// Package server provides HTTP endpoints for status monitoring and statistics
package server

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

	"git.eeqj.de/sneak/routewatch/internal/database"
	"git.eeqj.de/sneak/routewatch/internal/streamer"
	"git.eeqj.de/sneak/routewatch/internal/templates"
	"github.com/go-chi/chi/v5"
	"github.com/go-chi/chi/v5/middleware"
)

// Server provides HTTP endpoints for status monitoring
type Server struct {
	router   *chi.Mux
	db       database.Store
	streamer *streamer.Streamer
	logger   *slog.Logger
	srv      *http.Server
}

// New creates a new HTTP server
func New(db database.Store, streamer *streamer.Streamer, logger *slog.Logger) *Server {
	s := &Server{
		db:       db,
		streamer: streamer,
		logger:   logger,
	}

	s.setupRoutes()

	return s
}

// setupRoutes configures the HTTP routes
func (s *Server) setupRoutes() {
	r := chi.NewRouter()

	// Middleware
	r.Use(middleware.RequestID)
	r.Use(middleware.RealIP)
	r.Use(middleware.Logger)
	r.Use(middleware.Recoverer)
	const requestTimeout = 60 * time.Second
	r.Use(middleware.Timeout(requestTimeout))

	// Routes
	r.Get("/", s.handleRoot())
	r.Get("/status", s.handleStatusHTML())
	r.Get("/status.json", s.handleStatusJSON())

	// API routes
	r.Route("/api/v1", func(r chi.Router) {
		r.Get("/stats", s.handleStats())
	})

	s.router = r
}

// Start starts the HTTP server
func (s *Server) Start() error {
	port := os.Getenv("PORT")
	if port == "" {
		port = "8080"
	}

	const readHeaderTimeout = 10 * time.Second
	s.srv = &http.Server{
		Addr:              ":" + port,
		Handler:           s.router,
		ReadHeaderTimeout: readHeaderTimeout,
	}

	s.logger.Info("Starting HTTP server", "port", port)

	go func() {
		if err := s.srv.ListenAndServe(); err != nil && err != http.ErrServerClosed {
			s.logger.Error("HTTP server error", "error", err)
		}
	}()

	return nil
}

// Stop gracefully stops the HTTP server
func (s *Server) Stop(ctx context.Context) error {
	if s.srv == nil {
		return nil
	}

	s.logger.Info("Stopping HTTP server")

	return s.srv.Shutdown(ctx)
}

// handleRoot returns a handler that redirects to /status
func (s *Server) handleRoot() http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		http.Redirect(w, r, "/status", http.StatusSeeOther)
	}
}

// handleStatusJSON returns a handler that serves JSON statistics
func (s *Server) handleStatusJSON() http.HandlerFunc {
	// Stats represents the statistics response
	type Stats struct {
		Uptime         string  `json:"uptime"`
		TotalMessages  uint64  `json:"total_messages"`
		TotalBytes     uint64  `json:"total_bytes"`
		MessagesPerSec float64 `json:"messages_per_sec"`
		MbitsPerSec    float64 `json:"mbits_per_sec"`
		Connected      bool    `json:"connected"`
		ASNs           int     `json:"asns"`
		Prefixes       int     `json:"prefixes"`
		IPv4Prefixes   int     `json:"ipv4_prefixes"`
		IPv6Prefixes   int     `json:"ipv6_prefixes"`
		Peerings       int     `json:"peerings"`
		LiveRoutes     int     `json:"live_routes"`
	}

	return func(w http.ResponseWriter, _ *http.Request) {
		metrics := s.streamer.GetMetrics()

		// Get database stats
		dbStats, err := s.db.GetStats()
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)

			return
		}

		uptime := time.Since(metrics.ConnectedSince).Truncate(time.Second).String()
		if metrics.ConnectedSince.IsZero() {
			uptime = "0s"
		}

		const bitsPerMegabit = 1000000.0

		stats := Stats{
			Uptime:         uptime,
			TotalMessages:  metrics.TotalMessages,
			TotalBytes:     metrics.TotalBytes,
			MessagesPerSec: metrics.MessagesPerSec,
			MbitsPerSec:    metrics.BitsPerSec / bitsPerMegabit,
			Connected:      metrics.Connected,
			ASNs:           dbStats.ASNs,
			Prefixes:       dbStats.Prefixes,
			IPv4Prefixes:   dbStats.IPv4Prefixes,
			IPv6Prefixes:   dbStats.IPv6Prefixes,
			Peerings:       dbStats.Peerings,
			LiveRoutes:     dbStats.LiveRoutes,
		}

		w.Header().Set("Content-Type", "application/json")
		if err := json.NewEncoder(w).Encode(stats); err != nil {
			s.logger.Error("Failed to encode stats", "error", err)
		}
	}
}

// handleStats returns a handler that serves API v1 statistics
func (s *Server) handleStats() http.HandlerFunc {
	// StatsResponse represents the API statistics response
	type StatsResponse struct {
		Uptime         string  `json:"uptime"`
		TotalMessages  uint64  `json:"total_messages"`
		TotalBytes     uint64  `json:"total_bytes"`
		MessagesPerSec float64 `json:"messages_per_sec"`
		MbitsPerSec    float64 `json:"mbits_per_sec"`
		Connected      bool    `json:"connected"`
		ASNs           int     `json:"asns"`
		Prefixes       int     `json:"prefixes"`
		IPv4Prefixes   int     `json:"ipv4_prefixes"`
		IPv6Prefixes   int     `json:"ipv6_prefixes"`
		Peerings       int     `json:"peerings"`
		LiveRoutes     int     `json:"live_routes"`
	}

	return func(w http.ResponseWriter, _ *http.Request) {
		metrics := s.streamer.GetMetrics()

		// Get database stats
		dbStats, err := s.db.GetStats()
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)

			return
		}

		uptime := time.Since(metrics.ConnectedSince).Truncate(time.Second).String()
		if metrics.ConnectedSince.IsZero() {
			uptime = "0s"
		}

		const bitsPerMegabit = 1000000.0

		stats := StatsResponse{
			Uptime:         uptime,
			TotalMessages:  metrics.TotalMessages,
			TotalBytes:     metrics.TotalBytes,
			MessagesPerSec: metrics.MessagesPerSec,
			MbitsPerSec:    metrics.BitsPerSec / bitsPerMegabit,
			Connected:      metrics.Connected,
			ASNs:           dbStats.ASNs,
			Prefixes:       dbStats.Prefixes,
			IPv4Prefixes:   dbStats.IPv4Prefixes,
			IPv6Prefixes:   dbStats.IPv6Prefixes,
			Peerings:       dbStats.Peerings,
			LiveRoutes:     dbStats.LiveRoutes,
		}

		w.Header().Set("Content-Type", "application/json")
		if err := json.NewEncoder(w).Encode(stats); err != nil {
			s.logger.Error("Failed to encode stats", "error", err)
		}
	}
}

// handleStatusHTML returns a handler that serves the HTML status page
func (s *Server) handleStatusHTML() http.HandlerFunc {
	return func(w http.ResponseWriter, _ *http.Request) {
		w.Header().Set("Content-Type", "text/html; charset=utf-8")

		tmpl := templates.StatusTemplate()
		if err := tmpl.Execute(w, nil); err != nil {
			s.logger.Error("Failed to render template", "error", err)
			http.Error(w, "Internal Server Error", http.StatusInternalServerError)
		}
	}
}