1 files changed, 136 insertions, 0 deletions
diff --git a/main.go b/main.go
new file mode 100644
index 0000000..cd8c20f
--- /dev/null
+++ b/main.go
@@ -0,0 +1,136 @@
+package main
+
+import (
+	_ "embed"
+	"encoding/gob"
+	"io"
+	"log/slog"
+	"net/http"
+	"net/url"
+	"os"
+	"strings"
+	"sync"
+)
+
+//go:embed popup.html
+var popup string
+
+//go:embed notfound.html
+var notfound string
+
+//go:embed genericerror.html
+var genericerror string
+
+var migratedLock = sync.RWMutex{}
+var migrated = map[string]struct{}{}
+
+func migrate(id string) {
+	migratedLock.Lock()
+	migrated[id] = struct{}{}
+	migratedLock.Unlock()
+	slog.Info("Saving migrations", "id", id)
+	save()
+}
+func save() {
+	file, err := os.Create("migrated")
+	if err != nil {
+		slog.Warn("Could not create Migration-File", "err", err)
+		return
+	}
+	defer file.Close()
+	enc := gob.NewEncoder(file)
+	migratedLock.RLock()
+	defer migratedLock.RUnlock()
+	err = enc.Encode(migrated)
+	if err != nil {
+		slog.Warn("Could not encode migrations", "err", err)
+		return
+	}
+}
+
+func main() {
+	file, err := os.Open("migrated")
+	if err != nil {
+		slog.Warn("Could not open migration history", "err", err)
+		save()
+	} else {
+		dec := gob.NewDecoder(file)
+		dec.Decode(&migrated)
+	}
+
+	http.HandleFunc("GET /p/{id}", func(w http.ResponseWriter, r *http.Request) {
+		id := url.PathEscape(r.PathValue("id"))
+
+		migratedLock.RLock()
+		if _, ok := migrated[id]; ok {
+			migratedLock.RUnlock()
+			http.Redirect(w, r, "https://notes.stuve.fau.de/stuve-etherpad-migrated-"+id, 302)
+			return
+		}
+		migratedLock.RUnlock()
+
+		req, err := http.Get("http://127.0.0.1:9001/p/" + id + "/export/html")
+		if err != nil {
+			w.WriteHeader(502)
+			slog.Error("Could not fetch Pad as html", "err", err, "id", id)
+			w.Write([]byte(genericerror))
+			return
+		}
+		defer req.Body.Close()
+		if req.StatusCode == 404 {
+			w.WriteHeader(404)
+			slog.Error("Could not fetch Pad: 404", "id", id)
+			w.Write([]byte(notfound))
+			return
+		}
+		body, err := io.ReadAll(req.Body)
+		if req.StatusCode != 200 {
+			w.WriteHeader(req.StatusCode)
+			slog.Error("Could not fetch Pad", "id", id, "status", req.Status, "body", string(body))
+			w.Write([]byte(genericerror))
+			return
+		}
+		if err != nil {
+			w.WriteHeader(502)
+			slog.Error("Could not read entire body", "err", err, "id", id)
+			w.Write([]byte(genericerror))
+			return
+		}
+		w.Write([]byte(strings.Replace(string(body), "<body>", popup, 1)))
+	})
+	http.HandleFunc("POST /p/{id}", func(w http.ResponseWriter, r *http.Request) {
+		id := r.PathValue("id")
+		req, err := http.Get("http://127.0.0.1:9001/p/" + id + "/export/markdown")
+		if err != nil {
+			w.WriteHeader(502)
+			slog.Error("Could not fetch Pad as markdown", "err", err, "id", id)
+			w.Write([]byte(genericerror))
+			return
+		}
+		if req.StatusCode == 404 {
+			w.WriteHeader(404)
+			slog.Error("Could not fetch Pad: 404", "id", id)
+			w.Write([]byte(notfound))
+			return
+		}
+		if req.StatusCode != 200 {
+			body, err := io.ReadAll(req.Body)
+			w.WriteHeader(req.StatusCode)
+			slog.Error("Could not fetch Pad", "id", id, "status", req.Status, "body", string(body), "err", err)
+			w.Write([]byte(genericerror))
+			return
+		}
+		resp, err := http.Post("https://notes.stuve.fau.de/new/stuve-etherpad-migrated-"+id, "text/markdown", req.Body)
+		if resp.StatusCode != 200 {
+			body, err := io.ReadAll(resp.Body)
+			w.WriteHeader(req.StatusCode)
+			slog.Error("Could not Post Pad", "id", id, "status", req.Status, "body", string(body), "err", err)
+			w.Write([]byte(genericerror))
+			return
+		}
+		migrate(id)
+		http.Redirect(w, r, "https://notes.stuve.fau.de/stuve-etherpad-migrated-"+id, 302)
+	})
+	err = http.ListenAndServe("[::]:8080", nil)
+	panic(err)
+}