#pragma once
#include "adminive/http.hpp"
#include "adminive/status.hpp"
#include <algorithm>
#include <concepts>
#include <cstdint>
#include <functional>
#include <mutex>
#include <string>
#include <string_view>
#include <type_traits>
#include <utility>
#include <vector>
namespace adminive {
struct Collection_Query {
    std::size_t page{1};
    std::size_t per_page{20};
    std::string order_by;
    std::string order_dir;
};
template <Described_Type T, Json_Type Json, Basic_Lock Lock = std::mutex>
requires std::default_initializable<T> && std::copy_constructible<T> && std::assignable_from<T&, T>
class Collection_Service {
public:
    explicit Collection_Service(std::string path, std::vector<T> initial = {}) : path_(std::move(path)) {
        for(auto& value : initial) {
            entries_.push_back(Entry{next_id_++, std::move(value)});
        }
    }
    template <Described_Type Status>
    void register_overview_status(std::string api, std::uint64_t interval = 2000) {
        overview_status_api_ = std::move(api);
        overview_status_descriptor_ = to_status_descriptor_json<Json, Status>();
        overview_status_interval_ = interval;
    }
    template <auto Function>
    void register_status(std::uint64_t interval = 2000) {
        using Function_Type = decltype(Function);
        static_assert(std::is_member_function_pointer_v<Function_Type>);
        static_assert(std::is_invocable_v<Function_Type, T&>);
        using Status = std::remove_cvref_t<std::invoke_result_t<Function_Type, T&>>;
        static_assert(Described_Type<Status>);
        status_descriptor_ = to_status_descriptor_json<Json, Status>();
        status_interval_ = interval;
        status_reader_ = [](T& value) {
            return to_status_json<Json>(std::invoke(Function, value));
        };
    }
    const std::string& path() const noexcept {
        return path_;
    }
    bool has_status() const noexcept {
        return static_cast<bool>(status_reader_);
    }
    bool user_reorderable() const {
        return describe<T>().list_options().user_reorderable_;
    }
    std::size_t size() const {
        std::scoped_lock lock(mutex_);
        return entries_.size();
    }
    Json items_json() const {
        std::scoped_lock lock(mutex_);
        Json items = json_array<Json>();
        for(const auto& entry : entries_) {
            json_append(items, encode_entry(entry));
        }
        return items;
    }
    Json amis_schema() const {
        const Json* descriptor = status_reader_ ? &status_descriptor_ : nullptr;
        if(overview_status_api_.empty()) {
            return to_amis_crud_schema<Json, T>(path_, descriptor, status_interval_);
        }
        return to_amis_crud_status_schema<Json, T>(path_, overview_status_api_, overview_status_descriptor_, overview_status_interval_, descriptor, status_interval_);
    }
    Http_Response<Json> descriptor_response() const noexcept {
        return safe_response([&] {
            return make_http_success<Json>(to_descriptor_json<Json, T>());
        });
    }
    Http_Response<Json> amis_response() const noexcept {
        return safe_response([&] {
            return make_http_success<Json>(amis_schema());
        });
    }
    Http_Response<Json> status_descriptor_response() const noexcept {
        return safe_response([&] {
            if(!status_reader_) {
                return make_http_error<Json>(404, "item status is not configured");
            }
            return make_http_success<Json>(status_descriptor_);
        });
    }
    Http_Response<Json> status_response(std::uint64_t id) noexcept {
        return safe_response([&] {
            if(!status_reader_) {
                return make_http_error<Json>(404, "item status is not configured");
            }
            std::scoped_lock lock(mutex_);
            const auto iterator = find_entry(id);
            if(iterator == entries_.end()) {
                return make_http_error<Json>(404, "record not found");
            }
            return make_http_success<Json>(status_reader_(iterator->value));
        });
    }
    Http_Response<Json> list_response(Collection_Query query = {}) const noexcept {
        return safe_response([&] {
            std::scoped_lock lock(mutex_);
            std::vector<const Entry*> ordered_entries;
            ordered_entries.reserve(entries_.size());
            for(const auto& entry : entries_) {
                ordered_entries.push_back(&entry);
            }
            apply_sort(query, ordered_entries);
            const std::size_t page = query.page == 0 ? 1 : query.page;
            const std::size_t per_page = query.per_page == 0 ? 20 : query.per_page;
            const std::size_t page_index = page - 1;
            const std::size_t offset = page_index > ordered_entries.size() / per_page ? ordered_entries.size() : page_index * per_page;
            const std::size_t end = offset + std::min(per_page, ordered_entries.size() - offset);
            Json items = json_array<Json>();
            for(std::size_t index = offset; index < end; ++index) {
                json_append(items, encode_entry(*ordered_entries[index]));
            }
            Json data = json_object<Json>();
            json_set(data, "items", std::move(items));
            json_set(data, "total", ordered_entries.size());
            return make_http_success<Json>(std::move(data));
        });
    }
    Http_Response<Json> item_response(std::uint64_t id) const noexcept {
        return safe_response([&] {
            std::scoped_lock lock(mutex_);
            const auto iterator = find_entry(id);
            if(iterator == entries_.end()) {
                return make_http_error<Json>(404, "record not found");
            }
            return make_http_success<Json>(encode_entry(*iterator));
        });
    }
    Http_Response<Json> create_response(std::string_view body) noexcept {
        return safe_response([&] {
            Json input = parse_json<Json>(body);
            Json_Adapter<Json>::erase(input, "id");
            T value{};
            const auto result = apply_frontend_create<Json>(value, input);
            if(!result.success) {
                return make_http_error<Json>(422, result);
            }
            std::scoped_lock lock(mutex_);
            entries_.push_back(Entry{next_id_++, std::move(value)});
            return make_http_success<Json>(encode_entry(entries_.back()), "created");
        });
    }
    Http_Response<Json> update_response(std::uint64_t id, std::string_view body) noexcept {
        return safe_response([&] {
            Json patch = parse_json<Json>(body);
            Json_Adapter<Json>::erase(patch, "id");
            std::scoped_lock lock(mutex_);
            const auto iterator = find_entry(id);
            if(iterator == entries_.end()) {
                return make_http_error<Json>(404, "record not found");
            }
            const auto result = apply_frontend_patch<Json>(iterator->value, patch);
            if(!result.success) {
                return make_http_error<Json>(422, result);
            }
            return make_http_success<Json>(encode_entry(*iterator), result.message);
        });
    }
    Http_Response<Json> delete_response(std::uint64_t id) noexcept {
        return safe_response([&] {
            std::scoped_lock lock(mutex_);
            const auto iterator = find_entry(id);
            if(iterator == entries_.end()) {
                return make_http_error<Json>(404, "record not found");
            }
            entries_.erase(iterator);
            return make_http_success<Json>(json_object<Json>(), "deleted");
        });
    }
    Http_Response<Json> reorder_response(std::string_view body) noexcept {
        return safe_response([&] {
            const Json input = parse_json<Json>(body);
            const auto ids = read_order_ids(Json_Adapter<Json>::at(input, "ids"));
            std::scoped_lock lock(mutex_);
            reorder(ids);
            return make_http_success<Json>(json_object<Json>(), "reordered");
        });
    }
private:
    struct Entry {
        std::uint64_t id{};
        T value;
    };
    using Iterator = typename std::vector<Entry>::iterator;
    using Const_Iterator = typename std::vector<Entry>::const_iterator;
    template <class Function>
    static Http_Response<Json> safe_response(Function&& function) noexcept {
        try {
            return std::forward<Function>(function)();
        } catch(const Json_Assignment_Error& error) {
            return make_http_error<Json>(422, error.result());
        } catch(const Field_Validation_Error& error) {
            return make_http_error<Json>(422, object_commit_error<T>(error));
        } catch(const std::exception& error) {
            return make_http_error<Json>(400, error.what());
        } catch(...) {
            return make_http_error<Json>(500, "unknown server error");
        }
    }
    static int compare_json_values(const Json& left, const Json& right) {
        if(Json_Adapter<Json>::is_number(left) && Json_Adapter<Json>::is_number(right)) {
            const long double left_value = Json_Adapter<Json>::number(left);
            const long double right_value = Json_Adapter<Json>::number(right);
            return left_value < right_value ? -1 : left_value > right_value ? 1 : 0;
        }
        if(Json_Adapter<Json>::is_string(left) && Json_Adapter<Json>::is_string(right)) {
            const auto left_value = json_get<Json, std::string>(left);
            const auto right_value = json_get<Json, std::string>(right);
            return left_value < right_value ? -1 : left_value > right_value ? 1 : 0;
        }
        if(Json_Adapter<Json>::is_boolean(left) && Json_Adapter<Json>::is_boolean(right)) {
            const bool left_value = json_get<Json, bool>(left);
            const bool right_value = json_get<Json, bool>(right);
            return left_value == right_value ? 0 : left_value ? 1 : -1;
        }
        const std::string left_value = dump_json(left);
        const std::string right_value = dump_json(right);
        return left_value < right_value ? -1 : left_value > right_value ? 1 : 0;
    }
    static bool is_sortable_field(const std::string& name) {
        if(name == "id") {
            return true;
        }
        bool sortable{};
        std::apply([&](const auto&... field) {
            ((field.name() == name ? sortable = field.is_sortable() : false), ...);
        }, describe<T>().fields());
        return sortable;
    }
    static std::vector<std::uint64_t> read_order_ids(const Json& value) {
        std::vector<std::uint64_t> result;
        if(Json_Adapter<Json>::is_array(value)) {
            for(std::size_t index = 0; index < Json_Adapter<Json>::size(value); ++index) {
                const auto& item = Json_Adapter<Json>::at(value, index);
                result.push_back(Json_Adapter<Json>::is_string(item) ? std::stoull(json_get<Json, std::string>(item)) : json_get<Json, std::uint64_t>(item));
            }
            return result;
        }
        const std::string text = json_get<Json, std::string>(value);
        std::size_t begin{};
        while(begin < text.size()) {
            const auto end = text.find(',', begin);
            result.push_back(std::stoull(text.substr(begin, end == std::string::npos ? text.size() - begin : end - begin)));
            if(end == std::string::npos) {
                break;
            }
            begin = end + 1;
        }
        return result;
    }
    void apply_sort(const Collection_Query& query, std::vector<const Entry*>& entries) const {
        const auto descriptor = describe<T>();
        const auto& options = descriptor.list_options();
        const std::string order_by = query.order_by.empty() ? options.default_order_by : query.order_by;
        const std::string order_dir = query.order_by.empty() ? options.default_order_dir : query.order_dir.empty() ? "asc" : query.order_dir;
        if(order_by.empty() || !is_sortable_field(order_by)) {
            return;
        }
        const bool descending = order_dir == "desc";
        std::stable_sort(entries.begin(), entries.end(), [&](const Entry* left, const Entry* right) {
            int comparison{};
            if(order_by == "id") {
                comparison = left->id < right->id ? -1 : left->id > right->id ? 1 : 0;
            } else {
                const auto left_json = to_frontend_json<Json>(left->value);
                const auto right_json = to_frontend_json<Json>(right->value);
                comparison = compare_json_values(Json_Adapter<Json>::at(left_json, order_by), Json_Adapter<Json>::at(right_json, order_by));
            }
            return descending ? comparison > 0 : comparison < 0;
        });
    }
    Iterator find_entry(std::uint64_t id) {
        return std::find_if(entries_.begin(), entries_.end(), [id](const Entry& entry) {
            return entry.id == id;
        });
    }
    Const_Iterator find_entry(std::uint64_t id) const {
        return std::find_if(entries_.begin(), entries_.end(), [id](const Entry& entry) {
            return entry.id == id;
        });
    }
    static Json encode_entry(const Entry& entry) {
        Json result = to_frontend_json<Json>(entry.value);
        json_set(result, "id", entry.id);
        return result;
    }
    void reorder(const std::vector<std::uint64_t>& ids) {
        std::vector<Entry> remaining = std::move(entries_);
        std::vector<Entry> reordered;
        reordered.reserve(remaining.size());
        for(const auto id : ids) {
            const auto iterator = std::find_if(remaining.begin(), remaining.end(), [id](const Entry& entry) {
                return entry.id == id;
            });
            if(iterator != remaining.end()) {
                reordered.push_back(std::move(*iterator));
                remaining.erase(iterator);
            }
        }
        for(auto& entry : remaining) {
            reordered.push_back(std::move(entry));
        }
        entries_ = std::move(reordered);
    }
    std::string path_;
    std::string overview_status_api_;
    Json overview_status_descriptor_{};
    std::uint64_t overview_status_interval_{2000};
    Json status_descriptor_{};
    std::function<Json(T&)> status_reader_;
    std::uint64_t status_interval_{2000};
    std::vector<Entry> entries_;
    std::uint64_t next_id_{1};
    mutable Lock mutex_;
};
}