Actually make use of ApplicationURLOpener

Progress on #4

application.go

@@ -1,10 +1,13 @@
 package nasin
 
+import "fmt"
 import "log"
+import "flag"
 import "image"
 import "strings"
 import "net/url"
 import "git.tebibyte.media/tomo/tomo"
+import "git.tebibyte.media/tomo/objects"
 import "git.tebibyte.media/tomo/tomo/canvas"
 import "git.tebibyte.media/tomo/nasin/internal/registrar"
 
@@ -23,12 +26,27 @@ type ApplicationURLOpener interface {
 
 	// OpenURL opens a new window with the contents of the given URL. If the
 	// given URL is unsupported, it returns an error (for example, an image
-	// viewer is not expected to open a text file). If the URL scheme is
-	// empty, file:// is assumed.
+	// viewer is not expected to open a text file).
 	//
 	// Applications should support the file:// scheme at the very least, and
 	// should also support others like http:// and https:// if possible.
 	OpenURL (*url.URL) error
+
+	// OpenNone is called when the application is launched without any URLs
+	// to open. The application may create some sort of default starting
+	// window, or call tomo.Stop().
+	OpenNone ()
+}
+
+// ApplicationFlagAdder is an application that supports reading command line
+// flags.
+type ApplicationFlagAdder interface {
+	Application
+
+	// AddFlags is called before Init and given the default flag set that
+	// Nasin uses to parse command line arguments. Note that when this
+	// method is called, Tomo will not yet be initialized.
+	AddFlags (*flag.FlagSet)
 }
 
 // ApplicationDescription describes the name and type of an application.
@@ -105,15 +123,26 @@ func (role ApplicationRole) Icon () tomo.Icon {
 // RunApplication is like tomo.Run, but runs an application. If something fails
 // to initialize, an error is written to the standard logger.
 func RunApplication (application Application) {
+	// TODO: see #4
+
+	if application, ok := application.(ApplicationFlagAdder); ok {
+		application.AddFlags(flag.CommandLine)
+	}
+	flag.Parse()
+
 	err := registrar.RegisterBackend()
-	if err != nil { log.Fatal("nasin: could not register backend:", err) }
+	if err != nil { log.Fatalln("nasin: could not register backend:", err) }
 	err = tomo.Run(func () {
 		err := registrar.SetTheme()
-		if err != nil { log.Fatal("nasin: could not set theme:", err) }
+		if err != nil { log.Fatalln("nasin: could not set theme:", err) }
 		err = application.Init()
-		if err != nil { log.Fatal("nasin: could not run application:", err) }
+		if err != nil { log.Fatalln("nasin: could not run application:", err) }
+
+		// open URLs
+		args := flag.Args()
+		applicationOpenUrls(application, args...)
 	})
-	if err != nil { log.Fatal("nasin: could not run application:", err) }
+	if err != nil { log.Fatalln("nasin: could not run application:", err) }
 }
 
 // NewApplicationWindow creates a window for an application. It will
@@ -126,10 +155,50 @@ func NewApplicationWindow (application Application, bounds image.Rectangle) (tom
 	if err != nil { return nil, err }
 	description := application.Describe()
 	window.SetTitle(description.Name)
+
 	setApplicationWindowIcon(window, description)
 	return window, nil
 }
 
+func applicationOpenUrls (application Application, args ...string) {
+	if application, ok := application.(ApplicationURLOpener); ok {
+		if len(args) <= 0 {
+			application.OpenNone()
+		}
+
+		openedAny := false
+		for _, arg := range flag.Args() {
+			ur, err := url.Parse(arg)
+			if err != nil {
+				log.Fatalf (
+					"nasin: invalid URL %v: %v",
+					arg, err)
+			}
+			if ur.Scheme == "" {
+				ur.Scheme = "file"
+			}
+			err = application.OpenURL(ur)
+			if err != nil {
+				dialog, err := objects.NewDialogOk (
+					objects.DialogError, nil,
+					"Could Not Open URL",
+					fmt.Sprintf (
+						"Could not open %v: %v",
+						arg, err),
+					func () {
+						if !openedAny {
+							application.OpenNone()
+						}
+					})
+				if err != nil { log.Fatal(err) }
+				dialog.SetVisible(true)
+			}
+		}
+	} else {
+		log.Fatal("nasin: this application cannot open URLs")
+	}
+}
+
 func setApplicationWindowIcon (window tomo.Window, description ApplicationDescription) {
 	allSizes := func (icon tomo.Icon) (sizes []canvas.Texture) {
 		small  := icon.Texture(tomo.IconSizeSmall)

go.mod

@@ -4,6 +4,7 @@ go 1.20
 
 require (
 	git.tebibyte.media/tomo/backend v0.4.1
+	git.tebibyte.media/tomo/objects v0.19.0
 	git.tebibyte.media/tomo/tomo v0.38.0
 	git.tebibyte.media/tomo/xdg v0.1.0
 	golang.org/x/image v0.11.0

go.sum

@@ -1,6 +1,8 @@
 git.tebibyte.media/sashakoshka/xgbkb v1.0.0/go.mod h1:pNcE6TRO93vHd6q42SdwLSTTj25L0Yzggz7yLe0JV6Q=
 git.tebibyte.media/tomo/backend v0.4.1 h1:rpkyTAfp/PE56aSqKNxtSN+D/aBSW8wjJ/vTtSgqQhE=
 git.tebibyte.media/tomo/backend v0.4.1/go.mod h1:2G04zmKbzf5fA/xzsjoQRrN55BWZkB+vknFxd3ialZ0=
+git.tebibyte.media/tomo/objects v0.19.0 h1:ibnAoPvkPTiuJGlqQDnoGVZBQiUT/GZo1qqvDDUCK4w=
+git.tebibyte.media/tomo/objects v0.19.0/go.mod h1:GP5BZ6lc2F2D0OxERfr9r46PIk7jFlpq2/BWOpoQDqc=
 git.tebibyte.media/tomo/tomo v0.38.0 h1:K5TP67RxnszudeNfmGZiU5cFTRjFueXiI3NCsgw+05U=
 git.tebibyte.media/tomo/tomo v0.38.0/go.mod h1:C9EzepS9wjkTJjnZaPBh22YvVPyA4hbBAJVU20Rdmps=
 git.tebibyte.media/tomo/typeset v0.7.1 h1:aZrsHwCG5ZB4f5CruRFsxLv5ezJUCFUFsQJJso2sXQ8=