// Copyright (c) 2009-2012 The Bitcoin developers
// Distributed under the MIT/X11 software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

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

#include "checkpoints.h"

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

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 fSigcheckVerificationFactor = 5.0;

    struct CCheckpointData {
        const MapCheckpoints *mapCheckpoints;
        int64 nTimeLastCheckpoint;
        int64 nTransactionsLastCheckpoint;
        double fTransactionsPerDay;
    };

    // 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("0x841a2965955dd288cfa707a755d05a54e45f8bd476835ec9af4402a2b59a2967"))
        (  4032, uint256("0x9ce90e427198fc0ef05e5905ce3503725b80e26afd35a987965fd7e3d9cf0846"))
        (  8064, uint256("0xeb984353fc5190f210651f150c40b8a4bab9eeeff0b729fcb3987da694430d70"))
        ( 16128, uint256("0x602edf1859b7f9a6af809f1d9b0e6cb66fdc1d4d9dcd7a4bec03e12a1ccd153d"))
        ( 23420, uint256("0xd80fdf9ca81afd0bd2b2a90ac3a9fe547da58f2530ec874e978fce0b5101b507"))
        ( 50000, uint256("0x69dc37eb029b68f075a5012dcc0419c127672adb4f3a32882b2b3e71d07a20a6"))
        ( 80000, uint256("0x4fcb7c02f676a300503f49c764a89955a8f920b46a8cbecb4867182ecdb2e90a"))
        (120000, uint256("0xbd9d26924f05f6daa7f0155f32828ec89e8e29cee9e7121b026a7a3552ac6131"))
        (161500, uint256("0xdbe89880474f4bb4f75c227c77ba1cdc024991123b28b8418dbbf7798471ff43"))
        (179620, uint256("0x2ad9c65c990ac00426d18e446e0fd7be2ffa69e9a7dcb28358a50b2b78b9f709"))
        (240000, uint256("0x7140d1c4b4c2157ca217ee7636f24c9c73db39c4590c4e6eab2e3ea1555088aa"))
        (383640, uint256("0x2b6809f094a9215bafc65eb3f110a35127a34be94b7d0590a096c3f126c6f364"))
        ;
    static const CCheckpointData data = {
        &mapCheckpoints,
        1373072747, // * UNIX timestamp of last checkpoint block
        1664367,    // * total number of transactions between genesis and last checkpoint
                    //   (the tx=... number in the SetBestChain debug.log lines)
        10000.0     // * estimated number of transactions per day after checkpoint
    };

    static MapCheckpoints mapCheckpointsTestnet = 
        boost::assign::map_list_of
        (   546, uint256("000000002a936ca763904c3c35fce2f3556c559c0214345d31b1bcebf76acb70"))
        ( 35000, uint256("2af959ab4f12111ce947479bfcef16702485f04afd95210aa90fde7d1e4a64ad"))
        ;
    static const CCheckpointData dataTestnet = {
        &mapCheckpointsTestnet,
        1369685559,
        37581,
        300
    };

    const CCheckpointData &Checkpoints() {
        if (fTestNet)
            return dataTestnet;
        else
            return data;
    }

    bool CheckBlock(int nHeight, const uint256& hash)
    {
        if (fTestNet) return true; // Testnet has no checkpoints
        if (!GetBoolArg("-checkpoints", true))
            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) {
        if (pindex==NULL)
            return 0.0;

        int64 nNow = time(NULL);

        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 checkoint, 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 (fTestNet) return 0; // Testnet has no checkpoints
        if (!GetBoolArg("-checkpoints", true))
            return 0;

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

        return checkpoints.rbegin()->first;
    }

    CBlockIndex* GetLastCheckpoint(const std::map<uint256, CBlockIndex*>& mapBlockIndex)
    {
        if (fTestNet) return NULL; // Testnet has no checkpoints
        if (!GetBoolArg("-checkpoints", true))
            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;
    }
}
