Fix: Input handling for Windows to prevent first key loss

[Denish3436]

This PR solve issue #1167

[aymanbagabas]

Hi @Denish3436. Thank you for the PR. Could you please make sure you use LF line endings instead of CRLF?

[aymanbagabas]

LGTM, could you please fix the lint issues

[aymanbagabas]

@Denish3436 I've tried reproducing the bug with your example from #1167. The bug still happens even with this patch. However, using the v2-exp branch with the following patch seems to resolve the issue on v2. Still digging and trying to figure out why this happens on main.

diff --git a/cancelreader_windows.go b/cancelreader_windows.go
index 4aa5a75..a1a49c9 100644
--- a/cancelreader_windows.go
+++ b/cancelreader_windows.go
@@ -10,6 +10,7 @@ import (
 	"sync"
 	"time"
 
+	xwindows "github.com/charmbracelet/x/windows"
 	"github.com/muesli/cancelreader"
 	"golang.org/x/sys/windows"
 )
@@ -47,6 +48,10 @@ func newCancelreader(r io.Reader) (cancelreader.CancelReader, error) {
 		return fallback(r)
 	}
 
+	if err := xwindows.FlushConsoleInputBuffer(conin); err != nil {
+		return fallback(r)
+	}
+
 	originalMode, err := prepareConsole(conin,
 		windows.ENABLE_MOUSE_INPUT,
 		windows.ENABLE_WINDOW_INPUT,

The example i'm using

package main

import (
	"fmt"

	"github.com/charmbracelet/bubbles/v2/cursor"
	"github.com/charmbracelet/bubbles/v2/textinput"
	tea "github.com/charmbracelet/bubbletea/v2"
)

func Input(prompt, value string) {
	ti := textinput.New()
	ti.Prompt = prompt
	ti.Focus()
	p := tea.NewProgram(inputModel{textInput: ti})
	p.Run()
}

type inputModel struct {
	textInput textinput.Model
	quitting  bool
}

func (m inputModel) Init() (tea.Model, tea.Cmd) {
	return m, nil
}

func (m inputModel) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
	var cmd tea.Cmd

	switch msg := msg.(type) {
	case tea.KeyMsg:
		switch msg.String() {
		case "enter":
			m.textInput.Cursor.SetMode(cursor.CursorHide)
			m.quitting = true
			return m, tea.Quit
		}
	}
	m.textInput, cmd = m.textInput.Update(msg)
	return m, cmd
}

func (m inputModel) View() string {
	str := m.textInput.View()
	if m.quitting {
		return str + "\n"
	}
	return str
}

func main() {
	for i := 0; i < 2; i++ {
		Input(fmt.Sprintf("Test %d: ", i), "default")
	}
}

[aymanbagabas]

I've opened #1192 to fix this issue in v2.