package server

import (
	"net/http"
	"time"

	"github.com/go-chi/chi/v5"

	"git.avsdev.uk/Go/job-search/internal/config"
	"git.avsdev.uk/Go/job-search/internal/httpx"
	"git.avsdev.uk/Go/job-search/internal/middleware"
)

// routes builds the router. Middleware order (outermost first):
//
//	RealIP -> RequestID -> Logger -> Recoverer -> [global rate limit + hooks]
//	  -> RequestChecks (host, body cap) -> DefaultHeaders
//	  /api : NoStore -> Compress -> [api rate limit + hooks] -> CSRF
//	         -> RequireJSON
//	  /ws  : [ws rate limit + hooks] -> Origin check (hub)
func (s *Server) routes() (http.Handler, error) {
	conf := s.conf
	router := chi.NewRouter()

	router.Use(
		middleware.RealIP(middleware.RealIPOptions{
			Trusted:        s.trusted,
			Headers:        conf.Proxy.ClientIPHeaders,
			StripUntrusted: conf.Proxy.StripUntrusted,
		}),
		middleware.RequestID,
		middleware.Logger(middleware.WithLogger(s.untaggedLogger())),
		middleware.Recoverer(middleware.WithLogger(s.untaggedLogger())),
	)
	router.Use(s.groupStack(GroupGlobal, conf.RateLimits.Global)...)
	router.Use(
		middleware.RequestChecks(*conf),
		middleware.DefaultHeaders(conf.Headers),
	)

	compress, err := middleware.Compress()
	if err != nil {
		return nil, err
	}

	// API
	router.Route("/api", func(apiRouter chi.Router) {
		apiRouter.Use(middleware.NoStore, compress)
		apiRouter.Use(s.groupStack(GroupAPI, conf.RateLimits.API)...)
		apiRouter.Use(s.csrf.Protect, middleware.RequireJSON)

		apiRouter.NotFound(func(w http.ResponseWriter, r *http.Request) {
			httpx.WriteProblem(w, r, http.StatusNotFound, "no such endpoint")
		})
		apiRouter.MethodNotAllowed(func(w http.ResponseWriter, r *http.Request) {
			httpx.WriteProblem(w, r, http.StatusMethodNotAllowed, "")
		})

		apiRouter.Get("/health", s.health)
		if s.csrf.TokenEnabled() {
			apiRouter.Get("/csrf", s.csrf.IssueHandler)
		}
		s.api.Routes(apiRouter)
	})

	// WebSocket (no compression middleware: permessage-deflate is separate)
	webSocketStack := s.groupStack(GroupWebSocket, conf.WebSocket.ConnectionLimit)
	router.With(webSocketStack...).Get("/ws", s.hub.ServeHTTP)

	return router, nil
}

// groupStack returns the rate-limit hook (configured or overridden) followed
// by any user-supplied hook middleware for the group.
func (s *Server) groupStack(
	group Group, rule config.JSCRateLimitRule,
) []Middleware {
	var stack []Middleware
	if hook, ok := s.limiters[group]; ok && hook.set {
		if hook.limiter != nil {
			stack = append(stack, middleware.RateLimit(hook.limiter, hook.key))
		}
	} else if rule.Enabled && rule.PerSecond > 0 {
		limiter := middleware.NewKeyedLimiter(
			s.backgroundCtx,
			float64(rule.PerSecond),
			max(rule.Burst, 1),
			s.conf.RateLimits.IdleTTL,
		)
		stack = append(stack, middleware.RateLimit(limiter, middleware.KeyByIP))
	}
	return append(stack, s.hooks[group]...)
}

// health serves GET /api/health: the server's status and uptime, the number
// of WebSocket clients, and the client as the server sees it (after proxy
// processing).
func (s *Server) health(w http.ResponseWriter, r *http.Request) {
	client := middleware.Client(r)
	httpx.WriteJSON(w, http.StatusOK, map[string]any{
		"status":    "ok",
		"uptime":    time.Since(s.started).Round(time.Second).String(),
		"wsClients": s.hub.Count(),
		"client": map[string]any{
			"ip":       client.IP.String(),
			"scheme":   client.Scheme,
			"viaProxy": client.ViaProxy,
		},
	})
}