/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <fstream>
#include "Stream.hh"
#ifndef _WIN32
#include "unistd.h"
#include "fcntl.h"
#include "errno.h"

#ifndef O_BINARY
#define O_BINARY 0
#endif
#else
#include "Windows.h"

#ifdef min
#undef min
#endif
#endif

using std::auto_ptr;
using std::istream;
using std::ostream;

namespace avro {
namespace {
struct BufferCopyIn {
    virtual ~BufferCopyIn() { }
    virtual void seek(size_t len) = 0;
    virtual bool read(uint8_t* b, size_t toRead, size_t& actual) = 0;

};

struct FileBufferCopyIn : public BufferCopyIn {
#ifdef _WIN32
    HANDLE h_;
    FileBufferCopyIn(const char* filename) :
        h_(::CreateFile(filename, GENERIC_READ, 0, NULL, OPEN_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL)) {
        if (h_ == INVALID_HANDLE_VALUE) {
            throw Exception(boost::format("Cannot open file: %1%") % ::GetLastError());
        }
    }

    ~FileBufferCopyIn() {
        ::CloseHandle(h_);
    }

    void seek(size_t len) {
        if (::SetFilePointer(h_, len, NULL, FILE_CURRENT) != INVALID_SET_FILE_POINTER) {
            throw Exception(boost::format("Cannot skip file: %1%") % ::GetLastError());
        }
    }

    bool read(uint8_t* b, size_t toRead, size_t& actual) {
        DWORD dw = 0;
        if (! ::ReadFile(h_, b, toRead, &dw, NULL)) {
            throw Exception(boost::format("Cannot read file: %1%") % ::GetLastError());
        }
        actual = static_cast<size_t>(dw);
        return actual != 0;
    }
#else
    const int fd_;

    FileBufferCopyIn(const char* filename) :
        fd_(open(filename, O_RDONLY | O_BINARY)) {
        if (fd_ < 0) {
            throw Exception(boost::format("Cannot open file: %1%") %
                ::strerror(errno));
        }
    }

    ~FileBufferCopyIn() {
        ::close(fd_);
    }

    void seek(size_t len) {
        off_t r = ::lseek(fd_, len, SEEK_CUR);
        if (r == static_cast<off_t>(-1)) {
            throw Exception(boost::format("Cannot skip file: %1%") %
                strerror(errno));
        }
    }

    bool read(uint8_t* b, size_t toRead, size_t& actual) {
        int n = ::read(fd_, b, toRead);
        if (n > 0) {
            actual = n;
            return true;
        }
        return false;
    }
#endif
  
};

struct IStreamBufferCopyIn : public BufferCopyIn {
    istream& is_;

    IStreamBufferCopyIn(istream& is) : is_(is) {
    }

    void seek(size_t len) {
        if (! is_.seekg(len, std::ios_base::cur)) {
            throw Exception("Cannot skip stream");
        }
    }

    bool read(uint8_t* b, size_t toRead, size_t& actual) {
        is_.read(reinterpret_cast<char*>(b), toRead);
        if (is_.bad()) {
            return false;
        }
        actual = static_cast<size_t>(is_.gcount());
        return (! is_.eof() || actual != 0);
    }

};

}

class BufferCopyInInputStream : public InputStream {
    const size_t bufferSize_;
    uint8_t* const buffer_;
    auto_ptr<BufferCopyIn> in_;
    size_t byteCount_;
    uint8_t* next_;
    size_t available_;

    bool next(const uint8_t** data, size_t *size) {
        if (available_ == 0 && ! fill()) {
            return false;
        }
        *data = next_;
        *size = available_;
        next_ += available_;
        byteCount_ += available_;
        available_ = 0;
        return true;
    }

    void backup(size_t len) {
        next_ -= len;
        available_ += len;
        byteCount_ -= len;
    }

    void skip(size_t len) {
        while (len > 0) {
            if (available_ == 0) {
                in_->seek(len);
                byteCount_ += len;
                return;
            }
            size_t n = std::min(available_, len);
            available_ -= n;
            next_ += n;
            len -= n;
            byteCount_ += n;
        }
    }

    size_t byteCount() const { return byteCount_; }

    bool fill() {
        size_t n = 0;
        if (in_->read(buffer_, bufferSize_, n)) {
            next_ = buffer_;
            available_ = n;
            return true;
        }
        return false;
    }


public:
    BufferCopyInInputStream(auto_ptr<BufferCopyIn>& in, size_t bufferSize) :
        bufferSize_(bufferSize),
        buffer_(new uint8_t[bufferSize]),
        in_(in),
        byteCount_(0),
        next_(buffer_),
        available_(0) { }

    ~BufferCopyInInputStream() {
        delete[] buffer_;
    }
};

namespace {
struct BufferCopyOut {
    virtual ~BufferCopyOut() { }
    virtual void write(const uint8_t* b, size_t len) = 0;
};

struct FileBufferCopyOut : public BufferCopyOut {
#ifdef _WIN32
    HANDLE h_;
    FileBufferCopyOut(const char* filename) :
        h_(::CreateFile(filename, GENERIC_WRITE, 0, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL)) {
        if (h_ == INVALID_HANDLE_VALUE) {
            throw Exception(boost::format("Cannot open file: %1%") % ::GetLastError());
        }
    }

    ~FileBufferCopyOut() {
        ::CloseHandle(h_);
    }

    void write(const uint8_t* b, size_t len) {
        while (len > 0) {
            DWORD dw = 0;
            if (! ::WriteFile(h_, b, len, &dw, NULL)) {
                throw Exception(boost::format("Cannot read file: %1%") % ::GetLastError());
            }
            b += dw;
            len -= dw;
        }
    }
#else
    const int fd_;

    FileBufferCopyOut(const char* filename) :
        fd_(::open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY, 0644)) {

        if (fd_ < 0) {
            throw Exception(boost::format("Cannot open file: %1%") %
                ::strerror(errno));
        }
    }

    ~FileBufferCopyOut() {
        ::close(fd_);
    }

    void write(const uint8_t* b, size_t len) {
        if (::write(fd_, b, len) < 0) {
            throw Exception(boost::format("Cannot write file: %1%") %
                ::strerror(errno));
        }
    }
#endif
  
};

struct OStreamBufferCopyOut : public BufferCopyOut {
    ostream& os_;

    OStreamBufferCopyOut(ostream& os) : os_(os) {
    }

    void write(const uint8_t* b, size_t len) {
        os_.write(reinterpret_cast<const char*>(b), len);
    }

};

}

class BufferCopyOutputStream : public OutputStream {
    size_t bufferSize_;
    uint8_t* const buffer_;
    auto_ptr<BufferCopyOut> out_;
    uint8_t* next_;
    size_t available_;
    size_t byteCount_;

    // Invaiant: byteCount_ == byteswritten + bufferSize_ - available_;
    bool next(uint8_t** data, size_t* len) {
        if (available_ == 0) {
            flush();
        }
        *data = next_;
        *len = available_;
        next_ += available_;
        byteCount_ += available_;
        available_ = 0;
        return true;
    }

    void backup(size_t len) {
        available_ += len;
        next_ -= len;
        byteCount_ -= len;
    }

    uint64_t byteCount() const {
        return byteCount_;
    }

    void flush() {
        out_->write(buffer_, bufferSize_ - available_);
        next_ = buffer_;
        available_ = bufferSize_;
    }

public:
    BufferCopyOutputStream(auto_ptr<BufferCopyOut> out, size_t bufferSize) :
        bufferSize_(bufferSize),
        buffer_(new uint8_t[bufferSize]),
        out_(out),
        next_(buffer_),
        available_(bufferSize_), byteCount_(0) { }

    ~BufferCopyOutputStream() {
        delete[] buffer_;
    }
};

auto_ptr<InputStream> fileInputStream(const char* filename,
    size_t bufferSize)
{
    auto_ptr<BufferCopyIn> in(new FileBufferCopyIn(filename));
    return auto_ptr<InputStream>( new BufferCopyInInputStream(in, bufferSize));
}

auto_ptr<InputStream> istreamInputStream(istream& is,
    size_t bufferSize)
{
    auto_ptr<BufferCopyIn> in(new IStreamBufferCopyIn(is));
    return auto_ptr<InputStream>( new BufferCopyInInputStream(in, bufferSize));
}

auto_ptr<OutputStream> fileOutputStream(const char* filename,
    size_t bufferSize)
{
    auto_ptr<BufferCopyOut> out(new FileBufferCopyOut(filename));
    return auto_ptr<OutputStream>(new BufferCopyOutputStream(out, bufferSize));
}

auto_ptr<OutputStream> ostreamOutputStream(ostream& os,
    size_t bufferSize)
{
    auto_ptr<BufferCopyOut> out(new OStreamBufferCopyOut(os));
    return auto_ptr<OutputStream>(new BufferCopyOutputStream(out, bufferSize));
}


}   // namespace avro