// Copyright 2009-present MongoDB, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#pragma once

#include <bsoncxx/builder/stream/array_context-fwd.hpp>
#include <bsoncxx/builder/stream/key_context-fwd.hpp>
#include <bsoncxx/builder/stream/single_context-fwd.hpp>

#include <bsoncxx/array/value.hpp>
#include <bsoncxx/builder/concatenate.hpp>
#include <bsoncxx/builder/core.hpp>
#include <bsoncxx/builder/stream/closed_context.hpp>
#include <bsoncxx/builder/stream/helpers.hpp>
#include <bsoncxx/stdx/type_traits.hpp>

#include <bsoncxx/config/prelude.hpp>

namespace bsoncxx {
namespace v_noabi {
namespace builder {
namespace stream {

///
/// A stream context which expects any number of values.
///
/// The template argument can be used to hold additional information about
/// containing documents or arrays. I.e. value_context<> implies that this array
/// is a sub_array in a document, while array_context would indicated a sub_array
/// in an array. These types can be nested, such that contextual parsing (for
/// key/value pairs) and depth (to prevent an invalid array_close) are enforced
/// by the type system.
///
/// I.e.
/// builder << array_context << array_context << ...;
///
/// This builds a bson array with successively higher index keys
///
template <class base>
class array_context {
   public:
    ///
    /// Create an array_context given a core builder
    ///
    /// @param core
    ///   The core builder to orchestrate
    ///
    array_context(core* core) : _core(core) {}

    ///
    /// << operator for accepting a real value and appending it to the core
    ///   builder.
    ///
    /// @param t
    ///   The value to append
    ///
    template <class T>
    detail::requires_not_t<array_context&,
                           detail::is_invocable<T, array_context<>>,
                           detail::is_invocable<T, single_context>,
                           detail::is_alike<T, finalize_type>>
    operator<<(T&& t) {
        _core->append(std::forward<T>(t));
        return *this;
    }

    ///
    /// << operator for accepting a callable of the form void(array_context) or
    ///   void(single_context) and invoking it to perform 1 or more value appends
    ///   to the core builder.
    ///
    /// @param func
    ///   The callback to invoke
    ///
    template <typename Func>
    detail::requires_t<array_context&,
                       detail::disjunction<detail::is_invocable<Func, array_context>,
                                           detail::is_invocable<Func, single_context>>>
    operator<<(Func&& func) {
        detail::invoke(std::forward<Func>(func), *this);
        return *this;
    }

    ///
    /// << operator for finalizing the stream.
    ///
    /// This operation finishes all processing necessary to fully encode the
    /// bson bytes and returns an owning value.
    ///
    /// The argument must be a finalize_type token (it is otherwise ignored).
    ///
    /// @return A value type which holds the complete bson document.
    ///
    template <typename T>
    detail::requires_t<bsoncxx::v_noabi::array::value,
                       std::is_same<base, closed_context>,
                       detail::is_alike<T, finalize_type>>
    // VS2015U1 can't resolve the name.
    operator<<(T&&) {
        return _core->extract_array();
    }

    ///
    /// << operator for opening a new subdocument in the core builder.
    ///
    /// The argument must be an open_document_type token (it is otherwise ignored).
    ///
    key_context<array_context> operator<<(const open_document_type) {
        _core->open_document();
        return wrap_document();
    }

    ///
    /// << operator for concatenating another array.
    ///
    /// This operation concatenates all of the values from the passed document
    /// into the current stream. Keys are adjusted to match the existing array.
    ///
    /// @param array
    ///   An array to concatenate
    ///
    array_context operator<<(concatenate_array array) {
        _core->concatenate(array.view());
        return *this;
    }

    ///
    /// << operator for opening a new subarray in the core builder.
    ///
    /// The argument must be an open_document_type token (it is otherwise ignored).
    ///
    array_context<array_context> operator<<(const open_array_type) {
        _core->open_array();
        return wrap_array();
    }

    ///
    /// << operator for closing a subarray in the core builder.
    ///
    /// The argument must be a close_array_type token (it is otherwise ignored).
    ///
    base operator<<(const close_array_type) {
        _core->close_array();
        return unwrap();
    }

    ///
    /// Conversion operator which provides a rooted array context given any
    /// stream currently in a nested array_context.
    ///
    operator array_context<>() {
        return array_context<>(_core);
    }

    ///
    /// Conversion operator for single_context.
    ///
    /// @see
    /// - @ref bsoncxx::v_noabi::builder::stream::single_context
    ///
    operator single_context();

   private:
    base unwrap() {
        return base(_core);
    }

    array_context<array_context> wrap_array() {
        return array_context<array_context>(_core);
    }

    key_context<array_context> wrap_document() {
        return key_context<array_context>(_core);
    }

    core* _core;
};

}  // namespace stream
}  // namespace builder
}  // namespace v_noabi
}  // namespace bsoncxx

#include <bsoncxx/config/postlude.hpp>

///
/// @file
/// Provides @ref bsoncxx::v_noabi::builder::stream::array_context.
///
