Implement rudimentary link shortening service and wire everything together

internal/service/http.go

@@ -0,0 +1,83 @@
+package service
+
+import (
+	"database/sql"
+	"log/slog"
+	"net/http"
+	"slices"
+	"strings"
+
+	"git.kocoder.xyz/vt/shortener/internal/config"
+	"git.kocoder.xyz/vt/shortener/internal/database"
+)
+
+type Server struct {
+	conf *config.Config
+	db   *database.Queries
+}
+
+func NewServer(conf *config.Config, db *database.Queries) *Server {
+	return &Server{
+		conf: conf,
+		db:   db,
+	}
+}
+
+func (s *Server) ServeHTTP(w http.ResponseWriter, req *http.Request) {
+	ctx := req.Context()
+	path := req.URL.Path
+
+	path = strings.Trim(path, "/")
+
+	slog.InfoContext(ctx, "processing request", slog.String("path", path))
+
+	res, err := s.db.GetURLByShortCode(ctx, path)
+	if err != nil {
+		slog.ErrorContext(ctx, "failed to get url by short code", slog.String("path", path), slog.String("err", err.Error()))
+		w.WriteHeader(http.StatusInternalServerError)
+		return
+	}
+
+	forwardedFor := req.Header.Get("X-Forwarded-For")
+	remoteAddr := req.RemoteAddr
+
+	if slices.Contains(s.conf.TRUSTED_PROXIES, strings.Split(remoteAddr, ":")[0]) {
+		if strings.Contains(forwardedFor, ", ") {
+			remoteAddr = strings.Split(forwardedFor, ", ")[0]
+		} else {
+			remoteAddr = forwardedFor
+		}
+	}
+
+	slog.InfoContext(ctx, "tracking click", 
+		slog.String("ip", remoteAddr), 
+		slog.String("user_agent", req.UserAgent()), 
+		slog.String("referrer", req.Referer()),
+	)
+
+	_, err = s.db.TrackClick(ctx, database.TrackClickParams{
+		UrlID: res.UrlID,
+		UserAgent: sql.NullString{
+			String: req.UserAgent(),
+			Valid:  true,
+		},
+		Referrer: sql.NullString{
+			String: req.Referer(),
+			Valid:  true,
+		},
+		IpAddress: sql.NullString{
+			String: remoteAddr,
+			Valid:  true,
+		},
+	})
+
+	if err != nil {
+		slog.ErrorContext(ctx, "failed to track click", slog.String("err", err.Error()))
+		// Still continuing to redirect even if tracking fails, or we can return. 
+		// Usually we still want to redirect the user so they reach their destination.
+	}
+
+	slog.InfoContext(ctx, "redirecting to destination", slog.String("long_url", res.LongUrl))
+
+	http.Redirect(w, req, res.LongUrl, http.StatusFound)
+}