// app/admin/admin.go
// Admin API handlers for shared-sqs management
// Created: 2026-04-09
// Updated: 2026-04-10 — добавлены endpoints для управления очередями и просмотра сообщений
package admin

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

	"shared-sqs/app/models"
	"shared-sqs/app/tenant"

	"github.com/google/uuid"
	"github.com/gorilla/mux"
	log "github.com/sirupsen/logrus"
)

// ─── вспомогательная функция: найти очередь тенанта по имени ───────────────
// findQueue — возвращает ключ и очередь тенанта по имени, или "",nil если не найдено.
func findQueue(tenantAccessKey, queueName string) (string, *models.Queue) {
	key := tenantAccessKey + ":" + queueName
	models.SyncQueues.RLock()
	q, ok := models.SyncQueues.Queues[key]
	models.SyncQueues.RUnlock()
	if !ok {
		return "", nil
	}
	return key, q
}

// Handler — admin API handler, holds TenantStore и admin token
type Handler struct {
	store      *tenant.TenantStore
	adminToken string
}

// NewHandler — создаёт admin handler
func NewHandler(store *tenant.TenantStore, adminToken string) *Handler {
	return &Handler{store: store, adminToken: adminToken}
}

// RegisterRoutes — регистрирует admin маршруты на переданном router (с bearer auth)
func (h *Handler) RegisterRoutes(r *mux.Router) {
	adminRouter := r.PathPrefix("/admin").Subrouter()
	adminRouter.Use(h.bearerAuthMiddleware)
	adminRouter.HandleFunc("/tenants", h.createTenant).Methods("POST")
	adminRouter.HandleFunc("/tenants", h.listTenants).Methods("GET")
	adminRouter.HandleFunc("/tenants/{id}", h.getTenant).Methods("GET")
	adminRouter.HandleFunc("/tenants/{id}", h.deleteTenant).Methods("DELETE")
	adminRouter.HandleFunc("/tenants/{id}/queues", h.listTenantQueues).Methods("GET")
	adminRouter.HandleFunc("/tenants/{id}/queues", h.createTenantQueue).Methods("POST")
	adminRouter.HandleFunc("/tenants/{id}/queues/{queue}", h.deleteTenantQueue).Methods("DELETE")
	adminRouter.HandleFunc("/tenants/{id}/queues/{queue}/messages", h.peekQueueMessages).Methods("GET")
	adminRouter.HandleFunc("/tenants/{id}/queues/{queue}/messages", h.sendMessageToQueue).Methods("POST")
	adminRouter.HandleFunc("/tenants/{id}/queues/{queue}/messages", h.purgeQueue).Methods("DELETE")
	adminRouter.HandleFunc("/health", h.detailedHealth).Methods("GET")
}

// RegisterPublicRoutes — публичные маршруты для UI console (без auth)
// Дублируют admin API, но доступны без bearer token для удобства демо
// TODO: убрать или заменить на session-auth перед production
func (h *Handler) RegisterPublicRoutes(r *mux.Router) {
	ui := r.PathPrefix("/ui/api").Subrouter()
	ui.HandleFunc("/health", h.detailedHealth).Methods("GET")
	ui.HandleFunc("/tenants", h.listTenants).Methods("GET")
	ui.HandleFunc("/tenants", h.createTenant).Methods("POST")
	ui.HandleFunc("/tenants/{id}", h.getTenant).Methods("GET")
	ui.HandleFunc("/tenants/{id}", h.deleteTenant).Methods("DELETE")
	ui.HandleFunc("/tenants/{id}/queues", h.listTenantQueues).Methods("GET")
	ui.HandleFunc("/tenants/{id}/queues", h.createTenantQueue).Methods("POST")
	ui.HandleFunc("/tenants/{id}/queues/{queue}", h.deleteTenantQueue).Methods("DELETE")
	ui.HandleFunc("/tenants/{id}/queues/{queue}/messages", h.peekQueueMessages).Methods("GET")
	ui.HandleFunc("/tenants/{id}/queues/{queue}/messages", h.sendMessageToQueue).Methods("POST")
	ui.HandleFunc("/tenants/{id}/queues/{queue}/messages", h.purgeQueue).Methods("DELETE")
}

// bearerAuthMiddleware — проверяет Bearer token для admin API (Trap #12)
func (h *Handler) bearerAuthMiddleware(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		authHeader := r.Header.Get("Authorization")
		expected := "Bearer " + h.adminToken
		if authHeader != expected {
			w.Header().Set("Content-Type", "application/json")
			w.WriteHeader(http.StatusUnauthorized)
			json.NewEncoder(w).Encode(map[string]string{"error": "unauthorized"})
			return
		}
		next.ServeHTTP(w, r)
	})
}

// createTenantRequest — тело запроса POST /admin/tenants
type createTenantRequest struct {
	Name      string `json:"name"`
	MaxQueues int    `json:"max_queues"`
}

// tenantCreateResponse — ответ с secret_key (показывается ТОЛЬКО при создании)
type tenantCreateResponse struct {
	ID        string    `json:"id"`
	Name      string    `json:"name"`
	AccessKey string    `json:"access_key"`
	SecretKey string    `json:"secret_key"`
	MaxQueues int       `json:"max_queues"`
	CreatedAt time.Time `json:"created_at"`
	Active    bool      `json:"active"`
}

// tenantListItem — данные тенанта без secret_key (для List/Get)
type tenantListItem struct {
	ID        string    `json:"id"`
	Name      string    `json:"name"`
	AccessKey string    `json:"access_key"`
	MaxQueues int       `json:"max_queues"`
	CreatedAt time.Time `json:"created_at"`
	Active    bool      `json:"active"`
}

// createTenant — POST /admin/tenants
func (h *Handler) createTenant(w http.ResponseWriter, r *http.Request) {
	var req createTenantRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		w.Header().Set("Content-Type", "application/json")
		w.WriteHeader(http.StatusBadRequest)
		json.NewEncoder(w).Encode(map[string]string{"error": "invalid request body"})
		return
	}
	if req.Name == "" {
		w.Header().Set("Content-Type", "application/json")
		w.WriteHeader(http.StatusBadRequest)
		json.NewEncoder(w).Encode(map[string]string{"error": "name is required"})
		return
	}
	t, err := h.store.Create(req.Name, req.MaxQueues)
	if err != nil {
		log.Errorf("admin: failed to create tenant: %v", err)
		w.Header().Set("Content-Type", "application/json")
		w.WriteHeader(http.StatusInternalServerError)
		json.NewEncoder(w).Encode(map[string]string{"error": "failed to create tenant"})
		return
	}
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(http.StatusCreated)
	json.NewEncoder(w).Encode(tenantCreateResponse{
		ID:        t.ID,
		Name:      t.Name,
		AccessKey: t.AccessKey,
		SecretKey: t.SecretKey,
		MaxQueues: t.MaxQueues,
		CreatedAt: t.CreatedAt,
		Active:    t.Active,
	})
}

// listTenants — GET /admin/tenants
func (h *Handler) listTenants(w http.ResponseWriter, r *http.Request) {
	tenants := h.store.List()
	items := make([]tenantListItem, 0, len(tenants))
	for _, t := range tenants {
		items = append(items, tenantListItem{
			ID:        t.ID,
			Name:      t.Name,
			AccessKey: t.AccessKey,
			MaxQueues: t.MaxQueues,
			CreatedAt: t.CreatedAt,
			Active:    t.Active,
		})
	}
	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(items)
}

// getTenant — GET /admin/tenants/{id}
func (h *Handler) getTenant(w http.ResponseWriter, r *http.Request) {
	vars := mux.Vars(r)
	id := vars["id"]
	t, ok := h.store.GetByID(id)
	if !ok {
		w.Header().Set("Content-Type", "application/json")
		w.WriteHeader(http.StatusNotFound)
		json.NewEncoder(w).Encode(map[string]string{"error": "tenant not found"})
		return
	}
	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(tenantListItem{
		ID:        t.ID,
		Name:      t.Name,
		AccessKey: t.AccessKey,
		MaxQueues: t.MaxQueues,
		CreatedAt: t.CreatedAt,
		Active:    t.Active,
	})
}

// deleteTenant — DELETE /admin/tenants/{id}
// Удаляет тенанта И ВСЕ его очереди из SyncQueues (Trap #11: иначе memory leak)
func (h *Handler) deleteTenant(w http.ResponseWriter, r *http.Request) {
	vars := mux.Vars(r)
	id := vars["id"]
	t, ok := h.store.GetByID(id)
	if !ok {
		w.Header().Set("Content-Type", "application/json")
		w.WriteHeader(http.StatusNotFound)
		json.NewEncoder(w).Encode(map[string]string{"error": "tenant not found"})
		return
	}
	// Удаляем все очереди тенанта из SyncQueues
	prefix := t.AccessKey + ":"
	models.SyncQueues.Lock()
	for key := range models.SyncQueues.Queues {
		if strings.HasPrefix(key, prefix) {
			delete(models.SyncQueues.Queues, key)
		}
	}
	models.SyncQueues.Unlock()

	h.store.Delete(id)
	w.WriteHeader(http.StatusNoContent)
}

// listTenantQueues — GET /admin/tenants/{id}/queues
// Возвращает список очередей тенанта с количеством сообщений.
func (h *Handler) listTenantQueues(w http.ResponseWriter, r *http.Request) {
	vars := mux.Vars(r)
	id := vars["id"]
	t, ok := h.store.GetByID(id)
	if !ok {
		w.Header().Set("Content-Type", "application/json")
		w.WriteHeader(http.StatusNotFound)
		json.NewEncoder(w).Encode(map[string]string{"error": "tenant not found"})
		return
	}
	prefix := t.AccessKey + ":"
	type queueInfo struct {
		Name              string `json:"name"`
		Messages          int    `json:"messages"`
		NotVisible        int    `json:"not_visible"`
		VisibilityTimeout int    `json:"visibility_timeout"`
		MaxMessageSize    int    `json:"max_message_size"`
		RetentionPeriod   int    `json:"retention_period"`
	}
	queues := make([]queueInfo, 0)
	models.SyncQueues.RLock()
	for key, q := range models.SyncQueues.Queues {
		if strings.HasPrefix(key, prefix) {
			name := strings.TrimPrefix(key, prefix)
			visible := 0
			notVisible := 0
			for _, msg := range q.Messages {
				if msg.ReceiptHandle != "" {
					notVisible++
				} else {
					visible++
				}
			}
			queues = append(queues, queueInfo{
				Name:              name,
				Messages:          visible,
				NotVisible:        notVisible,
				VisibilityTimeout: q.VisibilityTimeout,
				MaxMessageSize:    q.MaximumMessageSize,
				RetentionPeriod:   q.MessageRetentionPeriod,
			})
		}
	}
	models.SyncQueues.RUnlock()
	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(queues)
}

// ─── QUEUE MANAGEMENT HANDLERS ────────────────────────────────────────────

// createQueueRequest — тело запроса POST .../queues
type createQueueRequest struct {
	Name string `json:"name"`
}

// createTenantQueue — POST /admin/tenants/{id}/queues
// Создаёт новую очередь для тенанта прямо в SyncQueues (без SQS-протокола).
// Проверяет лимит MaxQueues тенанта и уникальность имени.
func (h *Handler) createTenantQueue(w http.ResponseWriter, r *http.Request) {
	vars := mux.Vars(r)
	tid := vars["id"]
	t, ok := h.store.GetByID(tid)
	if !ok {
		jsonErr(w, http.StatusNotFound, "tenant not found")
		return
	}
	var req createQueueRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil || req.Name == "" {
		jsonErr(w, http.StatusBadRequest, "name is required")
		return
	}
	key := t.AccessKey + ":" + req.Name
	models.SyncQueues.Lock()
	if _, exists := models.SyncQueues.Queues[key]; exists {
		models.SyncQueues.Unlock()
		jsonErr(w, http.StatusConflict, "queue already exists")
		return
	}
	// Проверяем лимит очередей тенанта
	count := 0
	for k := range models.SyncQueues.Queues {
		if strings.HasPrefix(k, t.AccessKey+":") {
			count++
		}
	}
	if t.MaxQueues > 0 && count >= t.MaxQueues {
		models.SyncQueues.Unlock()
		jsonErr(w, http.StatusForbidden, "queue limit exceeded")
		return
	}
	models.SyncQueues.Queues[key] = &models.Queue{
		Name:                   req.Name,
		VisibilityTimeout:      30,
		MaximumMessageSize:     262144,
		MessageRetentionPeriod: 345600,
		Messages:               []models.SqsMessage{},
		Duplicates:             make(map[string]time.Time),
	}
	models.SyncQueues.Unlock()
	log.Infof("admin: created queue %s for tenant %s", req.Name, t.ID)
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(http.StatusCreated)
	json.NewEncoder(w).Encode(map[string]string{"name": req.Name, "status": "created"})
}

// deleteTenantQueue — DELETE /admin/tenants/{id}/queues/{queue}
// Удаляет очередь тенанта из SyncQueues вместе со всеми её сообщениями.
func (h *Handler) deleteTenantQueue(w http.ResponseWriter, r *http.Request) {
	vars := mux.Vars(r)
	tid, queueName := vars["id"], vars["queue"]
	t, ok := h.store.GetByID(tid)
	if !ok {
		jsonErr(w, http.StatusNotFound, "tenant not found")
		return
	}
	key := t.AccessKey + ":" + queueName
	models.SyncQueues.Lock()
	if _, exists := models.SyncQueues.Queues[key]; !exists {
		models.SyncQueues.Unlock()
		jsonErr(w, http.StatusNotFound, "queue not found")
		return
	}
	delete(models.SyncQueues.Queues, key)
	models.SyncQueues.Unlock()
	log.Infof("admin: deleted queue %s for tenant %s", queueName, t.ID)
	w.WriteHeader(http.StatusNoContent)
}

// peekMessageItem — одно сообщение в ответе peekQueueMessages (без receipt handle)
type peekMessageItem struct {
	ID       string `json:"id"`
	Body     string `json:"body"`
	MD5      string `json:"md5"`
	SentAt   string `json:"sent_at"`
	Receives int    `json:"receives"`
	InFlight bool   `json:"in_flight"`
}

// peekQueueMessages — GET /admin/tenants/{id}/queues/{queue}/messages?limit=50
// Peek-просмотр сообщений: НЕ удаляет, НЕ выставляет ReceiptHandle — только чтение.
// Это принципиальное отличие от SQS ReceiveMessage (который скрывает сообщения).
func (h *Handler) peekQueueMessages(w http.ResponseWriter, r *http.Request) {
	vars := mux.Vars(r)
	tid, queueName := vars["id"], vars["queue"]
	t, ok := h.store.GetByID(tid)
	if !ok {
		jsonErr(w, http.StatusNotFound, "tenant not found")
		return
	}
	_, q := findQueue(t.AccessKey, queueName)
	if q == nil {
		jsonErr(w, http.StatusNotFound, "queue not found")
		return
	}
	// Лимит по умолчанию 50, максимум 1000
	limit := 50
	if lv := r.URL.Query().Get("limit"); lv != "" {
		if n := 0; len(lv) > 0 {
			for _, c := range lv {
				if c < '0' || c > '9' {
					n = -1
					break
				}
				n = n*10 + int(c-'0')
			}
			if n > 0 && n <= 1000 {
				limit = n
			}
		}
	}
	models.SyncQueues.RLock()
	result := make([]peekMessageItem, 0, len(q.Messages))
	for i, msg := range q.Messages {
		if i >= limit {
			break
		}
		result = append(result, peekMessageItem{
			ID:       msg.Uuid,
			Body:     msg.MessageBody,
			MD5:      msg.MD5OfMessageBody,
			SentAt:   msg.SentTime.Format(time.RFC3339),
			Receives: msg.NumberOfReceives,
			InFlight: msg.ReceiptHandle != "",
		})
	}
	models.SyncQueues.RUnlock()
	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(result)
}

// sendMessageRequest — тело запроса POST .../messages
type sendMessageRequest struct {
	Body string `json:"body"`
}

// sendMessageToQueue — POST /admin/tenants/{id}/queues/{queue}/messages
// Отправляет сообщение напрямую в очередь минуя SQS-протокол.
// Используется только из UI console — для prod нужен нормальный SQS send.
func (h *Handler) sendMessageToQueue(w http.ResponseWriter, r *http.Request) {
	vars := mux.Vars(r)
	tid, queueName := vars["id"], vars["queue"]
	t, ok := h.store.GetByID(tid)
	if !ok {
		jsonErr(w, http.StatusNotFound, "tenant not found")
		return
	}
	key, q := findQueue(t.AccessKey, queueName)
	if q == nil {
		jsonErr(w, http.StatusNotFound, "queue not found")
		return
	}
	var req sendMessageRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil || req.Body == "" {
		jsonErr(w, http.StatusBadRequest, "body is required")
		return
	}
	msg := models.SqsMessage{
		MessageBody: req.Body,
		Uuid:        uuid.NewString(),
		SentTime:    time.Now(),
	}
	models.SyncQueues.Lock()
	models.SyncQueues.Queues[key].Messages = append(models.SyncQueues.Queues[key].Messages, msg)
	models.SyncQueues.Unlock()
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(http.StatusCreated)
	json.NewEncoder(w).Encode(map[string]string{"id": msg.Uuid, "status": "sent"})
}

// purgeQueue — DELETE /admin/tenants/{id}/queues/{queue}/messages
// Удаляет все сообщения из очереди (purge). Сама очередь остаётся.
func (h *Handler) purgeQueue(w http.ResponseWriter, r *http.Request) {
	vars := mux.Vars(r)
	tid, queueName := vars["id"], vars["queue"]
	t, ok := h.store.GetByID(tid)
	if !ok {
		jsonErr(w, http.StatusNotFound, "tenant not found")
		return
	}
	key, q := findQueue(t.AccessKey, queueName)
	if q == nil {
		jsonErr(w, http.StatusNotFound, "queue not found")
		return
	}
	models.SyncQueues.Lock()
	models.SyncQueues.Queues[key].Messages = models.SyncQueues.Queues[key].Messages[:0]
	models.SyncQueues.Unlock()
	log.Infof("admin: purged queue %s for tenant %s", queueName, t.ID)
	w.WriteHeader(http.StatusNoContent)
}

// jsonErr — вспомогательная функция: ответ с ошибкой в JSON
func jsonErr(w http.ResponseWriter, code int, msg string) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(code)
	json.NewEncoder(w).Encode(map[string]string{"error": msg})
}

// adminHealthDetail — ответ GET /admin/health
type adminHealthDetail struct {
	Status       string `json:"status"`
	TenantCount  int    `json:"tenant_count"`
	QueueCount   int    `json:"queue_count"`
	MessageCount int    `json:"message_count"`
}

// detailedHealth — GET /admin/health
func (h *Handler) detailedHealth(w http.ResponseWriter, r *http.Request) {
	tenants := h.store.List()
	models.SyncQueues.RLock()
	queueCount := len(models.SyncQueues.Queues)
	msgCount := 0
	for _, q := range models.SyncQueues.Queues {
		msgCount += len(q.Messages)
	}
	models.SyncQueues.RUnlock()

	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(adminHealthDetail{
		Status:       "ok",
		TenantCount:  len(tenants),
		QueueCount:   queueCount,
		MessageCount: msgCount,
	})
}