/* -*- Mode: C++; tab-width: 4; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/*
 *   Copyright 2024. Couchbase, 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 <couchbase/cas.hxx>
#include <couchbase/codec/default_json_transcoder.hxx>
#include <couchbase/codec/encoded_value.hxx>
#include <couchbase/codec/transcoder_traits.hxx>
#include <couchbase/result.hxx>

#include <chrono>
#include <optional>
#include <string>
#include <type_traits>
#include <utility>

/**
 * Represents a single item from the result of @ref collection#scan()
 *
 * @since 1.0.0
 * @uncommitted
 */
namespace couchbase
{
class scan_result_item : public result
{
  public:
    /**
     * Constructs an empty @ref scan_result_item.
     *
     * @since 1.0.0
     * @internal
     */
    scan_result_item() = default;

    /**
     * Constructs an instance representing a single item from the result of a scan operation.
     *
     * @param id the document ID
     * @param cas
     * @param value raw document contents along with flags describing its structure
     * @param expiry_time optional point in time when the document will expire
     *
     * @since 1.0.0
     * @internal
     */
    scan_result_item(std::string id,
                     couchbase::cas cas,
                     codec::encoded_value value,
                     std::optional<std::chrono::system_clock::time_point> expiry_time)
      : result{ cas }
      , id_{ std::move(id) }
      , id_only_{ false }
      , value_{ std::move(value) }
      , expiry_time_{ expiry_time }
    {
    }

    /**
     * Constructs an instance representing a single item from the result of an id-only scan operation.
     *
     * @param id the document ID
     *
     * @since 1.0.0
     * @internal
     */
    explicit scan_result_item(std::string id)
      : id_{ std::move(id) }
      , id_only_{ true }
    {
    }

    bool operator==(const scan_result_item& other) const
    {
        return id_ == other.id_ && cas() == other.cas();
    }

    /**
     * Returns the ID of the document
     *
     * @return document id
     *
     * @since 1.0.0
     * @committed
     */
    [[nodiscard]] auto id() const -> const std::string&
    {
        return id_;
    }

    /**
     * Returns whether this scan result item only contains the document ID. If true, accessing the content or CAS will
     * return the default values.
     *
     * @return whether this item comes from an id-only scan.
     *
     * @since 1.0.0
     * @committed
     */
    [[nodiscard]] auto id_only() const -> bool
    {
        return id_only_;
    }

    /**
     * Decodes the content of the document using given codec.
     *
     * @note This method always returns an empty `std::optional` unless
     * the {@link collection#scan()} request was made using {@link scan_options#ids_only()}
     * set to false.
     *
     * @tparam Document custom type that `Transcoder` returns
     * @tparam Transcoder type that has static function `decode` that takes codec::encoded_value and returns `Document`
     * @return decoded document content
     *
     * @since 1.0.0
     * @committed
     */
    template<typename Document,
             typename Transcoder = codec::default_json_transcoder,
             std::enable_if_t<!codec::is_transcoder_v<Document>, bool> = true,
             std::enable_if_t<codec::is_transcoder_v<Transcoder>, bool> = true>
    [[nodiscard]] auto content_as() const -> Document
    {
        if (id_only_) {
            return {};
        }
        return Transcoder::template decode<Document>(value_);
    }

    /**
     * If the document has an expiry, returns the point in time when the loaded
     * document expires.
     *
     * @note This method always returns an empty `std::optional` unless
     * the {@link collection#scan()} request was made using {@link scan_options#ids_only()}
     * set to false.
     *
     * @return expiry time if present
     *
     * @since 1.0.0
     * @uncommitted
     */
    [[nodiscard]] auto expiry_time() const -> const std::optional<std::chrono::system_clock::time_point>&
    {
        return expiry_time_;
    }

  private:
    std::string id_{};
    bool id_only_{};
    codec::encoded_value value_{};
    std::optional<std::chrono::system_clock::time_point> expiry_time_{};
};
} // namespace couchbase
