v0.1.0 initial commit

backend_wasm.go

@@ -0,0 +1,147 @@
+//go:build wasm
+
+package terminal
+
+import (
+	"syscall/js"
+)
+
+type wasmBackend struct {
+	width, height   int
+	inputCh         chan []byte
+	jsCallbacks     []js.Func
+	returnEmptyNext bool // Signal to return empty on next Read() for standalone ESC
+}
+
+const escapeTimeoutMs = 10
+
+func newBackend() Backend {
+	return &wasmBackend{
+		width:   80,
+		height:  24,
+		inputCh: make(chan []byte, 256),
+	}
+}
+
+func (b *wasmBackend) Init() error {
+	// Register JS callbacks
+	inputCb := js.FuncOf(func(_ js.Value, args []js.Value) any {
+		if len(args) > 0 {
+			data := make([]byte, args[0].Length())
+			js.CopyBytesToGo(data, args[0])
+			select {
+			case b.inputCh <- data:
+			default:
+				// Buffer full, drop input
+			}
+		}
+		return nil
+	})
+	b.jsCallbacks = append(b.jsCallbacks, inputCb)
+	js.Global().Set("goTerminalInput", inputCb)
+
+	resizeCb := js.FuncOf(func(_ js.Value, args []js.Value) any {
+		if len(args) >= 2 {
+			w, h := args[0].Int(), args[1].Int()
+			b.width, b.height = w, h
+			// Resize handler is set via SetResizeHandler, but we need to store it
+			// or have this callback call a method. For simplicity, we'll assign
+			// the handler to a struct field if we need dynamic updates,
+			// but here we rely on the struct field set by SetResizeHandler.
+			// However, SetResizeHandler might be called after Init.
+			// See below for corrected flow.
+		}
+		return nil
+	})
+	b.jsCallbacks = append(b.jsCallbacks, resizeCb)
+	js.Global().Set("goTerminalResize", resizeCb)
+
+	// Initial size query
+	if xterm := js.Global().Get("xterm"); !xterm.IsUndefined() {
+		b.width = xterm.Get("cols").Int()
+		b.height = xterm.Get("rows").Int()
+	}
+
+	return nil
+}
+
+func (b *wasmBackend) Fini() {
+	for _, cb := range b.jsCallbacks {
+		cb.Release()
+	}
+	js.Global().Delete("goTerminalInput")
+	js.Global().Delete("goTerminalResize")
+}
+
+func (b *wasmBackend) Size() (int, int) {
+	return b.width, b.height
+}
+
+func (b *wasmBackend) Write(p []byte) error {
+	arr := js.Global().Get("Uint8Array").New(len(p))
+	js.CopyBytesToJS(arr, p)
+	js.Global().Call("goTerminalWrite", arr)
+	return nil
+}
+
+func (b *wasmBackend) Read(stopCh <-chan struct{}) ([]byte, error) {
+	// After standalone ESC timeout, return empty to trigger readLoop's ESC emission
+	if b.returnEmptyNext {
+		b.returnEmptyNext = false
+		return nil, nil
+	}
+
+	select {
+	case data := <-b.inputCh:
+		// If we received exactly ESC, wait briefly for more data
+		// (in case it's start of escape sequence split across callbacks)
+		if len(data) == 1 && data[0] == 0x1b {
+			// Use JS setTimeout via a promise-based wait
+			moreCh := make(chan []byte, 1)
+
+			// Schedule timeout callback
+			var timeoutCb js.Func
+			timeoutCb = js.FuncOf(func(_ js.Value, _ []js.Value) any {
+				select {
+				case moreCh <- nil:
+				default:
+				}
+				timeoutCb.Release()
+				return nil
+			})
+			js.Global().Call("setTimeout", timeoutCb, escapeTimeoutMs)
+
+			// Wait for more data or timeout
+			select {
+			case more := <-b.inputCh:
+				// More data arrived, combine
+				return append(data, more...), nil
+			case <-moreCh:
+				// Timeout, standalone ESC confirmed
+				// Signal next Read() to return empty (triggers readLoop standalone ESC logic)
+				b.returnEmptyNext = true
+				return data, nil
+			case <-stopCh:
+				return nil, nil
+			}
+		}
+		return data, nil
+	case <-stopCh:
+		return nil, nil
+	}
+}
+
+func (b *wasmBackend) SetResizeHandler(handler func(width, height int)) {
+	// Overwrite the resize callback to include the handler invocation
+	// This ensures the handler acts on the latest registration
+	resizeCb := js.FuncOf(func(_ js.Value, args []js.Value) any {
+		if len(args) >= 2 {
+			w, h := args[0].Int(), args[1].Int()
+			b.width, b.height = w, h
+			handler(w, h)
+		}
+		return nil
+	})
+	b.jsCallbacks = append(b.jsCallbacks, resizeCb)
+	js.Global().Set("goTerminalResize", resizeCb)
+}