/* json11
 *
 * json11 is a tiny JSON library for C++11, providing JSON parsing and serialization.
 *
 * The core object provided by the library is json11::Json. A Json object represents any JSON
 * value: null, bool, number (int or double), string (std::string), array (std::vector), or
 * object (std::map).
 *
 * Json objects act like values: they can be assigned, copied, moved, compared for equality or
 * order, etc. There are also helper methods Json::dump, to serialize a Json to a string, and
 * Json::parse (static) to parse a std::string as a Json object.
 *
 * Internally, the various types of Json object are represented by the JsonValue class
 * hierarchy.
 *
 * A note on numbers - JSON specifies the syntax of number formatting but not its semantics,
 * so some JSON implementations distinguish between integers and floating-point numbers, while
 * some don't. In json11, we choose the latter. Because some JSON implementations (namely
 * Javascript itself) treat all numbers as the same type, distinguishing the two leads
 * to JSON that will be *silently* changed by a round-trip through those implementations.
 * Dangerous! To avoid that risk, json11 stores all numbers as double internally, but also
 * provides integer helpers.
 *
 * Fortunately, double-precision IEEE754 ('double') can precisely store any integer in the
 * range +/-2^53, which includes every 'int' on most systems. (Timestamps often use int64
 * or long long to avoid the Y2038K problem; a double storing microseconds since some epoch
 * will be exact for +/- 275 years.)
 */

 /* Copyright (c) 2013 Dropbox, Inc.
  *
  * 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.
  */

#pragma once

#include <string>
#include <vector>
#include <map>
#include <memory>
#include <initializer_list>

#ifdef _MSC_VER
#if _MSC_VER <= 1800 // VS 2013
#ifndef noexcept
#define noexcept throw()
#endif

#ifndef snprintf
#define snprintf _snprintf_s
#endif
#endif
#endif

namespace json11 {

    enum JsonParse {
        STANDARD, COMMENTS
    };

    class JsonValue;

    class Json final {
    public:
        // Types
        enum Type {
            NUL, NUMBER, BOOL, STRING, ARRAY, OBJECT
        };

        // Array and object typedefs
        typedef std::vector<Json> array;
        typedef std::map<std::string, Json> object;

        // Constructors for the various types of JSON value.
        Json() noexcept;                // NUL
        Json(std::nullptr_t) noexcept;  // NUL
        Json(double value);             // NUMBER
        Json(int value);                // NUMBER
        Json(bool value);               // BOOL
        Json(const std::string& value); // STRING
        Json(std::string&& value);      // STRING
        Json(const char* value);       // STRING
        Json(const array& values);      // ARRAY
        Json(array&& values);           // ARRAY
        Json(const object& values);     // OBJECT
        Json(object&& values);          // OBJECT

        // Implicit constructor: anything with a to_json() function.
        template <class T, class = decltype(&T::to_json)>
        Json(const T& t) : Json(t.to_json()) {}

        // Implicit constructor: map-like objects (std::map, std::unordered_map, etc)
        template <class M, typename std::enable_if<
            std::is_constructible<std::string, decltype(std::declval<M>().begin()->first)>::value
            && std::is_constructible<Json, decltype(std::declval<M>().begin()->second)>::value,
            int>::type = 0>
            Json(const M& m) : Json(object(m.begin(), m.end())) {}

        // Implicit constructor: vector-like objects (std::list, std::vector, std::set, etc)
        template <class V, typename std::enable_if<
            std::is_constructible<Json, decltype(*std::declval<V>().begin())>::value,
            int>::type = 0>
            Json(const V& v) : Json(array(v.begin(), v.end())) {}

        // This prevents Json(some_pointer) from accidentally producing a bool. Use
        // Json(bool(some_pointer)) if that behavior is desired.
        Json(void*) = delete;

        // Accessors
        Type type() const;

        bool is_null()   const { return type() == NUL; }
        bool is_number() const { return type() == NUMBER; }
        bool is_bool()   const { return type() == BOOL; }
        bool is_string() const { return type() == STRING; }
        bool is_array()  const { return type() == ARRAY; }
        bool is_object() const { return type() == OBJECT; }

        // Return the enclosed value if this is a number, 0 otherwise. Note that json11 does not
        // distinguish between integer and non-integer numbers - number_value() and int_value()
        // can both be applied to a NUMBER-typed object.
        double number_value() const;
        int int_value() const;

        // Return the enclosed value if this is a boolean, false otherwise.
        bool bool_value() const;
        // Return the enclosed string if this is a string, "" otherwise.
        const std::string& string_value() const;
        // Return the enclosed std::vector if this is an array, or an empty vector otherwise.
        const array& array_items() const;
        // Return the enclosed std::map if this is an object, or an empty map otherwise.
        const object& object_items() const;

        // Return a reference to arr[i] if this is an array, Json() otherwise.
        const Json& operator[](size_t i) const;
        // Return a reference to obj[key] if this is an object, Json() otherwise.
        const Json& operator[](const std::string& key) const;

        // Serialize.
        void dump(std::string& out) const;
        std::string dump() const {
            std::string out;
            dump(out);
            return out;
        }

        // Parse. If parse fails, return Json() and assign an error message to err.
        static Json parse(const std::string& in,
            std::string& err,
            JsonParse strategy = JsonParse::STANDARD);
        static Json parse(const char* in,
            std::string& err,
            JsonParse strategy = JsonParse::STANDARD) {
            if (in) {
                return parse(std::string(in), err, strategy);
            }
            else {
                err = "null input";
                return nullptr;
            }
        }
        // Parse multiple objects, concatenated or separated by whitespace
        static std::vector<Json> parse_multi(
            const std::string& in,
            std::string::size_type& parser_stop_pos,
            std::string& err,
            JsonParse strategy = JsonParse::STANDARD);

        static inline std::vector<Json> parse_multi(
            const std::string& in,
            std::string& err,
            JsonParse strategy = JsonParse::STANDARD) {
            std::string::size_type parser_stop_pos;
            return parse_multi(in, parser_stop_pos, err, strategy);
        }

        bool operator== (const Json& rhs) const;
        bool operator<  (const Json& rhs) const;
        bool operator!= (const Json& rhs) const { return !(*this == rhs); }
        bool operator<= (const Json& rhs) const { return !(rhs < *this); }
        bool operator>  (const Json& rhs) const { return  (rhs < *this); }
        bool operator>= (const Json& rhs) const { return !(*this < rhs); }

        /* has_shape(types, err)
         *
         * Return true if this is a JSON object and, for each item in types, has a field of
         * the given type. If not, return false and set err to a descriptive message.
         */
        typedef std::initializer_list<std::pair<std::string, Type>> shape;
        bool has_shape(const shape& types, std::string& err) const;

    private:
        std::shared_ptr<JsonValue> m_ptr;
    };

    // Internal class hierarchy - JsonValue objects are not exposed to users of this API.
    class JsonValue {
    protected:
        friend class Json;
        friend class JsonInt;
        friend class JsonDouble;
        virtual Json::Type type() const = 0;
        virtual bool equals(const JsonValue* other) const = 0;
        virtual bool less(const JsonValue* other) const = 0;
        virtual void dump(std::string& out) const = 0;
        virtual double number_value() const;
        virtual int int_value() const;
        virtual bool bool_value() const;
        virtual const std::string& string_value() const;
        virtual const Json::array& array_items() const;
        virtual const Json& operator[](size_t i) const;
        virtual const Json::object& object_items() const;
        virtual const Json& operator[](const std::string& key) const;
        virtual ~JsonValue() {}
    };

} // namespace json11