Example for duplex communication b/w Model & Background Goroutine

examples/duplex/README.md

@@ -0,0 +1,20 @@
+# Duplex (Model ⇋ Background Goroutine)
+<img width="380" src="./duplex.gif" alt="Duplex illustration"/>
+
+## How It Works
+
+The system operates using two channels:
+
+1. **Background Goroutine → Message Channel → Model**
+2. **Background Goroutine ← Users Channel ← Model**
+
+### Key Components
+- **Model**:
+    - Listens on the `MessageChannel`.
+    - Sends updates to the `UsersChannel` when the selected user changes.
+
+- **messageHandlerService (Background Goroutine)**:
+    - Listens on the `UsersChannel`.
+    - Adjusts message filtering based on the user selected in the TUI model.
+
+This duplex communication ensures that as the selected user changes in the Model, the `MessageHandlerService` dynamically adjusts its behavior.

examples/duplex/main.go

@@ -0,0 +1,66 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	tea "github.com/charmbracelet/bubbletea"
+	"log"
+	"math"
+	"math/rand/v2"
+	"time"
+)
+
+func main() {
+
+	ctx, cancel := context.WithCancel(context.Background())
+
+	msgChan := make(chan message)
+	userChan := make(chan username)
+
+	go messageHandlerService(msgChan, userChan, ctx)
+	m := initialModel(msgChan, userChan, cancel)
+
+	if _, err := tea.NewProgram(m, tea.WithAltScreen()).Run(); err != nil {
+		log.Fatal(err)
+	}
+
+}
+
+type username string
+
+type message string
+
+var dummyUsers = [4]username{"meowgorithm", "muesli", "aymanbagabas", "bashbunni"}
+
+// messageHandlerService is a dummy service, in a real world scenario, it could be
+// - A background service that may read from a socket connection and write messages to messageChan
+// - A background service tht may store messages to SQLite and then pass them to messageChan
+func messageHandlerService(msgChan chan<- message, modelChan <-chan username, ctx context.Context) {
+	var userSelectedInModel username // the user for which we'll send messages to TUI
+	var i uint64
+	for i = 1; i <= math.MaxUint64; i++ {
+		select {
+		case <-ctx.Done():
+			close(msgChan)
+			return
+
+		// here the model tells which conversation(username) is selected in the TUI
+		case userSelectedInModel = <-modelChan:
+
+		case <-time.After(100 * time.Millisecond): // some delay, so our machine doesn't fly away
+			randIdx := rand.Uint32N(uint32(len(dummyUsers)))
+			randUsr := dummyUsers[randIdx]
+			dummyMsg := message(fmt.Sprintf("Message #%d, from %s", i, randUsr))
+			// save all to DB
+			saveToSQLite(dummyMsg, randUsr)
+			// send the filtered one to Model
+			if randUsr == userSelectedInModel {
+				msgChan <- dummyMsg
+			}
+		}
+	}
+}
+
+func saveToSQLite(msg message, u username) {
+	// save here
+}

examples/duplex/model.go

@@ -0,0 +1,157 @@
+package main
+
+import (
+	"context"
+	"github.com/charmbracelet/bubbles/viewport"
+	tea "github.com/charmbracelet/bubbletea"
+	"github.com/charmbracelet/lipgloss"
+	"strings"
+)
+
+var (
+	terminalHeight, terminalWidth int
+
+	baseStyle = lipgloss.NewStyle().Foreground(lipgloss.Color("#3FFF50"))
+
+	evenMsgStyle = baseStyle.Align(lipgloss.Center).Italic(true)
+	oddMsgStyle  = evenMsgStyle.Faint(true)
+
+	convoUsernameStyle           = baseStyle.Faint(true)
+	partialSelConvoUsernameStyle = convoUsernameStyle.Faint(false)
+	selConvoUsernameStyle        = partialSelConvoUsernameStyle.Underline(true).Italic(true)
+)
+
+type Model struct {
+	msgVP viewport.Model
+	// communication from messageHandlerService to Model
+	msgChan <-chan message
+	// communication from Model to messageHandlerService
+	usernameChan     chan<- username
+	murderMsgService context.CancelFunc
+	partialSelTabIdx int
+	selTabIdx        int
+	msgs             []message
+}
+
+func initialModel(msgC <-chan message, userC chan<- username, cFunc context.CancelFunc) Model {
+	vp := viewport.New(0, 0)
+	vp.Style = lipgloss.NewStyle().
+		Border(lipgloss.RoundedBorder(), false, false, true, false).
+		BorderForeground(lipgloss.Color("#808080")).
+		Align(lipgloss.Center)
+
+	return Model{
+		msgChan:          msgC,
+		usernameChan:     userC,
+		murderMsgService: cFunc,
+		partialSelTabIdx: -1,
+		selTabIdx:        -1,
+		msgVP:            vp,
+	}
+
+}
+
+func (m Model) Init() tea.Cmd {
+	return m.listenForMsgs()
+}
+
+func (m Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
+
+	switch msg := msg.(type) {
+
+	case tea.WindowSizeMsg:
+		terminalWidth = msg.Width
+		terminalHeight = msg.Height
+		m.updateMsgVPDimensions()
+
+	case tea.KeyMsg:
+		switch msg.String() {
+		case "ctrl+c":
+			m.murderMsgService()
+			close(m.usernameChan)
+			return m, tea.Quit
+
+		case "tab":
+			m.partialSelTabIdx = (m.partialSelTabIdx + 1) % len(dummyUsers) // move tab index between usernames
+
+		case "enter":
+			if m.partialSelTabIdx >= 0 {
+				m.selTabIdx = m.partialSelTabIdx
+				m.usernameChan <- dummyUsers[m.selTabIdx]
+			}
+
+		case "esc":
+			m.usernameChan <- "" // no username selected
+			m.selTabIdx = -1
+			m.partialSelTabIdx = -1
+		}
+
+	case message:
+		m.msgs = append(m.msgs, msg)
+		m.setMsgVPContent() // set the updated msg slice render
+		m.msgVP.LineDown(2)
+		return m, tea.Batch(m.listenForMsgs(), m.handleMsgVPUpdate(msg)) // continue listening
+	}
+
+	return m, m.handleMsgVPUpdate(msg)
+
+}
+
+func (m Model) View() string {
+	usrBtns := m.renderConvoUserBtns()
+	help := lipgloss.NewStyle().Faint(true).MarginTop(1).Render("[ TAB | ENTER | ESC | CTRL + C ]")
+	s := lipgloss.JoinVertical(lipgloss.Center, m.msgVP.View(), usrBtns, help)
+	return lipgloss.Place(terminalWidth, terminalHeight, lipgloss.Center, lipgloss.Center, s)
+}
+
+// Helpers & Stuff -----------------------------------------------------------------------------------------------------
+
+func (m *Model) updateMsgVPDimensions() {
+	s := strings.Join([]string{string(dummyUsers[0]), string(dummyUsers[1]), string(dummyUsers[2]), string(dummyUsers[3])}, "   ")
+	m.msgVP.Width = lipgloss.Width(s) + 4
+	m.msgVP.Height = terminalHeight - 10
+}
+
+func (m *Model) handleMsgVPUpdate(msg tea.Msg) tea.Cmd {
+	var cmd tea.Cmd
+	m.msgVP, cmd = m.msgVP.Update(msg)
+	return cmd
+}
+
+func (m *Model) setMsgVPContent() {
+	var sb strings.Builder
+	w := m.msgVP.Width - m.msgVP.Style.GetHorizontalFrameSize()
+	for i, msg := range m.msgs {
+		// using styles to create visual hierarchy
+		if i%2 == 0 {
+			sb.WriteString(evenMsgStyle.Width(w).Render(string(msg)))
+		} else {
+			sb.WriteString(oddMsgStyle.Width(w).Render(string(msg)))
+		}
+		sb.WriteString("\n")
+	}
+	m.msgVP.SetContent(sb.String())
+}
+
+func (m Model) renderConvoUserBtns() string {
+	var sb strings.Builder
+	for i, usrname := range dummyUsers {
+		style := convoUsernameStyle
+		if i == m.selTabIdx {
+			style = selConvoUsernameStyle
+		} else if i == m.partialSelTabIdx {
+			style = partialSelConvoUsernameStyle
+		}
+		sb.WriteString(style.Render(string(usrname)))
+		if i < len(dummyUsers)-1 { // username divider
+			sb.WriteString(lipgloss.NewStyle().Faint(true).Render(" ⇋ "))
+		}
+	}
+	return sb.String()
+}
+
+func (m Model) listenForMsgs() tea.Cmd {
+	return func() tea.Msg {
+		return <-m.msgChan
+	}
+}

tutorials/go.mod

@@ -6,9 +6,9 @@ require github.com/charmbracelet/bubbletea v0.25.0
 
 require (
 	github.com/aymanbagabas/go-osc52/v2 v2.0.1 // indirect
-	github.com/charmbracelet/lipgloss v0.13.1 // indirect
-	github.com/charmbracelet/x/ansi v0.4.0 // indirect
-	github.com/charmbracelet/x/term v0.2.0 // indirect
+	github.com/charmbracelet/lipgloss v1.0.0 // indirect
+	github.com/charmbracelet/x/ansi v0.4.5 // indirect
+	github.com/charmbracelet/x/term v0.2.1 // indirect
 	github.com/erikgeiser/coninput v0.0.0-20211004153227-1c3628e74d0f // indirect
 	github.com/lucasb-eyer/go-colorful v1.2.0 // indirect
 	github.com/mattn/go-isatty v0.0.20 // indirect
@@ -18,8 +18,8 @@ require (
 	github.com/muesli/cancelreader v0.2.2 // indirect
 	github.com/muesli/termenv v0.15.2 // indirect
 	github.com/rivo/uniseg v0.4.7 // indirect
-	golang.org/x/sync v0.8.0 // indirect
-	golang.org/x/sys v0.26.0 // indirect
+	golang.org/x/sync v0.9.0 // indirect
+	golang.org/x/sys v0.27.0 // indirect
 	golang.org/x/text v0.13.0 // indirect
 )
 

tutorials/go.sum

@@ -2,10 +2,13 @@ github.com/aymanbagabas/go-osc52/v2 v2.0.1 h1:HwpRHbFMcZLEVr42D4p7XBqjyuxQH5SMiE
 github.com/aymanbagabas/go-osc52/v2 v2.0.1/go.mod h1:uYgXzlJ7ZpABp8OJ+exZzJJhRNQ2ASbcXHWsFqH8hp8=
 github.com/charmbracelet/lipgloss v0.13.1 h1:Oik/oqDTMVA01GetT4JdEC033dNzWoQHdWnHnQmXE2A=
 github.com/charmbracelet/lipgloss v0.13.1/go.mod h1:zaYVJ2xKSKEnTEEbX6uAHabh2d975RJ+0yfkFpRBz5U=
+github.com/charmbracelet/lipgloss v1.0.0/go.mod h1:U5fy9Z+C38obMs+T+tJqst9VGzlOYGj4ri9reL3qUlo=
 github.com/charmbracelet/x/ansi v0.4.0 h1:NqwHA4B23VwsDn4H3VcNX1W1tOmgnvY1NDx5tOXdnOU=
 github.com/charmbracelet/x/ansi v0.4.0/go.mod h1:dk73KoMTT5AX5BsX0KrqhsTqAnhZZoCBjs7dGWp4Ktw=
+github.com/charmbracelet/x/ansi v0.4.5/go.mod h1:dk73KoMTT5AX5BsX0KrqhsTqAnhZZoCBjs7dGWp4Ktw=
 github.com/charmbracelet/x/term v0.2.0 h1:cNB9Ot9q8I711MyZ7myUR5HFWL/lc3OpU8jZ4hwm0x0=
 github.com/charmbracelet/x/term v0.2.0/go.mod h1:GVxgxAbjUrmpvIINHIQnJJKpMlHiZ4cktEQCN6GWyF0=
+github.com/charmbracelet/x/term v0.2.1/go.mod h1:oQ4enTYFV7QN4m0i9mzHrViD7TQKvNEEkHUMCmsxdUg=
 github.com/erikgeiser/coninput v0.0.0-20211004153227-1c3628e74d0f h1:Y/CXytFA4m6baUTXGLOoWe4PQhGxaX0KpnayAqC48p4=
 github.com/erikgeiser/coninput v0.0.0-20211004153227-1c3628e74d0f/go.mod h1:vw97MGsxSvLiUE2X8qFplwetxpGLQrlU1Q9AUEIzCaM=
 github.com/lucasb-eyer/go-colorful v1.2.0 h1:1nnpGOrhyZZuNyfu1QjKiUICQ74+3FNCN69Aj6K7nkY=
@@ -27,9 +30,11 @@ github.com/rivo/uniseg v0.4.7 h1:WUdvkW8uEhrYfLC4ZzdpI2ztxP1I582+49Oc5Mq64VQ=
 github.com/rivo/uniseg v0.4.7/go.mod h1:FN3SvrM+Zdj16jyLfmOkMNblXMcoc8DfTHruCPUcx88=
 golang.org/x/sync v0.8.0 h1:3NFvSEYkUoMifnESzZl15y791HH1qU2xm6eCJU5ZPXQ=
 golang.org/x/sync v0.8.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk=
+golang.org/x/sync v0.9.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk=
 golang.org/x/sys v0.0.0-20210809222454-d867a43fc93e/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.26.0 h1:KHjCJyddX0LoSTb3J+vWpupP9p0oznkqVk/IfjymZbo=
 golang.org/x/sys v0.26.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+golang.org/x/sys v0.27.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/text v0.13.0 h1:ablQoSUd0tRdKxZewP80B+BaqeKJuVhuRxj/dkrun3k=
 golang.org/x/text v0.13.0/go.mod h1:TvPlkZtksWOMsz7fbANvkp4WM8x/WCo/om8BMLbz+aE=