlen=10)

    def contents(self, prev=-1):
        if not self._log_queue:
            return []
        offset, length = _calculate_bounds(prev, self._log_queue[0].pos, self._log_queue[-1].pos, len(self._log_queue))

        if offset >= 0:
            return (self._log_queue[i] for i in range(offset, length))
            # If offset < 0, there is a discontinuity in the queue positions
            # Use a slower approach to get the new content.
        else:
            return (x for x in self._log_queue if x.pos > prev)

    def push(self, item):
        self._log_queue.append(item)


class LogQueueCommonTest(PicardTestCase):
    def setUp(self):
        super().setUp()
        self.item_queue = MockLogItemQueue()


class LogQueueBoundsTestCase(LogQueueCommonTest):
    def test_1(self):
        # Common case where the item positions are within the max size of the queue
        # [0,1,2,3,4,5,6,7], len = 8, maxlen = 10, offset = 0
        for i in range(8):
            self.item_queue.push(MockLogItem(i))
        content_list = self.item_queue.contents()
        self.assertListEqual([x.pos for x in content_list], list(range(0, 8)))

    def test_2(self):
        # Common case where the item positions are outside the max size of the queue
        # Which means the positions do not match the index of items in the queue
        # [5,6,7,8,9,10,11,12,13,14], len = 10, offset = len - (last - prev) = 10 - (14-7) = 3
        for i in range(15):
            self.item_queue.push(MockLogItem(i))
        content_list = self.item_queue.contents(7)  # prev value
        self.assertListEqual([x.pos for x in content_list], list(range(8, 15)))

    def test_3(self):
        # Previous case but the previous item (2) was already removed from the queue
        # So we pick the first item in the queue in its place
        # [5,6,7,8,9,10,11,12,13,14], len = 10, maxlen = 10, prev = 5-1 = 4, offset = 0
        for i in range(15):
            self.item_queue.push(MockLogItem(i))
        content_list = self.item_queue.contents(2)
        self.assertListEqual([x.pos for x in content_list], list(range(5, 15)))

    def test_4(self):
        # In case we have only one element but use different prev values
        self.item_queue.push(MockLogItem(10))
        content_list = self.item_queue.contents()  # prev = -1 is smaller than 10, so we update prev from -1 to 10-1 = 9
        self.assertListEqual([x.pos for x in content_list], [10])

        content_list = self.item_queue.contents(2)  # prev = 2 is smaller than 10, so we update prev from 2 to 10-1 = 9
        self.assertListEqual([x.pos for x in content_list], [10])

        content_list = self.item_queue.contents(9)  # prev = 9 is smaller than 10, so we update prev from 9 to 10-1 = 9
        self.assertListEqual([x.pos for x in content_list], [10])

        content_list = self.item_queue.contents(10)  # prev = 10 is equal to 10, so we use it as is
        self.assertListEqual([x.pos for x in content_list], [])

        content_list = self.item_queue.contents(20)  # prev = 20 is bigger than 10, so we use it as is
        self.assertListEqual([x.pos for x in content_list], [])

    def test_5(self):
        # This shouldn't really happen, but here is a test for it
        # In case of a discontinuity e.g. [4,5,11], we have len = 3, prev = 3, last_pos=11,
        #   which results in offset = 3 - (11-4) = -4, which is completely absurd offset, when the correct would be 0
        self.item_queue.push(MockLogItem(4))
        self.item_queue.push(MockLogItem(5))
        self.item_queue.push(MockLogItem(11))
        content_list = self.item_queue.contents(3)
        self.assertListEqual([x.pos for x in content_list], [4, 5, 11])
