// Copyright (C) 2013-2014 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.

#include <dhcp/iface_mgr.h>
#include <dhcp/libdhcp++.h>
#include <dhcpsrv/cfgmgr.h>
#include <dhcpsrv/cfg_option.h>
#include <dhcpsrv/parsers/dhcp_parsers.h>
#include <hooks/hooks_manager.h>
#include <util/encode/hex.h>
#include <util/strutil.h>

#include <boost/algorithm/string.hpp>
#include <boost/foreach.hpp>
#include <boost/lexical_cast.hpp>

#include <map>
#include <string>
#include <vector>

using namespace std;
using namespace isc::asiolink;
using namespace isc::data;
using namespace isc::hooks;
using namespace isc::util;

namespace isc {
namespace dhcp {

// *********************** ParserContext  *************************

ParserContext::ParserContext(Option::Universe universe):
    boolean_values_(new BooleanStorage()),
    uint32_values_(new Uint32Storage()),
    string_values_(new StringStorage()),
    hooks_libraries_(),
    universe_(universe)
{
}

ParserContext::ParserContext(const ParserContext& rhs):
    boolean_values_(),
    uint32_values_(),
    string_values_(),
    hooks_libraries_(),
    universe_(rhs.universe_)
{
    copyContext(rhs);
}

ParserContext&
// The cppcheck version 1.56 doesn't recognize that copyContext
// copies all context fields.
// cppcheck-suppress operatorEqVarError
ParserContext::operator=(const ParserContext& rhs) {
    if (this != &rhs) {
        copyContext(rhs);
    }

    return (*this);
}

void
ParserContext::copyContext(const ParserContext& ctx) {
    copyContextPointer(ctx.boolean_values_, boolean_values_);
    copyContextPointer(ctx.uint32_values_, uint32_values_);
    copyContextPointer(ctx.string_values_, string_values_);
    copyContextPointer(ctx.hooks_libraries_, hooks_libraries_);
    // Copy universe.
    universe_ = ctx.universe_;
}

template<typename T>
void
ParserContext::copyContextPointer(const boost::shared_ptr<T>& source_ptr,
                                  boost::shared_ptr<T>& dest_ptr) {
    if (source_ptr) {
        dest_ptr.reset(new T(*source_ptr));
    } else {
        dest_ptr.reset();
    }
}


// **************************** DebugParser *************************

DebugParser::DebugParser(const std::string& param_name)
    :param_name_(param_name) {
}

void
DebugParser::build(ConstElementPtr new_config) {
    value_ = new_config;
    std::cout << "Build for token: [" << param_name_ << "] = ["
        << value_->str() << "]" << std::endl;
}

void
DebugParser::commit() {
    // Debug message. The whole DebugParser class is used only for parser
    // debugging, and is not used in production code. It is very convenient
    // to keep it around. Please do not turn this cout into logger calls.
    std::cout << "Commit for token: [" << param_name_ << "] = ["
                  << value_->str() << "]" << std::endl;
}

// **************************** BooleanParser  *************************

template<> void ValueParser<bool>::build(isc::data::ConstElementPtr value) {
    // Invoke common code for all specializations of build().
    buildCommon(value);
    // The Config Manager checks if user specified a
    // valid value for a boolean parameter: True or False.
    // We should have a boolean Element, use value directly
    try {
        value_ = value->boolValue();
    } catch (const isc::data::TypeError &) {
        isc_throw(BadValue, " Wrong value type for " << param_name_
                  << " : build called with a non-boolean element "
                  << "(" << value->getPosition() << ").");
    }
}

// **************************** Uin32Parser  *************************

template<> void ValueParser<uint32_t>::build(ConstElementPtr value) {
    // Invoke common code for all specializations of build().
    buildCommon(value);

    int64_t check;
    string x = value->str();
    try {
        check = boost::lexical_cast<int64_t>(x);
    } catch (const boost::bad_lexical_cast &) {
        isc_throw(BadValue, "Failed to parse value " << value->str()
                  << " as unsigned 32-bit integer "
                  "(" << value->getPosition() << ").");
    }
    if (check > std::numeric_limits<uint32_t>::max()) {
        isc_throw(BadValue, "Value " << value->str() << " is too large"
                  " for unsigned 32-bit integer "
                  "(" << value->getPosition() << ").");
    }
    if (check < 0) {
        isc_throw(BadValue, "Value " << value->str() << " is negative."
               << " Only 0 or larger are allowed for unsigned 32-bit integer "
                  "(" << value->getPosition() << ").");
    }

    // value is small enough to fit
    value_ = static_cast<uint32_t>(check);
}

// **************************** StringParser  *************************

template <> void ValueParser<std::string>::build(ConstElementPtr value) {
    // Invoke common code for all specializations of build().
    buildCommon(value);

    value_ = value->str();
    boost::erase_all(value_, "\"");
}

// ******************** InterfaceListConfigParser *************************

InterfaceListConfigParser::
InterfaceListConfigParser(const std::string& param_name,
                          ParserContextPtr global_context)
    : param_name_(param_name), global_context_(global_context) {
    if (param_name_ != "interfaces") {
        isc_throw(BadValue, "Internal error. Interface configuration "
            "parser called for the wrong parameter: " << param_name);
    }
}

void
InterfaceListConfigParser::build(ConstElementPtr value) {
    CfgIface cfg_iface;

    BOOST_FOREACH(ConstElementPtr iface, value->listValue()) {
        std::string iface_name = iface->stringValue();
        try {
            cfg_iface.use(global_context_->universe_ == Option::V4 ?
                          AF_INET : AF_INET6, iface_name);

        } catch (const std::exception& ex) {
            isc_throw(DhcpConfigError, "Failed to select interface: "
                      << ex.what() << " (" << value->getPosition() << ")");
        }
    }
    CfgMgr::instance().getStagingCfg()->setCfgIface(cfg_iface);
}

void
InterfaceListConfigParser::commit() {
    // Nothing to do.
}

// ******************** MACSourcesListConfigParser *************************

MACSourcesListConfigParser::
MACSourcesListConfigParser(const std::string& param_name,
                           ParserContextPtr global_context)
    : param_name_(param_name), global_context_(global_context) {
    if (param_name_ != "mac-sources") {
        isc_throw(BadValue, "Internal error. MAC sources configuration "
            "parser called for the wrong parameter: " << param_name);
    }
}

void
MACSourcesListConfigParser::build(ConstElementPtr value) {
    CfgIface cfg_iface;
    uint32_t source = 0;

    // By default, there's only one source defined: ANY.
    // If user specified anything, we need to get rid of that default.
    CfgMgr::instance().getStagingCfg()->clearMACSources();

    BOOST_FOREACH(ConstElementPtr source_elem, value->listValue()) {
        std::string source_str = source_elem->stringValue();
        try {
            source = Pkt::MACSourceFromText(source_str);
            CfgMgr::instance().getStagingCfg()->addMACSource(source);
        } catch (const std::exception& ex) {
            isc_throw(DhcpConfigError, "Failed to convert '"
                      << source_str << "' to any recognized MAC source:"
                      << ex.what() << " (" << value->getPosition() << ")");
        }
    }
}

void
MACSourcesListConfigParser::commit() {
    // Nothing to do.
}

// ******************** HooksLibrariesParser *************************

HooksLibrariesParser::HooksLibrariesParser(const std::string& param_name)
    : libraries_(), changed_(false)
{
    // Sanity check on the name.
    if (param_name != "hooks-libraries") {
        isc_throw(BadValue, "Internal error. Hooks libraries "
            "parser called for the wrong parameter: " << param_name);
    }
}

void
HooksLibrariesParser::build(ConstElementPtr value) {
    // Initialize.
    libraries_.clear();
    changed_ = false;

    // Extract the list of libraries.
    BOOST_FOREACH(ConstElementPtr iface, value->listValue()) {
        string libname = iface->str();
        boost::erase_all(libname, "\"");
        libraries_.push_back(libname);
    }

    // Check if the list of libraries has changed.  If not, nothing is done
    // - the command "DhcpN libreload" is required to reload the same
    // libraries (this prevents needless reloads when anything else in the
    // configuration is changed).
    vector<string> current_libraries = HooksManager::getLibraryNames();
    if (current_libraries == libraries_) {
        return;
    }

    // Library list has changed, validate each of the libraries specified.
    vector<string> error_libs = HooksManager::validateLibraries(libraries_);
    if (!error_libs.empty()) {

        // Construct the list of libraries in error for the message.
        string error_list = error_libs[0];
        for (int i = 1; i < error_libs.size(); ++i) {
            error_list += (string(", ") + error_libs[i]);
        }
        isc_throw(DhcpConfigError, "hooks libraries failed to validate - "
                  "library or libraries in error are: " << error_list
                  << " (" << value->getPosition() << ")");
    }

    // The library list has changed and the libraries are valid, so flag for
    // update when commit() is called.
    changed_ = true;
}

void
HooksLibrariesParser::commit() {
    /// Commits the list of libraries to the configuration manager storage if
    /// the list of libraries has changed.
    if (changed_) {
        // TODO Delete any stored CalloutHandles before reloading the
        // libraries
        HooksManager::loadLibraries(libraries_);
    }
}

// Method for testing
void
HooksLibrariesParser::getLibraries(std::vector<std::string>& libraries,
                                   bool& changed) {
    libraries = libraries_;
    changed = changed_;
}

// **************************** OptionDataParser *************************
OptionDataParser::OptionDataParser(const std::string&, const CfgOptionPtr& cfg,
                                   const uint16_t address_family)
    : boolean_values_(new BooleanStorage()),
      string_values_(new StringStorage()), uint32_values_(new Uint32Storage()),
      option_descriptor_(false), cfg_(cfg),
      address_family_(address_family) {
    // If configuration not specified, then it is a global configuration
    // scope.
    if (!cfg_) {
        cfg_ = CfgMgr::instance().getStagingCfg()->getCfgOption();
    }
}

void
OptionDataParser::build(ConstElementPtr option_data_entries) {
    BOOST_FOREACH(ConfigPair param, option_data_entries->mapValue()) {
        ParserPtr parser;
        if (param.first == "name" || param.first == "data" ||
            param.first == "space") {
            StringParserPtr name_parser(new StringParser(param.first,
                                        string_values_));
            parser = name_parser;
        } else if (param.first == "code") {
            Uint32ParserPtr code_parser(new Uint32Parser(param.first,
                                       uint32_values_));
            parser = code_parser;
        } else if (param.first == "csv-format") {
            BooleanParserPtr value_parser(new BooleanParser(param.first,
                                         boolean_values_));
            parser = value_parser;
        } else {
            isc_throw(DhcpConfigError,
                      "option-data parameter not supported: " << param.first
                      << " (" << param.second->getPosition() << ")");
        }

        parser->build(param.second);
        // Before we can create an option we need to get the data from
        // the child parsers. The only way to do it is to invoke commit
        // on them so as they store the values in appropriate storages
        // that this class provided to them. Note that this will not
        // modify values stored in the global storages so the configuration
        // will remain consistent even parsing fails somewhere further on.
        parser->commit();
    }

    // Try to create the option instance.
    createOption(option_data_entries);

    if (!option_descriptor_.option_) {
        isc_throw(isc::InvalidOperation,
            "parser logic error: no option has been configured and"
            " thus there is nothing to commit. Has build() been called?");
    }

    cfg_->add(option_descriptor_.option_, option_descriptor_.persistent_,
              option_space_);
}

void
OptionDataParser::commit() {
    // Does nothing
}

OptionalValue<uint32_t>
OptionDataParser::extractCode(ConstElementPtr parent) const {
    uint32_t code;
    try {
        code = uint32_values_->getParam("code");

    } catch (const exception& ex) {
        // The code parameter was not found. Return an unspecified
        // value.
        return (OptionalValue<uint32_t>());
    }

    if (code == 0) {
        isc_throw(DhcpConfigError, "option code must not be zero "
                  "(" << uint32_values_->getPosition("code", parent) << ")");

    } else if (address_family_ == AF_INET &&
               code > std::numeric_limits<uint8_t>::max()) {
        isc_throw(DhcpConfigError, "invalid option code '" << code
                << "', it must not be greater than '"
                  << static_cast<int>(std::numeric_limits<uint8_t>::max())
                  << "' (" << uint32_values_->getPosition("code", parent)
                  << ")");

    } else if (address_family_ == AF_INET6 &&
               code > std::numeric_limits<uint16_t>::max()) {
        isc_throw(DhcpConfigError, "invalid option code '" << code
                << "', it must not exceed '"
                  << std::numeric_limits<uint16_t>::max()
                  << "' (" << uint32_values_->getPosition("code", parent)
                  << ")");

    }

    return (OptionalValue<uint32_t>(code, OptionalValueState(true)));
}

OptionalValue<std::string>
OptionDataParser::extractName(ConstElementPtr parent) const {
    std::string name;
    try {
        name = string_values_->getParam("name");

    } catch (...) {
        return (OptionalValue<std::string>());
    }

    if (name.find(" ") != std::string::npos) {
        isc_throw(DhcpConfigError, "invalid option name '" << name
                  << "', space character is not allowed ("
                  << string_values_->getPosition("name", parent) << ")");
    }

    return (OptionalValue<std::string>(name, OptionalValueState(true)));
}

std::string
OptionDataParser::extractData() const {
    std::string data;
    try {
        data = string_values_->getParam("data");

    } catch (...) {
        // The "data" parameter was not found. Return an empty value.
        return (data);
    }

    return (data);
}

OptionalValue<bool>
OptionDataParser::extractCSVFormat() const {
    bool csv_format = true;
    try {
        csv_format = boolean_values_->getParam("csv-format");

    } catch (...) {
        return (OptionalValue<bool>(csv_format));
    }

    return (OptionalValue<bool>(csv_format, OptionalValueState(true)));
}

std::string
OptionDataParser::extractSpace() const {
    std::string space = address_family_ == AF_INET ? "dhcp4" : "dhcp6";
    try {
        space = string_values_->getParam("space");

    } catch (...) {
        return (space);
    }

    try {
        if (!OptionSpace::validateName(space)) {
            isc_throw(DhcpConfigError, "invalid option space name '"
                      << space << "'");
        }

        if ((space == DHCP4_OPTION_SPACE) && (address_family_ == AF_INET6)) {
            isc_throw(DhcpConfigError, "'" << DHCP4_OPTION_SPACE
                      << "' option space name is reserved for DHCPv4 server");

        } else if ((space == DHCP6_OPTION_SPACE) &&
                   (address_family_ == AF_INET)) {
            isc_throw(DhcpConfigError, "'" << DHCP6_OPTION_SPACE
                      << "' option space name is reserved for DHCPv6 server");
        }

    } catch (std::exception& ex) {
        // Append position of the option space parameter. Note, that in the case
        // when 'space' was not specified a default value will be used and we
        // should never get here. Therefore, it is ok to call getPosition for
        // the space parameter here as this parameter will always be specified.
        isc_throw(DhcpConfigError, ex.what() << " ("
                  << string_values_->getPosition("space") << ")");
    }

    return (space);
}

template<typename SearchKey>
OptionDefinitionPtr
OptionDataParser::findOptionDefinition(const std::string& option_space,
                                       const SearchKey& search_key) const {
    const Option::Universe u = address_family_ == AF_INET ?
        Option::V4 : Option::V6;
    OptionDefinitionPtr def;

    if ((option_space == DHCP4_OPTION_SPACE) ||
        (option_space == DHCP6_OPTION_SPACE)) {
        def = LibDHCP::getOptionDef(u, search_key);

    }

    if (!def) {
        // Check if this is a vendor-option. If it is, get vendor-specific
        // definition.
        uint32_t vendor_id = CfgOption::optionSpaceToVendorId(option_space);
        if (vendor_id) {
            def = LibDHCP::getVendorOptionDef(u, vendor_id, search_key);
        }
    }

    if (!def) {
        // Check if this is an option specified by a user.
        def = CfgMgr::instance().getStagingCfg()->getCfgOptionDef()
            ->get(option_space, search_key);
    }

    return (def);
}

void
OptionDataParser::createOption(ConstElementPtr option_data) {
    const Option::Universe universe = address_family_ == AF_INET ?
        Option::V4 : Option::V6;

    OptionalValue<uint32_t> code_param =  extractCode(option_data);
    OptionalValue<std::string> name_param = extractName(option_data);
    OptionalValue<bool> csv_format_param = extractCSVFormat();
    std::string data_param = extractData();
    std::string space_param = extractSpace();

    // Require that option code or option name is specified.
    if (!code_param.isSpecified() && !name_param.isSpecified()) {
        isc_throw(DhcpConfigError, "option data configuration requires one of"
                  " 'code' or 'name' parameters to be specified"
                  << " (" << option_data->getPosition() << ")");
    }

    // Try to find a corresponding option definition using option code or
    // option name.
    OptionDefinitionPtr def = code_param.isSpecified() ?
        findOptionDefinition(space_param, code_param) :
        findOptionDefinition(space_param, name_param);

    // If there is no definition, the user must not explicitly enable the
    // use of csv-format.
    if (!def) {
        // If explicitly requested that the CSV format is to be used,
        // the option definition is a must.
        if (csv_format_param.isSpecified() && csv_format_param) {
            isc_throw(DhcpConfigError, "definition for the option '"
                      << space_param << "." << name_param
                      << "' having code '" << code_param
                      << "' does not exist ("
                      << string_values_->getPosition("name", option_data)
                      << ")");

        // If there is no option definition and the option code is not specified
        // we have no means to find the option code.
        } else if (name_param.isSpecified() && !code_param.isSpecified()) {
            isc_throw(DhcpConfigError, "definition for the option '"
                      << space_param << "." << name_param
                      << " does not exist ("
                      << string_values_->getPosition("name", option_data));
        }
    }

    // Transform string of hexadecimal digits into binary format.
    std::vector<uint8_t> binary;
    std::vector<std::string> data_tokens;

    // If the definition is available and csv-format hasn't been explicitly
    // disabled, we will parse the data as comma separated values.
    if (def && (!csv_format_param.isSpecified() || csv_format_param)) {
        // If the option data is specified as a string of comma
        // separated values then we need to split this string into
        // individual values - each value will be used to initialize
        // one data field of an option.
        data_tokens = isc::util::str::tokens(data_param, ",");

    } else {
        // Otherwise, the option data is specified as a string of
        // hexadecimal digits that we have to turn into binary format.
        try {
            // The decodeHex function expects that the string contains an
            // even number of digits. If we don't meet this requirement,
            // we have to insert a leading 0.
            if (!data_param.empty() && data_param.length() % 2) {
                data_param = data_param.insert(0, "0");
            }
            util::encode::decodeHex(data_param, binary);
        } catch (...) {
            isc_throw(DhcpConfigError, "option data is not a valid"
                      << " string of hexadecimal digits: " << data_param
                      << " ("
                      << string_values_->getPosition("data", option_data)
                      << ")");
        }
    }

    OptionPtr option;
    if (!def) {
        // @todo We have a limited set of option definitions initalized at
        // the moment.  In the future we want to initialize option definitions
        // for all options.  Consequently an error will be issued if an option
        // definition does not exist for a particular option code. For now it is
        // ok to create generic option if definition does not exist.
        OptionPtr option(new Option(universe, static_cast<uint16_t>(code_param),
                                    binary));
        // The created option is stored in option_descriptor_ class member
        // until the commit stage when it is inserted into the main storage.
        // If an option with the same code exists in main storage already the
        // old option is replaced.
        option_descriptor_.option_ = option;
        option_descriptor_.persistent_ = false;

    } else {

        // Option name is specified it should match the name in the definition.
        if (name_param.isSpecified() && (def->getName() != name_param.get())) {
            isc_throw(DhcpConfigError, "specified option name '"
                      << name_param << "' does not match the "
                      << "option definition: '" << space_param
                      << "." << def->getName() << "' ("
                      << string_values_->getPosition("name", option_data)
                      << ")");
        }

        // Option definition has been found so let's use it to create
        // an instance of our option.
        try {
            OptionPtr option =
                !csv_format_param.isSpecified() || csv_format_param ?
                def->optionFactory(universe, def->getCode(), data_tokens) :
                def->optionFactory(universe, def->getCode(), binary);
            OptionDescriptor desc(option, false);
            option_descriptor_.option_ = option;
            option_descriptor_.persistent_ = false;

        } catch (const isc::Exception& ex) {
            isc_throw(DhcpConfigError, "option data does not match"
                      << " option definition (space: " << space_param
                      << ", code: " << def->getCode() << "): "
                      << ex.what() << " ("
                      << string_values_->getPosition("data", option_data)
                      << ")");
        }
    }

    // All went good, so we can set the option space name.
    option_space_ = space_param;
}

// **************************** OptionDataListParser *************************
OptionDataListParser::OptionDataListParser(const std::string&,
                                           const CfgOptionPtr& cfg,
                                           const uint16_t address_family)
    : cfg_(cfg), address_family_(address_family) {
}

void
OptionDataListParser::build(ConstElementPtr option_data_list) {
    BOOST_FOREACH(ConstElementPtr option_value, option_data_list->listValue()) {
        boost::shared_ptr<OptionDataParser>
            parser(new OptionDataParser("option-data", cfg_, address_family_));

        parser->build(option_value);
        parsers_.push_back(parser);
    }
}

void
OptionDataListParser::commit() {
    BOOST_FOREACH(ParserPtr parser, parsers_) {
        parser->commit();
    }
}

// ******************************** OptionDefParser ****************************
OptionDefParser::OptionDefParser(const std::string&,
                                 ParserContextPtr global_context)
    : boolean_values_(new BooleanStorage()),
      string_values_(new StringStorage()),
      uint32_values_(new Uint32Storage()),
      global_context_(global_context) {
}

void
OptionDefParser::build(ConstElementPtr option_def) {
    // Parse the elements that make up the option definition.
    BOOST_FOREACH(ConfigPair param, option_def->mapValue()) {
        std::string entry(param.first);
        ParserPtr parser;
        if (entry == "name" || entry == "type" || entry == "record-types"
            || entry == "space" || entry == "encapsulate") {
            StringParserPtr str_parser(new StringParser(entry,
                                       string_values_));
            parser = str_parser;
        } else if (entry == "code") {
            Uint32ParserPtr code_parser(new Uint32Parser(entry,
                                        uint32_values_));
            parser = code_parser;
        } else if (entry == "array") {
            BooleanParserPtr array_parser(new BooleanParser(entry,
                                         boolean_values_));
            parser = array_parser;
        } else {
            isc_throw(DhcpConfigError, "invalid parameter '" << entry
                      << "' (" << param.second->getPosition() << ")");
        }

        parser->build(param.second);
        parser->commit();
    }
    // Create an instance of option definition.
    createOptionDef(option_def);

    try {
        CfgMgr::instance().getStagingCfg()->getCfgOptionDef()->
            add(option_definition_, option_space_name_);

    } catch (const std::exception& ex) {
        // Append position if there is a failure.
        isc_throw(DhcpConfigError, ex.what() << " ("
                  << option_def->getPosition() << ")");
    }
}

void
OptionDefParser::commit() {
    // Do nothing.
}

void
OptionDefParser::createOptionDef(ConstElementPtr option_def_element) {
    // Check if mandatory parameters have been specified.
    std::string name;
    uint32_t code;
    std::string type;
    try {
        name = string_values_->getParam("name");
        code = uint32_values_->getParam("code");
        type = string_values_->getParam("type");
    } catch (const std::exception& ex) {
        isc_throw(DhcpConfigError, ex.what() << " ("
                  << option_def_element->getPosition() << ")");
    }

    bool array_type = boolean_values_->getOptionalParam("array", false);
    std::string record_types =
        string_values_->getOptionalParam("record-types", "");
    std::string space = string_values_->getOptionalParam("space",
              global_context_->universe_ == Option::V4 ? "dhcp4" : "dhcp6");
    std::string encapsulates =
        string_values_->getOptionalParam("encapsulate", "");

    if (!OptionSpace::validateName(space)) {
        isc_throw(DhcpConfigError, "invalid option space name '"
                  << space << "' ("
                  << string_values_->getPosition("space") << ")");
    }

    // Create option definition.
    OptionDefinitionPtr def;
    // We need to check if user has set encapsulated option space
    // name. If so, different constructor will be used.
    if (!encapsulates.empty()) {
        // Arrays can't be used together with sub-options.
        if (array_type) {
            isc_throw(DhcpConfigError, "option '" << space << "."
                      << "name" << "', comprising an array of data"
                      << " fields may not encapsulate any option space ("
                      << option_def_element->getPosition() << ")");

        } else if (encapsulates == space) {
            isc_throw(DhcpConfigError, "option must not encapsulate"
                      << " an option space it belongs to: '"
                      << space << "." << name << "' is set to"
                      << " encapsulate '" << space << "' ("
                      << option_def_element->getPosition() << ")");

        } else {
            def.reset(new OptionDefinition(name, code, type,
                        encapsulates.c_str()));
        }

    } else {
        def.reset(new OptionDefinition(name, code, type, array_type));

    }

    // Split the list of record types into tokens.
    std::vector<std::string> record_tokens =
    isc::util::str::tokens(record_types, ",");
    // Iterate over each token and add a record type into
    // option definition.
    BOOST_FOREACH(std::string record_type, record_tokens) {
        try {
            boost::trim(record_type);
            if (!record_type.empty()) {
                    def->addRecordField(record_type);
            }
        } catch (const Exception& ex) {
            isc_throw(DhcpConfigError, "invalid record type values"
                      << " specified for the option definition: "
                      << ex.what() << " ("
                      << string_values_->getPosition("record-types") << ")");
        }
    }

    // Validate the definition.
    try {
        def->validate();
    } catch (const std::exception& ex) {
        isc_throw(DhcpConfigError, ex.what()
                  << " (" << option_def_element->getPosition() << ")");
    }

    // Option definition has been created successfully.
    option_space_name_ = space;
    option_definition_ = def;
}

// ******************************** OptionDefListParser ************************
OptionDefListParser::OptionDefListParser(const std::string&,
                                         ParserContextPtr global_context)
    : global_context_(global_context) {
}

void
OptionDefListParser::build(ConstElementPtr option_def_list) {
    if (!option_def_list) {
        isc_throw(DhcpConfigError, "parser error: a pointer to a list of"
                  << " option definitions is NULL ("
                  << option_def_list->getPosition() << ")");
    }

    BOOST_FOREACH(ConstElementPtr option_def, option_def_list->listValue()) {
        boost::shared_ptr<OptionDefParser>
            parser(new OptionDefParser("single-option-def", global_context_));
        parser->build(option_def);
    }
}

void
OptionDefListParser::commit() {
    // Do nothing.
}

//****************************** RelayInfoParser ********************************
RelayInfoParser::RelayInfoParser(const std::string&,
                                 const isc::dhcp::Subnet::RelayInfoPtr& relay_info,
                                 const Option::Universe& family)
    :storage_(relay_info), local_(isc::asiolink::IOAddress(
                                  family == Option::V4 ? "0.0.0.0" : "::")),
     string_values_(new StringStorage()), family_(family) {
    if (!relay_info) {
        isc_throw(isc::dhcp::DhcpConfigError, "parser logic error: "
                  << "relay-info storage may not be NULL");
    }

};

void
RelayInfoParser::build(ConstElementPtr relay_info) {

    BOOST_FOREACH(ConfigPair param, relay_info->mapValue()) {
        ParserPtr parser(createConfigParser(param.first));
        parser->build(param.second);
        parser->commit();
    }

    // Get the IP address
    boost::scoped_ptr<asiolink::IOAddress> ip;
    try {
        ip.reset(new asiolink::IOAddress(string_values_->getParam("ip-address")));
    } catch (...)  {
        isc_throw(DhcpConfigError, "Failed to parse ip-address "
                  "value: " << string_values_->getParam("ip-address")
                  << " (" << string_values_->getPosition("ip-address") << ")");
    }

    if ( (ip->isV4() && family_ != Option::V4) ||
         (ip->isV6() && family_ != Option::V6) ) {
        isc_throw(DhcpConfigError, "ip-address field " << ip->toText()
                  << "does not have IP address of expected family type: "
                  << (family_ == Option::V4 ? "IPv4" : "IPv6")
                  << " (" << string_values_->getPosition("ip-address") << ")");
    }

    local_.addr_ = *ip;
}

isc::dhcp::ParserPtr
RelayInfoParser::createConfigParser(const std::string& parameter) {
    DhcpConfigParser* parser = NULL;
    if (parameter.compare("ip-address") == 0) {
        parser = new StringParser(parameter, string_values_);
    } else {
        isc_throw(NotImplemented,
                  "parser error: RelayInfoParser parameter not supported: "
                  << parameter);
    }

    return (isc::dhcp::ParserPtr(parser));
}

void
RelayInfoParser::commit() {
    *storage_ = local_;
}

//****************************** PoolsListParser ********************************
PoolsListParser::PoolsListParser(const std::string&, PoolStoragePtr pools)
    :pools_(pools), local_pools_(new PoolStorage()) {
    if (!pools_) {
        isc_throw(isc::dhcp::DhcpConfigError, "parser logic error: "
                  << "storage may not be NULL");
    }
}

void
PoolsListParser::build(ConstElementPtr pools) {
    BOOST_FOREACH(ConstElementPtr pool, pools->listValue()) {

        // Iterate over every structure on the pools list and invoke
        // a separate parser for it.
        ParserPtr parser = poolParserMaker(local_pools_);

        parser->build(pool);

        // Let's store the parser, but do not commit anything yet
        parsers_.push_back(parser);
    }
}

void PoolsListParser::commit() {

    // Commit each parser first. It will store the pool structure
    // in pools_.
    BOOST_FOREACH(ParserPtr parser, parsers_) {
        parser->commit();
    }

    if (pools_) {
        // local_pools_ holds the values produced by the build function.
        // At this point parsing should have completed successfuly so
        // we can append new data to the supplied storage.
        pools_->insert(pools_->end(), local_pools_->begin(), local_pools_->end());
    }
}

//****************************** PoolParser ********************************
PoolParser::PoolParser(const std::string&,  PoolStoragePtr pools)
        :pools_(pools) {

    if (!pools_) {
        isc_throw(isc::dhcp::DhcpConfigError, "parser logic error: "
                  << "storage may not be NULL");
    }
}

void
PoolParser::build(ConstElementPtr pool_structure) {

    ConstElementPtr text_pool = pool_structure->get("pool");

    if (!text_pool) {
        isc_throw(DhcpConfigError, "Mandatory 'pool' entry missing in "
                  "definition: (" << text_pool->getPosition() << ")");
    }

    // That should be a single pool representation. It should contain
    // text is form prefix/len or first - last. Note that spaces
    // are allowed
    string txt = text_pool->stringValue();

    // first let's remove any whitespaces
    boost::erase_all(txt, " "); // space
    boost::erase_all(txt, "\t"); // tabulation

    // Is this prefix/len notation?
    size_t pos = txt.find("/");
    if (pos != string::npos) {
        isc::asiolink::IOAddress addr("::");
        uint8_t len = 0;
        try {
            addr = isc::asiolink::IOAddress(txt.substr(0, pos));

            // start with the first character after /
            string prefix_len = txt.substr(pos + 1);

            // It is lexical cast to int and then downcast to uint8_t.
            // Direct cast to uint8_t (which is really an unsigned char)
            // will result in interpreting the first digit as output
            // value and throwing exception if length is written on two
            // digits (because there are extra characters left over).

            // No checks for values over 128. Range correctness will
            // be checked in Pool4 constructor.
            len = boost::lexical_cast<int>(prefix_len);
        } catch (...)  {
            isc_throw(DhcpConfigError, "Failed to parse pool "
                      "definition: " << text_pool->stringValue()
                      << " (" << text_pool->getPosition() << ")");
        }

        PoolPtr pool(poolMaker(addr, len));
        local_pools_.push_back(pool);
        return;
    }

    // Is this min-max notation?
    pos = txt.find("-");
    if (pos != string::npos) {
        // using min-max notation
        isc::asiolink::IOAddress min(txt.substr(0,pos));
        isc::asiolink::IOAddress max(txt.substr(pos + 1));

        PoolPtr pool(poolMaker(min, max));
        local_pools_.push_back(pool);
        return;
    }

    isc_throw(DhcpConfigError, "invalid pool definition: "
              << text_pool->stringValue() <<
              ". There are two acceptable formats <min address-max address>"
              " or <prefix/len> ("
              << text_pool->getPosition() << ")");
}

void
PoolParser::commit() {
    if (pools_) {
        // local_pools_ holds the values produced by the build function.
        // At this point parsing should have completed successfuly so
        // we can append new data to the supplied storage.
        pools_->insert(pools_->end(), local_pools_.begin(), local_pools_.end());
    }
}

//****************************** SubnetConfigParser *************************

SubnetConfigParser::SubnetConfigParser(const std::string&,
                                       ParserContextPtr global_context,
                                       const isc::asiolink::IOAddress& default_addr)
    : uint32_values_(new Uint32Storage()), string_values_(new StringStorage()),
      pools_(new PoolStorage()), global_context_(global_context),
      relay_info_(new isc::dhcp::Subnet::RelayInfo(default_addr)),
      options_(new CfgOption()) {
    // The first parameter should always be "subnet", but we don't check
    // against that here in case some wants to reuse this parser somewhere.
    if (!global_context_) {
        isc_throw(isc::dhcp::DhcpConfigError, "parser logic error: "
                 << "context storage may not be NULL");
    }

}

void
SubnetConfigParser::build(ConstElementPtr subnet) {
    BOOST_FOREACH(ConfigPair param, subnet->mapValue()) {
        // Host reservations must be parsed after subnet specific parameters.
        // Note that the reservation parsing will be invoked by the build()
        // in the derived classes, i.e. Subnet4ConfigParser and
        // Subnet6ConfigParser.
        if (param.first == "reservations") {
            continue;
        }

        ParserPtr parser;
        // When unsupported parameter is specified, the function called
        // below will thrown an exception. We have to catch this exception
        // to append the line number where the parameter is.
        try {
            parser.reset(createSubnetConfigParser(param.first));

        } catch (const std::exception& ex) {
            isc_throw(DhcpConfigError, ex.what() << " ("
                      << param.second->getPosition() << ")");
        }
        parser->build(param.second);
        parsers_.push_back(parser);
    }

    // In order to create new subnet we need to get the data out
    // of the child parsers first. The only way to do it is to
    // invoke commit on them because it will make them write
    // parsed data into storages we have supplied.
    // Note that triggering commits on child parsers does not
    // affect global data because we supplied pointers to storages
    // local to this object. Thus, even if this method fails
    // later on, the configuration remains consistent.
    BOOST_FOREACH(ParserPtr parser, parsers_) {
        parser->commit();
    }

    // Create a subnet.
    try {
        createSubnet();
    } catch (const std::exception& ex) {
        isc_throw(DhcpConfigError,
                  "subnet configuration failed (" << subnet->getPosition()
                  << "): " << ex.what());
    }
}

void
SubnetConfigParser::createSubnet() {
    std::string subnet_txt;
    try {
        subnet_txt = string_values_->getParam("subnet");
    } catch (const DhcpConfigError &) {
        // rethrow with precise error
        isc_throw(DhcpConfigError,
                 "mandatory 'subnet' parameter is missing for a subnet being"
                  " configured");
    }

    // Remove any spaces or tabs.
    boost::erase_all(subnet_txt, " ");
    boost::erase_all(subnet_txt, "\t");

    // The subnet format is prefix/len. We are going to extract
    // the prefix portion of a subnet string to create IOAddress
    // object from it. IOAddress will be passed to the Subnet's
    // constructor later on. In order to extract the prefix we
    // need to get all characters preceding "/".
    size_t pos = subnet_txt.find("/");
    if (pos == string::npos) {
        isc_throw(DhcpConfigError,
                  "Invalid subnet syntax (prefix/len expected):" << subnet_txt
                  << " (" << string_values_->getPosition("subnet") << ")");
    }

    // Try to create the address object. It also validates that
    // the address syntax is ok.
    isc::asiolink::IOAddress addr(subnet_txt.substr(0, pos));
    uint8_t len = boost::lexical_cast<unsigned int>(subnet_txt.substr(pos + 1));

    // Call the subclass's method to instantiate the subnet
    initSubnet(addr, len);

    // Add pools to it.
    for (PoolStorage::iterator it = pools_->begin(); it != pools_->end();
         ++it) {
        subnet_->addPool(*it);
    }

    // Configure interface, if defined

    // Get interface name. If it is defined, then the subnet is available
    // directly over specified network interface.
    std::string iface;
    try {
        iface = string_values_->getParam("interface");
    } catch (const DhcpConfigError &) {
        // iface not mandatory so swallow the exception
    }

    if (!iface.empty()) {
        if (!IfaceMgr::instance().getIface(iface)) {
            isc_throw(DhcpConfigError, "Specified interface name " << iface
                      << " for subnet " << subnet_->toText()
                      << " is not present" << " in the system ("
                      << string_values_->getPosition("interface") << ")");
        }

        subnet_->setIface(iface);
    }

    // Merge globally defined options to the subnet specific options.
    CfgMgr::instance().getStagingCfg()->getCfgOption()->mergeTo(*options_);
    // Copy all options to the subnet configuration.
    options_->copyTo(*subnet_->getCfgOption());
    // Append suboptions to the top-level options.
    subnet_->getCfgOption()->encapsulate();
}

isc::dhcp::Triplet<uint32_t>
SubnetConfigParser::getParam(const std::string& name) {
    uint32_t value = 0;
    try {
        // look for local value
        value = uint32_values_->getParam(name);
    } catch (const DhcpConfigError &) {
        try {
            // no local, use global value
            value = global_context_->uint32_values_->getParam(name);
        } catch (const DhcpConfigError &) {
            isc_throw(DhcpConfigError, "Mandatory parameter " << name
                      << " missing (no global default and no subnet-"
                      << "specific value)");
        }
    }

    return (Triplet<uint32_t>(value));
}

isc::dhcp::Triplet<uint32_t>
SubnetConfigParser::getOptionalParam(const std::string& name) {
    try {
        return (getParam(name));
    } catch (const DhcpConfigError &) {
        // No error. We will return an unspecified value.
    }
    return (Triplet<uint32_t>());
}

//**************************** D2ClientConfigParser **********************
D2ClientConfigParser::D2ClientConfigParser(const std::string& entry_name)
    : entry_name_(entry_name), boolean_values_(new BooleanStorage()),
      uint32_values_(new Uint32Storage()), string_values_(new StringStorage()),
      local_client_config_() {
}

D2ClientConfigParser::~D2ClientConfigParser() {
}

void
D2ClientConfigParser::build(isc::data::ConstElementPtr client_config) {
    BOOST_FOREACH(ConfigPair param, client_config->mapValue()) {
        ParserPtr parser;
        try {
            parser = createConfigParser(param.first);
        } catch (std::exception& ex) {
            // Catch exception in case the configuration contains the
            // unsupported parameter. In this case, we will need to
            // append the position of this element.
            isc_throw(DhcpConfigError, ex.what() << " ("
                      << param.second->getPosition() << ")");
        }

        parser->build(param.second);
        parser->commit();
    }

    /// @todo Create configuration from the configuration parameters. Because
    /// the validation of the D2 configuration is atomic, there is no way to
    /// tell which parameter is invalid. Therefore, we catch all exceptions
    /// and append the line number of the parent element. In the future we
    /// may should extend D2ClientConfig code so as it returns the name of
    /// the invalid parameter.
    try {
        bool enable_updates = boolean_values_->getParam("enable-updates");
        if (!enable_updates && (client_config->mapValue().size() == 1)) {
            // If enable-updates is the only parameter and it is false then
            // we're done.  This allows for an abbreviated configuration entry
            // that only contains that flag.  Use the default D2ClientConfig
            // constructor to a create a disabled instance.
            local_client_config_.reset(new D2ClientConfig());

            return;
        }

        // Get all parameters that are needed to create the D2ClientConfig.
        IOAddress server_ip =
            IOAddress(string_values_->getOptionalParam("server-ip",
                                                       D2ClientConfig::
                                                       DFT_SERVER_IP));

        uint32_t server_port =
            uint32_values_->getOptionalParam("server-port",
                                             D2ClientConfig::DFT_SERVER_PORT);

        // The default sender IP depends on the server IP family
        asiolink::IOAddress
            sender_ip(string_values_->
                      getOptionalParam("sender-ip",
                                       (server_ip.isV4() ?
                                        D2ClientConfig::DFT_V4_SENDER_IP :
                                        D2ClientConfig::DFT_V6_SENDER_IP)));

        uint32_t sender_port =
            uint32_values_->getOptionalParam("sender-port",
                                             D2ClientConfig::
                                             DFT_SENDER_PORT);
        uint32_t max_queue_size
            = uint32_values_->getOptionalParam("max-queue-size",
                                               D2ClientConfig::
                                               DFT_MAX_QUEUE_SIZE);

        dhcp_ddns::NameChangeProtocol ncr_protocol =
            dhcp_ddns::stringToNcrProtocol(string_values_->
                                           getOptionalParam("ncr-protocol",
                                                            D2ClientConfig::
                                                            DFT_NCR_PROTOCOL));
        dhcp_ddns::NameChangeFormat ncr_format
            = dhcp_ddns::stringToNcrFormat(string_values_->
                                           getOptionalParam("ncr-format",
                                                            D2ClientConfig::
                                                            DFT_NCR_FORMAT));
        std::string generated_prefix =
            string_values_->getOptionalParam("generated-prefix",
                                             D2ClientConfig::
                                             DFT_GENERATED_PREFIX);
        std::string qualifying_suffix =
            string_values_->getOptionalParam("qualifying-suffix",
                                             D2ClientConfig::
                                             DFT_QUALIFYING_SUFFIX);

        bool always_include_fqdn =
            boolean_values_->getOptionalParam("always-include-fqdn",
                                                D2ClientConfig::
                                                DFT_ALWAYS_INCLUDE_FQDN);

        bool override_no_update =
            boolean_values_->getOptionalParam("override-no-update",
                                              D2ClientConfig::
                                              DFT_OVERRIDE_NO_UPDATE);

        bool override_client_update =
            boolean_values_->getOptionalParam("override-client-update",
                                              D2ClientConfig::
                                              DFT_OVERRIDE_CLIENT_UPDATE);

        bool replace_client_name =
            boolean_values_->getOptionalParam("replace-client-name",
                                              D2ClientConfig::
                                              DFT_REPLACE_CLIENT_NAME);

        // Attempt to create the new client config.
        local_client_config_.reset(new D2ClientConfig(enable_updates,
                                                      server_ip,
                                                      server_port,
                                                      sender_ip,
                                                      sender_port,
                                                      max_queue_size,
                                                      ncr_protocol,
                                                      ncr_format,
                                                      always_include_fqdn,
                                                      override_no_update,
                                                      override_client_update,
                                                      replace_client_name,
                                                      generated_prefix,
                                                      qualifying_suffix));

    }  catch (const std::exception& ex) {
        isc_throw(DhcpConfigError, ex.what() << " ("
                  << client_config->getPosition() << ")");
    }
}

isc::dhcp::ParserPtr
D2ClientConfigParser::createConfigParser(const std::string& config_id) {
    DhcpConfigParser* parser = NULL;
    if ((config_id.compare("server-port") == 0) ||
        (config_id.compare("sender-port") == 0) ||
        (config_id.compare("max-queue-size") == 0)) {
        parser = new Uint32Parser(config_id, uint32_values_);
    } else if ((config_id.compare("server-ip") == 0) ||
        (config_id.compare("ncr-protocol") == 0) ||
        (config_id.compare("ncr-format") == 0) ||
        (config_id.compare("generated-prefix") == 0) ||
        (config_id.compare("sender-ip") == 0) ||
        (config_id.compare("qualifying-suffix") == 0)) {
        parser = new StringParser(config_id, string_values_);
    } else if ((config_id.compare("enable-updates") == 0) ||
        (config_id.compare("always-include-fqdn") == 0) ||
        (config_id.compare("allow-client-update") == 0) ||
        (config_id.compare("override-no-update") == 0) ||
        (config_id.compare("override-client-update") == 0) ||
        (config_id.compare("replace-client-name") == 0)) {
        parser = new BooleanParser(config_id, boolean_values_);
    } else {
        isc_throw(NotImplemented,
            "parser error: D2ClientConfig parameter not supported: "
            << config_id);
    }

    return (isc::dhcp::ParserPtr(parser));
}

void
D2ClientConfigParser::commit() {
    // @todo if local_client_config_ is empty then shutdown the listener...
    // @todo Should this also attempt to start a listener?
    // In keeping with Interface, Subnet, and Hooks parsers, then this
    // should initialize the listener.  Failure to init it, should cause
    // rollback.  This gets sticky, because who owns the listener instance?
    // Does CfgMgr maintain it or does the server class?  If the latter
    // how do we get that value here?
    // I'm thinkikng D2ClientConfig could contain the listener instance
    CfgMgr::instance().setD2ClientConfig(local_client_config_);
}

};  // namespace dhcp
};  // namespace isc