/*
Copyright (c) 2014, 2015, 2016 Jarryd Beck
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*/

#ifndef CXX_OPTS_HPP
#define CXX_OPTS_HPP

#if defined(__GNUC__)
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wnon-virtual-dtor"
#endif

#include <cstring>
#include <exception>
#include <iostream>
#include <map>
#include <memory>
#include <regex>
#include <sstream>
#include <string>
#include <unordered_set>
#include <vector>

//when we ask cxxopts to use Unicode, help strings are processed using ICU,
//which results in the correct lengths being computed for strings when they
//are formatted for the help output
//it is necessary to make sure that <unicode/unistr.h> can be found by the
//compiler, and that icu-uc is linked in to the binary.

#ifdef CXXOPTS_USE_UNICODE
#include <unicode/unistr.h>

namespace cxxopts
{
  typedef icu::UnicodeString String;

  inline
  String
  toLocalString(std::string s)
  {
    return icu::UnicodeString::fromUTF8(s);
  }

  class UnicodeStringIterator : public
    std::iterator<std::forward_iterator_tag, int32_t>
  {
    public:

    UnicodeStringIterator(const icu::UnicodeString* s, int32_t pos)
    : s(s)
    , i(pos)
    {
    }

    value_type
    operator*() const
    {
      return s->char32At(i);
    }

    bool
    operator==(const UnicodeStringIterator& rhs) const
    {
      return s == rhs.s && i == rhs.i;
    }

    bool
    operator!=(const UnicodeStringIterator& rhs) const
    {
      return !(*this == rhs);
    }

    UnicodeStringIterator&
    operator++()
    {
      ++i;
      return *this;
    }

    UnicodeStringIterator
    operator+(int32_t v)
    {
      return UnicodeStringIterator(s, i + v);
    }

    private:
    const icu::UnicodeString* s;
    int32_t i;
  };

  inline
  String&
  stringAppend(String&s, String a)
  {
    return s.append(std::move(a));
  }

  inline
  String&
  stringAppend(String& s, int n, UChar32 c)
  {
    for (int i = 0; i != n; ++i)
    {
      s.append(c);
    }

    return s;
  }

  template <typename Iterator>
  String&
  stringAppend(String& s, Iterator begin, Iterator end)
  {
    while (begin != end)
    {
      s.append(*begin);
      ++begin;
    }

    return s;
  }

  inline
  size_t
  stringLength(const String& s)
  {
    return s.length();
  }

  inline
  std::string
  toUTF8String(const String& s)
  {
    std::string result;
    s.toUTF8String(result);

    return result;
  }

  inline
  bool
  empty(const String& s)
  {
    return s.isEmpty();
  }
}

namespace std
{
  cxxopts::UnicodeStringIterator
  begin(const icu::UnicodeString& s)
  {
    return cxxopts::UnicodeStringIterator(&s, 0);
  }

  cxxopts::UnicodeStringIterator
  end(const icu::UnicodeString& s)
  {
    return cxxopts::UnicodeStringIterator(&s, s.length());
  }
}

//ifdef CXXOPTS_USE_UNICODE
#else

namespace cxxopts
{
    typedef std::string String;

    template <typename T>
    T
    toLocalString(T&& t)
    {
        return t;
    }

    inline
    size_t
    stringLength(const String& s)
    {
        return s.length();
    }

    inline
    String&
    stringAppend(String&s, String a)
    {
        return s.append(std::move(a));
    }

    inline
    String&
    stringAppend(String& s, size_t n, char c)
    {
        return s.append(n, c);
    }

    template <typename Iterator>
    String&
    stringAppend(String& s, Iterator begin, Iterator end)
    {
        return s.append(begin, end);
    }

    template <typename T>
    std::string
    toUTF8String(T&& t)
    {
        return std::forward<T>(t);
    }

    inline
    bool
    empty(const std::string& s)
    {
        return s.empty();
    }
}

//ifdef CXXOPTS_USE_UNICODE
#endif

namespace cxxopts
{
    class Value : public std::enable_shared_from_this<Value>
    {
    public:

        virtual void
        parse(const std::string& text) const = 0;

        virtual void
        parse() const = 0;

        virtual bool
        has_arg() const = 0;

        virtual bool
        has_default() const = 0;

        virtual bool
        is_container() const = 0;

        virtual bool
        has_implicit() const = 0;

        virtual std::string
        get_default_value() const = 0;

        virtual std::string
        get_implicit_value() const = 0;

        virtual std::shared_ptr<Value>
        default_value(const std::string& value) = 0;

        virtual std::shared_ptr<Value>
        implicit_value(const std::string& value) = 0;
    };

    class OptionException : public std::exception
    {
    public:
        OptionException(const std::string& message)
                : m_message(message)
        {
        }

        virtual const char*
        what() const noexcept
        {
            return m_message.c_str();
        }

    private:
        std::string m_message;
    };

    class OptionSpecException : public OptionException
    {
    public:

        OptionSpecException(const std::string& message)
                : OptionException(message)
        {
        }
    };

    class OptionParseException : public OptionException
    {
    public:
        OptionParseException(const std::string& message)
                : OptionException(message)
        {
        }
    };

    class option_exists_error : public OptionSpecException
    {
    public:
        option_exists_error(const std::string& option)
                : OptionSpecException(u8"Option ‘" + option + u8"’ already exists")
        {
        }
    };

    class invalid_option_format_error : public OptionSpecException
    {
    public:
        invalid_option_format_error(const std::string& format)
                : OptionSpecException(u8"Invalid option format ‘" + format + u8"’")
        {
        }
    };

    class option_not_exists_exception : public OptionParseException
    {
    public:
        option_not_exists_exception(const std::string& option)
                : OptionParseException(u8"Option ‘" + option + u8"’ does not exist")
        {
        }
    };

    class missing_argument_exception : public OptionParseException
    {
    public:
        missing_argument_exception(const std::string& option)
                : OptionParseException(u8"Option ‘" + option + u8"’ is missing an argument")
        {
        }
    };

    class option_requires_argument_exception : public OptionParseException
    {
    public:
        option_requires_argument_exception(const std::string& option)
                : OptionParseException(u8"Option ‘" + option + u8"’ requires an argument")
        {
        }
    };

    class option_not_has_argument_exception : public OptionParseException
    {
    public:
        option_not_has_argument_exception
                (
                        const std::string& option,
                        const std::string& arg
                )
                : OptionParseException(
                u8"Option ‘" + option + u8"’ does not take an argument, but argument‘"
                + arg + "’ given")
        {
        }
    };

    class option_not_present_exception : public OptionParseException
    {
    public:
        option_not_present_exception(const std::string& option)
                : OptionParseException(u8"Option ‘" + option + u8"’ not present")
        {
        }
    };

    class argument_incorrect_type : public OptionParseException
    {
    public:
        argument_incorrect_type
                (
                        const std::string& arg
                )
                : OptionParseException(
                u8"Argument ‘" + arg + u8"’ failed to parse"
        )
        {
        }
    };

    namespace values
    {
        template <typename T>
        void
        parse_value(const std::string& text, T& value)
        {
            std::istringstream is(text);
            if (!(is >> value))
            {
                throw argument_incorrect_type(text);
            }

            if (is.rdbuf()->in_avail() != 0)
            {
                throw argument_incorrect_type(text);
            }
        }

        inline
        void
        parse_value(const std::string& /*text*/, bool& value)
        {
            //TODO recognise on, off, yes, no, enable, disable
            //so that we can write --long=yes explicitly
            value = true;
        }

        inline
        void
        parse_value(const std::string& text, std::string& value)
        {
            value = text;
        }

        template <typename T>
        void
        parse_value(const std::string& text, std::vector<T>& value)
        {
            T v;
            parse_value(text, v);
            value.push_back(v);
        }

        template <typename T>
        struct value_has_arg
        {
            static constexpr bool value = true;
        };

        template <>
        struct value_has_arg<bool>
        {
            static constexpr bool value = false;
        };

        template <typename T>
        struct type_is_container
        {
            static constexpr bool value = false;
        };

        template <typename T>
        struct type_is_container<std::vector<T>>
        {
            static constexpr bool value = true;
        };

        template <typename T>
        class standard_value : public Value
        {
        public:
            standard_value()
                    : m_result(std::make_shared<T>())
                    , m_store(m_result.get())
            {
            }

            standard_value(T* t)
                    : m_store(t)
            {
            }

            void
            parse(const std::string& text) const
            {
                if (m_implicit && text.empty())
                {
                    parse_value(m_implicit_value, *m_store);
                }
                else
                {
                    parse_value(text, *m_store);
                }
            }

            bool
            is_container() const
            {
                return type_is_container<T>::value;
            }

            void
            parse() const
            {
                parse_value(m_default_value, *m_store);
            }

            bool
            has_arg() const
            {
                return value_has_arg<T>::value;
            }

            bool
            has_default() const
            {
                return m_default;
            }

            bool
            has_implicit() const
            {
                return m_implicit;
            }

            virtual std::shared_ptr<Value>
            default_value(const std::string& value){
                m_default = true;
                m_default_value = value;
                return shared_from_this();
            }

            virtual std::shared_ptr<Value>
            implicit_value(const std::string& value){
                m_implicit = true;
                m_implicit_value = value;
                return shared_from_this();
            }

            std::string
            get_default_value() const
            {
                return m_default_value;
            }

            std::string
            get_implicit_value() const
            {
                return m_implicit_value;
            }

            const T&
            get() const
            {
                if (m_store == nullptr)
                {
                    return *m_result;
                }
                else
                {
                    return *m_store;
                }
            }

        protected:
            std::shared_ptr<T> m_result;
            T* m_store;
            bool m_default = false;
            std::string m_default_value;
            bool m_implicit = false;
            std::string m_implicit_value;
        };
    }

    template <typename T>
    std::shared_ptr<Value>
    value()
    {
        return std::make_shared<values::standard_value<T>>();
    }

    template <typename T>
    std::shared_ptr<Value>
    value(T& t)
    {
        return std::make_shared<values::standard_value<T>>(&t);
    }

    class OptionAdder;

    class OptionDetails
    {
    public:
        OptionDetails
                (
                        const String& description,
                        std::shared_ptr<const Value> value
                )
                : m_desc(description)
                , m_value(value)
                , m_count(0)
        {
        }

        const String&
        description() const
        {
            return m_desc;
        }

        bool
        has_arg() const
        {
            return m_value->has_arg();
        }

        void
        parse(const std::string& text)
        {
            m_value->parse(text);
            ++m_count;
        }

        void
        parse_default()
        {
            m_value->parse();
        }

        int
        count() const
        {
            return m_count;
        }

        const Value& value() const {
            return *m_value;
        }

        template <typename T>
        const T&
        as() const
        {
#ifdef CXXOPTS_NO_RTTI
            return static_cast<const values::standard_value<T>&>(*m_value).get();
#else
            return dynamic_cast<const values::standard_value<T>&>(*m_value).get();
#endif
        }

    private:
        String m_desc;
        std::shared_ptr<const Value> m_value;
        int m_count;
    };

    struct HelpOptionDetails
    {
        std::string s;
        std::string l;
        String desc;
        bool has_arg;
        bool has_default;
        std::string default_value;
        bool has_implicit;
        std::string implicit_value;
        std::string arg_help;
        bool is_container;
    };

    struct HelpGroupDetails
    {
        std::string name;
        std::string description;
        std::vector<HelpOptionDetails> options;
    };

    class Options
    {
    public:

        Options(std::string program, std::string help_string = "")
                : m_program(std::move(program))
                , m_help_string(toLocalString(std::move(help_string)))
                , m_next_positional(m_positional.end())
        {
        }

        inline
        void
        parse(int& argc, char**& argv);

        inline
        OptionAdder
        add_options(std::string group = "");

        inline
        void
        add_option
                (
                        const std::string& group,
                        const std::string& s,
                        const std::string& l,
                        std::string desc,
                        std::shared_ptr<const Value> value,
                        std::string arg_help
                );

        int
        count(const std::string& o) const
        {
            auto iter = m_options.find(o);
            if (iter == m_options.end())
            {
                return 0;
            }

            return iter->second->count();
        }

        const OptionDetails&
        operator[](const std::string& option) const
        {
            auto iter = m_options.find(option);

            if (iter == m_options.end())
            {
                throw option_not_present_exception(option);
            }

            return *iter->second;
        }

        //parse positional arguments into the given option
        inline
        void
        parse_positional(std::string option);

        inline
        void
        parse_positional(std::vector<std::string> options);

        inline
        std::string
        help(const std::vector<std::string>& groups = {""}) const;

        inline
        const std::vector<std::string>
        groups() const;

        inline
        const HelpGroupDetails&
        group_help(const std::string& group) const;

    private:

        inline
        void
        add_one_option
                (
                        const std::string& option,
                        std::shared_ptr<OptionDetails> details
                );

        inline
        bool
        consume_positional(std::string a);

        inline
        void
        add_to_option(const std::string& option, const std::string& arg);

        inline
        void
        parse_option
                (
                        std::shared_ptr<OptionDetails> value,
                        const std::string& name,
                        const std::string& arg = ""
                );

        inline
        void
        checked_parse_arg
                (
                        int argc,
                        char* argv[],
                        int& current,
                        std::shared_ptr<OptionDetails> value,
                        const std::string& name
                );

        inline
        String
        help_one_group(const std::string& group) const;

        std::string m_program;
        String m_help_string;

        std::map<std::string, std::shared_ptr<OptionDetails>> m_options;
        std::vector<std::string> m_positional;
        std::vector<std::string>::iterator m_next_positional;
        std::unordered_set<std::string> m_positional_set;

        //mapping from groups to help options
        std::map<std::string, HelpGroupDetails> m_help;
    };

    class OptionAdder
    {
    public:

        OptionAdder(Options& options, std::string group)
                : m_options(options), m_group(std::move(group))
        {
        }

        inline
        OptionAdder&
        operator()
                (
                        const std::string& opts,
                        const std::string& desc,
                        std::shared_ptr<const Value> value
                        = ::cxxopts::value<bool>(),
                        std::string arg_help = ""
                );

    private:
        Options& m_options;
        std::string m_group;
    };

}

namespace cxxopts
{

    namespace
    {

        constexpr int OPTION_LONGEST = 30;
        constexpr int OPTION_DESC_GAP = 2;

        std::basic_regex<char> option_matcher
                ("--([[:alnum:]][-_[:alnum:]]+)(=(.*))?|-([[:alnum:]]+)");

        std::basic_regex<char> option_specifier
                ("(([[:alnum:]]),)?([[:alnum:]][-_[:alnum:]]+)");

        String
        format_option
                (
                        const HelpOptionDetails& o
                )
        {
            auto& s = o.s;
            auto& l = o.l;

            String result = "  ";

            if (s.size() > 0)
            {
                result += "-" + toLocalString(s) + ",";
            }
            else
            {
                result += "   ";
            }

            if (l.size() > 0)
            {
                result += " --" + toLocalString(l);
            }

            if (o.has_arg)
            {
                auto arg = o.arg_help.size() > 0 ? toLocalString(o.arg_help) : "arg";

                if (o.has_implicit)
                {
                    result += " [=" + arg + "(=" + toLocalString(o.implicit_value) + ")]";
                }
                else
                {
                    result += " " + arg;
                }
            }

            return result;
        }

        String
        format_description
                (
                        const HelpOptionDetails& o,
                        size_t start,
                        size_t width
                )
        {
            auto desc = o.desc;

            if (o.has_default)
            {
                desc += toLocalString(" (default: " + o.default_value + ")");
            }

            String result;

            auto current = std::begin(desc);
            auto startLine = current;
            auto lastSpace = current;

            auto size = size_t{};

            while (current != std::end(desc))
            {
                if (*current == ' ')
                {
                    lastSpace = current;
                }

                if (size > width)
                {
                    if (lastSpace == startLine)
                    {
                        stringAppend(result, startLine, current + 1);
                        stringAppend(result, "\n");
                        stringAppend(result, start, ' ');
                        startLine = current + 1;
                        lastSpace = startLine;
                    }
                    else
                    {
                        stringAppend(result, startLine, lastSpace);
                        stringAppend(result, "\n");
                        stringAppend(result, start, ' ');
                        startLine = lastSpace + 1;
                    }
                    size = 0;
                }
                else
                {
                    ++size;
                }

                ++current;
            }

            //append whatever is left
            stringAppend(result, startLine, current);

            return result;
        }
    }

    OptionAdder
    Options::add_options(std::string group)
    {
        return OptionAdder(*this, std::move(group));
    }

    OptionAdder&
    OptionAdder::operator()
            (
                    const std::string& opts,
                    const std::string& desc,
                    std::shared_ptr<const Value> value,
                    std::string arg_help
            )
    {
        std::match_results<const char*> result;
        std::regex_match(opts.c_str(), result, option_specifier);

        if (result.empty())
        {
            throw invalid_option_format_error(opts);
        }

        const auto& s = result[2];
        const auto& l = result[3];

        m_options.add_option(m_group, s.str(), l.str(), desc, value,
                             std::move(arg_help));

        return *this;
    }

    void
    Options::parse_option
            (
                    std::shared_ptr<OptionDetails> value,
                    const std::string& /*name*/,
                    const std::string& arg
            )
    {
        value->parse(arg);
    }

    void
    Options::checked_parse_arg
            (
                    int argc,
                    char* argv[],
                    int& current,
                    std::shared_ptr<OptionDetails> value,
                    const std::string& name
            )
    {
        if (current + 1 >= argc)
        {
            if (value->value().has_implicit())
            {
                parse_option(value, name, "");
            }
            else
            {
                throw missing_argument_exception(name);
            }
        }
        else
        {
            if (argv[current + 1][0] == '-' && value->value().has_implicit())
            {
                parse_option(value, name, "");
            }
            else
            {
                parse_option(value, name, argv[current + 1]);
                ++current;
            }
        }
    }

    void
    Options::add_to_option(const std::string& option, const std::string& arg)
    {
        auto iter = m_options.find(option);

        if (iter == m_options.end())
        {
            throw option_not_exists_exception(option);
        }

        parse_option(iter->second, option, arg);
    }

    bool
    Options::consume_positional(std::string a)
    {
        while (m_next_positional != m_positional.end())
        {
            auto iter = m_options.find(*m_next_positional);
            if (iter != m_options.end())
            {
                if (!iter->second->value().is_container())
                {
                    if (iter->second->count() == 0)
                    {
                        add_to_option(*m_next_positional, a);
                        ++m_next_positional;
                        return true;
                    }
                    else
                    {
                        ++m_next_positional;
                        continue;
                    }
                }
                else
                {
                    add_to_option(*m_next_positional, a);
                    return true;
                }
            }
            ++m_next_positional;
        }

        return false;
    }

    void
    Options::parse_positional(std::string option)
    {
        parse_positional(std::vector<std::string>{option});
    }

    void
    Options::parse_positional(std::vector<std::string> options)
    {
        m_positional = std::move(options);
        m_next_positional = m_positional.begin();

        m_positional_set.insert(m_positional.begin(), m_positional.end());
    }

    void
    Options::parse(int& argc, char**& argv)
    {
        int current = 1;

        int nextKeep = 1;

        bool consume_remaining = false;

        while (current != argc)
        {
            if (strcmp(argv[current], "--") == 0)
            {
                consume_remaining = true;
                ++current;
                break;
            }

            std::match_results<const char*> result;
            std::regex_match(argv[current], result, option_matcher);

            if (result.empty())
            {
                //not a flag

                //if true is returned here then it was consumed, otherwise it is
                //ignored
                if (consume_positional(argv[current]))
                {
                }
                else
                {
                    argv[nextKeep] = argv[current];
                    ++nextKeep;
                }
                //if we return from here then it was parsed successfully, so continue
            }
            else
            {
                //short or long option?
                if (result[4].length() != 0)
                {
                    const std::string& s = result[4];

                    for (std::size_t i = 0; i != s.size(); ++i)
                    {
                        std::string name(1, s[i]);
                        auto iter = m_options.find(name);

                        if (iter == m_options.end())
                        {
                            throw option_not_exists_exception(name);
                        }

                        auto value = iter->second;

                        //if no argument then just add it
                        if (!value->has_arg())
                        {
                            parse_option(value, name);
                        }
                        else
                        {
                            //it must be the last argument
                            if (i + 1 == s.size())
                            {
                                checked_parse_arg(argc, argv, current, value, name);
                            }
                            else if (value->value().has_implicit())
                            {
                                parse_option(value, name, "");
                            }
                            else
                            {
                                //error
                                throw option_requires_argument_exception(name);
                            }
                        }
                    }
                }
                else if (result[1].length() != 0)
                {
                    const std::string& name = result[1];

                    auto iter = m_options.find(name);

                    if (iter == m_options.end())
                    {
                        throw option_not_exists_exception(name);
                    }

                    auto opt = iter->second;

                    //equals provided for long option?
                    if (result[3].length() != 0)
                    {
                        //parse the option given

                        //but if it doesn't take an argument, this is an error
                        if (!opt->has_arg())
                        {
                            throw option_not_has_argument_exception(name, result[3]);
                        }

                        parse_option(opt, name, result[3]);
                    }
                    else
                    {
                        if (opt->has_arg())
                        {
                            //parse the next argument
                            checked_parse_arg(argc, argv, current, opt, name);
                        }
                        else
                        {
                            //parse with empty argument
                            parse_option(opt, name);
                        }
                    }
                }

            }

            ++current;
        }

        for (auto& opt : m_options)
        {
            auto& detail = opt.second;
            auto& value = detail->value();

            if(!detail->count() && value.has_default()){
                detail->parse_default();
            }
        }

        if (consume_remaining)
        {
            while (current < argc)
            {
                consume_positional(argv[current]);
                ++current;
            }
        }

        argc = nextKeep;

    }

    void
    Options::add_option
            (
                    const std::string& group,
                    const std::string& s,
                    const std::string& l,
                    std::string desc,
                    std::shared_ptr<const Value> value,
                    std::string arg_help
            )
    {
        auto stringDesc = toLocalString(std::move(desc));
        auto option = std::make_shared<OptionDetails>(stringDesc, value);

        if (s.size() > 0)
        {
            add_one_option(s, option);
        }

        if (l.size() > 0)
        {
            add_one_option(l, option);
        }

        //add the help details
        auto& options = m_help[group];

        options.options.emplace_back(HelpOptionDetails{s, l, stringDesc,
                                                       value->has_arg(),
                                                       value->has_default(), value->get_default_value(),
                                                       value->has_implicit(), value->get_implicit_value(),
                                                       std::move(arg_help),
                                                       value->is_container()});
    }

    void
    Options::add_one_option
            (
                    const std::string& option,
                    std::shared_ptr<OptionDetails> details
            )
    {
        auto in = m_options.emplace(option, details);

        if (!in.second)
        {
            throw option_exists_error(option);
        }
    }

    String
    Options::help_one_group(const std::string& g) const
    {
        typedef std::vector<std::pair<String, String>> OptionHelp;

        auto group = m_help.find(g);
        if (group == m_help.end())
        {
            return "";
        }

        OptionHelp format;

        size_t longest = 0;

        String result;

        if (!g.empty())
        {
            result += toLocalString(" " + g + " options:\n");
        }

        for (const auto& o : group->second.options)
        {
            if (o.is_container && m_positional_set.find(o.l) != m_positional_set.end())
            {
                continue;
            }

            auto s = format_option(o);
            longest = std::max(longest, stringLength(s));
            format.push_back(std::make_pair(s, String()));
        }

        longest = std::min(longest, static_cast<size_t>(OPTION_LONGEST));

        //widest allowed description
        auto allowed = size_t{76} - longest - OPTION_DESC_GAP;

        auto fiter = format.begin();
        for (const auto& o : group->second.options)
        {
            if (o.is_container && m_positional_set.find(o.l) != m_positional_set.end())
            {
                continue;
            }

            auto d = format_description(o, longest + OPTION_DESC_GAP, allowed);

            result += fiter->first;
            if (stringLength(fiter->first) > longest)
            {
                result += '\n';
                result += toLocalString(std::string(longest + OPTION_DESC_GAP, ' '));
            }
            else
            {
                result += toLocalString(std::string(longest + OPTION_DESC_GAP -
                                                    stringLength(fiter->first),
                                                    ' '));
            }
            result += d;
            result += '\n';

            ++fiter;
        }

        return result;
    }

    std::string
    Options::help(const std::vector<std::string>& groups) const
    {
        String result = m_help_string + "\nUsage:\n  " +
                        toLocalString(m_program) + " [OPTION...]";

        if (m_positional.size() > 0) {
            result += " positional parameters";
        }

        result += "\n\n";

        for (std::size_t i = 0; i < groups.size(); ++i)
        {
            String const& group_help = help_one_group(groups[i]);
            if (empty(group_help)) continue;
            result += group_help;
            if (i < groups.size() - 1)
            {
                result += '\n';
            }
        }

        return toUTF8String(result);
    }

    const std::vector<std::string>
    Options::groups() const
    {
        std::vector<std::string> g;

        std::transform(
                m_help.begin(),
                m_help.end(),
                std::back_inserter(g),
                [] (const std::map<std::string, HelpGroupDetails>::value_type& pair)
                {
                    return pair.first;
                }
        );

        return g;
    }

    const HelpGroupDetails&
    Options::group_help(const std::string& group) const
    {
        return m_help.at(group);
    }

}

#if defined(__GNU__)
#pragma GCC diagnostic pop
#endif

#endif //CXX_OPTS_HPP