From c162743200466b6d8d9e52d5666e1220c9cf67a2 Mon Sep 17 00:00:00 2001
From: Florian Fischer <florian.fischer@muhq.space>
Date: Mon, 31 Jul 2023 10:19:29 +0200
Subject: move song and connection code into separate files

---
 connection.go | 142 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 142 insertions(+)
 create mode 100644 connection.go

(limited to 'connection.go')

diff --git a/connection.go b/connection.go
new file mode 100644
index 0000000..4901fdd
--- /dev/null
+++ b/connection.go
@@ -0,0 +1,142 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"sync/atomic"
+
+	"muhq.space/go/wrms/llog"
+
+	"github.com/google/uuid"
+)
+
+type Connection struct {
+	wrms      *Wrms
+	Id        uuid.UUID
+	nr        uint64
+	closing   atomic.Bool
+	refs      atomic.Int64
+	Events    chan Event
+	w         http.ResponseWriter
+	flusher   http.Flusher
+	ctx       context.Context
+	cancel    func()
+	nextEvent uint64
+}
+
+const EVENT_BUFFER_SIZE = 3
+
+func (wrms *Wrms) newConnection(id uuid.UUID,
+	w http.ResponseWriter,
+	ctx context.Context,
+	cncl func()) *Connection {
+	// prepare the flusher
+	flusher, ok := w.(http.Flusher)
+	if !ok {
+		llog.Fatal("Flusher type assertion failed")
+	}
+
+	conn := &Connection{
+		wrms:    wrms,
+		Id:      id,
+		nr:      wrms.nextConnNr.Add(1),
+		Events:  make(chan Event, EVENT_BUFFER_SIZE),
+		w:       w,
+		flusher: flusher,
+		ctx:     ctx,
+		cancel:  cncl,
+	}
+
+	wrms.addConn(conn)
+	return conn
+}
+
+func (c *Connection) Send(ev Event) {
+	llog.DDebug("Sending %v to %v", ev, c.Id)
+	// Connection is closing -> not write to it
+	if c.closing.Load() {
+		return
+	}
+	// Register us as sender
+	c.refs.Add(1)
+	// Send the event
+	c.Events <- ev
+	// Deregister us as sender
+	c.refs.Add(-1)
+}
+
+func (conn *Connection) _send(evs []interface{}) error {
+	for _, ev := range evs {
+		data, err := json.Marshal(ev)
+		if err != nil {
+			llog.Warning("Encoding the initial command %v failed with %s", ev, err)
+			return err
+		}
+
+		sdata := string(data)
+		llog.Debug("Sending ev %s to %s", sdata, conn.Id)
+		fmt.Fprintf(conn.w, "data: %s\n\n", sdata)
+		conn.flusher.Flush()
+	}
+
+	return nil
+}
+
+func (conn *Connection) _sendEv(ev Event) error {
+	return conn._send([]interface{}{ev})
+}
+
+func (conn *Connection) serve() {
+	// Map to store future events to send them in order
+	toSend := make(map[uint64]*Event)
+
+	for {
+		var ev Event
+		// We have the next event -> send it
+		if toSend[conn.nextEvent] != nil {
+			ev = *toSend[conn.nextEvent]
+			delete(toSend, conn.nextEvent)
+			// We have not received the next event yet -> receive a new event
+		} else {
+			llog.DDebug("%v: Awaiting event %d", conn.Id, conn.nextEvent)
+			select {
+			case ev = <-conn.Events:
+			case <-conn.ctx.Done():
+				return
+			}
+			// We received a future object -> store it and continue
+			if ev.Id > conn.nextEvent {
+				llog.DDebug("%v: Received future event %d", conn.Id, ev.Id)
+				toSend[ev.Id] = &ev
+				continue
+			}
+		}
+
+		// increment the expected event id
+		if ev.Id == conn.nextEvent {
+			conn.nextEvent++
+		}
+
+		conn._sendEv(ev)
+	}
+}
+
+func (c *Connection) Close() {
+	llog.Info("Closing connection %s", c.Id)
+	// Remove the closing connection from the map
+	wrms.delConn(c)
+	// Announce that the connection is going to be closed
+	c.closing.Store(true)
+
+	// Consume all events from the registered senders
+	for c.refs.Load() > 0 {
+		select {
+		case <-c.Events:
+		default:
+		}
+	}
+
+	close(c.Events)
+}
-- 
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