/*
 * Copyright (c) 2017, Matias Fontanini
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 * * Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * * Redistributions in binary form must reproduce the above
 *   copyright notice, this list of conditions and the following disclaimer
 *   in the documentation and/or other materials provided with the
 *   distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#ifndef TINS_RADIOTAP_PARSER_H
#define TINS_RADIOTAP_PARSER_H

#include <stdint.h>
#include "../macros.h"
#include "../radiotap.h"
#include "../pdu_option.h"

namespace Tins {
namespace Utils {

struct RadioTapFlags;

/**
 * \brief Allows parsing RadioTap options
 *
 * RadioTap is a somehow tricky protocol to be parsed, as it has ordered flags,
 * alignment between options, etc. This class allows parsing options in a RadioTap
 * header without much trouble.
 */
class RadioTapParser {
public:
    /**
     * Represents the RadioTap namespace currently being parsed
     */
    enum NamespaceType {
        RADIOTAP_NS,
        VENDOR_NS,
        UNKNOWN_NS
    };

    typedef PDUOption<uint8_t, RadioTap> option;

    /**
     * The RadioTap header
     */
    TINS_BEGIN_PACK
    struct RadiotapHeader {
    #if TINS_IS_LITTLE_ENDIAN
        uint8_t version; 
        uint8_t padding;
    #else
        uint8_t padding;
        uint8_t version;
    #endif // TINS_IS_LITTLE_ENDIAN 
        uint16_t length;
        uint32_t flags;
    } TINS_END_PACK;

    /**
     * \brief Constructs a RadioTap parser around a payload
     *
     * Note that the payload is not copied, hence it must be kept in 
     * scope while the parser is still being used.
     *
     * The buffer should contain an entire RadioTap header, with optionally
     * extra data at the end, which will be ignored.
     *
     * \param buffer The buffer to be parsed
     */
    RadioTapParser(const std::vector<uint8_t>& buffer);

    /**
     * Gets the current namespace being parsed
     */
    NamespaceType current_namespace() const;

    /**
     * Gets the current field being parsed
     */
    RadioTap::PresentFlags current_field() const;

    /**
     * Gets the option the parsed is currently pointing at
     */
    option current_option();

    /**
     * Gets the pointer at which the current option is located
     */
    const uint8_t* current_option_ptr() const;

    /**
     * \brief Advances to the next option
     *
     * If there's a namespace change, this will handle that as well.
     *
     * \returns true iff advancing was successfull (e.g. false if we reached
     * the end of the header)
     */
    bool advance_field();
private:
    const uint8_t* find_options_start() const;
    bool advance_to_next_field(bool start_from_zero);
    bool advance_to_next_namespace();
    const RadioTapFlags* get_flags_ptr() const;
    bool is_field_set(uint32_t bit, const RadioTapFlags* flags) const;

    const uint8_t* start_;
    const uint8_t* end_; 
    const uint8_t* current_ptr_;
    NamespaceType current_namespace_;
    uint32_t current_bit_;
    uint32_t namespace_index_;
};

} // Utils
} // Tins

#endif // TINS_RADIOTAP_PARSER_H