// Copyright (c) 2009-2014 The Bitcoin developers
// Copyright (c) 2014-2015 The Dash developers
// Distributed under the MIT/X11 software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#include "checkpoints.h"

#include "main.h"
#include "uint256.h"

#include <stdint.h>

#include <boost/assign/list_of.hpp> // for 'map_list_of()'
#include <boost/foreach.hpp>

namespace Checkpoints
{
    typedef std::map<int, uint256> MapCheckpoints;

    // How many times we expect transactions after the last checkpoint to
    // be slower. This number is a compromise, as it can't be accurate for
    // every system. When reindexing from a fast disk with a slow CPU, it
    // can be up to 20, while when downloading from a slow network with a
    // fast multicore CPU, it won't be much higher than 1.
    static const double SIGCHECK_VERIFICATION_FACTOR = 5.0;

    struct CCheckpointData {
        const MapCheckpoints *mapCheckpoints;
        int64_t nTimeLastCheckpoint;
        int64_t nTransactionsLastCheckpoint;
        double fTransactionsPerDay;
    };

    bool fEnabled = true;

    // What makes a good checkpoint block?
    // + Is surrounded by blocks with reasonable timestamps
    //   (no blocks before with a timestamp after, none after with
    //    timestamp before)
    // + Contains no strange transactions
    static MapCheckpoints mapCheckpoints =
        boost::assign::map_list_of
        (  1500, uint256("0x000000aaf0300f59f49bc3e970bad15c11f961fe2347accffff19d96ec9778e3"))
        (  4991, uint256("0x000000003b01809551952460744d5dbb8fcbd6cbae3c220267bf7fa43f837367"))
        (  9918, uint256("0x00000000213e229f332c0ffbe34defdaa9e74de87f2d8d1f01af8d121c3c170b"))
        ( 16912, uint256("0x00000000075c0d10371d55a60634da70f197548dbbfa4123e12abfcbc5738af9"))
        ( 23912, uint256("0x0000000000335eac6703f3b1732ec8b2f89c3ba3a7889e5767b090556bb9a276"))
        ( 35457, uint256("0x0000000000b0ae211be59b048df14820475ad0dd53b9ff83b010f71a77342d9f"))
        ( 45479, uint256("0x000000000063d411655d590590e16960f15ceea4257122ac430c6fbe39fbf02d"))
        ( 55895, uint256("0x0000000000ae4c53a43639a4ca027282f69da9c67ba951768a20415b6439a2d7"))
        ( 68899, uint256("0x0000000000194ab4d3d9eeb1f2f792f21bb39ff767cb547fe977640f969d77b7"))
        ( 74619, uint256("0x000000000011d28f38f05d01650a502cc3f4d0e793fbc26e2a2ca71f07dc3842"))
        ( 75095, uint256("0x0000000000193d12f6ad352a9996ee58ef8bdc4946818a5fec5ce99c11b87f0d"))
        ( 88805, uint256("0x00000000001392f1652e9bf45cd8bc79dc60fe935277cd11538565b4a94fa85f"))
        ( 107996, uint256("0x00000000000a23840ac16115407488267aa3da2b9bc843e301185b7d17e4dc40"))
        ( 137993, uint256("0x00000000000cf69ce152b1bffdeddc59188d7a80879210d6e5c9503011929c3c"))
        ( 167996, uint256("0x000000000009486020a80f7f2cc065342b0c2fb59af5e090cd813dba68ab0fed"))
        ( 207992, uint256("0x00000000000d85c22be098f74576ef00b7aa00c05777e966aff68a270f1e01a5"))
        ( 217752, uint256("0x00000000000a7baeb2148272a7e14edf5af99a64af456c0afc23d15a0918b704"))
        ;
    static const CCheckpointData data = {
        &mapCheckpoints,
        1403283082, // * UNIX timestamp of last checkpoint block
        511516,     // * total number of transactions between genesis and last checkpoint
                    //   (the tx=... number in the SetBestChain debug.log lines)
        7701        // * estimated number of transactions per day after checkpoint
    };

    static MapCheckpoints mapCheckpointsTestnet =
        boost::assign::map_list_of
        ( 261, uint256("00000c26026d0815a7e2ce4fa270775f61403c040647ff2c3091f99e894a4618"))
        ;
    static const CCheckpointData dataTestnet = {
        &mapCheckpointsTestnet,
        1405699509,
        201,
        500
    };

    static MapCheckpoints mapCheckpointsRegtest =
        boost::assign::map_list_of
        ( 0, uint256("0x000008ca1832a4baf228eb1553c03d3a2c8e02399550dd6ea8d65cec3ef23d2e"))
        ;
    static const CCheckpointData dataRegtest = {
        &mapCheckpointsRegtest,
        0,
        0,
        0
    };

    const CCheckpointData &Checkpoints() {
        if (Params().NetworkID() == CChainParams::TESTNET)
            return dataTestnet;
        else if (Params().NetworkID() == CChainParams::MAIN)
            return data;
        else
            return dataRegtest;
    }

    bool CheckBlock(int nHeight, const uint256& hash)
    {
        if (!fEnabled)
            return true;

        const MapCheckpoints& checkpoints = *Checkpoints().mapCheckpoints;

        MapCheckpoints::const_iterator i = checkpoints.find(nHeight);
        if (i == checkpoints.end()) return true;
        return hash == i->second;
    }

    // Guess how far we are in the verification process at the given block index
    double GuessVerificationProgress(CBlockIndex *pindex, bool fSigchecks) {
        if (pindex==NULL)
            return 0.0;

        int64_t nNow = time(NULL);

        double fSigcheckVerificationFactor = fSigchecks ? SIGCHECK_VERIFICATION_FACTOR : 1.0;
        double fWorkBefore = 0.0; // Amount of work done before pindex
        double fWorkAfter = 0.0;  // Amount of work left after pindex (estimated)
        // Work is defined as: 1.0 per transaction before the last checkpoint, and
        // fSigcheckVerificationFactor per transaction after.

        const CCheckpointData &data = Checkpoints();

        if (pindex->nChainTx <= data.nTransactionsLastCheckpoint) {
            double nCheapBefore = pindex->nChainTx;
            double nCheapAfter = data.nTransactionsLastCheckpoint - pindex->nChainTx;
            double nExpensiveAfter = (nNow - data.nTimeLastCheckpoint)/86400.0*data.fTransactionsPerDay;
            fWorkBefore = nCheapBefore;
            fWorkAfter = nCheapAfter + nExpensiveAfter*fSigcheckVerificationFactor;
        } else {
            double nCheapBefore = data.nTransactionsLastCheckpoint;
            double nExpensiveBefore = pindex->nChainTx - data.nTransactionsLastCheckpoint;
            double nExpensiveAfter = (nNow - pindex->nTime)/86400.0*data.fTransactionsPerDay;
            fWorkBefore = nCheapBefore + nExpensiveBefore*fSigcheckVerificationFactor;
            fWorkAfter = nExpensiveAfter*fSigcheckVerificationFactor;
        }

        return fWorkBefore / (fWorkBefore + fWorkAfter);
    }

    int GetTotalBlocksEstimate()
    {
        if (!fEnabled)
            return 0;

        const MapCheckpoints& checkpoints = *Checkpoints().mapCheckpoints;

        return checkpoints.rbegin()->first;
    }

    CBlockIndex* GetLastCheckpoint(const std::map<uint256, CBlockIndex*>& mapBlockIndex)
    {
        if (!fEnabled)
            return NULL;

        const MapCheckpoints& checkpoints = *Checkpoints().mapCheckpoints;

        BOOST_REVERSE_FOREACH(const MapCheckpoints::value_type& i, checkpoints)
        {
            const uint256& hash = i.second;
            std::map<uint256, CBlockIndex*>::const_iterator t = mapBlockIndex.find(hash);
            if (t != mapBlockIndex.end())
                return t->second;
        }
        return NULL;
    }
}