middleware.go

package main

import (
	"context"
	"encoding/json"
	"fmt"
	"log/slog"
	"net/http"
	"time"
)

// statusWriter wraps ResponseWriter to capture the status code.
type statusWriter struct {
	http.ResponseWriter
	code int
}

func (w *statusWriter) WriteHeader(code int) {
	w.code = code
	w.ResponseWriter.WriteHeader(code)
}

func loggingMiddleware(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		start := time.Now()
		sw := &statusWriter{ResponseWriter: w, code: 200}
		next.ServeHTTP(sw, r)
		slog.Info("request",
			"method", r.Method,
			"path", r.URL.Path,
			"status", sw.code,
			"ms", time.Since(start).Milliseconds(),
		)
	})
}

func authMiddleware(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if token != "" {
			auth := r.Header.Get("Authorization")
			if auth != "Bearer "+token {
				jsonErr(w, 401, fmt.Errorf("unauthorized"))
				return
			}
		}
		next.ServeHTTP(w, r)
	})
}

func corsMiddleware(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Access-Control-Allow-Origin", "*")
		w.Header().Set("Access-Control-Allow-Methods", "GET, POST, OPTIONS")
		w.Header().Set("Access-Control-Allow-Headers", "Authorization, Content-Type")
		if r.Method == "OPTIONS" {
			w.WriteHeader(204)
			return
		}
		next.ServeHTTP(w, r)
	})
}

// cancelOnClientDone cancels the given cancel func when the HTTP client disconnects.
func cancelOnClientDone(reqCtx context.Context, cancel context.CancelFunc) {
	<-reqCtx.Done()
	cancel()
}

func jsonResp(w http.ResponseWriter, code int, data any) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(code)
	if err := json.NewEncoder(w).Encode(data); err != nil {
		slog.Error("json encode", "err", err)
	}
}

func jsonErr(w http.ResponseWriter, code int, err error) {
	jsonResp(w, code, map[string]string{"error": err.Error()})
}