Rework wikilinks feature

main.go

@@ -10,6 +10,7 @@ import (
 	"io/fs"
 	"log"
 	"net/http"
+	"net/url"
 	"os"
 	"path"
 	"path/filepath"
@@ -105,7 +106,7 @@ func main() {
 		log.Fatal(err)
 	}
 
-	initMarkdown(root)
+	initMarkdown()
 
 	authKey, err := loadOrCreateAuthKey(root)
 	if err != nil {
@@ -220,7 +221,7 @@ func (h *handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 			// POSTs must not be redirected — the form action has no trailing
 			// slash (path.Clean strips it) and the content would be lost.
 			if !strings.HasSuffix(r.URL.Path, "/") && r.Method != http.MethodPost {
-				http.Redirect(w, r, r.URL.Path+"/", http.StatusMovedPermanently)
+				http.Redirect(w, r, slashedURL(r.URL), http.StatusMovedPermanently)
 				return
 			}
 			h.serveDir(w, r, urlPath, fsPath)
@@ -232,14 +233,39 @@ func (h *handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 
 	if info.IsDir() {
 		if urlPath != "/" {
+			// Pages must live at a slash-terminated URL: embed destinations are
+			// relative, so "/Trips/Japan" would resolve them against "/Trips/".
+			if !strings.HasSuffix(r.URL.Path, "/") && r.Method != http.MethodPost {
+				http.Redirect(w, r, slashedURL(r.URL), http.StatusMovedPermanently)
+				return
+			}
 			urlPath += "/"
 		}
 		h.serveDir(w, r, urlPath, fsPath)
 	} else {
+		// ?w= on a file's own URL serves a thumbnail. Embeds use this form so
+		// their <img src> can stay relative to the page; /_thumb/<abs path>
+		// stays for listings, which have absolute paths on hand anyway. A file
+		// with no thumbnailer ignores the parameter and serves normally.
+		if r.URL.Query().Has("w") && hasThumbnail(fsPath) {
+			h.serveThumbnail(w, r, fsPath)
+			return
+		}
 		http.ServeFile(w, r, fsPath)
 	}
 }
 
+// slashedURL returns u's path with a trailing slash appended and the query
+// string intact — the canonical page form that relative destinations resolve
+// against.
+func slashedURL(u *url.URL) string {
+	target := u.Path + "/"
+	if u.RawQuery != "" {
+		target += "?" + u.RawQuery
+	}
+	return target
+}
+
 func (h *handler) serveDir(w http.ResponseWriter, r *http.Request, urlPath, fsPath string) {
 	_, editMode := r.URL.Query()["edit"]
 
@@ -373,7 +399,7 @@ func (h *handler) handlePost(w http.ResponseWriter, r *http.Request, urlPath, fs
 		return
 	}
 	if _, ok := query["move"]; ok {
-		h.handleMove(w, r, urlPath, fsPath, query.Get("move"), query.Has("links"), query.Has("merge"))
+		h.handleMove(w, r, urlPath, fsPath, query.Get("move"), query.Has("merge"))
 		return
 	}
 	if query.Has("toggle") {