// Создано: 2026-04-06
// Изменено: 2026-04-12 (замена Kafka lag → SQS queue stats)
// iot_admin_stats_handler.go — handler для страницы администратора IoT.
//
// Endpoints:
//   GET /iot-admin/stats — JSON с агрегированной статистикой (защищён ADMIN_STATS_TOKEN)
//
// Источники данных:
//   - PostgreSQL (IoTPG): counts per tenant, last 1h/24h, latest rows
//   - SQS: approximate message count (ApproximateNumberOfMessages)
//   - K8s: статус подов iot-mqtt-bridge и iot-sqs-consumer
//
// Авторизация: Bearer из env ADMIN_STATS_TOKEN.
// Если ADMIN_STATS_TOKEN не задан — endpoint возвращает 503.

package handler

import (
	"context"
	"fmt"
	"net/http"
	"os"
	"strconv"
	"strings"
	"time"

	"github.com/aws/aws-sdk-go-v2/aws"
	"github.com/aws/aws-sdk-go-v2/credentials"
	"github.com/aws/aws-sdk-go-v2/service/sqs"
	sqstypes "github.com/aws/aws-sdk-go-v2/service/sqs/types"
	corev1 "k8s.io/api/core/v1"
	"sigs.k8s.io/controller-runtime/pkg/client"
)

// iotAdminPodStatus — краткая информация о k8s pod для страницы администратора.
type iotAdminPodStatus struct {
	Name     string `json:"name"`
	Phase    string `json:"phase"`
	Ready    bool   `json:"ready"`
	Restarts int32  `json:"restarts"`
	Age      string `json:"age"`
}

// iotAdminSQSStats — информация о SQS очереди для мониторинга.
type iotAdminSQSStats struct {
	ApproximateMessages           int64  `json:"approximate_messages"`
	ApproximateMessagesNotVisible int64  `json:"approximate_messages_not_visible"`
	Error                         string `json:"error,omitempty"`
}

// AdminStats обрабатывает GET /iot-admin/stats.
// Проверяет Bearer-токен из ADMIN_STATS_TOKEN, затем собирает и возвращает статистику.
func (h *Handler) AdminStats(w http.ResponseWriter, r *http.Request) {
	adminToken := os.Getenv("ADMIN_STATS_TOKEN")
	if adminToken == "" {
		writeJSON(w, http.StatusServiceUnavailable, errResp("admin stats not configured: ADMIN_STATS_TOKEN not set"))
		return
	}

	authHeader := r.Header.Get("Authorization")
	if !strings.HasPrefix(authHeader, "Bearer ") || strings.TrimPrefix(authHeader, "Bearer ") != adminToken {
		writeJSON(w, http.StatusUnauthorized, errResp("unauthorized"))
		return
	}

	ctx, cancel := context.WithTimeout(r.Context(), 15*time.Second)
	defer cancel()

	result := map[string]any{
		"collected_at": time.Now().UTC(),
	}

	// PostgreSQL: статистика по всем tenant
	if h.IoTPG != nil {
		pgStats, err := h.IoTPG.GetAdminStats(ctx)
		if err != nil {
			result["postgres"] = map[string]any{"reachable": false, "error": err.Error()}
		} else {
			result["postgres"] = pgStats
		}
	} else {
		result["postgres"] = map[string]any{"reachable": false, "error": "IoTPG not configured"}
	}

	// SQS: approximate message count для очереди iot-telemetry
	result["sqs"] = h.collectIotSQSStats(ctx)

	// K8s: статус подов bridge и consumer
	result["pods"] = h.collectIotPodStatuses(ctx)

	writeJSON(w, http.StatusOK, result)
}

// collectIotSQSStats получает ApproximateNumberOfMessages из SQS очереди.
// Использует SQS_ENDPOINT, SQS_ACCESS_KEY, SQS_SECRET_KEY, SQS_QUEUE_NAME из env.
func (h *Handler) collectIotSQSStats(ctx context.Context) iotAdminSQSStats {
	endpoint := os.Getenv("SQS_ENDPOINT")
	accessKey := os.Getenv("SQS_ACCESS_KEY")
	secretKey := os.Getenv("SQS_SECRET_KEY")
	queueName := os.Getenv("SQS_QUEUE_NAME")
	if queueName == "" {
		queueName = "iot-telemetry"
	}
	region := os.Getenv("SQS_REGION")
	if region == "" {
		region = "us-east-1"
	}

	if endpoint == "" || accessKey == "" || secretKey == "" {
		return iotAdminSQSStats{Error: "SQS credentials not configured (SQS_ENDPOINT, SQS_ACCESS_KEY, SQS_SECRET_KEY)"}
	}

	sqsClient := sqs.New(sqs.Options{
		Region: region,
		Credentials: credentials.NewStaticCredentialsProvider(
			accessKey, secretKey, "",
		),
		BaseEndpoint: aws.String(endpoint),
	})

	// Получаем URL очереди
	queueUrlOut, err := sqsClient.GetQueueUrl(ctx, &sqs.GetQueueUrlInput{
		QueueName: aws.String(queueName),
	})
	if err != nil {
		return iotAdminSQSStats{Error: fmt.Sprintf("GetQueueUrl: %v", err)}
	}

	// Запрашиваем атрибуты очереди — approximate message counts
	attrsOut, err := sqsClient.GetQueueAttributes(ctx, &sqs.GetQueueAttributesInput{
		QueueUrl: queueUrlOut.QueueUrl,
		AttributeNames: []sqstypes.QueueAttributeName{
			sqstypes.QueueAttributeNameApproximateNumberOfMessages,
			sqstypes.QueueAttributeNameApproximateNumberOfMessagesNotVisible,
		},
	})
	if err != nil {
		return iotAdminSQSStats{Error: fmt.Sprintf("GetQueueAttributes: %v", err)}
	}

	approxMsg, _ := strconv.ParseInt(attrsOut.Attributes["ApproximateNumberOfMessages"], 10, 64)
	approxNotVisible, _ := strconv.ParseInt(attrsOut.Attributes["ApproximateNumberOfMessagesNotVisible"], 10, 64)

	return iotAdminSQSStats{
		ApproximateMessages:           approxMsg,
		ApproximateMessagesNotVisible: approxNotVisible,
	}
}

// collectIotPodStatuses собирает статус k8s pods для bridge и consumer по label app={name}.
func (h *Handler) collectIotPodStatuses(ctx context.Context) map[string]any {
	result := map[string]any{}

	for _, appLabel := range []string{"iot-mqtt-bridge", "iot-sqs-consumer"} {
		podList := &corev1.PodList{}
		if err := h.K8s.List(ctx, podList,
			client.InNamespace("sless"),
			client.MatchingLabels{"app": appLabel},
		); err != nil {
			result[appLabel] = map[string]any{"error": err.Error()}
			continue
		}
		if len(podList.Items) == 0 {
			result[appLabel] = map[string]any{"status": "not found"}
			continue
		}

		pod := podList.Items[0]
		var restarts int32
		for _, cs := range pod.Status.ContainerStatuses {
			restarts += cs.RestartCount
		}
		ready := false
		for _, cond := range pod.Status.Conditions {
			if cond.Type == corev1.PodReady && cond.Status == corev1.ConditionTrue {
				ready = true
			}
		}

		result[appLabel] = iotAdminPodStatus{
			Name:     pod.Name,
			Phase:    string(pod.Status.Phase),
			Ready:    ready,
			Restarts: restarts,
			Age:      iotFormatAge(pod.CreationTimestamp.Time),
		}
	}

	return result
}

// iotFormatAge возвращает человекочитаемый возраст (s/m/h/d) pod-а.
func iotFormatAge(created time.Time) string {
	d := time.Since(created)
	switch {
	case d < time.Minute:
		return fmt.Sprintf("%ds", int(d.Seconds()))
	case d < time.Hour:
		return fmt.Sprintf("%dm", int(d.Minutes()))
	case d < 24*time.Hour:
		return fmt.Sprintf("%dh", int(d.Hours()))
	default:
		return fmt.Sprintf("%dd", int(d.Hours()/24))
	}
}