// Package auth provides API key authentication middleware.
package auth

import (
	"net/http"
)

// Middleware returns a Chi middleware that validates the X-API-Key header.
func Middleware(apiKey string) func(http.Handler) http.Handler {
	return func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			header := r.Header.Get("X-API-Key")
			if apiKey == "" {
				// No API key configured — allow all requests (kiosk mode)
				next.ServeHTTP(w, r)
				return
			}
			if header == "" || header != apiKey {
				w.Header().Set("Content-Type", "application/json")
				w.WriteHeader(http.StatusUnauthorized)
				w.Write([]byte(`{"error":"unauthorized"}`))
				return
			}
			next.ServeHTTP(w, r)
		})
	}
}

// ExtractKey reads and returns the API key from the request, or empty string.
func ExtractKey(r *http.Request) string {
	return r.Header.Get("X-API-Key")
}