next.orly.dev/app/handle-req.go

package app

import (
	"context"
	"errors"

	"encoders.orly/envelopes/closedenvelope"
	"encoders.orly/envelopes/eoseenvelope"
	"encoders.orly/envelopes/eventenvelope"
	"encoders.orly/envelopes/reqenvelope"
	"encoders.orly/event"
	"encoders.orly/filter"
	"encoders.orly/tag"
	"github.com/dgraph-io/badger/v4"
	"lol.mleku.dev/chk"
	"lol.mleku.dev/log"
	"utils.orly/normalize"
	"utils.orly/pointers"
)

func (l *Listener) HandleReq(c context.Context, msg []byte) (
	err error,
) {
	var rem []byte
	env := reqenvelope.New()
	if rem, err = env.Unmarshal(msg); chk.E(err) {
		return normalize.Error.Errorf(err.Error())
	}
	if len(rem) > 0 {
		log.I.F("extra '%s'", rem)
	}
	var events event.S
	for _, f := range *env.Filters {
		if pointers.Present(f.Limit) {
			if *f.Limit == 0 {
				continue
			}
		}
		if events, err = l.QueryEvents(c, f); chk.E(err) {
			if errors.Is(err, badger.ErrDBClosed) {
				return
			}
			err = nil
		}
	}
	// write out the events to the socket
	seen := make(map[string]struct{})
	for _, ev := range events {
		// track the IDs we've sent
		seen[string(ev.ID)] = struct{}{}
		var res *eventenvelope.Result
		if res, err = eventenvelope.NewResultWith(
			env.Subscription, ev,
		); chk.E(err) {
			return
		}
		if err = res.Write(l); chk.E(err) {
			return
		}
	}
	// write the EOSE to signal to the client that all events found have been
	// sent.
	if err = eoseenvelope.NewFrom(env.Subscription).
		Write(l); chk.E(err) {
		return
	}
	// if the query was for just Ids, we know there can't be any more results,
	// so cancel the subscription.
	cancel := true
	var subbedFilters filter.S
	for _, f := range *env.Filters {
		if f.Ids.Len() < 1 {
			cancel = false
			subbedFilters = append(subbedFilters, f)
		} else {
			// remove the IDs that we already sent
			var notFounds [][]byte
			for _, ev := range events {
				if _, ok := seen[string(ev.ID)]; ok {
					continue
				}
				notFounds = append(notFounds, ev.ID)
			}
			// if all were found, don't add to subbedFilters
			if len(notFounds) == 0 {
				continue
			}
			// rewrite the filter Ids to remove the ones we already sent
			f.Ids = tag.NewFromBytesSlice(notFounds...)
			// add the filter to the list of filters we're subscribing to
			subbedFilters = append(subbedFilters, f)
		}
		// also, if we received the limit number of events, subscription ded
		if pointers.Present(f.Limit) {
			if len(events) < int(*f.Limit) {
				cancel = false
			}
		}
	}
	receiver := make(event.C, 32)
	// if the subscription should be cancelled, do so
	if !cancel {
		l.publishers.Receive(
			&W{
				Conn:     l.conn,
				remote:   l.remote,
				Id:       string(env.Subscription),
				Receiver: receiver,
				Filters:  env.Filters,
			},
		)
	} else {
		if err = closedenvelope.NewFrom(
			env.Subscription, nil,
		).Write(l); chk.E(err) {
			return
		}
	}
	return
}