// Copyright (c) 2011-2015 The Bitcoin Core developers
// Copyright (c) 2017-2020 The Bitcoin developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
//
#include <timedata.h>

#include <netaddress.h>
#include <noui.h>
#include <warnings.h>

#include <test/setup_common.h>

#include <string>

#include <boost/test/unit_test.hpp>

BOOST_FIXTURE_TEST_SUITE(timedata_tests, BasicTestingSetup)

BOOST_AUTO_TEST_CASE(util_MedianFilter) {
    CMedianFilter<int> filter(5, 15);

    BOOST_CHECK_EQUAL(filter.median(), 15);

    filter.input(20); // [15 20]
    BOOST_CHECK_EQUAL(filter.median(), 17);

    filter.input(30); // [15 20 30]
    BOOST_CHECK_EQUAL(filter.median(), 20);

    filter.input(3); // [3 15 20 30]
    BOOST_CHECK_EQUAL(filter.median(), 17);

    filter.input(7); // [3 7 15 20 30]
    BOOST_CHECK_EQUAL(filter.median(), 15);

    filter.input(18); // [3 7 18 20 30]
    BOOST_CHECK_EQUAL(filter.median(), 18);

    filter.input(0); // [0 3 7 18 30]
    BOOST_CHECK_EQUAL(filter.median(), 7);

    // lastly, check the .sorted() array matches what we expect
    const auto expectedSorted = decltype(filter.sorted()) {{0, 3, 7, 18, 30}};
    BOOST_CHECK(filter.sorted() == expectedSorted);
}

static void MultiAddTimeData(int n, int64_t offset) {
    static int cnt = 0;
    for (int i = 0; i < n; ++i) {
        CNetAddr addr;
        addr.SetInternal(std::to_string(++cnt));
        AddTimeData(addr, offset);
    }
}

BOOST_AUTO_TEST_CASE(addtimedata) {
    BOOST_CHECK_EQUAL(GetTimeOffset(), 0);

    // Part 1: Add large offsets to test a warning message that our clock may be
    // wrong.
    MultiAddTimeData(3, DEFAULT_MAX_TIME_ADJUSTMENT + 1);
    // Filter size is 1 + 3 = 4: It is always initialized with a single element
    // (offset 0)

    noui_suppress();
    // filter size 5
    MultiAddTimeData(1, DEFAULT_MAX_TIME_ADJUSTMENT + 1);
    noui_reconnect();

    BOOST_CHECK(GetWarnings("gui").find("clock is wrong") != std::string::npos);

    // nTimeOffset is not changed if the median of offsets exceeds
    // DEFAULT_MAX_TIME_ADJUSTMENT
    BOOST_CHECK_EQUAL(GetTimeOffset(), 0);

    // Part 2: Test positive and negative medians by adding more offsets
    // filter size 9
    MultiAddTimeData(4, 100);
    BOOST_CHECK_EQUAL(GetTimeOffset(), 100);
    // filter size 19
    MultiAddTimeData(10, -100);
    BOOST_CHECK_EQUAL(GetTimeOffset(), -100);

    // Part 3: Test behaviour when filter has reached maximum number of offsets
    const int MAX_SAMPLES = 200;
    int nfill = (MAX_SAMPLES - 3 - 19) / 2; // 89
    MultiAddTimeData(nfill, 100);
    // filter size MAX_SAMPLES - 3
    MultiAddTimeData(nfill, -100);
    BOOST_CHECK_EQUAL(GetTimeOffset(), -100);

    MultiAddTimeData(2, 100);
    // filter size MAX_SAMPLES -1, median is the initial 0 offset
    // since we added same number of positive/negative offsets

    BOOST_CHECK_EQUAL(GetTimeOffset(), 0);

    // After the number of offsets has reached MAX_SAMPLES -1 (=199),
    // nTimeOffset will never change because it is only updated when the number
    // of elements in the filter becomes odd. It was decided not to fix this
    // because it prevents possible attacks. See the comment in AddTimeData() or
    // issue #4521 for a more detailed explanation.

    // filter median is 100 now, but nTimeOffset will not change
    MultiAddTimeData(2, 100);
    BOOST_CHECK_EQUAL(GetTimeOffset(), 0);

    // We want this test to end with nTimeOffset==0, otherwise subsequent tests
    // of the suite will fail.
}

BOOST_AUTO_TEST_SUITE_END()
