package session

import (
	"context"
	"errors"

	"google.golang.org/grpc/metadata"
)

const (
	UidKey = "uid"
)

var (
	UnauthorizedRequestError = errors.New("unauthorized request")
)

type RpcSubject struct {
	Uid string
}

func NewRpcSubject(uid string) *RpcSubject {
	return &RpcSubject{
		Uid: uid,
	}
}

func PutSubject(ctx context.Context, subject *RpcSubject) context.Context {
	return metadata.NewOutgoingContext(ctx, metadata.Pairs(UidKey, subject.Uid))
}

func GetSubject(ctx context.Context) (*RpcSubject, error) {
	uid, ok := GetUid(ctx)
	if !ok {
		return nil, UnauthorizedRequestError
	}
	return &RpcSubject{Uid: uid}, nil
}

func GetUid(ctx context.Context) (string, bool) {
	md, ok := metadata.FromIncomingContext(ctx)
	if !ok {
		return "", false
	}
	uids := md.Get(UidKey)
	if len(uids) == 0 {
		return "", false
	}
	return uids[0], true
}