// Package middleware provides HTTP middleware for the chat server.
package middleware

import (
	"log/slog"
	"net"
	"net/http"
	"time"

	"git.eeqj.de/sneak/chat/internal/config"
	"git.eeqj.de/sneak/chat/internal/globals"
	"git.eeqj.de/sneak/chat/internal/logger"
	basicauth "github.com/99designs/basicauth-go"
	"github.com/go-chi/chi/middleware"
	"github.com/go-chi/cors"
	metrics "github.com/slok/go-http-metrics/metrics/prometheus"
	ghmm "github.com/slok/go-http-metrics/middleware"
	"github.com/slok/go-http-metrics/middleware/std"
	"github.com/spf13/viper"
	"go.uber.org/fx"
)

const corsMaxAge = 300

// Params defines the dependencies for creating Middleware.
type Params struct {
	fx.In

	Logger  *logger.Logger
	Globals *globals.Globals
	Config  *config.Config
}

// Middleware provides HTTP middleware handlers.
type Middleware struct {
	log    *slog.Logger
	params *Params
}

// New creates a new Middleware instance.
func New(_ fx.Lifecycle, params Params) (*Middleware, error) {
	s := new(Middleware)
	s.params = &params
	s.log = params.Logger.Get()

	return s, nil
}

func ipFromHostPort(hp string) string {
	h, _, err := net.SplitHostPort(hp)
	if err != nil {
		return ""
	}

	if len(h) > 0 && h[0] == '[' {
		return h[1 : len(h)-1]
	}

	return h
}

type loggingResponseWriter struct {
	http.ResponseWriter

	statusCode int
}

// newLoggingResponseWriter wraps a ResponseWriter to capture the status code.
func newLoggingResponseWriter(w http.ResponseWriter) *loggingResponseWriter {
	return &loggingResponseWriter{w, http.StatusOK}
}

func (lrw *loggingResponseWriter) WriteHeader(code int) {
	lrw.statusCode = code
	lrw.ResponseWriter.WriteHeader(code)
}

// Logging returns middleware that logs each HTTP request.
func (s *Middleware) Logging() func(http.Handler) http.Handler {
	return func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			start := time.Now()
			lrw := newLoggingResponseWriter(w)
			ctx := r.Context()

			defer func() {
				latency := time.Since(start)

				reqID, _ := ctx.Value(middleware.RequestIDKey).(string)

				s.log.InfoContext(ctx, "request",
					"request_start", start,
					"method", r.Method,
					"url", r.URL.String(),
					"useragent", r.UserAgent(),
					"request_id", reqID,
					"referer", r.Referer(),
					"proto", r.Proto,
					"remoteIP", ipFromHostPort(r.RemoteAddr),
					"status", lrw.statusCode,
					"latency_ms", latency.Milliseconds(),
				)
			}()

			next.ServeHTTP(lrw, r)
		})
	}
}

// CORS returns middleware that handles Cross-Origin Resource Sharing.
func (s *Middleware) CORS() func(http.Handler) http.Handler {
	return cors.Handler(cors.Options{
		AllowedOrigins:   []string{"*"},
		AllowedMethods:   []string{"GET", "POST", "PUT", "DELETE", "OPTIONS"},
		AllowedHeaders:   []string{"Accept", "Authorization", "Content-Type", "X-CSRF-Token"},
		ExposedHeaders:   []string{"Link"},
		AllowCredentials: false,
		MaxAge:           corsMaxAge,
	})
}

// Auth returns middleware that performs authentication.
func (s *Middleware) Auth() func(http.Handler) http.Handler {
	return func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			s.log.Info("AUTH: before request")
			next.ServeHTTP(w, r)
		})
	}
}

// Metrics returns middleware that records HTTP metrics.
func (s *Middleware) Metrics() func(http.Handler) http.Handler {
	mdlw := ghmm.New(ghmm.Config{
		Recorder: metrics.NewRecorder(metrics.Config{}),
	})

	return func(next http.Handler) http.Handler {
		return std.Handler("", mdlw, next)
	}
}

// MetricsAuth returns middleware that protects metrics with basic auth.
func (s *Middleware) MetricsAuth() func(http.Handler) http.Handler {
	return basicauth.New(
		"metrics",
		map[string][]string{
			viper.GetString("METRICS_USERNAME"): {
				viper.GetString("METRICS_PASSWORD"),
			},
		},
	)
}