// Package server provides the HTTP server for kindexr, including the /health endpoint.
package server

import (
	"encoding/json"
	"net/http"

	"github.com/go-chi/chi/v5"
	"github.com/go-chi/chi/v5/middleware"
	"git.utn.lol/enki/kindexr/internal/config"
	"git.utn.lol/enki/kindexr/internal/db"
	"git.utn.lol/enki/kindexr/internal/torznab"
)

// Server holds the HTTP server state.
type Server struct {
	cfg             *config.Config
	db              *db.DB
	router          chi.Router
	version         string
	connectedRelays func() int // returns live relay count; nil = always 0
}

// New creates a new Server with the given config, database, and version string.
func New(cfg *config.Config, database *db.DB, version string) *Server {
	s := &Server{
		cfg:     cfg,
		db:      database,
		version: version,
	}
	s.router = s.buildRouter()
	return s
}

// SetConnectedRelays wires in a function that returns the current connected
// relay count. Call this after the reader is started.
func (s *Server) SetConnectedRelays(fn func() int) {
	s.connectedRelays = fn
}

// Handler returns the root http.Handler for the server.
func (s *Server) Handler() http.Handler {
	return s.router
}

// buildRouter wires up all routes and middleware.
func (s *Server) buildRouter() chi.Router {
	r := chi.NewRouter()
	r.Use(middleware.Logger)
	r.Use(middleware.Recoverer)

	r.Get("/health", s.healthHandler)

	tz := torznab.New(s.cfg, s.db, s.version)
	tz.Mount(r)

	return r
}

// healthResponse is the JSON body returned by GET /health.
type healthResponse struct {
	Status          string `json:"status"`
	Version         string `json:"version"`
	RelaysConnected int    `json:"relays_connected"`
	EventsTotal     int64  `json:"events_total"`
	LastEventAt     *int64 `json:"last_event_at"`
}

// healthHandler handles GET /health.
func (s *Server) healthHandler(w http.ResponseWriter, r *http.Request) {
	stats, err := s.db.GetStats(r.Context())
	if err != nil {
		http.Error(w, `{"error":"internal server error"}`, http.StatusInternalServerError)
		return
	}

	relaysConnected := 0
	if s.connectedRelays != nil {
		relaysConnected = s.connectedRelays()
	}

	resp := healthResponse{
		Status:          "ok",
		Version:         s.version,
		RelaysConnected: relaysConnected,
		EventsTotal:     stats.EventsTotal,
		LastEventAt:     stats.LastEventAt,
	}

	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(http.StatusOK)
	_ = json.NewEncoder(w).Encode(resp)
}