// Copyright (c) 2014 The Bitcoin Core developers
// Copyright (c) 2019 The OPALCOIN developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#include "coins.h"
#include "script/standard.h"
#include "uint256.h"
#include "utilstrencodings.h"
#include "test/test_opalcoin.h"

#include <vector>
#include <map>

#include <boost/test/unit_test.hpp>

namespace
{
class CCoinsViewTest : public CCoinsView
{
    uint256 hashBestBlock_;
    std::map<uint256, CCoins> map_;

public:
    bool GetCoins(const uint256& txid, CCoins& coins) const
    {
        std::map<uint256, CCoins>::const_iterator it = map_.find(txid);
        if (it == map_.end()) {
            return false;
        }
        coins = it->second;
        if (coins.IsPruned() && InsecureRandBool() == 0) {
            // Randomly return false in case of an empty entry.
            return false;
        }
        return true;
    }

    bool HaveCoins(const uint256& txid) const
    {
        CCoins coins;
        return GetCoins(txid, coins);
    }

    uint256 GetBestBlock() const { return hashBestBlock_; }

    bool BatchWrite(CCoinsMap& mapCoins, const uint256& hashBlock)
    {
        for (CCoinsMap::iterator it = mapCoins.begin(); it != mapCoins.end(); ) {
            map_[it->first] = it->second.coins;
            if (it->second.coins.IsPruned() && InsecureRandRange(3) == 0) {
                // Randomly delete empty entries on write.
                map_.erase(it->first);
            }
            mapCoins.erase(it++);
        }
        mapCoins.clear();
        hashBestBlock_ = hashBlock;
        return true;
    }

    bool GetStats(CCoinsStats& stats) const { return false; }
};
}

BOOST_FIXTURE_TEST_SUITE(coins_tests, BasicTestingSetup)

static const unsigned int NUM_SIMULATION_ITERATIONS = 40000;

// This is a large randomized insert/remove simulation test on a variable-size
// stack of caches on top of CCoinsViewTest.
//
// It will randomly create/update/delete CCoins entries to a tip of caches, with
// txids picked from a limited list of random 256-bit hashes. Occasionally, a
// new tip is added to the stack of caches, or the tip is flushed and removed.
//
// During the process, booleans are kept to make sure that the randomized
// operation hits all branches.
BOOST_AUTO_TEST_CASE(coins_cache_simulation_test)
{
    // Various coverage trackers.
    bool removed_all_caches = false;
    bool reached_4_caches = false;
    bool added_an_entry = false;
    bool removed_an_entry = false;
    bool updated_an_entry = false;
    bool found_an_entry = false;
    bool missed_an_entry = false;

    // A simple map to track what we expect the cache stack to represent.
    std::map<uint256, CCoins> result;

    // The cache stack.
    CCoinsViewTest base; // A CCoinsViewTest at the bottom.
    std::vector<CCoinsViewCache*> stack; // A stack of CCoinsViewCaches on top.
    stack.push_back(new CCoinsViewCache(&base)); // Start with one cache.

    // Use a limited set of random transaction ids, so we do test overwriting entries.
    std::vector<uint256> txids;
    txids.resize(NUM_SIMULATION_ITERATIONS / 8);
    for (unsigned int i = 0; i < txids.size(); i++) {
        txids[i] = InsecureRand256();
    }

    for (unsigned int i = 0; i < NUM_SIMULATION_ITERATIONS; i++) {
        // Do a random modification.
        {
            uint256 txid = txids[InsecureRandRange(txids.size())]; // txid we're going to modify in this iteration.
            CCoins& coins = result[txid];
            CCoinsModifier entry = stack.back()->ModifyCoins(txid);
            BOOST_CHECK(coins == *entry);
            if (InsecureRandRange(5) == 0 || coins.IsPruned()) {
                if (coins.IsPruned()) {
                    added_an_entry = true;
                } else {
                    updated_an_entry = true;
                }
                coins.nVersion = InsecureRand32();
                coins.vout.resize(1);
                coins.vout[0].nValue = InsecureRand32();
                *entry = coins;
            } else {
                coins.Clear();
                entry->Clear();
                removed_an_entry = true;
            }
        }

        // Once every 1000 iterations and at the end, verify the full cache.
        if (InsecureRandRange(1000) == 1 || i == NUM_SIMULATION_ITERATIONS - 1) {
            for (std::map<uint256, CCoins>::iterator it = result.begin(); it != result.end(); it++) {
                const CCoins* coins = stack.back()->AccessCoins(it->first);
                if (coins) {
                    BOOST_CHECK(*coins == it->second);
                    found_an_entry = true;
                } else {
                    BOOST_CHECK(it->second.IsPruned());
                    missed_an_entry = true;
                }
            }
        }

        if (InsecureRandRange(100) == 0) {
            // Every 100 iterations, change the cache stack.
            if (stack.size() > 0 && InsecureRandBool() == 0) {
                stack.back()->Flush();
                delete stack.back();
                stack.pop_back();
            }
            if (stack.size() == 0 || (stack.size() < 4 && InsecureRandBool())) {
                CCoinsView* tip = &base;
                if (stack.size() > 0) {
                    tip = stack.back();
                } else {
                    removed_all_caches = true;
                }
                stack.push_back(new CCoinsViewCache(tip));
                if (stack.size() == 4) {
                    reached_4_caches = true;
                }
            }
        }
    }

    // Clean up the stack.
    while (stack.size() > 0) {
        delete stack.back();
        stack.pop_back();
    }

    // Verify coverage.
    BOOST_CHECK(removed_all_caches);
    BOOST_CHECK(reached_4_caches);
    BOOST_CHECK(added_an_entry);
    BOOST_CHECK(removed_an_entry);
    BOOST_CHECK(updated_an_entry);
    BOOST_CHECK(found_an_entry);
    BOOST_CHECK(missed_an_entry);
}

BOOST_AUTO_TEST_CASE(ccoins_serialization)
{
    // Good example
    CDataStream ss1(ParseHex("0108835800816115944e077fe7c803cfa57f29b36bf87c1d35b4934b"), SER_DISK, CLIENT_VERSION);
    CCoins cc1;
    ss1 >> cc1;
    BOOST_CHECK_EQUAL(cc1.nVersion, 1);
    BOOST_CHECK_EQUAL(cc1.fCoinBase, false);
    BOOST_CHECK_EQUAL(cc1.nHeight, 870987);
    BOOST_CHECK_EQUAL(cc1.vout.size(), 2);
    BOOST_CHECK_EQUAL(cc1.IsAvailable(0), false);
    BOOST_CHECK_EQUAL(cc1.IsAvailable(1), true);
    BOOST_CHECK_EQUAL(cc1.vout[1].nValue, 60000000000ULL);
    BOOST_CHECK_EQUAL(HexStr(cc1.vout[1].scriptPubKey), HexStr(GetScriptForDestination(CKeyID(uint160(ParseHex("816115944e077fe7c803cfa57f29b36bf87c1d35"))))));

    // Good example
    CDataStream ss2(ParseHex("0111044086ef97d5790061b01caab50f1b8e9c50a5057eb43c2d9563a4eebbd123008c988f1a4a4de2161e0f50aac7f17e7f9555caa482d21f"), SER_DISK, CLIENT_VERSION);
    CCoins cc2;
    ss2 >> cc2;
    BOOST_CHECK_EQUAL(cc2.nVersion, 1);
    BOOST_CHECK_EQUAL(cc2.fCoinBase, true);
    BOOST_CHECK_EQUAL(cc2.nHeight, 59807);
    BOOST_CHECK_EQUAL(cc2.vout.size(), 17);
    for (int i = 0; i < 17; i++) {
        BOOST_CHECK_EQUAL(cc2.IsAvailable(i), i == 4 || i == 16);
    }
    BOOST_CHECK_EQUAL(cc2.vout[4].nValue, 234925952);
    BOOST_CHECK_EQUAL(HexStr(cc2.vout[4].scriptPubKey), HexStr(GetScriptForDestination(CKeyID(uint160(ParseHex("61b01caab50f1b8e9c50a5057eb43c2d9563a4ee"))))));
    BOOST_CHECK_EQUAL(cc2.vout[16].nValue, 110397);
    BOOST_CHECK_EQUAL(HexStr(cc2.vout[16].scriptPubKey), HexStr(GetScriptForDestination(CKeyID(uint160(ParseHex("8c988f1a4a4de2161e0f50aac7f17e7f9555caa4"))))));

    // Smallest possible example
    CDataStream ssx(SER_DISK, CLIENT_VERSION);
    BOOST_CHECK_EQUAL(HexStr(ssx.begin(), ssx.end()), "");

    CDataStream ss3(ParseHex("0004000600"), SER_DISK, CLIENT_VERSION);
    CCoins cc3;
    ss3 >> cc3;
    BOOST_CHECK_EQUAL(cc3.nVersion, 0);
    BOOST_CHECK_EQUAL(cc3.fCoinBase, false);
    BOOST_CHECK_EQUAL(cc3.nHeight, 0);
    BOOST_CHECK_EQUAL(cc3.vout.size(), 1);
    BOOST_CHECK_EQUAL(cc3.IsAvailable(0), true);
    BOOST_CHECK_EQUAL(cc3.vout[0].nValue, 0);
    BOOST_CHECK_EQUAL(cc3.vout[0].scriptPubKey.size(), 0);

    // scriptPubKey that ends beyond the end of the stream
    CDataStream ss4(ParseHex("0004000800"), SER_DISK, CLIENT_VERSION);
    try {
        CCoins cc4;
        ss4 >> cc4;
        BOOST_CHECK_MESSAGE(false, "We should have thrown");
    } catch (const std::ios_base::failure& e) {
    }

    // Very large scriptPubKey (3*10^9 bytes) past the end of the stream
    CDataStream tmp(SER_DISK, CLIENT_VERSION);
    uint64_t x = 3000000000ULL;
    tmp << VARINT(x);
    BOOST_CHECK_EQUAL(HexStr(tmp.begin(), tmp.end()), "8a95c0bb00");
    CDataStream ss5(ParseHex("0002008a95c0bb0000"), SER_DISK, CLIENT_VERSION);
    try {
        CCoins cc5;
        ss5 >> cc5;
        BOOST_CHECK_MESSAGE(false, "We should have thrown");
    } catch (const std::ios_base::failure& e) {
    }
}

BOOST_AUTO_TEST_SUITE_END()
