todo.txt integration

todo.go

@@ -0,0 +1,62 @@
+package main
+
+import (
+	"net/http"
+	"os"
+	"path/filepath"
+)
+
+// Root todo.txt rail widget (assets/todo-rail.js). /_todo reads and writes the
+// single wiki-root todo.txt — the path is fixed, so there is no traversal
+// surface. GET returns the raw text (404 when the file is absent, which the
+// widget treats as "render nothing"); POST replaces the whole file atomically.
+// Unlike the index.md save path, empty content does NOT delete the file: the
+// widget has no in-UI way to recreate it, so an empty save keeps an empty file.
+
+func (h *handler) todoPath() string {
+	return filepath.Join(h.root, "todo.txt")
+}
+
+func (h *handler) handleTodo(w http.ResponseWriter, r *http.Request) {
+	if !h.checkAuth(w, r) {
+		return
+	}
+	switch r.Method {
+	case http.MethodGet:
+		h.handleTodoGet(w, r)
+	case http.MethodPost:
+		h.handleTodoPost(w, r)
+	default:
+		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
+	}
+}
+
+func (h *handler) handleTodoGet(w http.ResponseWriter, r *http.Request) {
+	data, err := os.ReadFile(h.todoPath())
+	if err != nil {
+		if os.IsNotExist(err) {
+			http.NotFound(w, r)
+			return
+		}
+		http.Error(w, "read failed: "+err.Error(), http.StatusInternalServerError)
+		return
+	}
+	// The rail re-fetches on every page load; a heuristically cached copy
+	// would show stale todos after an edit.
+	w.Header().Set("Cache-Control", "no-store")
+	w.Header().Set("Content-Type", "text/plain; charset=utf-8")
+	w.Write(data)
+}
+
+func (h *handler) handleTodoPost(w http.ResponseWriter, r *http.Request) {
+	if err := r.ParseForm(); err != nil {
+		http.Error(w, "bad request", http.StatusBadRequest)
+		return
+	}
+	content := r.FormValue("content")
+	if err := writeFileAtomic(h.todoPath(), []byte(content), 0644); err != nil {
+		http.Error(w, "write failed: "+err.Error(), http.StatusInternalServerError)
+		return
+	}
+	w.WriteHeader(http.StatusNoContent)
+}