#include <Gosu/Platform.hpp>
#if defined(GOSU_IS_WIN)

#include "WinUtility.hpp"
#include <Gosu/IO.hpp>
#include <Gosu/Utility.hpp>
#include <windows.h>
using namespace std;

// TODO: Error checking

struct Gosu::File::Impl
{
    HANDLE handle = INVALID_HANDLE_VALUE;

    ~Impl()
    {
        if (handle != INVALID_HANDLE_VALUE) {
            CloseHandle(handle);
        }
    }
};

Gosu::File::File(const string& filename, FileMode mode)
: pimpl(new Impl)
{
    DWORD access;
    switch (mode) {
    case FM_READ:
        access = GENERIC_READ;
        break;
    case FM_REPLACE:
        access = GENERIC_WRITE;
        break;
    case FM_ALTER:
        access = GENERIC_READ | GENERIC_WRITE;
        break;
    }
    DWORD share_mode = FILE_SHARE_READ;
    DWORD creation_disp = (mode == FM_READ) ? OPEN_EXISTING : OPEN_ALWAYS;

    wstring wfilename = utf8_to_wstring(filename);
    pimpl->handle = CreateFileW(wfilename.c_str(), access, share_mode, 0, creation_disp,
                                FILE_ATTRIBUTE_NORMAL, 0);
    if (pimpl->handle == INVALID_HANDLE_VALUE) {
        throw_last_winapi_error("opening " + filename);
    }
    if (mode == FM_REPLACE) {
        resize(0);
    }
}

Gosu::File::~File()
{
}

size_t Gosu::File::size() const
{
    return GetFileSize(pimpl->handle, 0);
}

void Gosu::File::resize(size_t new_size)
{
    if (SetFilePointer(pimpl->handle, new_size, 0, FILE_BEGIN) == INVALID_SET_FILE_POINTER) {
        throw_last_winapi_error("setting the file pointer");
    }
    winapi_check(SetEndOfFile(pimpl->handle), "resizing a file");
}

void Gosu::File::read(size_t offset, size_t length, void* dest_buffer) const
{
    if (SetFilePointer(pimpl->handle, offset, 0, FILE_BEGIN) == INVALID_SET_FILE_POINTER) {
        throw_last_winapi_error("setting the file pointer");
    }
    DWORD dummy;
    winapi_check(ReadFile(pimpl->handle, dest_buffer, length, &dummy, 0));
}

void Gosu::File::write(size_t offset, size_t length, const void* source_buffer)
{
    if (SetFilePointer(pimpl->handle, offset, 0, FILE_BEGIN) == INVALID_SET_FILE_POINTER) {
        throw_last_winapi_error("setting the file pointer");
    }
    DWORD dummy;
    winapi_check(WriteFile(pimpl->handle, source_buffer, length, &dummy, 0));
}

#endif