OpenRCT2/src/core/FileStream.hpp

#pragma once

#include "../common.h"

#include <SDL.h>
#include "IStream.hpp"

enum
{
    FILE_MODE_OPEN,
    FILE_MODE_WRITE
};

/**
 * A stream for reading and writing to files. Wraps an SDL_RWops, SDL2's cross platform file stream.
 */
class FileStream : public IStream
{
private:
    SDL_RWops * _file;
    bool        _canRead;
    bool        _canWrite;
    bool        _disposed;

public:
    FileStream(const utf8 * path, int fileMode)
    {
        const char * mode;
        switch (fileMode) {
        case FILE_MODE_OPEN:
            mode = "rb";
            _canRead = true;
            _canWrite = false;
            break;
        case FILE_MODE_WRITE:
            mode = "wb";
            _canRead = false;
            _canWrite = true;
            break;
        default:
            throw;
        }

        _file = SDL_RWFromFile(path, mode);
        if (_file == nullptr)
        {
            throw IOException(SDL_GetError());
        }

        _disposed = false;
    }

    ~FileStream()
    {
        Dispose();
    }

    void Dispose() override
    {
        if (!_disposed)
        {
            _disposed = true;
            SDL_RWclose(_file);
        }
    }

    bool CanRead()  const override { return _canRead;  }
    bool CanWrite() const override { return _canWrite; }

    uint64 GetLength()   const override { return SDL_RWsize(_file); }
    uint64 GetPosition() const override { return SDL_RWtell(_file); }

    void SetPosition(uint64 position) override
    {
        Seek(position, STREAM_SEEK_BEGIN);
    }

    void Seek(sint64 offset, int origin) override
    {
        switch (origin) {
        case STREAM_SEEK_BEGIN:
            SDL_RWseek(_file, offset, RW_SEEK_SET);
            break;
        case STREAM_SEEK_CURRENT:
            SDL_RWseek(_file, offset, RW_SEEK_CUR);
            break;
        case STREAM_SEEK_END:
            SDL_RWseek(_file, offset, RW_SEEK_END);
            break;
        }
    }

    void Read(void * buffer, uint64 length) override
    {
        if (SDL_RWread(_file, buffer, (size_t)length, 1) != 1)
        {
            throw IOException("Attempted to read past end of file.");
        }
    }

    void Write(const void * buffer, uint64 length) override
    {
        if (SDL_RWwrite(_file, buffer, (size_t)length, 1) != 1)
        {
            throw IOException("Unable to write to file.");
        }
    }
};