feat(backend): avatar migration stuff

migration-tools/avatar-proxy/main.go

@@ -0,0 +1,103 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"log"
+	"net/http"
+	"os"
+	"strconv"
+
+	"github.com/go-chi/chi/v5"
+	"github.com/jackc/pgx/v5"
+	"github.com/jackc/pgx/v5/pgxpool"
+)
+
+type Proxy struct {
+	OldAvatarBase string `json:"old_avatar_base"`
+	NewAvatarBase string `json:"new_avatar_base"`
+	FlagBase      string `json:"flag_base"`
+
+	Port     int    `json:"port"`
+	Database string `json:"database"`
+
+	db *pgxpool.Pool
+}
+
+type EntityWithAvatar struct {
+	ID             uint64
+	LegacyID       string
+	Avatar         string
+	AvatarMigrated bool
+}
+
+func main() {
+	b, err := os.ReadFile("config.json")
+	if err != nil {
+		log.Fatalln("error reading config:", err)
+	}
+
+	p := &Proxy{}
+	err = json.Unmarshal(b, p)
+	if err != nil {
+		log.Fatalln("error parsing config:", err)
+	}
+
+	p.db, err = pgxpool.New(context.Background(), p.Database)
+	if err != nil {
+		log.Fatalln("error connecting to database:", err)
+	}
+
+	r := chi.NewRouter()
+
+	r.HandleFunc(`/flags/{hash:[\da-f]+}.webp`, func(w http.ResponseWriter, r *http.Request) {
+		http.Redirect(w, r, fmt.Sprintf("%s%s", p.FlagBase, r.URL.Path), http.StatusTemporaryRedirect)
+	})
+	r.Get(`/members/{id:[\d]+}/avatars/{hash:[\da-f]+}.webp`, p.proxyHandler("member"))
+	r.Get(`/users/{id:[\d]+}/avatars/{hash:[\da-f]+}.webp`, p.proxyHandler("user"))
+	r.NotFound(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusNotFound)
+		w.Write([]byte("file not found"))
+	})
+
+	log.Printf("serving on port %v", p.Port)
+
+	err = http.ListenAndServe(":"+strconv.Itoa(p.Port), r)
+	if err != nil {
+		log.Fatalf("listening on port %v: %v", p.Port, err)
+	}
+}
+
+func (p *Proxy) proxyHandler(avatarType string) func(http.ResponseWriter, *http.Request) {
+	return func(w http.ResponseWriter, r *http.Request) {
+		id := chi.URLParam(r, "id")
+		hash := chi.URLParam(r, "hash")
+
+		var e EntityWithAvatar
+		// don't do this normally, kids. avatarType can only be "user" or "member" so it's fine here but this is a BAD idea otherwise.
+		err := p.db.QueryRow(
+			r.Context(), "SELECT id, legacy_id, avatar, avatar_migrated FROM "+avatarType+"s WHERE id = $1 AND avatar = $2",
+			id, hash,
+		).Scan(&e.ID, &e.LegacyID, &e.Avatar, &e.AvatarMigrated)
+		if err != nil {
+			if errors.Is(err, pgx.ErrNoRows) {
+				w.WriteHeader(http.StatusNotFound)
+				w.Write([]byte("avatar not found"))
+				return
+			}
+
+			log.Printf("error getting avatar for %s %s: %v", avatarType, id, err)
+			w.WriteHeader(http.StatusInternalServerError)
+			w.Write([]byte("internal server error"))
+			return
+		}
+
+		if e.AvatarMigrated {
+			http.Redirect(w, r, fmt.Sprintf("%s/%ss/%d/avatars/%s.webp", p.NewAvatarBase, avatarType, e.ID, e.Avatar), http.StatusTemporaryRedirect)
+		} else {
+			http.Redirect(w, r, fmt.Sprintf("%s/%ss/%s/%s.webp", p.OldAvatarBase, avatarType, e.LegacyID, e.Avatar), http.StatusTemporaryRedirect)
+		}
+	}
+}