// Copyright (c) Mainflux
// SPDX-License-Identifier: Apache-2.0

package api

import (
	"context"
	"encoding/json"
	"net/http"

	"github.com/go-chi/chi/v5"
	"github.com/go-kit/kit/endpoint"
	kithttp "github.com/go-kit/kit/transport/http"
	"github.com/mainflux/mainflux/internal/api"
	"github.com/mainflux/mainflux/internal/apiutil"
	gapi "github.com/mainflux/mainflux/internal/groups/api"
	"github.com/mainflux/mainflux/logger"
	"github.com/mainflux/mainflux/pkg/errors"
	"github.com/mainflux/mainflux/pkg/groups"
	"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
)

// MakeHandler returns a HTTP handler for Groups API endpoints.
func groupsHandler(svc groups.Service, r *chi.Mux, logger logger.Logger) http.Handler {
	opts := []kithttp.ServerOption{
		kithttp.ServerErrorEncoder(apiutil.LoggingErrorEncoder(logger, api.EncodeError)),
	}

	r.Route("/groups", func(r chi.Router) {
		r.Post("/", otelhttp.NewHandler(kithttp.NewServer(
			gapi.CreateGroupEndpoint(svc),
			gapi.DecodeGroupCreate,
			api.EncodeResponse,
			opts...,
		), "create_group").ServeHTTP)

		r.Get("/{groupID}", otelhttp.NewHandler(kithttp.NewServer(
			gapi.ViewGroupEndpoint(svc),
			gapi.DecodeGroupRequest,
			api.EncodeResponse,
			opts...,
		), "view_group").ServeHTTP)

		r.Put("/{groupID}", otelhttp.NewHandler(kithttp.NewServer(
			gapi.UpdateGroupEndpoint(svc),
			gapi.DecodeGroupUpdate,
			api.EncodeResponse,
			opts...,
		), "update_group").ServeHTTP)

		r.Get("/", otelhttp.NewHandler(kithttp.NewServer(
			gapi.ListGroupsEndpoint(svc, "users"),
			gapi.DecodeListGroupsRequest,
			api.EncodeResponse,
			opts...,
		), "list_groups").ServeHTTP)

		r.Get("/{groupID}/children", otelhttp.NewHandler(kithttp.NewServer(
			gapi.ListGroupsEndpoint(svc, "users"),
			gapi.DecodeListChildrenRequest,
			api.EncodeResponse,
			opts...,
		), "list_children").ServeHTTP)

		r.Get("/{groupID}/parents", otelhttp.NewHandler(kithttp.NewServer(
			gapi.ListGroupsEndpoint(svc, "users"),
			gapi.DecodeListParentsRequest,
			api.EncodeResponse,
			opts...,
		), "list_parents").ServeHTTP)

		r.Post("/{groupID}/enable", otelhttp.NewHandler(kithttp.NewServer(
			gapi.EnableGroupEndpoint(svc),
			gapi.DecodeChangeGroupStatus,
			api.EncodeResponse,
			opts...,
		), "enable_group").ServeHTTP)

		r.Post("/{groupID}/disable", otelhttp.NewHandler(kithttp.NewServer(
			gapi.DisableGroupEndpoint(svc),
			gapi.DecodeChangeGroupStatus,
			api.EncodeResponse,
			opts...,
		), "disable_group").ServeHTTP)

		r.Post("/{groupID}/users/assign", otelhttp.NewHandler(kithttp.NewServer(
			assignUsersEndpoint(svc),
			decodeAssignUsersRequest,
			api.EncodeResponse,
			opts...,
		), "assign_users").ServeHTTP)

		r.Post("/{groupID}/users/unassign", otelhttp.NewHandler(kithttp.NewServer(
			unassignUsersEndpoint(svc),
			decodeUnassignUsersRequest,
			api.EncodeResponse,
			opts...,
		), "unassign_users").ServeHTTP)
	})

	// The ideal placeholder name should be {channelID}, but gapi.DecodeListGroupsRequest uses {memberID} as a placeholder for the ID.
	// So here, we are using {memberID} as the placeholder.
	r.Get("/channels/{memberID}/groups", otelhttp.NewHandler(kithttp.NewServer(
		gapi.ListGroupsEndpoint(svc, "channels"),
		gapi.DecodeListGroupsRequest,
		api.EncodeResponse,
		opts...,
	), "list_groups_by_channel_id").ServeHTTP)

	r.Get("/users/{memberID}/groups", otelhttp.NewHandler(kithttp.NewServer(
		gapi.ListGroupsEndpoint(svc, "users"),
		gapi.DecodeListGroupsRequest,
		api.EncodeResponse,
		opts...,
	), "list_groups_by_user_id").ServeHTTP)
	return r
}

func decodeAssignUsersRequest(_ context.Context, r *http.Request) (interface{}, error) {
	req := assignUsersReq{
		token:   apiutil.ExtractBearerToken(r),
		groupID: chi.URLParam(r, "groupID"),
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		return nil, errors.Wrap(apiutil.ErrValidation, errors.Wrap(err, errors.ErrMalformedEntity))
	}
	return req, nil
}

func decodeUnassignUsersRequest(_ context.Context, r *http.Request) (interface{}, error) {
	req := unassignUsersReq{
		token:   apiutil.ExtractBearerToken(r),
		groupID: chi.URLParam(r, "groupID"),
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		return nil, errors.Wrap(apiutil.ErrValidation, errors.Wrap(err, errors.ErrMalformedEntity))
	}
	return req, nil
}

func assignUsersEndpoint(svc groups.Service) endpoint.Endpoint {
	return func(ctx context.Context, request interface{}) (interface{}, error) {
		req := request.(assignUsersReq)

		if err := req.validate(); err != nil {
			return nil, errors.Wrap(apiutil.ErrValidation, err)
		}
		if err := svc.Assign(ctx, req.token, req.groupID, req.Relation, "users", req.UserIDs...); err != nil {
			return nil, err
		}
		return assignUsersRes{}, nil
	}
}

func unassignUsersEndpoint(svc groups.Service) endpoint.Endpoint {
	return func(ctx context.Context, request interface{}) (interface{}, error) {
		req := request.(unassignUsersReq)

		if err := req.validate(); err != nil {
			return nil, errors.Wrap(apiutil.ErrValidation, err)
		}

		if err := svc.Unassign(ctx, req.token, req.groupID, req.Relation, "users", req.UserIDs...); err != nil {
			return nil, err
		}
		return unassignUsersRes{}, nil
	}
}