From 54ad3ebee662362d06eade0009b16493ed34c326 Mon Sep 17 00:00:00 2001
From: Sasha Koshka <sashakoshka@tebibyte.media>
Date: Thu, 11 Jul 2024 03:56:25 -0400
Subject: [PATCH] Add machinery for INCR

---
 v2/claim.go | 81 +++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 78 insertions(+), 3 deletions(-)

diff --git a/v2/claim.go b/v2/claim.go
index d394207..d9304ea 100644
--- a/v2/claim.go
+++ b/v2/claim.go
@@ -9,6 +9,16 @@ import "github.com/jezek/xgbutil/xprop"
 import "github.com/jezek/xgbutil/xevent"
 import "github.com/jezek/xgbutil/xwindow"
 
+const format8bit  byte = 8
+const format16bit byte = 16
+const format32bit byte = 32
+
+type claimRequest struct {
+	reader io.ReadSeekCloser
+	ty     xproto.Atom // must be "INCR"
+	event  xevent.SelectionRequestEvent
+}
+
 // Claim represents a claim that a window has on a particular selection.
 type Claim struct {
 	window    *xwindow.Window
@@ -16,6 +26,8 @@ type Claim struct {
 	selection xproto.Atom
 	timestamp xproto.Timestamp
 	active    bool
+
+	requests map[xproto.Atom] claimRequest
 }
 
 // NewClaim claims ownership of a specified selection, and allows using data
@@ -57,6 +69,7 @@ func NewClaim (window *xwindow.Window, selection xproto.Atom, data Data, timesta
 		data:      data,
 		selection: selection,
 		timestamp: timestamp,
+		requests:  make(map[xproto.Atom] claimRequest),
 	}, nil
 }
 
@@ -165,7 +178,7 @@ func (claim *Claim) HandleSelectionRequest (
 		// send that list to the requestor
 		atomAtom, err := xprop.Atm(claim.window.X, "ATOM")
 		if err != nil { die(); return }
-		claim.fulfillSelectionRequest(data, 32, atomAtom, event)
+		claim.fulfillSelectionRequest(data, format32bit, atomAtom, event)
 
 	default:
 		// respond with data
@@ -175,7 +188,7 @@ func (claim *Claim) HandleSelectionRequest (
 		data, err := io.ReadAll(reader)
 		reader.Close()
 		if err != nil { die() }
-		claim.fulfillSelectionRequest(data, 8, event.Target, event)
+		claim.fulfillSelectionRequest(data, format8bit, event.Target, event)
 	}
 }
 
@@ -186,7 +199,69 @@ func (claim *Claim) HandlePropertyNotify (
 	connection *xgbutil.XUtil,
 	event xevent.PropertyNotifyEvent,
 ) {
-	// TODO
+	// The selection owner then:
+	// ... Waits between each append for a PropertyNotify (state==Deleted)
+	// event that shows that the requestor has read the data. The reason for
+	// doing this is to limit the consumption of space in the server.
+
+	// FIXME check for state==Deleted
+	// if the request does not exist, the property was either modified in
+	// error or the request has already finished. either way, we simply
+	// exit.
+	request, ok := claim.requests[event.Atom]
+	if !ok { return }
+
+	done := func () {
+		request.reader.Close()
+		delete(claim.requests, request.event.Property)
+	}
+	
+	die := func () {
+		done()
+		claim.refuseSelectionRequest(request.event)
+	}
+
+	// FIXME change the length of this if maximum-request-size is smaller
+	buffer := [1024]byte { }
+	size, err := request.reader.Read(buffer[:])
+	if err != nil { die(); return }
+	dataRead := buffer[:size]
+
+	if len(dataRead) > 0 {
+		// there is more data to send
+		
+		// ... Appends the data in suitable-size chunks to the same property on
+		// the same window as the selection reply with a type corresponding to
+		// the actual type of the converted selection. The size should be less
+		// than the maximum-request-size in the connection handshake.
+		format := format8bit
+		err = xproto.ChangePropertyChecked (
+			claim.window.X.Conn(),
+			xproto.PropModeAppend, request.event.Requestor,
+			request.event.Property,
+			request.ty, format,
+			uint32(len(dataRead) / (int(format) / 8)), dataRead).Check()
+		if err != nil { die(); return }
+		
+	} else {
+		// all data has been sent
+	
+		// ... Waits (after the entire data has been transferred to the
+		// server) until a PropertyNotify (state==Deleted) event that
+		// shows that the data has been read by the requestor and then
+		// writes zero-length data to the property.
+
+		format := format8bit
+		err := xproto.ChangePropertyChecked (
+			claim.window.X.Conn(),
+			xproto.PropModeAppend, request.event.Requestor,
+			request.event.Property,
+			request.ty, format,
+			0, nil).Check()
+		if err != nil { die(); return }
+
+		done()
+	}
 }
 
 // While the selection claim is active, HandleSelectionClear should be called