// Copyright (c) 2010 Satoshi Nakamoto

// Copyright (c) 2009-present 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 <chain.h>

#include <chainparams.h>

#include <coins.h>

#include <index/txindex.h>

#include <merkleblock.h>

#include <node/blockstorage.h>

#include <primitives/transaction.h>

#include <rpc/blockchain.h>

#include <rpc/server.h>

#include <rpc/server_util.h>

#include <rpc/util.h>

#include <univalue.h>

#include <util/strencodings.h>

#include <validation.h>

using node::GetTransaction;

static RPCMethod gettxoutproof()

{

    return RPCMethod{

        "gettxoutproof",

        "Returns a hex-encoded proof that \"txid\" was included in a block.\n"

        "\nNOTE: By default this function only works sometimes. This is when there is an\n"

        "unspent output in the utxo for this transaction. To make it always work,\n"

        "you need to maintain a transaction index, using the -txindex command line option or\n"

        "specify the block in which the transaction is included manually (by blockhash).\n",

        {

            {"txids", RPCArg::Type::ARR, RPCArg::Optional::NO, "The txids to filter",

                {

                    {"txid", RPCArg::Type::STR_HEX, RPCArg::Optional::OMITTED, "A transaction hash"},

                },

            },

            {"blockhash", RPCArg::Type::STR_HEX, RPCArg::Optional::OMITTED, "If specified, looks for txid in the block with this hash"},

        },

        RPCResult{

            RPCResult::Type::STR, "data", "A string that is a serialized, hex-encoded data for the proof."

        },

        RPCExamples{""},

        [](const RPCMethod& self, const JSONRPCRequest& request) -> UniValue

        {

            std::set<Txid> setTxids;

            UniValue txids = request.params[0].get_array();

            if (txids.empty()) {

                throw JSONRPCError(RPC_INVALID_PARAMETER, "Parameter 'txids' cannot be empty");

            }

            for (unsigned int idx = 0; idx < txids.size(); idx++) {

                auto ret{setTxids.insert(Txid::FromUint256(ParseHashV(txids[idx], "txid")))};

                if (!ret.second) {

                    throw JSONRPCError(RPC_INVALID_PARAMETER, std::string("Invalid parameter, duplicated txid: ") + txids[idx].get_str());

                }

            }

            const CBlockIndex* pblockindex = nullptr;

            uint256 hashBlock;

            ChainstateManager& chainman = EnsureAnyChainman(request.context);

            if (!request.params[1].isNull()) {

                LOCK(cs_main);

                hashBlock = ParseHashV(request.params[1], "blockhash");

                pblockindex = chainman.m_blockman.LookupBlockIndex(hashBlock);

                if (!pblockindex) {

                    throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Block not found");

                }

            } else {

                LOCK(cs_main);

                Chainstate& active_chainstate = chainman.ActiveChainstate();

                // Loop through txids and try to find which block they're in. Exit loop once a block is found.

                for (const auto& tx : setTxids) {

                    const Coin& coin{AccessByTxid(active_chainstate.CoinsTip(), tx)};

                    if (!coin.IsSpent()) {

                        pblockindex = active_chainstate.m_chain[coin.nHeight];

                        break;

                    }

                }

            }

            // Allow txindex to catch up if we need to query it and before we acquire cs_main.

            if (g_txindex && !pblockindex) {

                g_txindex->BlockUntilSyncedToCurrentChain();

            }

            if (pblockindex == nullptr) {

                const CTransactionRef tx = GetTransaction(/*block_index=*/nullptr, /*mempool=*/nullptr, *setTxids.begin(), chainman.m_blockman, hashBlock);

                if (!tx || hashBlock.IsNull()) {

                    throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Transaction not yet in block");

                }

                LOCK(cs_main);

                pblockindex = chainman.m_blockman.LookupBlockIndex(hashBlock);

                if (!pblockindex) {

                    throw JSONRPCError(RPC_INTERNAL_ERROR, "Transaction index corrupt");

                }

            }

            {

                LOCK(cs_main);

                CheckBlockDataAvailability(chainman.m_blockman, *pblockindex, /*check_for_undo=*/false);

            }

            CBlock block;

            if (!chainman.m_blockman.ReadBlock(block, *pblockindex)) {

                throw JSONRPCError(RPC_INTERNAL_ERROR, "Can't read block from disk");

            }

            unsigned int ntxFound = 0;

            for (const auto& tx : block.vtx) {

                if (setTxids.contains(tx->GetHash())) {

                    ntxFound++;

                }

            }

            if (ntxFound != setTxids.size()) {

                throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Not all transactions found in specified or retrieved block");

            }

            DataStream ssMB{};

            CMerkleBlock mb(block, setTxids);

            ssMB << mb;

            std::string strHex = HexStr(ssMB);

            return strHex;

        },

    };

}

static RPCMethod verifytxoutproof()

{

    return RPCMethod{

        "verifytxoutproof",

        "Verifies that a proof points to a transaction in a block, returning the transaction it commits to\n"

        "and throwing an RPC error if the block is not in our best chain\n",

        {

            {"proof", RPCArg::Type::STR_HEX, RPCArg::Optional::NO, "The hex-encoded proof generated by gettxoutproof"},

        },

        RPCResult{

            RPCResult::Type::ARR, "", "",

            {

                {RPCResult::Type::STR_HEX, "txid", "The txid(s) which the proof commits to, or empty array if the proof cannot be validated."},

            }

        },

        RPCExamples{""},

        [](const RPCMethod& self, const JSONRPCRequest& request) -> UniValue

        {

            CMerkleBlock merkleBlock;

            SpanReader{ParseHexV(request.params[0], "proof")} >> merkleBlock;

            UniValue res(UniValue::VARR);

            std::vector<Txid> vMatch;

            std::vector<unsigned int> vIndex;

            if (merkleBlock.txn.ExtractMatches(vMatch, vIndex) != merkleBlock.header.hashMerkleRoot)

                return res;

            ChainstateManager& chainman = EnsureAnyChainman(request.context);

            LOCK(cs_main);

            const CBlockIndex* pindex = chainman.m_blockman.LookupBlockIndex(merkleBlock.header.GetHash());

            if (!pindex || !chainman.ActiveChain().Contains(*pindex) || pindex->nTx == 0) {

                throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Block not found in chain");

            }

            // Check if proof is valid, only add results if so

            if (pindex->nTx == merkleBlock.txn.GetNumTransactions()) {

                for (const auto& txid : vMatch) {

                    res.push_back(txid.GetHex());

                }

            }

            return res;

        },

    };

}

void RegisterTxoutProofRPCCommands(CRPCTable& t)

{

    static const CRPCCommand commands[]{

        {"blockchain", &gettxoutproof},

        {"blockchain", &verifytxoutproof},

    };

    for (const auto& c : commands) {

        t.appendCommand(c.name, &c);

    }

}