From 831b10b09bca8a46c3e16441be81cdc6952ce099 Mon Sep 17 00:00:00 2001
From: Adam Mathes <adam@trenchant.org>
Date: Sun, 17 Dec 2017 19:21:00 -0800
Subject: add filesystem watcher

---
 main.go | 76 +++++++++++++++++++++++++++++++++++++++++++++++++++--------------
 1 file changed, 60 insertions(+), 16 deletions(-)

diff --git a/main.go b/main.go
index 5536742..97aad6f 100644
--- a/main.go
+++ b/main.go
@@ -10,23 +10,25 @@ import (
 	"adammathes.com/snkt/vlog"
 	"adammathes.com/snkt/web"
 	"fmt"
+	"github.com/fsnotify/fsnotify"
 	flag "github.com/ogier/pflag"
 )
 
 func main() {
 
 	var configFile, init_dir string
-	var build, preview, version, verbose, help bool
+	var build, preview, version, verbose, help, watch bool
 
 	flag.StringVarP(&configFile, "config", "c", "config.yml", "`configuration` file")
 	flag.StringVarP(&init_dir, "init", "i", "", "initialize new site at `directory`")
-	flag.BoolVarP(&build, "build", "b", false, "build site")
-	flag.BoolVarP(&preview, "preview", "p", false, "preview site with local HTTP server")
-	flag.BoolVarP(&help, "help", "h", false, "print help message")
-	flag.BoolVarP(&verbose, "verbose", "v", false, "log actions during build to STDOUT")
+	flag.BoolVarP(&build, "build", "b", false, "generates site from input files and templates")
+	flag.BoolVarP(&preview, "preview", "p", false, "preview site via spawned HTTP server")
+	flag.BoolVarP(&help, "help", "h", false, "print usage information")
+	flag.BoolVarP(&verbose, "verbose", "v", false, "log operations during build to STDOUT")
+	flag.BoolVarP(&watch, "watch", "w", false, "watch configured input text dir, rebuild on changes")
 	flag.Parse()
 
-	if !help && !build && !preview && !version && init_dir == "" {
+	if !watch && !help && !build && !preview && !version && init_dir == "" {
 		flag.Usage()
 		return
 	}
@@ -36,26 +38,68 @@ func main() {
 		return
 	}
 	if help {
-		fmt.Printf("please see README.md\n")
+		flag.Usage()
+		fmt.Printf("code and docs: https://github.com/adammathes/snkt \n")
 		return
 	}
+
 	config.Init(configFile)
 	if verbose {
 		config.Config.Verbose = true
 	}
-
 	render.Init()
+
 	if build {
-		var s site.Site
-		vlog.Printf("reading posts...\n")
-		s.Read()
-		vlog.Printf("writing posts and archives...\n")
-		s.Write()
+		buildSite()
 	}
 
 	if preview {
-		fmt.Printf("spawning preview at [%s] of [%s]\n",
-			config.Config.PreviewDir, config.Config.PreviewServer)
-		web.Serve(config.Config.PreviewServer, config.Config.PreviewDir)
+		fmt.Printf("spawning preview server [%s] of [%s]\n",
+			config.Config.PreviewServer, config.Config.PreviewDir)
+		go func() {
+			web.Serve(config.Config.PreviewServer, config.Config.PreviewDir)
+		}()
+	}
+
+	if watch {
+		fmt.Printf("watching directory %s\n", config.Config.TxtDir)
+		watchSite()
+	}
+}
+
+func buildSite() {
+	var s site.Site
+	vlog.Printf("reading posts...\n")
+	s.Read()
+	vlog.Printf("writing posts and archives...\n")
+	s.Write()
+}
+
+func watchSite() {
+	watcher, err := fsnotify.NewWatcher()
+	if err != nil {
+		panic(err)
+	}
+	defer watcher.Close()
+
+	done := make(chan bool)
+	go func() {
+		for {
+			select {
+			case event := <-watcher.Events:
+				if event.Op&fsnotify.Write == fsnotify.Write {
+					fmt.Printf("rebuilding\n")
+					buildSite()
+				}
+			case err := <-watcher.Errors:
+				vlog.Printf("error: %v", err)
+			}
+		}
+	}()
+
+	err = watcher.Add(config.Config.TxtDir)
+	if err != nil {
+		panic(err)
 	}
+	<-done
 }
-- 
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