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)
}