Add HTTP example demonstrating I/O

examples/http/main.go

@@ -0,0 +1,85 @@
+package main
+
+// A simple program that counts down from 5 and then exits.
+
+import (
+	"errors"
+	"fmt"
+	"log"
+	"net/http"
+	"time"
+
+	"github.com/charmbracelet/tea"
+)
+
+const url = "https://charm.sh/"
+
+type Model struct {
+	Status int
+	Error  error
+}
+
+type statusMsg int
+
+func main() {
+	p := tea.NewProgram(initialize, update, view, nil)
+	if err := p.Start(); err != nil {
+		log.Fatal(err)
+	}
+}
+
+func initialize() (tea.Model, tea.Cmd) {
+	return Model{0, nil}, checkServer
+}
+
+func update(msg tea.Msg, model tea.Model) (tea.Model, tea.Cmd) {
+	m, _ := model.(Model)
+
+	switch msg := msg.(type) {
+
+	case tea.KeyMsg:
+		switch msg.String() {
+		case "esc":
+			fallthrough
+		case "break":
+			fallthrough
+		case "q":
+			return m, tea.Quit
+		default:
+			return m, nil
+		}
+
+	case statusMsg:
+		m.Status = int(msg)
+		return m, tea.Quit
+
+	case tea.ErrMsg:
+		// TODO: get the error out of tea.ErrMsg less hackily
+		m.Error = errors.New(msg.Error())
+		return m, nil
+
+	default:
+		return m, nil
+	}
+}
+
+func view(model tea.Model) string {
+	m, _ := model.(Model)
+	if m.Error != nil {
+		return fmt.Sprintf("Something went wrong: %s", m.Error)
+	} else if m.Status == 0 {
+		return fmt.Sprintf("Checking %s...", url)
+	}
+	return fmt.Sprintf("The server said: %d %s", m.Status, http.StatusText(m.Status))
+}
+
+func checkServer() tea.Msg {
+	c := &http.Client{
+		Timeout: 10 * time.Second,
+	}
+	res, err := c.Get(url)
+	if err != nil {
+		return tea.NewErrMsg(err.Error())
+	}
+	return statusMsg(res.StatusCode)
+}