Support ?landing=1 to always show landing page

This supports admins previewing changes to the landing page.

Ref T565

app.go

@@ -186,21 +186,28 @@ func handleViewHome(app *App, w http.ResponseWriter, r *http.Request) error {
 	}
 
 	// Multi-user instance
-	u := getUserSession(app, r)
-	if u != nil {
-		// User is logged in, so show the Pad
-		return handleViewPad(app, w, r)
-	}
+	forceLanding := r.FormValue("landing") == "1"
+	if !forceLanding {
+		// Show correct page based on user auth status and configured landing path
+		u := getUserSession(app, r)
+		if u != nil {
+			// User is logged in, so show the Pad
+			return handleViewPad(app, w, r)
+		}
 
-	if land := app.cfg.App.LandingPath(); land != "/" {
-		return impart.HTTPError{http.StatusFound, land}
+		if land := app.cfg.App.LandingPath(); land != "/" {
+			return impart.HTTPError{http.StatusFound, land}
+		}
 	}
 
 	p := struct {
 		page.StaticPage
 		Flashes []template.HTML
+
+		ForcedLanding bool
 	}{
-		StaticPage: pageForReq(app, r),
+		StaticPage:    pageForReq(app, r),
+		ForcedLanding: forceLanding,
 	}
 
 	// Get error messages

pages/landing.tmpl

@@ -76,20 +76,20 @@ form dd {
 					<label>
 						<dt>Username</dt>
 						<dd>
-							<input type="text" id="alias" name="alias" style="width: 100%; box-sizing: border-box;" tabindex="1" autofocus />
+							<input type="text" id="alias" name="alias" style="width: 100%; box-sizing: border-box;" tabindex="1" autofocus {{if .ForcedLanding}}disabled{{end}} />
 							{{if .Federation}}<p id="alias-site" class="demo">@<strong>your-username</strong>@{{.FriendlyHost}}</p>{{else}}<p id="alias-site" class="demo">{{.FriendlyHost}}/<strong>your-username</strong></p>{{end}}
 						</dd>
 					</label>
 					<label>
 						<dt>Password</dt>
-						<dd><input type="password" id="password" name="pass" autocomplete="new-password" placeholder="" tabindex="2" style="width: 100%; box-sizing: border-box;" /></dd>
+						<dd><input type="password" id="password" name="pass" autocomplete="new-password" placeholder="" tabindex="2" style="width: 100%; box-sizing: border-box;" {{if .ForcedLanding}}disabled{{end}} /></dd>
 					</label>
 					<label>
 						<dt>Email (optional)</dt>
-						<dd><input type="email" name="email" id="email" style="letter-spacing: 1px; width: 100%; box-sizing: border-box;" placeholder="me@example.com" tabindex="3" /></dd>
+						<dd><input type="email" name="email" id="email" style="letter-spacing: 1px; width: 100%; box-sizing: border-box;" placeholder="me@example.com" tabindex="3" {{if .ForcedLanding}}disabled{{end}} /></dd>
 					</label>
 					<dt>
-						<button id="btn-create" type="submit" style="margin-top: 0">Create blog</button>
+						<button id="btn-create" type="submit" style="margin-top: 0" {{if .ForcedLanding}}disabled{{end}}>Create blog</button>
 					</dt>
 				</dl>
 			</form>