package live

import (
	"context"
	"errors"
	"time"

	kratoserrors "github.com/go-kratos/kratos/v3/errors"
)

var (
	ErrFollowNotFound = kratoserrors.NotFound("LIVE_FOLLOW_NOT_FOUND", "follow relation not found")
	ErrFollowInvalid  = kratoserrors.BadRequest("LIVE_FOLLOW_INVALID_ARGUMENT", "invalid follow argument")
)

type Follow struct {
	ID           uint
	UserID       uint
	RoomID       uint
	AnchorUserID uint
	CreatedAt    time.Time
}

type FollowRepo interface {
	Get(context.Context, uint, uint) (*Follow, error)
	Create(context.Context, *Follow) (*Follow, error)
	Delete(context.Context, uint, uint) error
}

type FollowUsecase struct{ repo FollowRepo }

func NewFollowUsecase(repo FollowRepo) *FollowUsecase { return &FollowUsecase{repo: repo} }

func (uc *FollowUsecase) Get(ctx context.Context, userID, roomID uint) (*Follow, error) {
	if userID == 0 || roomID == 0 {
		return nil, ErrFollowInvalid
	}
	return uc.repo.Get(ctx, userID, roomID)
}

func (uc *FollowUsecase) Follow(ctx context.Context, userID, roomID uint) (*Follow, error) {
	if userID == 0 || roomID == 0 {
		return nil, ErrFollowInvalid
	}
	if existing, err := uc.repo.Get(ctx, userID, roomID); err == nil {
		return existing, nil
	} else if !errors.Is(err, ErrFollowNotFound) {
		return nil, err
	}
	return uc.repo.Create(ctx, &Follow{UserID: userID, RoomID: roomID})
}

func (uc *FollowUsecase) Unfollow(ctx context.Context, userID, roomID uint) error {
	if userID == 0 || roomID == 0 {
		return ErrFollowInvalid
	}
	return uc.repo.Delete(ctx, userID, roomID)
}