// Copyright (C) 2011-2013 Internet Systems Consortium, Inc. ("ISC")
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
// AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
// OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
// PERFORMANCE OF THIS SOFTWARE.

#ifndef LIBDHCP_H
#define LIBDHCP_H

#include <dhcp/option_definition.h>
#include <dhcp/pkt6.h>
#include <util/buffer.h>

#include <iostream>

namespace isc {
namespace dhcp {

class LibDHCP {

public:

    /// Map of factory functions.
    typedef std::map<unsigned short, Option::Factory*>  FactoryMap;

    /// @brief Return collection of option definitions.
    ///
    /// Method returns the collection of DHCP standard DHCP
    /// option definitions.
    /// @todo DHCPv4 option definitions are not implemented. For now
    /// this function will throw isc::NotImplemented in case of attempt
    /// to get option definitions for V4 universe.
    ///
    /// @param u universe of the options (V4 or V6).
    ///
    /// @return collection of option definitions.
    static const OptionDefContainer& getOptionDefs(const Option::Universe u);

    /// @brief Return the first option definition matching a
    /// particular option code.
    ///
    /// @param u universe (V4 or V6)
    /// @param code option code.
    ///
    /// @return reference to an option definition being requested
    /// or NULL pointer if option definition has not been found.
    static OptionDefinitionPtr getOptionDef(const Option::Universe u,
                                            const uint16_t code);

    /// @brief Check if the specified option is a standard option.
    ///
    /// @param u universe (V4 or V6)
    /// @param code option code.
    ///
    /// @return true if the specified option is a standard option.
    /// @todo We already create option definitions for the subset if
    /// standard options. We are aiming that this function checks
    /// the presence of the standard option definition and if it finds
    /// it, then the true value is returned. However, at this point
    /// this is not doable because some of the definitions (for less
    /// important options) are not created yet.
    static bool isStandardOption(const Option::Universe u,
                                 const uint16_t code);

    /// @brief Factory function to create instance of option.
    ///
    /// Factory method creates instance of specified option. The option
    /// to be created has to have corresponding factory function
    /// registered with \ref LibDHCP::OptionFactoryRegister.
    ///
    /// @param u universe of the option (V4 or V6)
    /// @param type option-type
    /// @param buf option-buffer
    ///
    /// @return instance of option.
    ///
    /// @throw isc::InvalidOperation if there is no factory function registered
    ///        for the specified option type.
    static isc::dhcp::OptionPtr optionFactory(isc::dhcp::Option::Universe u,
                                              uint16_t type,
                                              const OptionBuffer& buf);

    /// @brief Stores options in a buffer.
    ///
    /// Stores all options defined in options containers in a on-wire
    /// format in output buffer specified by buf.
    ///
    /// May throw different exceptions if option assembly fails. There
    /// may be different reasons (option too large, option malformed,
    /// too many options etc.)
    ///
    /// @param buf output buffer (assembled options will be stored here)
    /// @param options collection of options to store to
    static void packOptions(isc::util::OutputBuffer& buf,
                            const isc::dhcp::OptionCollection& options);

    /// @brief Parses provided buffer as DHCPv4 options and creates Option objects.
    ///
    /// Parses provided buffer and stores created Option objects
    /// in options container.
    ///
    /// @param buf Buffer to be parsed.
    /// @param option_space A name of the option space which holds definitions
    /// of to be used to parse options in the packets.
    /// @param options Reference to option container. Options will be
    ///        put here.
    static size_t unpackOptions4(const OptionBuffer& buf,
                                 const std::string& option_space,
                                 isc::dhcp::OptionCollection& options);

    /// @brief Parses provided buffer as DHCPv6 options and creates Option objects.
    ///
    /// Parses provided buffer and stores created Option objects in options
    /// container. The last two parameters are optional and are used in
    /// relay parsing. If they are specified, relay-msg option is not created,
    /// but rather those two parameters are specified to point out where
    /// the relay-msg option resides and what is its length. This is perfromance
    /// optimization that avoids unnecessary copying of potentially large
    /// relay-msg option. It is not used for anything, except in the next
    /// iteration its content will be treated as buffer to be parsed.
    ///
    /// @param buf Buffer to be parsed.
    /// @param option_space A name of the option space which holds definitions
    /// of to be used to parse options in the packets.
    /// @param options Reference to option container. Options will be
    ///        put here.
    /// @param relay_msg_offset reference to a size_t structure. If specified,
    ///        offset to beginning of relay_msg option will be stored in it.
    /// @param relay_msg_len reference to a size_t structure. If specified,
    ///        length of the relay_msg option will be stored in it.
    /// @return offset to the first byte after last parsed option
    static size_t unpackOptions6(const OptionBuffer& buf,
                                 const std::string& option_space,
                                 isc::dhcp::OptionCollection& options,
                                 size_t* relay_msg_offset = 0,
                                 size_t* relay_msg_len = 0);

    /// Registers factory method that produces options of specific option types.
    ///
    /// @throw isc::BadValue if provided the type is already registered, has
    ///        too large a value or an invalid universe is specified.
    ///
    /// @param u universe of the option (V4 or V6)
    /// @param type option-type
    /// @param factory function pointer
    static void OptionFactoryRegister(Option::Universe u,
                                      uint16_t type,
                                      Option::Factory * factory);

private:

    /// Initialize standard DHCPv4 option definitions.
    ///
    /// The method creates option definitions for all DHCPv4 options.
    /// Currently this function is not implemented.
    ///
    /// @throw std::bad alloc if system went out of memory.
    /// @throw MalformedOptionDefinition if any of the definitions
    /// are incorrect. This is programming error.
    static void initStdOptionDefs4();

    /// Initialize standard DHCPv6 option definitions.
    ///
    /// The method creates option definitions for all DHCPv6 options.
    ///
    /// @throw std::bad_alloc if system went out of memory.
    /// @throw MalformedOptionDefinition if any of the definitions
    /// is incorrect. This is a programming error.
    static void initStdOptionDefs6();

    /// pointers to factories that produce DHCPv6 options
    static FactoryMap v4factories_;

    /// pointers to factories that produce DHCPv6 options
    static FactoryMap v6factories_;

    /// Container with DHCPv4 option definitions.
    static OptionDefContainer v4option_defs_;

    /// Container with DHCPv6 option definitions.
    static OptionDefContainer v6option_defs_;
};

}
}

#endif // LIBDHCP_H