package httpapp

import (
	"compress/gzip"
	"io"
	"net/http"
	"strings"
)

// compressionMiddleware provides gzip compression for responses
func (a *App) compressionMiddleware(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		// Check if client accepts gzip
		if !strings.Contains(r.Header.Get("Accept-Encoding"), "gzip") {
			next.ServeHTTP(w, r)
			return
		}

		// Skip compression for certain content types
		contentType := r.Header.Get("Content-Type")
		if strings.HasPrefix(contentType, "image/") ||
			strings.HasPrefix(contentType, "video/") ||
			strings.HasPrefix(contentType, "application/zip") {
			next.ServeHTTP(w, r)
			return
		}

		// Create gzip writer
		gz := gzip.NewWriter(w)
		defer gz.Close()

		// Set headers
		w.Header().Set("Content-Encoding", "gzip")
		w.Header().Set("Vary", "Accept-Encoding")

		// Wrap response writer
		gzw := &gzipResponseWriter{
			ResponseWriter: w,
			Writer:         gz,
		}

		next.ServeHTTP(gzw, r)
	})
}

// gzipResponseWriter wraps http.ResponseWriter with gzip compression
type gzipResponseWriter struct {
	http.ResponseWriter
	Writer io.Writer
}

func (gzw *gzipResponseWriter) Write(b []byte) (int, error) {
	return gzw.Writer.Write(b)
}