// Copyright (c) 2020-2021 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
//
#include <chainparams.h>
#include <consensus/validation.h>
#include <random.h>
#include <rpc/blockchain.h>
#include <sync.h>
#include <test/util/chainstate.h>
#include <test/util/setup_common.h>
#include <uint256.h>
#include <validation.h>

#include <vector>

#include <boost/test/unit_test.hpp>

BOOST_FIXTURE_TEST_SUITE(validation_chainstate_tests, ChainTestingSetup)

//! Test resizing coins-related Chainstate caches during runtime.
//!
BOOST_AUTO_TEST_CASE(validation_chainstate_resize_caches)
{
    ChainstateManager& manager = *Assert(m_node.chainman);
    CTxMemPool& mempool = *Assert(m_node.mempool);

    //! Create and add a Coin with DynamicMemoryUsage of 80 bytes to the given view.
    auto add_coin = [](CCoinsViewCache& coins_view) -> COutPoint {
        Coin newcoin;
        uint256 txid = InsecureRand256();
        COutPoint outp{txid, 0};
        newcoin.nHeight = 1;
        newcoin.out.nValue = InsecureRand32();
        newcoin.out.scriptPubKey.assign((uint32_t)56, 1);
        coins_view.AddCoin(outp, std::move(newcoin), false);

        return outp;
    };

    Chainstate& c1 = WITH_LOCK(cs_main, return manager.InitializeChainstate(&mempool));
    c1.InitCoinsDB(
        /*cache_size_bytes=*/1 << 23, /*in_memory=*/true, /*should_wipe=*/false);
    WITH_LOCK(::cs_main, c1.InitCoinsCache(1 << 23));
    BOOST_REQUIRE(c1.LoadGenesisBlock()); // Need at least one block loaded to be able to flush caches

    // Add a coin to the in-memory cache, upsize once, then downsize.
    {
        LOCK(::cs_main);
        auto outpoint = add_coin(c1.CoinsTip());

        // Set a meaningless bestblock value in the coinsview cache - otherwise we won't
        // flush during ResizecoinsCaches() and will subsequently hit an assertion.
        c1.CoinsTip().SetBestBlock(InsecureRand256());

        BOOST_CHECK(c1.CoinsTip().HaveCoinInCache(outpoint));

        c1.ResizeCoinsCaches(
            1 << 24,  // upsizing the coinsview cache
            1 << 22  // downsizing the coinsdb cache
        );

        // View should still have the coin cached, since we haven't destructed the cache on upsize.
        BOOST_CHECK(c1.CoinsTip().HaveCoinInCache(outpoint));

        c1.ResizeCoinsCaches(
            1 << 22,  // downsizing the coinsview cache
            1 << 23  // upsizing the coinsdb cache
        );

        // The view cache should be empty since we had to destruct to downsize.
        BOOST_CHECK(!c1.CoinsTip().HaveCoinInCache(outpoint));
    }
}

//! Test UpdateTip behavior for both active and background chainstates.
//!
//! When run on the background chainstate, UpdateTip should do a subset
//! of what it does for the active chainstate.
BOOST_FIXTURE_TEST_CASE(chainstate_update_tip, TestChain100Setup)
{
    ChainstateManager& chainman = *Assert(m_node.chainman);
    uint256 curr_tip = ::g_best_block;

    // Mine 10 more blocks, putting at us height 110 where a valid assumeutxo value can
    // be found.
    mineBlocks(10);

    // After adding some blocks to the tip, best block should have changed.
    BOOST_CHECK(::g_best_block != curr_tip);

    BOOST_REQUIRE(CreateAndActivateUTXOSnapshot(m_node, m_path_root));

    // Ensure our active chain is the snapshot chainstate.
    BOOST_CHECK(WITH_LOCK(::cs_main, return chainman.IsSnapshotActive()));

    curr_tip = ::g_best_block;

    // Mine a new block on top of the activated snapshot chainstate.
    mineBlocks(1);  // Defined in TestChain100Setup.

    // After adding some blocks to the snapshot tip, best block should have changed.
    BOOST_CHECK(::g_best_block != curr_tip);

    curr_tip = ::g_best_block;

    BOOST_CHECK_EQUAL(chainman.GetAll().size(), 2);

    Chainstate& background_cs{*[&] {
        for (Chainstate* cs : chainman.GetAll()) {
            if (cs != &chainman.ActiveChainstate()) {
                return cs;
            }
        }
        assert(false);
    }()};

    // Create a block to append to the validation chain.
    std::vector<CMutableTransaction> noTxns;
    CScript scriptPubKey = CScript() << ToByteVector(coinbaseKey.GetPubKey()) << OP_CHECKSIG;
    CBlock validation_block = this->CreateBlock(noTxns, scriptPubKey, background_cs);
    auto pblock = std::make_shared<const CBlock>(validation_block);
    BlockValidationState state;
    CBlockIndex* pindex = nullptr;
    const CChainParams& chainparams = Params();
    bool newblock = false;

    // TODO: much of this is inlined from ProcessNewBlock(); just reuse PNB()
    // once it is changed to support multiple chainstates.
    {
        LOCK(::cs_main);
        bool checked = CheckBlock(*pblock, state, chainparams.GetConsensus());
        BOOST_CHECK(checked);
        bool accepted = background_cs.AcceptBlock(
            pblock, state, &pindex, true, nullptr, &newblock, true);
        BOOST_CHECK(accepted);
    }
    // UpdateTip is called here
    bool block_added = background_cs.ActivateBestChain(state, pblock);

    // Ensure tip is as expected
    BOOST_CHECK_EQUAL(background_cs.m_chain.Tip()->GetBlockHash(), validation_block.GetHash());

    // g_best_block should be unchanged after adding a block to the background
    // validation chain.
    BOOST_CHECK(block_added);
    BOOST_CHECK_EQUAL(curr_tip, ::g_best_block);
}

BOOST_AUTO_TEST_SUITE_END()