implement live-reloading dev server

Squashed commit of the following:

commit 02f077432202af4d633eb2cad81dfdaa6921317f
Author: Alan Pearce <alan@alanpearce.eu>
Date:   Sat Apr 27 21:09:14 2024 +0200

    builder: only remove output directory if set and in dev mode

commit 47001e01c55fa6e74aafeda04ebc3e4e7c47eba0
Author: Alan Pearce <alan@alanpearce.eu>
Date:   Sat Apr 27 21:03:37 2024 +0200

    implement live reload on dev server

commit 411ec969f61e4b73439f1c54ea29f75135ecc618
Author: Alan Pearce <alan@alanpearce.eu>
Date:   Sat Apr 27 20:59:26 2024 +0200

    server: implement graceful shutdown

commit 5400132eb6eb1b638e0b3fd4265f51611c92d473
Author: Alan Pearce <alan@alanpearce.eu>
Date:   Sat Apr 27 20:41:07 2024 +0200

    add some debug logs

commit 3c9b678197c044603950232d222f501ef74d7873
Author: Alan Pearce <alan@alanpearce.eu>
Date:   Sat Apr 27 20:39:09 2024 +0200

    prefix log output with executable name

commit 300e24c179e390e9d3f5aeab4471c97f17f1fa64
Author: Alan Pearce <alan@alanpearce.eu>
Date:   Sat Apr 27 20:29:42 2024 +0200

    don't panic inside internal packages, return error instead

commit fe2715d330402ad67fe866471bed89c7238ad2ec
Author: Alan Pearce <alan@alanpearce.eu>
Date:   Fri Apr 26 01:18:29 2024 +0200

    config: use a table to configure CSP headers

commit d012553aaf78a436fa8871830b5d720a9e292d4b
Author: Alan Pearce <alan@alanpearce.eu>
Date:   Thu Apr 25 17:13:39 2024 +0200

    dev: create basic dev server to build and serve from a temporary directory

commit a1d11d3e69650d9b43ca1b1d7b7ccc05a808d5c1
Author: Alan Pearce <alan@alanpearce.eu>
Date:   Thu Apr 25 13:02:22 2024 +0200

    remove unused redirect_other_hostnames config option

commit fd67b19b5c7f76f0c3579e8a05ef20a618e90be7
Author: Alan Pearce <alan@alanpearce.eu>
Date:   Thu Apr 25 12:58:53 2024 +0200

    server: make port a string, which is what go uses

commit c798e8e736c0649008cade337158399470a9099b
Author: Alan Pearce <alan@alanpearce.eu>
Date:   Thu Apr 25 12:58:33 2024 +0200

    config: remove unused port variable

commit f94882b9001f3b0855e26b26b4a84b96e3deb22b
Author: Alan Pearce <alan@alanpearce.eu>
Date:   Thu Apr 25 12:49:10 2024 +0200

    re-organise module layout

1 files changed, 39 insertions, 11 deletions

diff --git a/cmd/server/main.go b/cmd/server/main.go
index b6817d8..bae215a 100644
--- a/cmd/server/main.go
+++ b/cmd/server/main.go
@@ -5,7 +5,10 @@ import (
 	"log"
 	"log/slog"
 	"os"
-	cfg "website/internal/config"
+	"os/signal"
+	"sync"
+
+	"website/internal/server"
 
 	"github.com/ardanlabs/conf/v3"
 	"github.com/pkg/errors"
@@ -16,20 +19,14 @@ var (
 	ShortSHA  string
 )
 
-type Config struct {
-	Production             bool    `conf:"default:false"`
-	ListenAddress          string  `conf:"default:localhost"`
-	Port                   uint16  `conf:"default:3000,short:p"`
-	BaseURL                cfg.URL `conf:"default:http://localhost:3000,short:b"`
-	RedirectOtherHostnames bool    `conf:"default:false"`
-}
-
 func main() {
 	if os.Getenv("DEBUG") != "" {
 		slog.SetLogLoggerLevel(slog.LevelDebug)
 	}
+	log.SetFlags(log.LstdFlags | log.Lmsgprefix)
+	log.SetPrefix("server: ")
 
-	runtimeConfig := Config{}
+	runtimeConfig := server.Config{}
 	help, err := conf.Parse("", &runtimeConfig)
 	if err != nil {
 		if errors.Is(err, conf.ErrHelpWanted) {
@@ -39,5 +36,36 @@ func main() {
 		log.Panicf("parsing runtime configuration: %v", err)
 	}
 
-	startServer(&runtimeConfig)
+	c := make(chan os.Signal, 2)
+	signal.Notify(c, os.Interrupt)
+	sv, err := server.New(&runtimeConfig)
+	if err != nil {
+		log.Fatalf("error setting up server: %v", err)
+	}
+	wg := &sync.WaitGroup{}
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		sig := <-c
+		log.Printf("signal captured: %v", sig)
+		<-sv.Stop()
+		slog.Debug("server stopped")
+	}()
+
+	sErr := make(chan error)
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		sErr <- sv.Start()
+	}()
+	if !runtimeConfig.InDevServer {
+		log.Printf("server listening on %s", sv.Addr)
+	}
+
+	err = <-sErr
+	if err != nil {
+		// Error starting or closing listener:
+		log.Fatalf("error: %v", err)
+	}
+	wg.Wait()
 }