#include <test/jtx/Env.h>
#include <test/unit_test/SuiteJournal.h>

#include <xrpld/core/ConfigSections.h>

#include <xrpl/basics/BasicConfig.h>
#include <xrpl/basics/Log.h>
#include <xrpl/basics/chrono.h>
#include <xrpl/beast/unit_test.h>
#include <xrpl/ledger/AmendmentTable.h>
#include <xrpl/protocol/Feature.h>
#include <xrpl/protocol/PublicKey.h>
#include <xrpl/protocol/STValidation.h>
#include <xrpl/protocol/SecretKey.h>
#include <xrpl/protocol/TxFlags.h>
#include <xrpl/protocol/digest.h>
#include <xrpl/protocol/jss.h>

namespace xrpl {

class AmendmentTable_test final : public beast::unit_test::suite
{
private:
    static uint256
    amendmentId(std::string in)
    {
        sha256_hasher h;
        using beast::hash_append;
        hash_append(h, in);
        auto const d = static_cast<sha256_hasher::result_type>(h);
        uint256 result;
        std::memcpy(result.data(), d.data(), d.size());
        return result;
    }

    static Section
    makeSection(std::string const& name, std::vector<std::string> const& amendments)
    {
        Section section(name);
        for (auto const& a : amendments)
            section.append(to_string(amendmentId(a)) + " " + a);
        return section;
    }

    static Section
    makeSection(std::vector<std::string> const& amendments)
    {
        return makeSection("Test", amendments);
    }

    static Section
    makeSection(uint256 const& amendment)
    {
        Section section("Test");
        section.append(to_string(amendment) + " " + to_string(amendment));
        return section;
    }

    std::unique_ptr<Config>
    makeConfig()
    {
        auto cfg = test::jtx::envconfig();
        cfg->section(SECTION_AMENDMENTS) = makeSection(SECTION_AMENDMENTS, enabled_);
        cfg->section(SECTION_VETO_AMENDMENTS) = makeSection(SECTION_VETO_AMENDMENTS, vetoed_);
        return cfg;
    }

    static std::vector<AmendmentTable::FeatureInfo>
    makeFeatureInfo(std::vector<std::string> const& amendments, VoteBehavior voteBehavior)
    {
        std::vector<AmendmentTable::FeatureInfo> result;
        result.reserve(amendments.size());
        for (auto const& a : amendments)
        {
            result.emplace_back(a, amendmentId(a), voteBehavior);
        }
        return result;
    }

    static std::vector<AmendmentTable::FeatureInfo>
    makeDefaultYes(std::vector<std::string> const& amendments)
    {
        return makeFeatureInfo(amendments, VoteBehavior::DefaultYes);
    }

    static std::vector<AmendmentTable::FeatureInfo>
    makeDefaultYes(uint256 const amendment)
    {
        std::vector<AmendmentTable::FeatureInfo> result{
            {to_string(amendment), amendment, VoteBehavior::DefaultYes}};
        return result;
    }

    static std::vector<AmendmentTable::FeatureInfo>
    makeDefaultNo(std::vector<std::string> const& amendments)
    {
        return makeFeatureInfo(amendments, VoteBehavior::DefaultNo);
    }

    static std::vector<AmendmentTable::FeatureInfo>
    makeObsolete(std::vector<std::string> const& amendments)
    {
        return makeFeatureInfo(amendments, VoteBehavior::Obsolete);
    }

    template <class Arg, class... Args>
    static size_t
    totalsize(std::vector<Arg> const& src, Args const&... args)
    {
        if constexpr (sizeof...(args) > 0)
            return src.size() + totalsize(args...);
        return src.size();
    }

    template <class Arg, class... Args>
    static void
    combine_arg(std::vector<Arg>& dest, std::vector<Arg> const& src, Args const&... args)
    {
        assert(dest.capacity() >= dest.size() + src.size());
        std::copy(src.begin(), src.end(), std::back_inserter(dest));
        if constexpr (sizeof...(args) > 0)
            combine_arg(dest, args...);
    }

    template <class Arg, class... Args>
    static std::vector<Arg>
    combine(
        // Pass "left" by value. The values will need to be copied one way or
        // another, so just reuse it.
        std::vector<Arg> left,
        std::vector<Arg> const& right,
        Args const&... args)
    {
        left.reserve(totalsize(left, right, args...));

        combine_arg(left, right, args...);

        return left;
    }

    // All useful amendments are supported amendments.
    // Enabled amendments are typically a subset of supported amendments.
    // Vetoed amendments should be supported but not enabled.
    // Unsupported amendments may be added to the AmendmentTable.
    std::vector<std::string> const yes_{"g", "i", "k", "m", "o", "q", "r", "s", "t", "u"};
    std::vector<std::string> const enabled_{"b", "d", "f", "h", "j", "l", "n", "p"};
    std::vector<std::string> const vetoed_{"a", "c", "e"};
    std::vector<std::string> const obsolete_{"0", "1", "2"};
    std::vector<std::string> const allSupported_{combine(yes_, enabled_, vetoed_, obsolete_)};
    std::vector<std::string> const unsupported_{"v", "w", "x"};
    std::vector<std::string> const unsupportedMajority_{"y", "z"};

    Section const emptySection_;
    std::vector<AmendmentTable::FeatureInfo> const emptyYes_;

    test::SuiteJournal journal_;

public:
    AmendmentTable_test() : journal_("AmendmentTable_test", *this)
    {
    }

    std::unique_ptr<AmendmentTable>
    makeTable(
        Application& app,
        std::chrono::seconds majorityTime,
        std::vector<AmendmentTable::FeatureInfo> const& supported,
        Section const& enabled,
        Section const& vetoed)
    {
        return make_AmendmentTable(app, majorityTime, supported, enabled, vetoed, journal_);
    }

    std::unique_ptr<AmendmentTable>
    makeTable(
        test::jtx::Env& env,
        std::chrono::seconds majorityTime,
        std::vector<AmendmentTable::FeatureInfo> const& supported,
        Section const& enabled,
        Section const& vetoed)
    {
        return makeTable(env.app(), majorityTime, supported, enabled, vetoed);
    }

    std::unique_ptr<AmendmentTable>
    makeTable(test::jtx::Env& env, std::chrono::seconds majorityTime)
    {
        static std::vector<AmendmentTable::FeatureInfo> const supported = combine(
            makeDefaultYes(yes_),
            // Use non-intuitive default votes for "enabled_" and "vetoed_"
            // so that when the tests later explicitly enable or veto them,
            // we can be certain that they are not simply going by their
            // default vote setting.
            makeDefaultNo(enabled_),
            makeDefaultYes(vetoed_),
            makeObsolete(obsolete_));
        return makeTable(
            env.app(), majorityTime, supported, makeSection(enabled_), makeSection(vetoed_));
    }

    void
    testConstruct()
    {
        testcase("Construction");
        test::jtx::Env env{*this, makeConfig()};
        auto table = makeTable(env, weeks(1));

        for (auto const& a : allSupported_)
            BEAST_EXPECT(table->isSupported(amendmentId(a)));

        for (auto const& a : yes_)
            BEAST_EXPECT(table->isSupported(amendmentId(a)));

        for (auto const& a : enabled_)
            BEAST_EXPECT(table->isSupported(amendmentId(a)));

        for (auto const& a : vetoed_)
        {
            BEAST_EXPECT(table->isSupported(amendmentId(a)));
            BEAST_EXPECT(!table->isEnabled(amendmentId(a)));
        }

        for (auto const& a : obsolete_)
        {
            BEAST_EXPECT(table->isSupported(amendmentId(a)));
            BEAST_EXPECT(!table->isEnabled(amendmentId(a)));
        }
    }

    void
    testGet()
    {
        testcase("Name to ID mapping");

        test::jtx::Env env{*this, makeConfig()};
        auto table = makeTable(env, weeks(1));

        for (auto const& a : yes_)
            BEAST_EXPECT(table->find(a) == amendmentId(a));
        for (auto const& a : enabled_)
            BEAST_EXPECT(table->find(a) == amendmentId(a));
        for (auto const& a : vetoed_)
            BEAST_EXPECT(table->find(a) == amendmentId(a));
        for (auto const& a : obsolete_)
            BEAST_EXPECT(table->find(a) == amendmentId(a));
        for (auto const& a : unsupported_)
            BEAST_EXPECT(!table->find(a));
        for (auto const& a : unsupportedMajority_)
            BEAST_EXPECT(!table->find(a));

        // Vetoing an unsupported amendment should add the amendment to table.
        // Verify that unsupportedID is not in table.
        uint256 const unsupportedID = amendmentId(unsupported_[0]);
        {
            Json::Value const unsupp =
                table->getJson(unsupportedID, true)[to_string(unsupportedID)];
            BEAST_EXPECT(unsupp.size() == 0);
        }

        // After vetoing unsupportedID verify that it is in table.
        table->veto(unsupportedID);
        {
            Json::Value const unsupp =
                table->getJson(unsupportedID, true)[to_string(unsupportedID)];
            BEAST_EXPECT(unsupp[jss::vetoed].asBool());
        }
    }

    void
    testBadConfig()
    {
        auto const yesVotes = makeDefaultYes(yes_);
        auto const section = makeSection(vetoed_);
        auto const id = to_string(amendmentId(enabled_[0]));

        testcase("Bad Config");

        {  // Two arguments are required - we pass one
            Section test = section;
            test.append(id);

            try
            {
                test::jtx::Env env{*this, makeConfig()};
                if (makeTable(env, weeks(2), yesVotes, test, emptySection_))
                    fail("Accepted only amendment ID");
            }
            catch (std::exception const& e)
            {
                BEAST_EXPECT(e.what() == "Invalid entry '" + id + "' in [Test]");
            }
        }

        {  // Two arguments are required - we pass three
            Section test = section;
            test.append(id + " Test Name");

            try
            {
                test::jtx::Env env{*this, makeConfig()};
                if (makeTable(env, weeks(2), yesVotes, test, emptySection_))
                    fail("Accepted extra arguments");
            }
            catch (std::exception const& e)
            {
                BEAST_EXPECT(e.what() == "Invalid entry '" + id + " Test Name' in [Test]");
            }
        }

        {
            auto sid = id;
            sid.resize(sid.length() - 1);

            Section test = section;
            test.append(sid + " Name");

            try
            {
                test::jtx::Env env{*this, makeConfig()};
                if (makeTable(env, weeks(2), yesVotes, test, emptySection_))
                    fail("Accepted short amendment ID");
            }
            catch (std::exception const& e)
            {
                BEAST_EXPECT(e.what() == "Invalid entry '" + sid + " Name' in [Test]");
            }
        }

        {
            auto sid = id;
            sid.resize(sid.length() + 1, '0');

            Section test = section;
            test.append(sid + " Name");

            try
            {
                test::jtx::Env env{*this, makeConfig()};
                if (makeTable(env, weeks(2), yesVotes, test, emptySection_))
                    fail("Accepted long amendment ID");
            }
            catch (std::exception const& e)
            {
                BEAST_EXPECT(e.what() == "Invalid entry '" + sid + " Name' in [Test]");
            }
        }

        {
            auto sid = id;
            sid.resize(sid.length() - 1);
            sid.push_back('Q');

            Section test = section;
            test.append(sid + " Name");

            try
            {
                test::jtx::Env env{*this, makeConfig()};
                if (makeTable(env, weeks(2), yesVotes, test, emptySection_))
                    fail("Accepted non-hex amendment ID");
            }
            catch (std::exception const& e)
            {
                BEAST_EXPECT(e.what() == "Invalid entry '" + sid + " Name' in [Test]");
            }
        }
    }

    void
    testEnableVeto()
    {
        testcase("enable and veto");

        test::jtx::Env env{*this, makeConfig()};
        std::unique_ptr<AmendmentTable> table = makeTable(env, weeks(2));

        // Note which entries are enabled (convert the amendment names to IDs)
        std::set<uint256> allEnabled;
        for (auto const& a : enabled_)
            allEnabled.insert(amendmentId(a));

        for (uint256 const& a : allEnabled)
            BEAST_EXPECT(table->enable(a));

        // So far all enabled amendments are supported.
        BEAST_EXPECT(!table->hasUnsupportedEnabled());

        // Verify all enables are enabled and nothing else.
        for (std::string const& a : yes_)
        {
            uint256 const supportedID = amendmentId(a);
            bool const enabled = table->isEnabled(supportedID);
            bool const found = allEnabled.contains(supportedID);
            BEAST_EXPECTS(
                enabled == found,
                a + (enabled ? " enabled " : " disabled ") + (found ? " found" : " not found"));
        }

        // All supported and unVetoed amendments should be returned as desired.
        {
            std::set<uint256> vetoed;
            for (std::string const& a : vetoed_)
                vetoed.insert(amendmentId(a));

            std::vector<uint256> const desired = table->getDesired();
            for (uint256 const& a : desired)
                BEAST_EXPECT(not vetoed.contains(a));

            // Unveto an amendment that is already not vetoed.  Shouldn't
            // hurt anything, but the values returned by getDesired()
            // shouldn't change.
            BEAST_EXPECT(!table->unVeto(amendmentId(yes_[1])));
            BEAST_EXPECT(desired == table->getDesired());
        }

        // UnVeto one of the vetoed amendments.  It should now be desired.
        {
            uint256 const unvetoedID = amendmentId(vetoed_[0]);
            BEAST_EXPECT(table->unVeto(unvetoedID));

            std::vector<uint256> const desired = table->getDesired();
            BEAST_EXPECT(std::find(desired.begin(), desired.end(), unvetoedID) != desired.end());
        }

        // Veto all supported amendments.  Now desired should be empty.
        for (std::string const& a : allSupported_)
        {
            table->veto(amendmentId(a));
        }
        BEAST_EXPECT(table->getDesired().empty());

        // Enable an unsupported amendment.
        {
            BEAST_EXPECT(!table->hasUnsupportedEnabled());
            table->enable(amendmentId(unsupported_[0]));
            BEAST_EXPECT(table->hasUnsupportedEnabled());
        }
    }

    // Make a list of trusted validators.
    // Register the validators with AmendmentTable and return the list.
    static std::vector<std::pair<PublicKey, SecretKey>>
    makeValidators(int num, std::unique_ptr<AmendmentTable> const& table)
    {
        std::vector<std::pair<PublicKey, SecretKey>> ret;
        ret.reserve(num);
        hash_set<PublicKey> trustedValidators;
        trustedValidators.reserve(num);
        for (int i = 0; i < num; ++i)
        {
            auto const& back = ret.emplace_back(randomKeyPair(KeyType::secp256k1));
            trustedValidators.insert(back.first);
        }
        table->trustChanged(trustedValidators);
        return ret;
    }

    static NetClock::time_point
    hourTime(std::chrono::hours h)
    {
        return NetClock::time_point{h};
    }

    // Execute a pretend consensus round for a flag ledger
    static void
    doRound(
        Rules const& rules,
        AmendmentTable& table,
        std::chrono::hours hour,
        std::vector<std::pair<PublicKey, SecretKey>> const& validators,
        std::vector<std::pair<uint256, int>> const& votes,
        std::vector<uint256>& ourVotes,
        std::set<uint256>& enabled,
        majorityAmendments_t& majority)
    {
        // Do a round at the specified time
        // Returns the amendments we voted for

        // Parameters:
        // table:      Our table of known and vetoed amendments
        // validators: The addresses of validators we trust
        // votes:      Amendments and the number of validators who vote for them
        // ourVotes:   The amendments we vote for in our validation
        // enabled:    In/out enabled amendments
        // majority:   In/our majority amendments (and when they got a majority)

        auto const roundTime = hourTime(hour);

        // Build validations
        std::vector<std::shared_ptr<STValidation>> validations;
        validations.reserve(validators.size());

        int i = 0;
        for (auto const& [pub, sec] : validators)
        {
            ++i;
            std::vector<uint256> field;

            for (auto const& [hash, nVotes] : votes)
            {
                if (nVotes >= i)
                {
                    // We vote yes on this amendment
                    field.push_back(hash);
                }
            }

            auto v = std::make_shared<STValidation>(
                xrpl::NetClock::time_point{}, pub, sec, calcNodeID(pub), [&field](STValidation& v) {
                    if (!field.empty())
                        v.setFieldV256(sfAmendments, STVector256(sfAmendments, field));
                    v.setFieldU32(sfLedgerSequence, 6180339);
                });

            validations.emplace_back(v);
        }

        ourVotes = table.doValidation(enabled);

        auto actions = table.doVoting(rules, roundTime, enabled, majority, validations);
        for (auto const& [hash, action] : actions)
        {
            // This code assumes other validators do as we do

            switch (action)
            {
                case 0:
                    // amendment goes from majority to enabled
                    if (enabled.contains(hash))
                        Throw<std::runtime_error>("enabling already enabled");
                    if (!majority.contains(hash))
                        Throw<std::runtime_error>("enabling without majority");
                    enabled.insert(hash);
                    majority.erase(hash);
                    break;

                case tfGotMajority:
                    if (majority.contains(hash))
                        Throw<std::runtime_error>("got majority while having majority");
                    majority[hash] = roundTime;
                    break;

                case tfLostMajority:
                    if (!majority.contains(hash))
                        Throw<std::runtime_error>("lost majority without majority");
                    majority.erase(hash);
                    break;

                default:
                    Throw<std::runtime_error>("unknown action");
            }
        }
    }

    // No vote on unknown amendment
    void
    testNoOnUnknown(FeatureBitset const& feat)
    {
        testcase("Vote NO on unknown");

        auto const testAmendment = amendmentId("TestAmendment");

        test::jtx::Env env{*this, feat};
        auto table = makeTable(env, weeks(2), emptyYes_, emptySection_, emptySection_);

        auto const validators = makeValidators(10, table);

        std::vector<std::pair<uint256, int>> votes;
        std::vector<uint256> ourVotes;
        std::set<uint256> enabled;
        majorityAmendments_t majority;

        doRound(
            env.current()->rules(),
            *table,
            weeks{1},
            validators,
            votes,
            ourVotes,
            enabled,
            majority);
        BEAST_EXPECT(ourVotes.empty());
        BEAST_EXPECT(enabled.empty());
        BEAST_EXPECT(majority.empty());

        uint256 const unsupportedID = amendmentId(unsupported_[0]);
        {
            Json::Value const unsupp =
                table->getJson(unsupportedID, false)[to_string(unsupportedID)];
            BEAST_EXPECT(unsupp.size() == 0);
        }

        table->veto(unsupportedID);
        {
            Json::Value const unsupp =
                table->getJson(unsupportedID, false)[to_string(unsupportedID)];
            BEAST_EXPECT(!unsupp[jss::vetoed].asBool());
        }

        votes.emplace_back(testAmendment, validators.size());

        votes.emplace_back(testAmendment, validators.size());

        doRound(
            env.current()->rules(),
            *table,
            weeks{2},
            validators,
            votes,
            ourVotes,
            enabled,
            majority);
        BEAST_EXPECT(ourVotes.empty());
        BEAST_EXPECT(enabled.empty());

        majority[testAmendment] = hourTime(weeks{1});

        // Note that the simulation code assumes others behave as we do,
        // so the amendment won't get enabled
        doRound(
            env.current()->rules(),
            *table,
            weeks{5},
            validators,
            votes,
            ourVotes,
            enabled,
            majority);
        BEAST_EXPECT(ourVotes.empty());
        BEAST_EXPECT(enabled.empty());
    }

    // No vote on vetoed amendment
    void
    testNoOnVetoed(FeatureBitset const& feat)
    {
        testcase("Vote NO on vetoed");

        auto const testAmendment = amendmentId("vetoedAmendment");

        test::jtx::Env env{*this, feat};
        auto table = makeTable(env, weeks(2), emptyYes_, emptySection_, makeSection(testAmendment));

        auto const validators = makeValidators(10, table);

        std::vector<std::pair<uint256, int>> votes;
        std::vector<uint256> ourVotes;
        std::set<uint256> enabled;
        majorityAmendments_t majority;

        doRound(
            env.current()->rules(),
            *table,
            weeks{1},
            validators,
            votes,
            ourVotes,
            enabled,
            majority);
        BEAST_EXPECT(ourVotes.empty());
        BEAST_EXPECT(enabled.empty());
        BEAST_EXPECT(majority.empty());

        votes.emplace_back(testAmendment, validators.size());

        doRound(
            env.current()->rules(),
            *table,
            weeks{2},
            validators,
            votes,
            ourVotes,
            enabled,
            majority);
        BEAST_EXPECT(ourVotes.empty());
        BEAST_EXPECT(enabled.empty());

        majority[testAmendment] = hourTime(weeks{1});

        doRound(
            env.current()->rules(),
            *table,
            weeks{5},
            validators,
            votes,
            ourVotes,
            enabled,
            majority);
        BEAST_EXPECT(ourVotes.empty());
        BEAST_EXPECT(enabled.empty());
    }

    // Vote on and enable known, not-enabled amendment
    void
    testVoteEnable(FeatureBitset const& feat)
    {
        testcase("voteEnable");

        test::jtx::Env env{*this, feat};
        auto table = makeTable(env, weeks(2), makeDefaultYes(yes_), emptySection_, emptySection_);

        auto const validators = makeValidators(10, table);

        std::vector<std::pair<uint256, int>> votes;
        std::vector<uint256> ourVotes;
        std::set<uint256> enabled;
        majorityAmendments_t majority;

        // Week 1: We should vote for all known amendments not enabled
        doRound(
            env.current()->rules(),
            *table,
            weeks{1},
            validators,
            votes,
            ourVotes,
            enabled,
            majority);
        BEAST_EXPECT(ourVotes.size() == yes_.size());
        BEAST_EXPECT(enabled.empty());
        for (auto const& i : yes_)
            BEAST_EXPECT(not majority.contains(amendmentId(i)));

        // Now, everyone votes for this feature
        for (auto const& i : yes_)
            votes.emplace_back(amendmentId(i), validators.size());

        // Week 2: We should recognize a majority
        doRound(
            env.current()->rules(),
            *table,
            weeks{2},
            validators,
            votes,
            ourVotes,
            enabled,
            majority);
        BEAST_EXPECT(ourVotes.size() == yes_.size());
        BEAST_EXPECT(enabled.empty());

        for (auto const& i : yes_)
            BEAST_EXPECT(majority[amendmentId(i)] == hourTime(weeks{2}));

        // Week 5: We should enable the amendment
        doRound(
            env.current()->rules(),
            *table,
            weeks{5},
            validators,
            votes,
            ourVotes,
            enabled,
            majority);
        BEAST_EXPECT(enabled.size() == yes_.size());

        // Week 6: We should remove it from our votes and from having a majority
        doRound(
            env.current()->rules(),
            *table,
            weeks{6},
            validators,
            votes,
            ourVotes,
            enabled,
            majority);
        BEAST_EXPECT(enabled.size() == yes_.size());
        BEAST_EXPECT(ourVotes.empty());
        for (auto const& i : yes_)
            BEAST_EXPECT(not majority.contains(amendmentId(i)));
    }

    // Detect majority at 80%, enable later
    void
    testDetectMajority(FeatureBitset const& feat)
    {
        testcase("detectMajority");

        auto const testAmendment = amendmentId("detectMajority");
        test::jtx::Env env{*this, feat};
        auto table =
            makeTable(env, weeks(2), makeDefaultYes(testAmendment), emptySection_, emptySection_);

        auto const validators = makeValidators(16, table);

        std::set<uint256> enabled;
        majorityAmendments_t majority;

        for (int i = 0; i <= 17; ++i)
        {
            std::vector<std::pair<uint256, int>> votes;
            std::vector<uint256> ourVotes;

            if ((i > 0) && (i < 17))
                votes.emplace_back(testAmendment, i);

            doRound(
                env.current()->rules(),
                *table,
                weeks{i},
                validators,
                votes,
                ourVotes,
                enabled,
                majority);

            if (i < 13)  // 13 => 13/16 = 0.8125 => > 80%
            {
                // We are voting yes, not enabled, no majority
                BEAST_EXPECT(!ourVotes.empty());
                BEAST_EXPECT(enabled.empty());
                BEAST_EXPECT(majority.empty());
            }
            else if (i < 15)
            {
                // We have a majority, not enabled, keep voting
                BEAST_EXPECT(!ourVotes.empty());
                BEAST_EXPECT(!majority.empty());
                BEAST_EXPECT(enabled.empty());
            }
            else if (i == 15)
            {
                // enable, keep voting, remove from majority
                BEAST_EXPECT(!ourVotes.empty());
                BEAST_EXPECT(majority.empty());
                BEAST_EXPECT(!enabled.empty());
            }
            else
            {
                // Done, we should be enabled and not voting
                BEAST_EXPECT(ourVotes.empty());
                BEAST_EXPECT(majority.empty());
                BEAST_EXPECT(!enabled.empty());
            }
        }
    }

    // Detect loss of majority
    void
    testLostMajority(FeatureBitset const& feat)
    {
        testcase("lostMajority");

        auto const testAmendment = amendmentId("lostMajority");

        test::jtx::Env env{*this, feat};
        auto table =
            makeTable(env, weeks(8), makeDefaultYes(testAmendment), emptySection_, emptySection_);

        auto const validators = makeValidators(16, table);

        std::set<uint256> enabled;
        majorityAmendments_t majority;

        {
            // establish majority
            std::vector<std::pair<uint256, int>> votes;
            std::vector<uint256> ourVotes;

            votes.emplace_back(testAmendment, validators.size());

            doRound(
                env.current()->rules(),
                *table,
                weeks{1},
                validators,
                votes,
                ourVotes,
                enabled,
                majority);

            BEAST_EXPECT(enabled.empty());
            BEAST_EXPECT(!majority.empty());
        }

        for (int i = 1; i < 8; ++i)
        {
            std::vector<std::pair<uint256, int>> votes;
            std::vector<uint256> ourVotes;

            // Gradually reduce support
            votes.emplace_back(testAmendment, validators.size() - i);

            doRound(
                env.current()->rules(),
                *table,
                weeks{i + 1},
                validators,
                votes,
                ourVotes,
                enabled,
                majority);

            if (i < 4)  // 16 - 3 = 13 => 13/16 = 0.8125 => > 80%
            {           // 16 - 4 = 12 => 12/16 = 0.75 => < 80%
                // We are voting yes, not enabled, majority
                BEAST_EXPECT(!ourVotes.empty());
                BEAST_EXPECT(enabled.empty());
                BEAST_EXPECT(!majority.empty());
            }
            else
            {
                // No majority, not enabled, keep voting
                BEAST_EXPECT(!ourVotes.empty());
                BEAST_EXPECT(majority.empty());
                BEAST_EXPECT(enabled.empty());
            }
        }
    }

    // Exercise the UNL changing while voting is in progress.
    void
    testChangedUNL(FeatureBitset const& feat)
    {
        testcase("changedUNL");

        auto const testAmendment = amendmentId("changedUNL");
        test::jtx::Env env{*this, feat};
        auto table =
            makeTable(env, weeks(8), makeDefaultYes(testAmendment), emptySection_, emptySection_);

        std::vector<std::pair<PublicKey, SecretKey>> validators = makeValidators(10, table);

        std::set<uint256> enabled;
        majorityAmendments_t majority;

        {
            // 10 validators with 2 voting against won't get majority.
            std::vector<std::pair<uint256, int>> votes;
            std::vector<uint256> ourVotes;

            votes.emplace_back(testAmendment, validators.size() - 2);

            doRound(
                env.current()->rules(),
                *table,
                weeks{1},
                validators,
                votes,
                ourVotes,
                enabled,
                majority);

            BEAST_EXPECT(enabled.empty());
            BEAST_EXPECT(majority.empty());
        }

        // Add one new validator to the UNL.
        validators.emplace_back(randomKeyPair(KeyType::secp256k1));

        // A lambda that updates the AmendmentTable with the latest
        // trusted validators.
        auto callTrustChanged = [](std::vector<std::pair<PublicKey, SecretKey>> const& validators,
                                   std::unique_ptr<AmendmentTable> const& table) {
            // We need a hash_set to pass to trustChanged.
            hash_set<PublicKey> trustedValidators;
            trustedValidators.reserve(validators.size());
            std::for_each(
                validators.begin(), validators.end(), [&trustedValidators](auto const& val) {
                    trustedValidators.insert(val.first);
                });

            // Tell the AmendmentTable that the UNL changed.
            table->trustChanged(trustedValidators);
        };

        // Tell the table that there's been a change in trusted validators.
        callTrustChanged(validators, table);

        {
            // 11 validators with 2 voting against gains majority.
            std::vector<std::pair<uint256, int>> votes;
            std::vector<uint256> ourVotes;

            votes.emplace_back(testAmendment, validators.size() - 2);

            doRound(
                env.current()->rules(),
                *table,
                weeks{2},
                validators,
                votes,
                ourVotes,
                enabled,
                majority);

            BEAST_EXPECT(enabled.empty());
            BEAST_EXPECT(!majority.empty());
        }
        {
            // One of the validators goes flaky and doesn't send validations
            // (without the UNL changing) so the amendment loses majority.
            std::pair<PublicKey, SecretKey> const savedValidator = validators.front();
            validators.erase(validators.begin());

            std::vector<std::pair<uint256, int>> votes;
            std::vector<uint256> ourVotes;

            votes.emplace_back(testAmendment, validators.size() - 2);

            doRound(
                env.current()->rules(),
                *table,
                weeks{3},
                validators,
                votes,
                ourVotes,
                enabled,
                majority);

            BEAST_EXPECT(enabled.empty());
            BEAST_EXPECT(majority.empty());

            // Simulate the validator re-syncing to the network by adding it
            // back to the validators vector
            validators.insert(validators.begin(), savedValidator);

            votes.front().second = validators.size() - 2;

            doRound(
                env.current()->rules(),
                *table,
                weeks{4},
                validators,
                votes,
                ourVotes,
                enabled,
                majority);

            BEAST_EXPECT(enabled.empty());
            BEAST_EXPECT(!majority.empty());

            // Finally, remove one validator from the UNL and see that majority
            // is lost.
            validators.erase(validators.begin());

            // Tell the table that there's been a change in trusted validators.
            callTrustChanged(validators, table);

            votes.front().second = validators.size() - 2;

            doRound(
                env.current()->rules(),
                *table,
                weeks{5},
                validators,
                votes,
                ourVotes,
                enabled,
                majority);

            BEAST_EXPECT(enabled.empty());
            BEAST_EXPECT(majority.empty());
        }
    }

    // Exercise a validator losing connectivity and then regaining it after
    // extended delays.  Depending on how long that delay is an amendment
    // either will or will not go live.
    void
    testValidatorFlapping(FeatureBitset const& feat)
    {
        testcase("validatorFlapping");

        // We run a test where a validator flaps on and off every 23 hours
        // and another one one where it flaps on and off every 25 hours.
        //
        // Since the local validator vote record expires after 24 hours,
        // with 23 hour flapping the amendment will go live.  But with 25
        // hour flapping the amendment will not go live.
        for (int flapRateHours : {23, 25})
        {
            test::jtx::Env env{*this, feat};
            auto const testAmendment = amendmentId("validatorFlapping");
            auto table = makeTable(
                env, weeks(1), makeDefaultYes(testAmendment), emptySection_, emptySection_);

            // Make two lists of validators, one with a missing validator, to
            // make it easy to simulate validator flapping.
            auto const allValidators = makeValidators(11, table);
            decltype(allValidators)
                const mostValidators(allValidators.begin() + 1, allValidators.end());
            BEAST_EXPECT(allValidators.size() == mostValidators.size() + 1);

            std::set<uint256> enabled;
            majorityAmendments_t majority;

            std::vector<std::pair<uint256, int>> votes;
            std::vector<uint256> ourVotes;

            votes.emplace_back(testAmendment, allValidators.size() - 2);

            int delay = flapRateHours;
            // Loop for 1 week plus a day.
            for (int hour = 1; hour < (24 * 8); ++hour)
            {
                decltype(allValidators) const& thisHoursValidators =
                    (delay < flapRateHours) ? mostValidators : allValidators;
                delay = delay == flapRateHours ? 0 : delay + 1;

                votes.front().second = thisHoursValidators.size() - 2;

                using namespace std::chrono;
                doRound(
                    env.current()->rules(),
                    *table,
                    hours(hour),
                    thisHoursValidators,
                    votes,
                    ourVotes,
                    enabled,
                    majority);

                if (hour <= (24 * 7) || flapRateHours > 24)
                {
                    // The amendment should not be enabled under any
                    // circumstance until one week has elapsed.
                    BEAST_EXPECT(enabled.empty());

                    // If flapping is less than 24 hours, there should be
                    // no flapping.  Otherwise we should only have majority
                    // if allValidators vote -- which means there are no
                    // missing validators.
                    bool const expectMajority =
                        (delay <= 24) ? true : &thisHoursValidators == &allValidators;
                    BEAST_EXPECT(majority.empty() != expectMajority);
                }
                else
                {
                    // We're...
                    //  o Past one week, and
                    //  o AmendmentFlapping was less than 24 hours.
                    // The amendment should be enabled.
                    BEAST_EXPECT(!enabled.empty());
                    BEAST_EXPECT(majority.empty());
                }
            }
        }
    }

    void
    testHasUnsupported()
    {
        testcase("hasUnsupportedEnabled");

        using namespace std::chrono_literals;
        weeks constexpr w(1);
        test::jtx::Env env{*this, makeConfig()};
        auto table = makeTable(env, w);
        BEAST_EXPECT(!table->hasUnsupportedEnabled());
        BEAST_EXPECT(!table->firstUnsupportedExpected());
        BEAST_EXPECT(table->needValidatedLedger(1));

        std::set<uint256> enabled;
        std::for_each(unsupported_.begin(), unsupported_.end(), [&enabled](auto const& s) {
            enabled.insert(amendmentId(s));
        });

        majorityAmendments_t majority;
        table->doValidatedLedger(1, enabled, majority);
        BEAST_EXPECT(table->hasUnsupportedEnabled());
        BEAST_EXPECT(!table->firstUnsupportedExpected());

        NetClock::duration t{1000s};
        std::for_each(
            unsupportedMajority_.begin(),
            unsupportedMajority_.end(),
            [&majority, &t](auto const& s) {
                majority[amendmentId(s)] = NetClock::time_point{--t};
            });

        table->doValidatedLedger(1, enabled, majority);
        BEAST_EXPECT(table->hasUnsupportedEnabled());
        BEAST_EXPECT(
            table->firstUnsupportedExpected() &&
            *table->firstUnsupportedExpected() == NetClock::time_point{t} + w);

        // Make sure the table knows when it needs an update.
        BEAST_EXPECT(!table->needValidatedLedger(256));
        BEAST_EXPECT(table->needValidatedLedger(257));
    }

    void
    testFeature(FeatureBitset const& feat)
    {
        testNoOnUnknown(feat);
        testNoOnVetoed(feat);
        testVoteEnable(feat);
        testDetectMajority(feat);
        testLostMajority(feat);
        testChangedUNL(feat);
        testValidatorFlapping(feat);
    }

    void
    run() override
    {
        FeatureBitset const all{test::jtx::testable_amendments()};

        testConstruct();
        testGet();
        testBadConfig();
        testEnableVeto();
        testHasUnsupported();
        testFeature(all);
    }
};

BEAST_DEFINE_TESTSUITE(AmendmentTable, app, xrpl);

}  // namespace xrpl
