package servicecontroller

import (
	"bytes"
	"context"
	"crypto/subtle"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"log"
	"net/http"
	"net/url"
	"strings"
	"sync"
	"time"

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

	"neuralhunt/internal/customer"
)

type Config struct {
	ID                        string
	Name                      string
	MasterURL                 string
	AdvertiseURL              string
	SharedSecret              string
	ControlAddr               string
	AdminAddr                 string
	AdminUser                 string
	AdminPassword             string
	AdminCookieSecureMode     string
	MaxWorkers                int
	MaxRunning                int
	HeartbeatInterval         time.Duration
	DefaultWorkerImage        string
	WorkerNetworkOverride     string
	WorkerRegisterURLOverride string
	GameURLOverride           string
	RegistryUsername          string
	RegistryPassword          string
	RegistryServer            string
}

type Service struct {
	docker        *customer.DockerClient
	cfg           Config
	hc            *http.Client
	adminSessions sync.Map
	regMu         sync.RWMutex
	lastRegOK     bool
	lastRegAt     time.Time
	lastRegErr    string
}

func New(docker *customer.DockerClient, cfg Config) *Service {
	if cfg.MaxWorkers <= 0 {
		cfg.MaxWorkers = 1000
	}
	if cfg.MaxRunning <= 0 {
		cfg.MaxRunning = 100
	}
	if cfg.HeartbeatInterval < 5*time.Second {
		cfg.HeartbeatInterval = 15 * time.Second
	}
	return &Service{docker: docker, cfg: cfg, hc: &http.Client{Timeout: 10 * time.Second}}
}

func jsonOut(w http.ResponseWriter, status int, v any) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(status)
	_ = json.NewEncoder(w).Encode(v)
}
func decode(r *http.Request, v any, limit int64) error {
	if limit <= 0 {
		limit = 1 << 20
	}
	d := json.NewDecoder(io.LimitReader(r.Body, limit))
	d.DisallowUnknownFields()
	return d.Decode(v)
}

func requestIsHTTPS(r *http.Request) bool {
	if r.TLS != nil {
		return true
	}
	proto := strings.TrimSpace(strings.Split(r.Header.Get("X-Forwarded-Proto"), ",")[0])
	return strings.EqualFold(proto, "https")
}

func (s *Service) security(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("X-Content-Type-Options", "nosniff")
		w.Header().Set("X-Frame-Options", "DENY")
		w.Header().Set("Referrer-Policy", "no-referrer")
		w.Header().Set("Permissions-Policy", "camera=(), microphone=(), geolocation=()")
		w.Header().Set("Content-Security-Policy", "default-src 'self'; base-uri 'none'; object-src 'none'; frame-ancestors 'none'; script-src 'self'; style-src 'self'; img-src 'self' data:; connect-src 'self'; form-action 'self'")
		if requestIsHTTPS(r) {
			w.Header().Set("Strict-Transport-Security", "max-age=31536000")
		}
		next.ServeHTTP(w, r)
	})
}

func (s *Service) authorized(r *http.Request) bool {
	provided := strings.TrimSpace(strings.TrimPrefix(r.Header.Get("Authorization"), "Bearer "))
	secret := strings.TrimSpace(s.cfg.SharedSecret)
	return len(provided) == len(secret) && len(secret) >= 24 && subtle.ConstantTimeCompare([]byte(provided), []byte(secret)) == 1
}
func (s *Service) requireControl(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if !s.authorized(r) {
			jsonOut(w, http.StatusUnauthorized, map[string]string{"error": "unauthorized"})
			return
		}
		next.ServeHTTP(w, r)
	})
}

func (s *Service) counts(ctx context.Context) (total, running int, err error) {
	items, err := s.docker.ManagedContainers(ctx)
	if err != nil {
		return 0, 0, err
	}
	for _, item := range items {
		if strings.TrimSpace(item.WorkerID) == "" {
			continue
		}
		total++
		if item.Running {
			running++
		}
	}
	return total, running, nil
}

func (s *Service) ControlRoutes() http.Handler {
	r := chi.NewRouter()
	r.Use(s.security)
	r.Group(func(r chi.Router) {
		r.Use(s.requireControl)
		r.Get("/internal/health", s.health)
		r.Post("/internal/image/ensure", s.ensureImage)
		r.Post("/internal/image/pull", s.pullImage)
		r.Post("/internal/volumes", s.createVolume)
		r.Delete("/internal/volumes/{name}", s.removeVolume)
		r.Post("/internal/workers", s.createWorker)
		r.Post("/internal/workers/{id}/start", s.startWorker)
		r.Post("/internal/workers/{id}/stop", s.stopWorker)
		r.Delete("/internal/workers/{id}", s.removeWorker)
		r.Get("/internal/workers/{id}/running", s.runningWorker)
		r.Post("/internal/workers/{id}/file/get", s.getWorkerFile)
		r.Post("/internal/workers/{id}/file/put", s.putWorkerFile)
	})
	return r
}

func (s *Service) health(w http.ResponseWriter, r *http.Request) {
	total, running, err := s.counts(r.Context())
	if err != nil {
		jsonOut(w, http.StatusServiceUnavailable, map[string]any{"ok": false, "error": err.Error()})
		return
	}
	jsonOut(w, http.StatusOK, map[string]any{"ok": true, "controller_id": s.cfg.ID, "name": s.cfg.Name, "workers": total, "running": running, "max_workers": s.cfg.MaxWorkers, "max_running": s.cfg.MaxRunning})
}

func (s *Service) ensureImage(w http.ResponseWriter, r *http.Request) {
	var in struct {
		Image        string `json:"image"`
		AutoPull     bool   `json:"auto_pull"`
		RegistryAuth string `json:"registry_auth"`
	}
	if decode(r, &in, 256<<10) != nil || strings.TrimSpace(in.Image) == "" {
		jsonOut(w, 400, map[string]string{"error": "image required"})
		return
	}
	if err := s.docker.EnsureImage(r.Context(), in.Image, in.AutoPull, in.RegistryAuth); err != nil {
		jsonOut(w, 502, map[string]string{"error": err.Error()})
		return
	}
	jsonOut(w, 200, map[string]bool{"ok": true})
}
func (s *Service) pullImage(w http.ResponseWriter, r *http.Request) {
	var in struct {
		Image        string `json:"image"`
		RegistryAuth string `json:"registry_auth"`
	}
	if decode(r, &in, 256<<10) != nil || strings.TrimSpace(in.Image) == "" {
		jsonOut(w, 400, map[string]string{"error": "image required"})
		return
	}
	if err := s.docker.PullImage(r.Context(), in.Image, in.RegistryAuth); err != nil {
		jsonOut(w, 502, map[string]string{"error": err.Error()})
		return
	}
	jsonOut(w, 200, map[string]bool{"ok": true})
}
func (s *Service) createVolume(w http.ResponseWriter, r *http.Request) {
	var in struct {
		Name string `json:"name"`
	}
	if decode(r, &in, 64<<10) != nil || strings.TrimSpace(in.Name) == "" {
		jsonOut(w, 400, map[string]string{"error": "name required"})
		return
	}
	if err := s.docker.CreateVolume(r.Context(), in.Name); err != nil {
		jsonOut(w, 502, map[string]string{"error": err.Error()})
		return
	}
	jsonOut(w, 200, map[string]bool{"ok": true})
}
func (s *Service) removeVolume(w http.ResponseWriter, r *http.Request) {
	if err := s.docker.RemoveVolume(r.Context(), chi.URLParam(r, "name")); err != nil {
		jsonOut(w, 502, map[string]string{"error": err.Error()})
		return
	}
	jsonOut(w, 200, map[string]bool{"ok": true})
}
func (s *Service) createWorker(w http.ResponseWriter, r *http.Request) {
	var cfg customer.WorkerContainerConfig
	if decode(r, &cfg, 1<<20) != nil || strings.TrimSpace(cfg.WorkerID) == "" || strings.TrimSpace(cfg.Image) == "" {
		jsonOut(w, 400, map[string]string{"error": "invalid worker config"})
		return
	}
	if v := strings.TrimSpace(s.cfg.WorkerNetworkOverride); v != "" {
		cfg.Network = v
	}
	if v := strings.TrimSpace(s.cfg.WorkerRegisterURLOverride); v != "" {
		cfg.RegisterURL = v
	}
	if v := strings.TrimSpace(s.cfg.GameURLOverride); v != "" {
		cfg.GameURL = v
	}
	total, _, err := s.counts(r.Context())
	if err != nil {
		jsonOut(w, 502, map[string]string{"error": err.Error()})
		return
	}
	if total >= s.cfg.MaxWorkers {
		jsonOut(w, 503, map[string]string{"error": "service controller worker capacity reached"})
		return
	}
	id, err := s.docker.CreateWorker(r.Context(), cfg)
	if err != nil {
		jsonOut(w, 502, map[string]string{"error": err.Error()})
		return
	}
	jsonOut(w, 201, map[string]string{"id": id})
}
func (s *Service) startWorker(w http.ResponseWriter, r *http.Request) {
	_, running, err := s.counts(r.Context())
	if err != nil {
		jsonOut(w, 502, map[string]string{"error": err.Error()})
		return
	}
	if running >= s.cfg.MaxRunning {
		jsonOut(w, 503, map[string]string{"error": "service controller running capacity reached"})
		return
	}
	if err := s.docker.Start(r.Context(), chi.URLParam(r, "id")); err != nil {
		jsonOut(w, 502, map[string]string{"error": err.Error()})
		return
	}
	jsonOut(w, 200, map[string]bool{"ok": true})
}
func (s *Service) stopWorker(w http.ResponseWriter, r *http.Request) {
	var in struct {
		Seconds int `json:"seconds"`
	}
	_ = decode(r, &in, 64<<10)
	if err := s.docker.Stop(r.Context(), chi.URLParam(r, "id"), in.Seconds); err != nil && !strings.Contains(err.Error(), "304") {
		jsonOut(w, 502, map[string]string{"error": err.Error()})
		return
	}
	jsonOut(w, 200, map[string]bool{"ok": true})
}
func (s *Service) removeWorker(w http.ResponseWriter, r *http.Request) {
	if err := s.docker.Remove(r.Context(), chi.URLParam(r, "id")); err != nil {
		jsonOut(w, 502, map[string]string{"error": err.Error()})
		return
	}
	jsonOut(w, 200, map[string]bool{"ok": true})
}
func (s *Service) runningWorker(w http.ResponseWriter, r *http.Request) {
	running, err := s.docker.Running(r.Context(), chi.URLParam(r, "id"))
	if err != nil {
		jsonOut(w, 502, map[string]string{"error": err.Error()})
		return
	}
	jsonOut(w, 200, map[string]bool{"running": running})
}
func (s *Service) getWorkerFile(w http.ResponseWriter, r *http.Request) {
	var in struct {
		Path string `json:"path"`
	}
	if decode(r, &in, 64<<10) != nil || strings.TrimSpace(in.Path) == "" {
		jsonOut(w, 400, map[string]string{"error": "path required"})
		return
	}
	b, err := s.docker.GetFile(r.Context(), chi.URLParam(r, "id"), in.Path)
	if err != nil {
		jsonOut(w, 502, map[string]string{"error": err.Error()})
		return
	}
	jsonOut(w, 200, map[string]any{"data": b})
}
func (s *Service) putWorkerFile(w http.ResponseWriter, r *http.Request) {
	var in struct {
		Dir  string `json:"dir"`
		Name string `json:"name"`
		Data []byte `json:"data"`
	}
	if decode(r, &in, 2<<20) != nil || strings.TrimSpace(in.Dir) == "" || strings.TrimSpace(in.Name) == "" || len(in.Data) == 0 {
		jsonOut(w, 400, map[string]string{"error": "dir/name/data required"})
		return
	}
	if err := s.docker.PutFile(r.Context(), chi.URLParam(r, "id"), in.Dir, in.Name, in.Data); err != nil {
		jsonOut(w, 502, map[string]string{"error": err.Error()})
		return
	}
	jsonOut(w, 200, map[string]bool{"ok": true})
}

const adminCookie = "neuralhunt_service_controller_admin"

func (s *Service) adminCookieSecure(r *http.Request) bool {
	switch strings.ToLower(strings.TrimSpace(s.cfg.AdminCookieSecureMode)) {
	case "0", "false", "no", "off":
		return false
	case "1", "true", "yes", "on":
		return true
	case "", "auto":
		return requestIsHTTPS(r)
	default:
		return true
	}
}
func (s *Service) setAdminCookie(w http.ResponseWriter, r *http.Request, value string, ttl time.Duration) {
	http.SetCookie(w, &http.Cookie{Name: adminCookie, Value: value, Path: "/", HttpOnly: true, Secure: s.adminCookieSecure(r), SameSite: http.SameSiteStrictMode, MaxAge: int(ttl.Seconds()), Expires: time.Now().UTC().Add(ttl)})
}
func (s *Service) clearAdminCookie(w http.ResponseWriter, r *http.Request) {
	http.SetCookie(w, &http.Cookie{Name: adminCookie, Value: "", Path: "/", HttpOnly: true, Secure: s.adminCookieSecure(r), SameSite: http.SameSiteStrictMode, MaxAge: -1, Expires: time.Unix(1, 0).UTC()})
}
func (s *Service) requireAdmin(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		c, err := r.Cookie(adminCookie)
		if err != nil {
			jsonOut(w, 401, map[string]string{"error": "unauthorized"})
			return
		}
		v, ok := s.adminSessions.Load(c.Value)
		exp, _ := v.(time.Time)
		if !ok || time.Now().After(exp) {
			s.adminSessions.Delete(c.Value)
			jsonOut(w, 401, map[string]string{"error": "unauthorized"})
			return
		}
		next.ServeHTTP(w, r)
	})
}

func (s *Service) AdminRoutes(ui http.Handler) http.Handler {
	r := chi.NewRouter()
	r.Use(s.security)
	r.Post("/api/admin/login", s.adminLogin)
	r.Post("/api/admin/logout", s.adminLogout)
	r.Group(func(r chi.Router) {
		r.Use(s.requireAdmin)
		r.Get("/api/admin/overview", s.adminOverview)
		r.Post("/api/admin/workers/{id}/start", s.adminStart)
		r.Post("/api/admin/workers/{id}/stop", s.adminStop)
		r.Post("/api/admin/workers/{id}/restart", s.adminRestart)
		r.Post("/api/admin/workers/stop-all", s.adminStopAll)
		r.Post("/api/admin/image/pull", s.adminPullImage)
	})
	r.Mount("/", ui)
	return r
}
func (s *Service) adminLogin(w http.ResponseWriter, r *http.Request) {
	var in struct{ Username, Password string }
	if decode(r, &in, 64<<10) != nil {
		jsonOut(w, 400, map[string]string{"error": "bad json"})
		return
	}
	if subtle.ConstantTimeCompare([]byte(in.Username), []byte(s.cfg.AdminUser)) != 1 || subtle.ConstantTimeCompare([]byte(in.Password), []byte(s.cfg.AdminPassword)) != 1 {
		time.Sleep(250 * time.Millisecond)
		jsonOut(w, 401, map[string]string{"error": "invalid credentials"})
		return
	}
	sid := customer.RandomToken(32)
	s.adminSessions.Store(sid, time.Now().Add(12*time.Hour))
	s.setAdminCookie(w, r, sid, 12*time.Hour)
	jsonOut(w, 200, map[string]bool{"ok": true})
}
func (s *Service) adminLogout(w http.ResponseWriter, r *http.Request) {
	if c, err := r.Cookie(adminCookie); err == nil {
		s.adminSessions.Delete(c.Value)
	}
	s.clearAdminCookie(w, r)
	jsonOut(w, 200, map[string]bool{"ok": true})
}
func (s *Service) adminOverview(w http.ResponseWriter, r *http.Request) {
	items, err := s.docker.ManagedContainers(r.Context())
	if err != nil {
		jsonOut(w, 502, map[string]string{"error": err.Error()})
		return
	}
	total, running := 0, 0
	var workers []customer.ManagedContainer
	for _, item := range items {
		if item.WorkerID == "" {
			continue
		}
		total++
		if item.Running {
			running++
		}
		workers = append(workers, item)
	}
	regOK, regAt, regErr := s.registrationStatus()
	jsonOut(w, 200, map[string]any{"controller": map[string]any{"id": s.cfg.ID, "name": s.cfg.Name, "advertise_url": s.cfg.AdvertiseURL, "master_url": s.cfg.MasterURL, "max_workers": s.cfg.MaxWorkers, "max_running": s.cfg.MaxRunning, "worker_image": s.cfg.DefaultWorkerImage, "master_connected": regOK, "master_last_attempt": regAt, "master_last_error": regErr}, "workers": workers, "total": total, "running": running})
}
func (s *Service) adminStart(w http.ResponseWriter, r *http.Request) {
	if err := s.docker.Start(r.Context(), chi.URLParam(r, "id")); err != nil {
		jsonOut(w, 502, map[string]string{"error": err.Error()})
		return
	}
	jsonOut(w, 200, map[string]bool{"ok": true})
}
func (s *Service) adminStop(w http.ResponseWriter, r *http.Request) {
	if err := s.docker.Stop(r.Context(), chi.URLParam(r, "id"), 5); err != nil && !strings.Contains(err.Error(), "304") {
		jsonOut(w, 502, map[string]string{"error": err.Error()})
		return
	}
	jsonOut(w, 200, map[string]bool{"ok": true})
}
func (s *Service) adminRestart(w http.ResponseWriter, r *http.Request) {
	id := chi.URLParam(r, "id")
	_ = s.docker.Stop(r.Context(), id, 5)
	if err := s.docker.Start(r.Context(), id); err != nil {
		jsonOut(w, 502, map[string]string{"error": err.Error()})
		return
	}
	jsonOut(w, 200, map[string]bool{"ok": true})
}
func (s *Service) adminStopAll(w http.ResponseWriter, r *http.Request) {
	items, err := s.docker.ManagedContainers(r.Context())
	if err != nil {
		jsonOut(w, 502, map[string]string{"error": err.Error()})
		return
	}
	stopped := 0
	var warnings []string
	for _, item := range items {
		if item.WorkerID == "" || !item.Running {
			continue
		}
		if err := s.docker.Stop(r.Context(), item.ID, 5); err != nil && !strings.Contains(err.Error(), "304") {
			warnings = append(warnings, item.WorkerID+": "+err.Error())
			continue
		}
		stopped++
	}
	jsonOut(w, 200, map[string]any{"ok": len(warnings) == 0, "stopped": stopped, "warnings": warnings})
}
func (s *Service) adminPullImage(w http.ResponseWriter, r *http.Request) {
	image := strings.TrimSpace(s.cfg.DefaultWorkerImage)
	if image == "" {
		jsonOut(w, 400, map[string]string{"error": "SC_WORKER_IMAGE is empty"})
		return
	}
	auth, err := customer.RegistryAuthHeader(s.cfg.RegistryUsername, s.cfg.RegistryPassword, s.cfg.RegistryServer)
	if err != nil {
		jsonOut(w, 400, map[string]string{"error": err.Error()})
		return
	}
	if err := s.docker.PullImage(r.Context(), image, auth); err != nil {
		jsonOut(w, 502, map[string]string{"error": err.Error()})
		return
	}
	jsonOut(w, 200, map[string]any{"ok": true, "image": image})
}

func (s *Service) setRegistrationStatus(ok bool, err error) {
	s.regMu.Lock()
	defer s.regMu.Unlock()
	s.lastRegOK = ok
	s.lastRegAt = time.Now().UTC()
	if err != nil {
		s.lastRegErr = err.Error()
	} else {
		s.lastRegErr = ""
	}
}

func (s *Service) registrationStatus() (bool, time.Time, string) {
	s.regMu.RLock()
	defer s.regMu.RUnlock()
	return s.lastRegOK, s.lastRegAt, s.lastRegErr
}

func (s *Service) registerOnce(ctx context.Context) error {
	total, running, err := s.counts(ctx)
	if err != nil {
		return err
	}
	payload := map[string]any{"id": s.cfg.ID, "name": s.cfg.Name, "base_url": strings.TrimRight(s.cfg.AdvertiseURL, "/"), "protocol_version": 1, "max_workers": s.cfg.MaxWorkers, "max_running": s.cfg.MaxRunning, "reported_workers": total, "reported_running": running}
	b, _ := json.Marshal(payload)
	endpoint := strings.TrimRight(s.cfg.MasterURL, "/") + "/internal/controllers/register"
	req, err := http.NewRequestWithContext(ctx, http.MethodPost, endpoint, bytes.NewReader(b))
	if err != nil {
		return err
	}
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("Authorization", "Bearer "+s.cfg.SharedSecret)
	resp, err := s.hc.Do(req)
	if err != nil {
		return err
	}
	defer resp.Body.Close()
	body, _ := io.ReadAll(io.LimitReader(resp.Body, 16<<10))
	if resp.StatusCode/100 != 2 {
		return fmt.Errorf("master register HTTP %d: %s", resp.StatusCode, strings.TrimSpace(string(body)))
	}
	return nil
}

func (s *Service) RunRegistration(ctx context.Context) {
	ticker := time.NewTicker(s.cfg.HeartbeatInterval)
	defer ticker.Stop()
	for {
		callCtx, cancel := context.WithTimeout(ctx, 8*time.Second)
		err := s.registerOnce(callCtx)
		cancel()
		s.setRegistrationStatus(err == nil, err)
		if err != nil && !errors.Is(err, context.Canceled) {
			log.Printf("service-controller registration: %v", err)
		}
		select {
		case <-ctx.Done():
			return
		case <-ticker.C:
		}
	}
}

func ValidateConfig(cfg Config) error {
	if strings.TrimSpace(cfg.ID) == "" {
		return errors.New("SC_ID is required and must remain stable for this host")
	}
	if strings.TrimSpace(cfg.MasterURL) == "" {
		return errors.New("SC_MASTER_URL is required")
	}
	if strings.TrimSpace(cfg.AdvertiseURL) == "" {
		return errors.New("SC_ADVERTISE_URL is required")
	}
	for _, raw := range []string{cfg.MasterURL, cfg.AdvertiseURL} {
		u, err := url.Parse(raw)
		if err != nil || u.Host == "" || (u.Scheme != "http" && u.Scheme != "https") {
			return fmt.Errorf("invalid controller URL %q", raw)
		}
	}
	secret := strings.TrimSpace(cfg.SharedSecret)
	if len(secret) < 32 || strings.Contains(strings.ToLower(secret), "replace-with") || strings.Contains(strings.ToLower(secret), "change-me") {
		return errors.New("SERVICE_CONTROLLER_SHARED_SECRET must be a unique random value of at least 32 characters")
	}
	adminPass := strings.TrimSpace(cfg.AdminPassword)
	if len(adminPass) < 16 || strings.Contains(strings.ToLower(adminPass), "replace-with") || strings.Contains(strings.ToLower(adminPass), "change-me") {
		return errors.New("SC_ADMIN_PASSWORD must be a unique value of at least 16 characters")
	}
	return nil
}