feat: add devmode flag; introduce live reload support; update examples

.gitignore

@@ -30,3 +30,6 @@ go.work.sum
 # Editor/IDE
 # .idea/
 # .vscode/
+
+# Via related
+.via

configuration.go

@@ -9,10 +9,17 @@ const (
 	LogLevelDebug
 )
 
+// Plugin is a func that can mutate the given *via.V app runtime. It is useful to integrate popular JS/CSS UI libraries or tools.
 type Plugin func(v *V)
 
 // Config defines configuration options for the via application
 type Options struct {
+	// The development mode flag. If true, enables server and browser auto-reload on `.go` file changes.
+	DevMode bool
+
+	// The http server address. e.g. ':3000'
+	ServerAddress string
+
 	// Level of the logs to write to stdout.
 	// Options: Error, Warn, Info, Debug.
 	LogLvl LogLevel

context.go

@@ -6,7 +6,6 @@ import (
 	"log"
 	"reflect"
 	"sync"
-	"time"
 
 	"github.com/go-via/via/h"
 	"github.com/starfederation/datastar-go/datastar"
@@ -25,7 +24,6 @@ type Context struct {
 	actionRegistry    map[string]func()
 	signals           map[string]*signal
 	signalsMux        sync.Mutex
-	createdAt         time.Time
 }
 
 // View defines the UI rendered by this context.
@@ -116,14 +114,6 @@ func (c *Context) getActionFn(id string) (func(), error) {
 	return nil, fmt.Errorf("action '%s' not found", id)
 }
 
-func (c *Context) Signals() map[string]*signal {
-	if c.signals == nil {
-		c.app.logErr(c, "failed to get signal: nil signals in ctx")
-		return make(map[string]*signal)
-	}
-	return c.signals
-}
-
 // Signal creates a reactive signal and initializes it with the given value.
 // Use Bind() to link the value of input elements to the signal and Text() to
 // display the signal value and watch the UI update live as the input changes.
@@ -179,6 +169,11 @@ func (c *Context) injectSignals(sigs map[string]any) {
 	}
 	for k, v := range sigs {
 		if _, ok := c.signals[k]; !ok {
+			c.signals[k] = &signal{
+				id: k,
+				t:  reflect.TypeOf(v),
+				v:  reflect.ValueOf(v),
+			}
 			continue
 		}
 		c.signals[k].v = reflect.ValueOf(v)
@@ -313,6 +308,5 @@ func newContext(id string, a *V) *Context {
 		componentRegistry: make(map[string]*Context),
 		actionRegistry:    make(map[string]func()),
 		signals:           make(map[string]*signal),
-		createdAt:         time.Now(),
 	}
 }

go.mod

@@ -9,6 +9,8 @@ require github.com/starfederation/datastar-go v1.0.3
 require (
 	github.com/CAFxX/httpcompression v0.0.9 // indirect
 	github.com/andybalholm/brotli v1.2.0 // indirect
+	github.com/fsnotify/fsnotify v1.9.0 // indirect
 	github.com/klauspost/compress v1.18.0 // indirect
 	github.com/valyala/bytebufferpool v1.0.0 // indirect
+	golang.org/x/sys v0.13.0 // indirect
 )

go.sum

@@ -6,6 +6,8 @@ github.com/andybalholm/brotli v1.2.0/go.mod h1:rzTDkvFWvIrjDXZHkuS16NPggd91W3kUS
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/fsnotify/fsnotify v1.9.0 h1:2Ml+OJNzbYCTzsxtv8vKSFD9PbJjmhYF14k/jKC7S9k=
+github.com/fsnotify/fsnotify v1.9.0/go.mod h1:8jBTzvmWwFyi3Pb8djgCCO5IBqzKJ/Jwo8TRcHyHii0=
 github.com/google/brotli/go/cbrotli v0.0.0-20230829110029-ed738e842d2f h1:jopqB+UTSdJGEJT8tEqYyE29zN91fi2827oLET8tl7k=
 github.com/google/brotli/go/cbrotli v0.0.0-20230829110029-ed738e842d2f/go.mod h1:nOPhAkwVliJdNTkj3gXpljmWhjc4wCaVqbMJcPKWP4s=
 github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
@@ -35,6 +37,8 @@ github.com/valyala/gozstd v1.20.1 h1:xPnnnvjmaDDitMFfDxmQ4vpx0+3CdTg2o3lALvXTU/g
 github.com/valyala/gozstd v1.20.1/go.mod h1:y5Ew47GLlP37EkTB+B4s7r6A5rdaeB7ftbl9zoYiIPQ=
 github.com/xyproto/randomstring v1.0.5 h1:YtlWPoRdgMu3NZtP45drfy1GKoojuR7hmRcnhZqKjWU=
 github.com/xyproto/randomstring v1.0.5/go.mod h1:rgmS5DeNXLivK7YprL0pY+lTuhNQW3iGxZ18UQApw/E=
+golang.org/x/sys v0.13.0 h1:Af8nKPmuFypiUBjVoU9V20FiaFXOcuZI21p0ycVYYGE=
+golang.org/x/sys v0.13.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=

internal/examples/counter/main.go

@@ -33,5 +33,5 @@ func main() {
 		})
 	})
 
-	v.Start(":3000")
+	v.Start()
 }

internal/examples/countercomp/main.go

@@ -22,7 +22,7 @@ func main() {
 		})
 	})
 
-	v.Start(":3000")
+	v.Start()
 }
 
 func counterCompFn(c *via.Context) {

internal/examples/greeter/main.go

@@ -30,5 +30,5 @@ func main() {
 		})
 	})
 
-	v.Start(":3000")
+	v.Start()
 }

internal/examples/livereload/livereload.go

@@ -1,54 +0,0 @@
-package main
-
-import (
-	"net/http"
-
-	"github.com/go-via/via"
-	"github.com/go-via/via/h"
-)
-
-func LiveReloadPlugin(v *via.V) {
-	v.HandleFunc("GET /dev/reload", func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Content-Type", "text/event-stream")
-		w.Header().Set("Cache-Control", "no-cache")
-		w.Header().Set("Connection", "keep-alive")
-		w.Header().Set("Access-Control-Allow-Origin", "*")
-
-		<-r.Context().Done()
-	})
-	v.AppendToFoot(h.Script(h.Raw(`
-		if (window.location.hostname === 'localhost' || window.location.hostname === '127.0.0.1') {
-			const evtSource = new EventSource('/dev/reload');
-			let overlay = null;
-			let showTimer = null;
-			
-			evtSource.onerror = () => {
-				evtSource.close();
-				
-				showTimer = setTimeout(() => {
-					if (!overlay) {
-						overlay = document.createElement('div');
-						overlay.style.cssText = 'position: fixed; top: 50%; left: 50%; transform: translate(-50%, -50%); background: rgba(200, 200, 200, 0.95); padding: 20px 40px; border-radius: 8px; color: #333; font-size: 24px; z-index: 999999; font-family: -apple-system, sans-serif;';
-						overlay.textContent = '🔌 Reconnecting...';
-						document.body.appendChild(overlay);
-					}
-				}, 1000);
-				
-				(async function poll() {
-					for (let i = 0; i < 100; i++) {
-						try {
-							const res = await fetch('/', { method: 'HEAD', signal: AbortSignal.timeout(1000) });
-							if (res.ok) {
-								clearTimeout(showTimer);
-								if (overlay) overlay.remove();
-								location.reload();
-								return;
-							}
-						} catch (e) {}
-						await new Promise(r => setTimeout(r, 50));
-					}
-				})();
-			};
-		}
-`)))
-}

internal/examples/livereload/main.go

@@ -12,7 +12,8 @@ func main() {
 
 	v.Config(via.Options{
 		DocumentTitle: "Live Reload",
-		Plugins:       []via.Plugin{LiveReloadPlugin},
+		DevMode:       true,
+		LogLvl:        via.LogLevelDebug,
 	})
 
 	v.Page("/", func(c *via.Context) {
@@ -26,7 +27,7 @@ func main() {
 
 		c.View(func() h.H {
 			return h.Div(
-				h.H1(h.Text("Live Reload")),
+				h.H1(h.Text("Live Reload with Via DevMode !!!")),
 				h.P(h.Textf("Count: %d", data.Count)),
 				h.P(h.Span(h.Text("Step: ")), h.Span(step.Text())),
 				h.Label(
@@ -38,5 +39,5 @@ func main() {
 		})
 	})
 
-	v.Start(":3000")
+	v.Start()
 }

internal/examples/picocss/main.go

@@ -26,5 +26,5 @@ func main() {
 			)
 		})
 	})
-	v.Start(":3000")
+	v.Start()
 }

internal/examples/plugins/main.go

@@ -33,7 +33,7 @@ func main() {
 			)
 		})
 	})
-	v.Start(":3000")
+	v.Start()
 }
 
 func PicoCSSPlugin(v *via.V) {

internal/examples/realtimechart/main.go

@@ -28,7 +28,7 @@ func main() {
 		})
 	})
 
-	v.Start(":3000")
+	v.Start()
 }
 
 func chartCompFn(c *via.Context) {

via.go

@@ -9,9 +9,13 @@ import (
 	"crypto/rand"
 	_ "embed"
 	"encoding/hex"
+	"encoding/json"
 	"fmt"
 	"log"
 	"net/http"
+	"os"
+	"path"
+	"path/filepath"
 	"strings"
 	"sync"
 
@@ -25,12 +29,14 @@ var datastarJS []byte
 // V is the root application.
 // It manages page routing, user sessions, and SSE connections for live updates.
 type V struct {
-	cfg                  Options
-	mux                  *http.ServeMux
-	contextRegistry      map[string]*Context
-	contextRegistryMutex sync.RWMutex
-	documentHeadIncludes []h.H
-	documentFootIncludes []h.H
+	cfg                       Options
+	mux                       *http.ServeMux
+	contextRegistry           map[string]*Context
+	contextRegistryMutex      sync.RWMutex
+	documentHeadIncludes      []h.H
+	documentFootIncludes      []h.H
+	devModePageInitFnMap      map[string]func(*Context)
+	devModePageInitFnMapMutex sync.Mutex
 }
 
 func (v *V) logErr(c *Context, format string, a ...any) {
@@ -46,7 +52,7 @@ func (v *V) logWarn(c *Context, format string, a ...any) {
 	if c != nil && c.id != "" {
 		cRef = fmt.Sprintf("via-ctx=%q ", c.id)
 	}
-	if v.cfg.LogLvl <= LogLevelWarn {
+	if v.cfg.LogLvl >= LogLevelWarn {
 		log.Printf("[warn] %smsg=%q", cRef, fmt.Sprintf(format, a...))
 	}
 }
@@ -56,7 +62,7 @@ func (v *V) logInfo(c *Context, format string, a ...any) {
 	if c != nil && c.id != "" {
 		cRef = fmt.Sprintf("via-ctx=%q ", c.id)
 	}
-	if v.cfg.LogLvl <= LogLevelInfo {
+	if v.cfg.LogLvl >= LogLevelInfo {
 		log.Printf("[info] %smsg=%q", cRef, fmt.Sprintf(format, a...))
 	}
 }
@@ -86,6 +92,12 @@ func (v *V) Config(cfg Options) {
 			}
 		}
 	}
+	if cfg.DevMode != v.cfg.DevMode {
+		v.cfg.DevMode = cfg.DevMode
+	}
+	if cfg.ServerAddress != "" {
+		v.cfg.ServerAddress = cfg.ServerAddress
+	}
 }
 
 // AppendToHead appends the given h.H nodes to the head of the base HTML document.
@@ -106,7 +118,6 @@ func (v *V) AppendToFoot(elements ...h.H) {
 			v.documentFootIncludes = append(v.documentFootIncludes, el)
 		}
 	}
-
 }
 
 // Page registers a route and its associated page handler.
@@ -119,7 +130,12 @@ func (v *V) AppendToFoot(elements ...h.H) {
 //			return h.H1(h.Text("Hello, Via!"))
 //		})
 //	})
-func (v *V) Page(route string, composeContext func(c *Context)) {
+func (v *V) Page(route string, initContextFn func(c *Context)) {
+	if v.cfg.DevMode {
+		v.devModePageInitFnMapMutex.Lock()
+		defer v.devModePageInitFnMapMutex.Unlock()
+		v.devModePageInitFnMap[route] = initContextFn
+	}
 	v.mux.HandleFunc("GET "+route, http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		if strings.Contains(r.URL.Path, "favicon") {
 			return
@@ -127,7 +143,7 @@ func (v *V) Page(route string, composeContext func(c *Context)) {
 		id := fmt.Sprintf("%s_/%s", route, genRandID())
 		c := newContext(id, v)
 		v.logDebug(c, "GET %s", route)
-		composeContext(c)
+		initContextFn(c)
 		v.registerCtx(c.id, c)
 		headElements := v.documentHeadIncludes
 		headElements = append(headElements, h.Meta(h.Data("signals", fmt.Sprintf("{'via-ctx':'%s'}", id))))
@@ -146,6 +162,10 @@ func (v *V) Page(route string, composeContext func(c *Context)) {
 func (v *V) registerCtx(id string, c *Context) {
 	v.contextRegistryMutex.Lock()
 	defer v.contextRegistryMutex.Unlock()
+	if c == nil {
+		v.logErr(c, "failed to add nil context to registry")
+		return
+	}
 	v.contextRegistry[id] = c
 	v.logDebug(c, "new context added to registry")
 }
@@ -174,83 +194,158 @@ func (v *V) HandleFunc(pattern string, f http.HandlerFunc) {
 }
 
 // Start starts the Via HTTP server on the given address.
-func (v *V) Start(addr string) {
-	v.logInfo(nil, "via started")
-	log.Fatalf("via failed: %v", http.ListenAndServe(addr, v.mux))
+func (v *V) Start() {
+	v.logInfo(nil, "via started on address: %s", v.cfg.ServerAddress)
+	log.Fatalf("[fatal] %v", http.ListenAndServe(v.cfg.ServerAddress, v.mux))
+}
+
+func (v *V) persistCtx(c *Context) error {
+	idsplit := strings.Split(c.id, "_")
+	if len(idsplit) < 2 {
+		return fmt.Errorf("failed to identify ctx page route")
+	}
+	route := idsplit[0]
+	ctxmap := map[string]any{"id": c.id, "route": route}
+
+	p := path.Join(".via", "devmode", "ctx.json")
+	if err := os.MkdirAll(filepath.Dir(p), 0755); err != nil {
+		return fmt.Errorf("failed to create directory for devmode files: %v", err)
+	}
+
+	file, err := os.Create(p)
+	if err != nil {
+		return fmt.Errorf("failed to create file in devmode directory: %v", err)
+	}
+	defer file.Close()
+
+	encoder := json.NewEncoder(file)
+	if err := encoder.Encode(ctxmap); err != nil {
+		return fmt.Errorf("failed to encode ctx: %s", err)
+	}
+	return nil
+}
+
+func (v *V) restoreCtx() *Context {
+	p := path.Join(".via", "devmode", "ctx.json")
+	file, err := os.Open(p)
+	if err != nil {
+		fmt.Println("Error opening file:", err)
+		return nil
+	}
+	defer file.Close()
+	var ctxmap map[string]any
+	if err := json.NewDecoder(file).Decode(&ctxmap); err != nil {
+		fmt.Println("Error restoring ctx:", err)
+		return nil
+	}
+	ctxId, ok := ctxmap["id"].(string)
+	if !ok {
+		fmt.Println("Error restoring ctx")
+		return nil
+	}
+	pageRoute, ok := ctxmap["route"].(string)
+	if !ok {
+		fmt.Println("Error restoring ctx")
+		return nil
+	}
+	pageInitFn, ok := v.devModePageInitFnMap[pageRoute]
+	if !ok {
+		fmt.Println("devmode failed to restore ctx: ")
+		return nil
+	}
+
+	c := newContext(ctxId, v)
+	pageInitFn(c)
+	return c
 }
 
 // New creates a new Via application with default configuration.
 func New() *V {
 	mux := http.NewServeMux()
-	app := &V{
-		mux:             mux,
-		contextRegistry: make(map[string]*Context),
+	v := &V{
+		mux:                  mux,
+		contextRegistry:      make(map[string]*Context),
+		devModePageInitFnMap: make(map[string]func(*Context)),
 		cfg: Options{
-			LogLvl:        LogLevelDebug,
-			DocumentTitle: "Via Application",
+			DevMode:       false,
+			ServerAddress: ":3000",
+			LogLvl:        LogLevelInfo,
+			DocumentTitle: "⚡ Via",
 		},
 	}
 
-	app.mux.HandleFunc("GET /_datastar.js", func(w http.ResponseWriter, r *http.Request) {
+	v.mux.HandleFunc("GET /_datastar.js", func(w http.ResponseWriter, r *http.Request) {
 		w.Header().Set("Content-Type", "application/javascript")
 		_, _ = w.Write(datastarJS)
 	})
 
-	app.mux.HandleFunc("GET /_sse", func(w http.ResponseWriter, r *http.Request) {
+	v.mux.HandleFunc("GET /_sse", func(w http.ResponseWriter, r *http.Request) {
 		var sigs map[string]any
 		_ = datastar.ReadSignals(r, &sigs)
+		if v.cfg.DevMode && len(v.contextRegistry) == 0 {
+			restoredC := v.restoreCtx()
+			if restoredC != nil {
+				restoredC.injectSignals(sigs)
+				v.registerCtx(restoredC.id, restoredC)
+			}
+		}
 		cID, _ := sigs["via-ctx"].(string)
-		c, err := app.getCtx(cID)
+		c, err := v.getCtx(cID)
 		if err != nil {
-			app.logErr(nil, "failed to render page: %v", err)
+			v.logErr(nil, "failed to render page: %v", err)
 			return
 		}
 		c.sse = datastar.NewSSE(w, r)
-		app.logDebug(c, "SSE connection established")
-		c.SyncSignals()
+		v.logDebug(c, "SSE connection established")
+		if v.cfg.DevMode {
+			c.Sync()
+			v.persistCtx(c)
+		} else {
+			c.SyncSignals()
+		}
 		<-c.sse.Context().Done()
 		c.sse = nil
-		app.logDebug(c, "SSE connection closed")
+		v.logDebug(c, "SSE connection closed")
 	})
-	app.mux.HandleFunc("GET /_action/{id}", func(w http.ResponseWriter, r *http.Request) {
+	v.mux.HandleFunc("GET /_action/{id}", func(w http.ResponseWriter, r *http.Request) {
 		actionID := r.PathValue("id")
 		var sigs map[string]any
 		_ = datastar.ReadSignals(r, &sigs)
 		cID, _ := sigs["via-ctx"].(string)
 		active_ctx_count := 0
 		inactive_ctx_count := 0
-		for _, c := range app.contextRegistry {
+		for _, c := range v.contextRegistry {
 			if c.sse != nil {
 				active_ctx_count++
 				continue
 			}
 			inactive_ctx_count++
 		}
-		app.logDebug(nil, "active_ctx_count=%d inactive_ctx_count=%d", active_ctx_count, inactive_ctx_count)
-		c, err := app.getCtx(cID)
+		v.logDebug(nil, "active_ctx_count=%d inactive_ctx_count=%d", active_ctx_count, inactive_ctx_count)
+		c, err := v.getCtx(cID)
 		if err != nil {
-			app.logErr(nil, "action '%s' failed: %v", actionID, err)
+			v.logErr(nil, "action '%s' failed: %v", actionID, err)
 			return
 		}
 		actionFn, err := c.getActionFn(actionID)
 		if err != nil {
-			app.logDebug(c, "action '%s' failed: %v", actionID, err)
+			v.logDebug(c, "action '%s' failed: %v", actionID, err)
 			return
 		}
 		// log err if actionFn panics
 		defer func() {
 			if r := recover(); r != nil {
-				app.logErr(c, "action '%s' failed: %v", actionID, r)
+				v.logErr(c, "action '%s' failed: %v", actionID, r)
 			}
 		}()
 		c.signalsMux.Lock()
 		defer c.signalsMux.Unlock()
-		app.logDebug(c, "signals=%v", sigs)
+		v.logDebug(c, "signals=%v", sigs)
 		c.injectSignals(sigs)
 		actionFn()
 
 	})
-	return app
+	return v
 }
 
 func genRandID() string {