#pragma once

#include "uint256.h"
#include "csha256.h"
#include "serialize.h"

/* ----------- Bitcoin Hash ------------------------------------------------- */
/** A hasher class for Bitcoin's 256-bit hash (double SHA-256). */
class CHash256
{
private:
    CSHA256 sha;
public:
    static const size_t OUTPUT_SIZE = CSHA256::OUTPUT_SIZE;

    void Finalize(unsigned char hash[OUTPUT_SIZE])
    {
        unsigned char buf[sha.OUTPUT_SIZE];
        sha.Finalize(buf);
        sha.Reset().Write(buf, sha.OUTPUT_SIZE).Finalize(hash);
    }

    CHash256& Write(const unsigned char *data, size_t len)
    {
        sha.Write(data, len);
        return *this;
    }

    CHash256& Reset()
    {
        sha.Reset();
        return *this;
    }
};
/** Compute the 256-bit hash of an object. */
template<typename T1>
inline uint256 Hash(const T1 pbegin, const T1 pend)
{
    static const unsigned char pblank[1] = {};
    uint256 result;
    CHash256().Write(pbegin == pend ? pblank : (const unsigned char*)&pbegin[0], (pend - pbegin) * sizeof(pbegin[0]))
              .Finalize((unsigned char*)&result);
    return result;
}

/** Compute the 256-bit hash of the concatenation of two objects. */
template<typename T1, typename T2>
inline uint256 Hash(const T1 p1begin, const T1 p1end,
                    const T2 p2begin, const T2 p2end) {
    static const unsigned char pblank[1] = {};
    uint256 result;
    CHash256().Write(p1begin == p1end ? pblank : (const unsigned char*)&p1begin[0], (p1end - p1begin) * sizeof(p1begin[0]))
              .Write(p2begin == p2end ? pblank : (const unsigned char*)&p2begin[0], (p2end - p2begin) * sizeof(p2begin[0]))
              .Finalize((unsigned char*)&result);
    return result;
}

/** Compute the 256-bit hash of the concatenation of three objects. */
template<typename T1, typename T2, typename T3>
inline uint256 Hash(const T1 p1begin, const T1 p1end,
                    const T2 p2begin, const T2 p2end,
                    const T3 p3begin, const T3 p3end) {
    static const unsigned char pblank[1] = {};
    uint256 result;
    CHash256().Write(p1begin == p1end ? pblank : (const unsigned char*)&p1begin[0], (p1end - p1begin) * sizeof(p1begin[0]))
              .Write(p2begin == p2end ? pblank : (const unsigned char*)&p2begin[0], (p2end - p2begin) * sizeof(p2begin[0]))
              .Write(p3begin == p3end ? pblank : (const unsigned char*)&p3begin[0], (p3end - p3begin) * sizeof(p3begin[0]))
              .Finalize((unsigned char*)&result);
    return result;
}

/** Compute the 256-bit hash of the concatenation of four objects. */
template<typename T1, typename T2, typename T3, typename T4>
inline uint256 Hash(const T1 p1begin, const T1 p1end,
                    const T2 p2begin, const T2 p2end,
                    const T3 p3begin, const T3 p3end,
                    const T4 p4begin, const T4 p4end) {
    static const unsigned char pblank[1] = {};
    uint256 result;
    CHash256().Write(p1begin == p1end ? pblank : (const unsigned char*)&p1begin[0], (p1end - p1begin) * sizeof(p1begin[0]))
              .Write(p2begin == p2end ? pblank : (const unsigned char*)&p2begin[0], (p2end - p2begin) * sizeof(p2begin[0]))
              .Write(p3begin == p3end ? pblank : (const unsigned char*)&p3begin[0], (p3end - p3begin) * sizeof(p3begin[0]))
              .Write(p4begin == p4end ? pblank : (const unsigned char*)&p4begin[0], (p4end - p4begin) * sizeof(p4begin[0]))
              .Finalize((unsigned char*)&result);
    return result;
}

/** Compute the 256-bit hash of the concatenation of five objects. */
template<typename T1, typename T2, typename T3, typename T4, typename T5>
inline uint256 Hash(const T1 p1begin, const T1 p1end,
                    const T2 p2begin, const T2 p2end,
                    const T3 p3begin, const T3 p3end,
                    const T4 p4begin, const T4 p4end,
                    const T5 p5begin, const T5 p5end) {
    static const unsigned char pblank[1] = {};
    uint256 result;
    CHash256().Write(p1begin == p1end ? pblank : (const unsigned char*)&p1begin[0], (p1end - p1begin) * sizeof(p1begin[0]))
              .Write(p2begin == p2end ? pblank : (const unsigned char*)&p2begin[0], (p2end - p2begin) * sizeof(p2begin[0]))
              .Write(p3begin == p3end ? pblank : (const unsigned char*)&p3begin[0], (p3end - p3begin) * sizeof(p3begin[0]))
              .Write(p4begin == p4end ? pblank : (const unsigned char*)&p4begin[0], (p4end - p4begin) * sizeof(p4begin[0]))
              .Write(p5begin == p5end ? pblank : (const unsigned char*)&p5begin[0], (p5end - p5begin) * sizeof(p5begin[0]))
              .Finalize((unsigned char*)&result);
    return result;
}

/** Compute the 256-bit hash of the concatenation of six objects. */
template<typename T1, typename T2, typename T3, typename T4, typename T5, typename T6>
inline uint256 Hash(const T1 p1begin, const T1 p1end,
                    const T2 p2begin, const T2 p2end,
                    const T3 p3begin, const T3 p3end,
                    const T4 p4begin, const T4 p4end,
                    const T5 p5begin, const T5 p5end,
                    const T6 p6begin, const T6 p6end) {
    static const unsigned char pblank[1] = {};
    uint256 result;
    CHash256().Write(p1begin == p1end ? pblank : (const unsigned char*)&p1begin[0], (p1end - p1begin) * sizeof(p1begin[0]))
              .Write(p2begin == p2end ? pblank : (const unsigned char*)&p2begin[0], (p2end - p2begin) * sizeof(p2begin[0]))
              .Write(p3begin == p3end ? pblank : (const unsigned char*)&p3begin[0], (p3end - p3begin) * sizeof(p3begin[0]))
              .Write(p4begin == p4end ? pblank : (const unsigned char*)&p4begin[0], (p4end - p4begin) * sizeof(p4begin[0]))
              .Write(p5begin == p5end ? pblank : (const unsigned char*)&p5begin[0], (p5end - p5begin) * sizeof(p5begin[0]))
              .Write(p6begin == p6end ? pblank : (const unsigned char*)&p6begin[0], (p6end - p6begin) * sizeof(p6begin[0]))
              .Finalize((unsigned char*)&result);
    return result;
}

/** A writer stream (for serialization) that computes a 256-bit hash. */
class CHashWriter
{
private:
    CHash256 ctx;

public:
    int nType;
    int nVersion;

    CHashWriter(int nTypeIn, int nVersionIn) : nType(nTypeIn), nVersion(nVersionIn) {}

    CHashWriter& write(const char *pch, size_t size) {
        ctx.Write((const unsigned char*)pch, size);
        return (*this);
    }

    // invalidates the object
    uint256 GetHash() {
        uint256 result;
        ctx.Finalize((unsigned char*)&result);
        return result;
    }

    template<typename T>
    CHashWriter& operator<<(const T& obj) {
        // Serialize to this stream
        ::Serialize(*this, obj, nType, nVersion);
        return (*this);
    }
};

/** Compute the 256-bit hash of an object's serialization. */
template<typename T>
uint256 SerializeHash(const T& obj, int nType=(1 << 2), int nVersion=70208)
{
    CHashWriter ss(nType, nVersion);
    ss << obj;
    return ss.GetHash();
}