package entity

import "time"

const (
	RelationNone   RelationKind = 0
	RelationFriend RelationKind = 1
	RelationBlock  RelationKind = 2

	StatusNone   EdgeStatus = 0
	StatusFriend EdgeStatus = 1
)

// RelationKind is the viewer-centric JSON `relation` (not the table column).
type RelationKind int

func (k RelationKind) Valid() bool {
	return k == RelationNone || k == RelationFriend || k == RelationBlock
}

// EdgeStatus is persisted as friend_relations.status.
type EdgeStatus int

func (s EdgeStatus) Valid() bool {
	return s == StatusNone || s == StatusFriend
}

const (
	ListDefault = 20
	ListMax     = 100
)

// Relation is one directed edge: UserID's view of FriendID.
type Relation struct {
	ID        int64
	UserID    int64
	FriendID  int64
	Status    EdgeStatus
	Remark    string
	Blocked   bool
	Pinned    bool
	Source    Source
	CreatedAt time.Time
	UpdatedAt time.Time
}

func (r *Relation) Active() bool {
	return r != nil && r.Status == StatusFriend
}

func NewFriendEdge(userID, friendID int64, remark string, source Source, at time.Time) *Relation {
	return &Relation{
		UserID: userID, FriendID: friendID, Status: StatusFriend,
		Remark: remark, Source: source, CreatedAt: at, UpdatedAt: at,
	}
}

func ClampLimit(limit int) int {
	if limit <= 0 {
		return ListDefault
	}
	if limit > ListMax {
		return ListMax
	}
	return limit
}

// ViewRelation is the viewer-centric relation: friend, blocked-by-me, or none.
func ViewRelation(friend, blockedByMe bool) RelationKind {
	if blockedByMe {
		return RelationBlock
	}
	if friend {
		return RelationFriend
	}
	return RelationNone
}