/*****************************************************************************
 *
 * This file is part of Mapnik (c++ mapping toolkit)
 *
 * Copyright (C) 2014 Artem Pavlenko
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 *****************************************************************************/

#ifndef MAPNIK_VALUE_HPP
#define MAPNIK_VALUE_HPP

// mapnik
#include <mapnik/value_types.hpp>
#include <mapnik/value_hash.hpp>
#include <mapnik/util/conversions.hpp>
#include <mapnik/util/variant.hpp>

// stl
#include <string>
#include <cmath>
#include <memory>

#include <iosfwd>
#include <cstddef>
#include <new>

// icu
#include <unicode/unistr.h>
#include <unicode/ustring.h>

namespace mapnik  {

inline void to_utf8(mapnik::value_unicode_string const& input, std::string & target)
{
    if (input.isEmpty()) return;

    const int BUF_SIZE = 256;
    char buf [BUF_SIZE];
    int len;

    UErrorCode err = U_ZERO_ERROR;
    u_strToUTF8(buf, BUF_SIZE, &len, input.getBuffer(), input.length(), &err);
    if (err == U_BUFFER_OVERFLOW_ERROR || err == U_STRING_NOT_TERMINATED_WARNING )
    {
        const std::unique_ptr<char[]> buf_ptr(new char [len+1]);
        err = U_ZERO_ERROR;
        u_strToUTF8(buf_ptr.get() , len + 1, &len, input.getBuffer(), input.length(), &err);
        target.assign(buf_ptr.get() , static_cast<std::size_t>(len));
    }
    else
    {
        target.assign(buf, static_cast<std::size_t>(len));
    }
}

using value_base = util::variant<value_null, value_bool, value_integer,value_double, value_unicode_string>;

namespace impl {

struct equals

{
    bool operator() (value_integer lhs, value_double rhs) const
    {
        return  lhs == rhs;
    }

    bool operator() (value_bool lhs, value_double rhs) const
    {
        return  lhs == rhs;
    }

    bool operator() (value_double lhs, value_integer rhs) const
    {
        return  lhs == rhs;
    }

    bool operator() (value_bool lhs, value_integer rhs) const
    {
        return  lhs == rhs;
    }

    bool operator() (value_integer lhs, value_bool rhs) const
    {
        return  lhs == rhs;
    }

    bool operator() (value_double lhs, value_bool rhs) const
    {
        return  lhs == rhs;
    }

    bool operator() (value_unicode_string const& lhs,
                     value_unicode_string const& rhs) const
    {
        return  (lhs == rhs) ? true: false;
    }

    template <typename T>
    bool operator() (T lhs, T rhs) const
    {
        return lhs == rhs;
    }

    template <typename T, typename U>
    bool operator() (T const&, U const&) const
    {
        return false;
    }
};

struct not_equals

{
    template <typename T, typename U>
    bool operator() (const T &, const U &) const
    {
        return true;
    }

    template <typename T>
    bool operator() (T lhs, T rhs) const
    {
        return lhs != rhs;
    }

    bool operator() (value_integer lhs, value_double rhs) const
    {
        return  lhs != rhs;
    }

    bool operator() (value_bool lhs, value_double rhs) const
    {
        return  lhs != rhs;
    }

    bool operator() (value_double lhs, value_integer rhs) const
    {
        return  lhs != rhs;
    }

    bool operator() (value_bool lhs, value_integer rhs) const
    {
        return  lhs != rhs;
    }

    bool operator() (value_integer lhs, value_bool rhs) const
    {
        return  lhs != rhs;
    }

    bool operator() (value_double lhs, value_bool rhs) const
    {
        return  lhs != rhs;
    }

    bool operator() (value_unicode_string const& lhs,
                     value_unicode_string const& rhs) const
    {
        return  (lhs != rhs)? true : false;
    }

    // back compatibility shim to equate empty string with null for != test
    // https://github.com/mapnik/mapnik/issues/1859
    // TODO - consider removing entire specialization at Mapnik 3.x
    bool operator() (value_null, value_unicode_string const& rhs) const
    {
        if (rhs.isEmpty()) return false;
        return true;
    }

};

struct greater_than

{
    template <typename T, typename U>
    bool operator()(const T &, const U &) const
    {
        return false;
    }

    template <typename T>
    bool operator()(T lhs, T rhs) const
    {
        return lhs > rhs;
    }

    bool operator() (value_integer lhs, value_double rhs) const
    {
        return  lhs > rhs;
    }

    bool operator() (value_double lhs, value_integer rhs) const
    {
        return  lhs > rhs;
    }

    bool operator() (value_unicode_string const& lhs, value_unicode_string const& rhs) const
    {
        return  (lhs > rhs) ? true : false ;
    }

    bool operator() (value_null, value_null) const
    {
        return false;
    }
};

struct greater_or_equal

{
    template <typename T, typename U>
    bool operator()(const T &, const U &) const
    {
        return false;
    }

    template <typename T>
    bool operator() (T lhs, T rhs) const
    {
        return lhs >= rhs;
    }

    bool operator() (value_integer lhs, value_double rhs) const
    {
        return  lhs >= rhs;
    }

    bool operator() (value_double lhs, value_integer rhs) const
    {
        return  lhs >= rhs;
    }

    bool operator() (value_unicode_string const& lhs, value_unicode_string const& rhs) const
    {
        return ( lhs >= rhs ) ? true : false ;
    }

    bool operator() (value_null, value_null) const
    {
        return false;
    }
};

struct less_than

{
    template <typename T, typename U>
    bool operator()(const T &, const U &) const
    {
        return false;
    }

    template <typename T>
    bool operator()(T lhs, T rhs) const
    {
        return lhs < rhs;
    }

    bool operator() (value_integer lhs, value_double rhs) const
    {
        return  lhs < rhs;
    }

    bool operator() (value_double lhs, value_integer rhs) const
    {
        return  lhs < rhs;
    }

    bool operator()(value_unicode_string const& lhs,
                    value_unicode_string const& rhs ) const
    {
        return (lhs < rhs) ? true : false ;
    }

    bool operator() (value_null, value_null) const
    {
        return false;
    }
};

struct less_or_equal

{
    template <typename T, typename U>
    bool operator()(const T &, const U &) const
    {
        return false;
    }

    template <typename T>
    bool operator()(T lhs, T rhs) const
    {
        return lhs <= rhs;
    }

    bool operator() (value_integer lhs, value_double rhs) const
    {
        return  lhs <= rhs;
    }

    bool operator() (value_double lhs, value_integer rhs) const
    {
        return  lhs <= rhs;
    }

    bool operator()(value_unicode_string const& lhs,
                    value_unicode_string const& rhs ) const
    {
        return (lhs <= rhs) ? true : false ;
    }

    bool operator() (value_null, value_null) const
    {
        return false;
    }
};

template <typename V>
struct add
{
    using value_type = V;
    value_type operator() (value_unicode_string const& lhs ,
                           value_unicode_string const& rhs ) const
    {
        return lhs + rhs;
    }

    value_type operator() (value_double lhs, value_integer rhs) const
    {
        return lhs + rhs;
    }

    value_type operator() (value_integer lhs, value_double rhs) const
    {
        return lhs + rhs;
    }

    value_type operator() (value_unicode_string const& lhs, value_null) const
    {
        return lhs;
    }

    value_type operator() (value_null, value_unicode_string const& rhs) const
    {
        return rhs;
    }

    template <typename R>
    value_type operator() (value_unicode_string const& lhs, R const& rhs) const
    {
        std::string val;
        if (util::to_string(val,rhs))
            return lhs + value_unicode_string(val.c_str());
        return lhs;
    }

    template <typename L>
    value_type operator() (L const& lhs , value_unicode_string const& rhs) const
    {
        std::string val;
        if (util::to_string(val,lhs))
            return value_unicode_string(val.c_str()) + rhs;
        return rhs;
    }

    template <typename T>
    value_type operator() (T lhs, T rhs) const
    {
        return lhs + rhs ;
    }

    template <typename T1, typename T2>
    value_type operator() (T1 const& lhs, T2 const&) const
    {
        return lhs;
    }

    value_type operator() (value_bool lhs, value_bool rhs) const
    {
        return value_integer(lhs + rhs);
    }
};

template <typename V>
struct sub
{
    using value_type = V;
    template <typename T1, typename T2>
    value_type operator() (T1 const& lhs, T2 const&) const
    {
        return lhs;
    }

    template <typename T>
    value_type operator() (T lhs, T rhs) const
    {
        return lhs - rhs ;
    }

    value_type operator() (value_unicode_string const&,
                           value_unicode_string const&) const
    {
        return value_type();
    }

    value_type operator() (value_double lhs, value_integer rhs) const
    {
        return lhs - rhs;
    }

    value_type operator() (value_integer lhs, value_double rhs) const
    {
        return lhs - rhs;
    }

    value_type operator() (value_bool lhs, value_bool rhs) const
    {
        return value_integer(lhs - rhs);
    }
};

template <typename V>
struct mult
{
    using value_type = V;
    template <typename T1, typename T2>
    value_type operator() (T1 const& lhs , T2 const& ) const
    {
        return lhs;
    }
    template <typename T>
    value_type operator() (T lhs, T rhs) const
    {
        return lhs * rhs;
    }

    value_type operator() (value_unicode_string const&,
                           value_unicode_string const&) const
    {
        return value_type();
    }

    value_type operator() (value_double lhs, value_integer rhs) const
    {
        return lhs * rhs;
    }

    value_type operator() (value_integer lhs, value_double rhs) const
    {
        return lhs * rhs;
    }

    value_type operator() (value_bool, value_bool) const
    {
        return value_integer(0);
    }
};

template <typename V>
struct div
{
    using value_type = V;
    template <typename T1, typename T2>
    value_type operator() (T1 const& lhs, T2 const&) const
    {
        return lhs;
    }

    template <typename T>
    value_type operator() (T lhs, T rhs) const
    {
        if (rhs == 0) return value_type();
        return lhs / rhs;
    }

    value_type operator() (value_bool, value_bool) const
    {
        return false;
    }

    value_type operator() (value_unicode_string const&,
                           value_unicode_string const&) const
    {
        return value_type();
    }

    value_type operator() (value_double lhs, value_integer rhs) const
    {
        if (rhs == 0) return value_type();
        return lhs / rhs;
    }

    value_type operator() (value_integer lhs, value_double rhs) const
    {
        if (rhs == 0) return value_type();
        return lhs / rhs;
    }
};

template <typename V>
struct mod
{
    using value_type = V;
    template <typename T1, typename T2>
    value_type operator() (T1 const& lhs, T2 const&) const
    {
        return lhs;
    }

    template <typename T>
    value_type operator() (T lhs, T rhs) const
    {
        return lhs % rhs;
    }

    value_type operator() (value_unicode_string const&,
                           value_unicode_string const&) const
    {
        return value_type();
    }

    value_type operator() (value_bool,
                           value_bool) const
    {
        return false;
    }

    value_type operator() (value_double lhs, value_integer rhs) const
    {
        return std::fmod(lhs, static_cast<value_double>(rhs));
    }

    value_type operator() (value_integer lhs, value_double rhs) const
    {
        return std::fmod(static_cast<value_double>(lhs), rhs);
    }

    value_type operator() (value_double lhs, value_double rhs) const
    {
        return std::fmod(lhs, rhs);
    }
};

template <typename V>
struct negate
{
    using value_type = V;

    template <typename T>
    value_type operator() (T val) const
    {
        return -val;
    }

    value_type operator() (value_null val) const
    {
        return val;
    }

    value_type operator() (value_bool val) const
    {
        return val ? value_integer(-1) : value_integer(0);
    }

    value_type operator() (value_unicode_string const&) const
    {
        return value_type();
    }
};

// converters
template <typename T>
struct convert {};

template <>
struct convert<value_bool>
{
    value_bool operator() (value_bool val) const
    {
        return val;
    }

    value_bool operator() (value_unicode_string const& ustr) const
    {
        return !ustr.isEmpty();
    }

    value_bool operator() (value_null const&) const
    {
        return false;
    }

    template <typename T>
    value_bool operator() (T val) const
    {
        return val > 0 ? true : false;
    }
};

template <>
struct convert<value_double>
{
    value_double operator() (value_double val) const
    {
        return val;
    }

    value_double operator() (value_integer val) const
    {
        return static_cast<value_double>(val);
    }

    value_double operator() (value_bool val) const
    {
        return static_cast<value_double>(val);
    }

    value_double operator() (std::string const& val) const
    {
        value_double result;
        if (util::string2double(val,result))
            return result;
        return 0;
    }

    value_double operator() (value_unicode_string const& val) const
    {
        std::string utf8;
        to_utf8(val,utf8);
        return operator()(utf8);
    }

    value_double operator() (value_null const&) const
    {
        return 0.0;
    }
};

template <>
struct convert<value_integer>
{
    value_integer operator() (value_integer val) const
    {
        return val;
    }

    value_integer operator() (value_double val) const
    {
        return static_cast<value_integer>(rint(val));
    }

    value_integer operator() (value_bool val) const
    {
        return static_cast<value_integer>(val);
    }

    value_integer operator() (std::string const& val) const
    {
        value_integer result;
        if (util::string2int(val,result))
            return result;
        return value_integer(0);
    }

    value_integer operator() (value_unicode_string const& val) const
    {
        std::string utf8;
        to_utf8(val,utf8);
        return operator()(utf8);
    }

    value_integer operator() (value_null const&) const
    {
        return value_integer(0);
    }
};

template <>
struct convert<std::string>
{
    template <typename T>
    std::string operator() (T val) const
    {
        std::string str;
        util::to_string(str, val);
        return str;
    }

    // specializations
    std::string operator() (value_unicode_string const& val) const
    {
        std::string utf8;
        to_utf8(val,utf8);
        return utf8;
    }

    std::string operator() (value_double val) const
    {
        std::string str;
        util::to_string(str, val); // TODO set precision(16)
        return str;
    }

    std::string operator() (value_bool val) const
    {
        return val ? "true": "false";
    }

    std::string operator() (value_null const&) const
    {
        return "";
    }
};

struct to_unicode
{

    template <typename T>
    value_unicode_string operator() (T val) const
    {
        std::string str;
        util::to_string(str,val);
        return value_unicode_string(str.c_str());
    }

    // specializations
    value_unicode_string const& operator() (value_unicode_string const& val) const
    {
        return val;
    }

    value_unicode_string operator() (value_double val) const
    {
        std::string str;
        util::to_string(str,val);
        return value_unicode_string(str.c_str());
    }

    value_unicode_string operator() (value_bool val) const
    {
        if (val) {
            std::string str("true");
            return value_unicode_string(str.c_str());
        }
        std::string str("false");
        return value_unicode_string(str.c_str());
    }

    value_unicode_string operator() (value_null const&) const
    {
        return value_unicode_string("");
    }
};

struct to_expression_string
{
    explicit to_expression_string(char quote = '\'')
        : quote_(quote) {}

    std::string operator() (value_unicode_string const& val) const
    {
        std::string utf8;
        to_utf8(val,utf8);
        return quote_ + utf8 + quote_;
    }

    std::string operator() (value_integer val) const
    {
        std::string output;
        util::to_string(output,val);
        return output;
    }

    std::string operator() (value_double val) const
    {
        std::string output;
        util::to_string(output,val); // TODO precision(16)
        return output;
    }

    std::string operator() (value_bool val) const
    {
        return val ? "true":"false";
    }

    std::string operator() (value_null const&) const
    {
        return "null";
    }

    const char quote_;
};

} // namespace impl

namespace value_adl_barrier {

class value : public value_base
{
    friend const value operator+(value const&,value const&);
    friend const value operator-(value const&,value const&);
    friend const value operator*(value const&,value const&);
    friend const value operator/(value const&,value const&);
    friend const value operator%(value const&,value const&);

public:
    value () noexcept //-- comment out for VC++11
        : value_base(value_null()) {}

    value (value const& other) = default;

    value( value && other) noexcept = default;

    template <typename T>
    value ( T const& val)
        : value_base(typename detail::mapnik_value_type<T>::type(val)) {}

    template <typename T>
    value ( T && val)
        : value_base(typename detail::mapnik_value_type<T>::type(val)) {}

    value & operator=( value const& other) = default;

    bool operator==(value const& other) const
    {
        return util::apply_visitor(impl::equals(),*this,other);
    }

    bool operator!=(value const& other) const
    {
        return util::apply_visitor(impl::not_equals(),*this,other);
    }

    bool operator>(value const& other) const
    {
        return util::apply_visitor(impl::greater_than(),*this,other);
    }

    bool operator>=(value const& other) const
    {
        return util::apply_visitor(impl::greater_or_equal(),*this,other);
    }

    bool operator<(value const& other) const
    {
        return util::apply_visitor(impl::less_than(),*this,other);
    }

    bool operator<=(value const& other) const
    {
        return util::apply_visitor(impl::less_or_equal(),*this,other);
    }

    value operator- () const
    {
        return util::apply_visitor(impl::negate<value>(), *this);
    }

    bool is_null() const;

    template <typename T>
    T convert() const
    {
        return util::apply_visitor(impl::convert<T>(),*this);
    }

    value_bool to_bool() const
    {
        return util::apply_visitor(impl::convert<value_bool>(),*this);
    }

    std::string to_expression_string(char quote = '\'') const
    {
        return util::apply_visitor(impl::to_expression_string(quote),*this);
    }

    std::string to_string() const
    {
        return util::apply_visitor(impl::convert<std::string>(),*this);
    }

    value_unicode_string to_unicode() const
    {
        return util::apply_visitor(impl::to_unicode(),*this);
    }

    value_double to_double() const
    {
        return util::apply_visitor(impl::convert<value_double>(),*this);
    }

    value_integer to_int() const
    {
        return util::apply_visitor(impl::convert<value_integer>(),*this);
    }
};

inline const value operator+(value const& p1,value const& p2)
{
    return value(util::apply_visitor(impl::add<value>(),p1, p2));
}

inline const value operator-(value const& p1,value const& p2)
{

    return value(util::apply_visitor(impl::sub<value>(),p1, p2));
}

inline const value operator*(value const& p1,value const& p2)
{

    return value(util::apply_visitor(impl::mult<value>(),p1, p2));
}

inline const value operator/(value const& p1,value const& p2)
{

    return value(util::apply_visitor(impl::div<value>(),p1, p2));
}

inline const value operator%(value const& p1,value const& p2)
{

    return value(util::apply_visitor(impl::mod<value>(),p1, p2));
}

template <typename charT, typename traits>
inline std::basic_ostream<charT,traits>&
operator << (std::basic_ostream<charT,traits>& out,
             value const& v)
{
    out << v.to_string();
    return out;
}

// hash function
inline std::size_t hash_value(value const& val)
{
    return mapnik_hash_value(val);
}

} // namespace value_adl_barrier

using value_adl_barrier::value;
using value_adl_barrier::operator<<;

namespace detail {

struct is_null_visitor
{
    bool operator() (value const& val) const
    {
        return val.is_null();
    }

    bool operator() (value_null const&) const
    {
        return true;
    }

    template <typename T>
    bool operator() (T const&) const
    {
        return false;
    }
};

} // namespace detail

inline bool value::is_null() const
{
    return util::apply_visitor(mapnik::detail::is_null_visitor(), *this);
}

} // namespace mapnik

#endif // MAPNIK_VALUE_HPP
