// SPDX-License-Identifier: AGPL-3.0-or-later

package middleware

import (
	"net/http"
	"strings"
)

// BasePath strips a configured path prefix from incoming requests so the
// router sees paths without the prefix. This enables deployment at both
// faves.example.com (basePath="") and example.com/faves (basePath="/faves").
func BasePath(prefix string) func(http.Handler) http.Handler {
	return func(next http.Handler) http.Handler {
		if prefix == "" {
			return next
		}
		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			// Strip the prefix from the URL path.
			if strings.HasPrefix(r.URL.Path, prefix) {
				r.URL.Path = strings.TrimPrefix(r.URL.Path, prefix)
				if r.URL.Path == "" {
					r.URL.Path = "/"
				}
				// Also update RawPath if present.
				if r.URL.RawPath != "" {
					r.URL.RawPath = strings.TrimPrefix(r.URL.RawPath, prefix)
					if r.URL.RawPath == "" {
						r.URL.RawPath = "/"
					}
				}
			}
			next.ServeHTTP(w, r)
		})
	}
}