package handler

import (
	"context"
	"time"

	"github.com/google/uuid"
	"github.com/micro/services/seen/domain"

	"github.com/micro/micro/v3/service/errors"
	"github.com/micro/micro/v3/service/logger"
	pb "github.com/micro/services/seen/proto"
	"google.golang.org/protobuf/types/known/timestamppb"
)

var (
	ErrMissingUserID       = errors.BadRequest("MISSING_USER_ID", "Missing UserID")
	ErrMissingResourceID   = errors.BadRequest("MISSING_RESOURCE_ID", "Missing ResourceID")
	ErrMissingResourceIDs  = errors.BadRequest("MISSING_RESOURCE_IDS", "Missing ResourceIDs")
	ErrMissingResourceType = errors.BadRequest("MISSING_RESOURCE_TYPE", "Missing ResourceType")
	ErrStore               = errors.InternalServerError("STORE_ERROR", "Error connecting to the store")
)

type Seen struct {
	Domain *domain.Domain
}

// Set a resource as seen by a user. If no timestamp is provided, the current time is used.
func (s *Seen) Set(ctx context.Context, req *pb.SetRequest, rsp *pb.SetResponse) error {
	// validate the request
	if len(req.UserId) == 0 {
		return ErrMissingUserID
	}
	if len(req.ResourceId) == 0 {
		return ErrMissingResourceID
	}
	if len(req.ResourceType) == 0 {
		return ErrMissingResourceType
	}

	// default the timestamp
	if req.Timestamp == nil {
		req.Timestamp = timestamppb.New(time.Now())
	}

	// write the object to the store
	err := s.Domain.Create(domain.Seen{
		ID:           uuid.New().String(),
		UserID:       req.UserId,
		ResourceID:   req.ResourceId,
		ResourceType: req.ResourceType,
		Timestamp:    req.Timestamp.AsTime(),
	})
	if err != nil {
		logger.Errorf("Error with store: %v", err)
		return ErrStore
	}

	return nil
}

// Unset a resource as seen, used in cases where a user viewed a resource but wants to override
// this so they remember to action it in the future, e.g. "Mark this as unread".
func (s *Seen) Unset(ctx context.Context, req *pb.UnsetRequest, rsp *pb.UnsetResponse) error {
	// validate the request
	if len(req.UserId) == 0 {
		return ErrMissingUserID
	}
	if len(req.ResourceId) == 0 {
		return ErrMissingResourceID
	}
	if len(req.ResourceType) == 0 {
		return ErrMissingResourceType
	}

	// delete the object from the store
	err := s.Domain.Delete(domain.Seen{
		UserID:       req.UserId,
		ResourceID:   req.ResourceId,
		ResourceType: req.ResourceType,
	})
	if err != nil {
		logger.Errorf("Error with store: %v", err)
		return ErrStore
	}

	return nil
}

// Read returns the timestamps at which various resources were seen by a user. If no timestamp
// is returned for a given resource_id, it indicates that resource has not yet been seen by the
// user.
func (s *Seen) Read(ctx context.Context, req *pb.ReadRequest, rsp *pb.ReadResponse) error {
	// validate the request
	if len(req.UserId) == 0 {
		return ErrMissingUserID
	}
	if len(req.ResourceIds) == 0 {
		return ErrMissingResourceIDs
	}
	if len(req.ResourceType) == 0 {
		return ErrMissingResourceType
	}

	// query the store
	data, err := s.Domain.Read(req.UserId, req.ResourceType, req.ResourceIds)
	if err != nil {
		logger.Errorf("Error with store: %v", err)
		return ErrStore
	}

	// serialize the response
	rsp.Timestamps = make(map[string]*timestamppb.Timestamp, len(data))
	for uid, ts := range data {
		rsp.Timestamps[uid] = timestamppb.New(ts)
	}

	return nil
}