/*
 * Copyright (c) 2021, kleines Filmröllchen <filmroellchen@serenityos.org>.
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#pragma once

#include <AK/Error.h>
#include <AK/NonnullOwnPtr.h>
#include <AK/OwnPtr.h>
#include <AK/Span.h>
#include <AK/TypedTransfer.h>
#include <LibCore/Stream.h>

namespace Core::Stream {

/// A stream class that allows for reading/writing on a preallocated memory area
/// using a single read/write head.
class FixedMemoryStream final : public SeekableStream {
public:
    static ErrorOr<NonnullOwnPtr<FixedMemoryStream>> construct(Bytes bytes);
    static ErrorOr<NonnullOwnPtr<FixedMemoryStream>> construct(ReadonlyBytes bytes);

    virtual bool is_eof() const override;
    virtual bool is_open() const override;
    virtual void close() override;
    virtual ErrorOr<void> truncate(off_t) override;
    virtual ErrorOr<Bytes> read(Bytes bytes) override;

    virtual ErrorOr<off_t> seek(i64 offset, SeekMode seek_mode = SeekMode::SetPosition) override;

    virtual ErrorOr<size_t> write(ReadonlyBytes bytes) override;
    virtual ErrorOr<void> write_entire_buffer(ReadonlyBytes bytes) override;

    Bytes bytes();
    ReadonlyBytes bytes() const;
    size_t offset() const;
    size_t remaining() const;

private:
    explicit FixedMemoryStream(Bytes bytes);
    explicit FixedMemoryStream(ReadonlyBytes bytes);

    Bytes m_bytes;
    size_t m_offset { 0 };
    bool m_writing_enabled { true };
};

}