package notify

import (
	"bytes"
	"encoding/json"
	"fmt"
	"io"
	"log"
	"net/http"
	"strings"
	"sync"
	"time"

	"gitea.dooplex.hu/admin/felhom-controller/internal/settings"
)

// Notifier sends notification events to the hub relay service.
// Non-blocking: fires requests in goroutines, logs errors but doesn't retry aggressively.
type Notifier struct {
	hubURL     string
	apiKey     string
	customerID string
	httpClient *http.Client
	logger     *log.Logger
	enabled    bool
	settings   *settings.Settings

	mu        sync.Mutex
	cooldowns map[string]time.Time // event_type -> last notification time

	// prevHealthStatus tracks the previous health check status for change detection
	prevHealthStatus string
}

// New creates a new Notifier. Returns a no-op notifier if hub is not enabled.
func New(hubURL, apiKey, customerID string, sett *settings.Settings, logger *log.Logger) *Notifier {
	enabled := hubURL != "" && apiKey != ""
	if enabled {
		logger.Printf("[INFO] Notifier enabled (hub: %s)", hubURL)
	} else {
		logger.Printf("[INFO] Notifier disabled (hub not configured)")
	}

	return &Notifier{
		hubURL:     hubURL,
		apiKey:     apiKey,
		customerID: customerID,
		httpClient: &http.Client{Timeout: 10 * time.Second},
		logger:     logger,
		enabled:    enabled,
		settings:   sett,
		cooldowns:  make(map[string]time.Time),
	}
}

// IsEnabled returns whether the notifier has a configured hub connection.
func (n *Notifier) IsEnabled() bool {
	return n.enabled
}

// preferencesRequest is the JSON payload sent to the hub preferences endpoint.
type preferencesRequest struct {
	CustomerID    string   `json:"customer_id"`
	Email         string   `json:"email"`
	EnabledEvents []string `json:"enabled_events"`
}

// SyncPreferences pushes the current notification preferences to the hub.
// Called after the user saves notification settings on the settings page.
// Synchronous — returns error for the handler to display to the user.
func (n *Notifier) SyncPreferences(email string, enabledEvents []string) error {
	if !n.enabled {
		return fmt.Errorf("hub nem konfigurált")
	}

	payload := preferencesRequest{
		CustomerID:    n.customerID,
		Email:         email,
		EnabledEvents: enabledEvents,
	}

	jsonData, err := json.Marshal(payload)
	if err != nil {
		return fmt.Errorf("marshal: %w", err)
	}

	url := n.hubURL + "/api/v1/preferences"
	req, err := http.NewRequest("POST", url, bytes.NewReader(jsonData))
	if err != nil {
		return fmt.Errorf("request: %w", err)
	}
	req.Header.Set("Authorization", "Bearer "+n.apiKey)
	req.Header.Set("Content-Type", "application/json")

	resp, err := n.httpClient.Do(req)
	if err != nil {
		return fmt.Errorf("hub elérhetetlen: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode >= 400 {
		body, _ := io.ReadAll(io.LimitReader(resp.Body, 512))
		return fmt.Errorf("hub hiba (%d): %s", resp.StatusCode, string(body))
	}

	n.logger.Printf("[INFO] Notification preferences synced to hub: email=%s, events=%v", email, enabledEvents)
	return nil
}

// notifyRequest is the JSON payload sent to the hub.
type notifyRequest struct {
	CustomerID string `json:"customer_id"`
	EventType  string `json:"event_type"`
	Severity   string `json:"severity"`
	Message    string `json:"message"`
	Details    string `json:"details,omitempty"`
}

// Notify sends a notification event to the hub relay.
// Checks local cooldown and event preferences before sending.
// Non-blocking: fires the HTTP request in a goroutine.
func (n *Notifier) Notify(eventType, severity, message, details string) {
	if !n.enabled {
		return
	}

	prefs := n.settings.GetNotificationPrefs()
	if prefs.Email == "" {
		return // No email configured, skip
	}

	// Check if event is enabled in preferences
	eventEnabled := false
	for _, e := range prefs.EnabledEvents {
		if e == eventType {
			eventEnabled = true
			break
		}
	}
	if !eventEnabled {
		return
	}

	// Check cooldown
	cooldownDuration := time.Duration(prefs.CooldownHours) * time.Hour
	if cooldownDuration == 0 {
		cooldownDuration = 6 * time.Hour
	}

	n.mu.Lock()
	lastSent, exists := n.cooldowns[eventType]
	if exists && time.Since(lastSent) < cooldownDuration {
		n.mu.Unlock()
		n.logger.Printf("[DEBUG] Notification cooldown active for %s (sent %s ago)", eventType, time.Since(lastSent).Round(time.Minute))
		return
	}
	n.cooldowns[eventType] = time.Now()
	n.mu.Unlock()

	// Fire the notification in a goroutine (non-blocking)
	go func() {
		payload := notifyRequest{
			CustomerID: n.customerID,
			EventType:  eventType,
			Severity:   severity,
			Message:    message,
			Details:    details,
		}

		jsonData, err := json.Marshal(payload)
		if err != nil {
			n.logger.Printf("[ERROR] Failed to marshal notification: %v", err)
			return
		}

		url := n.hubURL + "/api/v1/notify"
		req, err := http.NewRequest("POST", url, bytes.NewReader(jsonData))
		if err != nil {
			n.logger.Printf("[ERROR] Failed to create notification request: %v", err)
			return
		}
		req.Header.Set("Authorization", "Bearer "+n.apiKey)
		req.Header.Set("Content-Type", "application/json")

		resp, err := n.httpClient.Do(req)
		if err != nil {
			n.logger.Printf("[WARN] Failed to send notification to hub: %v", err)
			return
		}
		defer resp.Body.Close()

		if resp.StatusCode >= 400 {
			n.logger.Printf("[WARN] Hub notification returned %d for %s/%s", resp.StatusCode, eventType, severity)
			return
		}

		n.logger.Printf("[INFO] Notification sent: %s (%s) — %s", eventType, severity, message)
	}()
}

// NotifyHealthChange checks if health status changed and sends appropriate notifications.
// Call this after each health check with the new report status/issues/warnings.
func (n *Notifier) NotifyHealthChange(status string, issues, warnings []string) {
	if !n.enabled {
		return
	}

	prev := n.prevHealthStatus
	n.prevHealthStatus = status

	// Only notify on status degradation (ok→warn, ok→fail, warn→fail)
	if prev == "" {
		return // First run, just record status
	}
	if statusRank(status) <= statusRank(prev) {
		return // Status improved or stayed the same
	}

	// Notify about each issue/warning
	for _, issue := range issues {
		n.Notify("container_unhealthy", "critical", issue, "")
	}
	for _, w := range warnings {
		// Determine specific event type from warning message
		eventType := classifyWarning(w)
		n.Notify(eventType, "warning", w, "")
	}
}

// NotifyBackupFailed sends a notification about a backup failure.
func (n *Notifier) NotifyBackupFailed(message, details string) {
	n.Notify("backup_failed", "critical", message, details)
}

// NotifyDBDumpFailed sends a notification about a database dump failure.
func (n *Notifier) NotifyDBDumpFailed(message, details string) {
	n.Notify("db_dump_failed", "critical", message, details)
}

// NotifyIntegrityFailed sends a notification about a backup integrity check failure.
func (n *Notifier) NotifyIntegrityFailed(message, details string) {
	n.Notify("integrity_failed", "warning", message, details)
}

// NotifyUpdateSuccess sends a notification about a successful controller update.
func (n *Notifier) NotifyUpdateSuccess(fromVer, toVer string) {
	n.Notify("update_success", "info",
		fmt.Sprintf("Controller frissítve: %s → %s", fromVer, toVer), "")
}

// NotifyUpdateFailed sends a notification about a failed controller update.
func (n *Notifier) NotifyUpdateFailed(targetVer, errMsg string) {
	n.Notify("update_failed", "warning",
		fmt.Sprintf("Controller frissítés sikertelen: %s — %s", targetVer, errMsg), "")
}

// SendTest sends a test notification for verifying the notification flow.
func (n *Notifier) SendTest() error {
	if !n.enabled {
		return fmt.Errorf("notifications not enabled (hub not configured)")
	}

	payload := notifyRequest{
		CustomerID: n.customerID,
		EventType:  "test",
		Severity:   "info",
		Message:    "Teszt értesítés a Felhom rendszerből",
		Details:    "Ha ezt az emailt megkapta, az értesítések megfelelően működnek.",
	}

	jsonData, err := json.Marshal(payload)
	if err != nil {
		return fmt.Errorf("marshal: %w", err)
	}

	url := n.hubURL + "/api/v1/notify"
	req, err := http.NewRequest("POST", url, bytes.NewReader(jsonData))
	if err != nil {
		return fmt.Errorf("request: %w", err)
	}
	req.Header.Set("Authorization", "Bearer "+n.apiKey)
	req.Header.Set("Content-Type", "application/json")

	resp, err := n.httpClient.Do(req)
	if err != nil {
		return fmt.Errorf("send: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode >= 400 {
		return fmt.Errorf("hub returned %d", resp.StatusCode)
	}

	return nil
}

func statusRank(status string) int {
	switch status {
	case "ok":
		return 0
	case "warn":
		return 1
	case "fail":
		return 2
	default:
		return 0
	}
}

func classifyWarning(message string) string {
	// Try to classify the warning message into a specific event type
	switch {
	case contains(message, "disk") || contains(message, "Disk") || contains(message, "SSD") || contains(message, "HDD"):
		if contains(message, "critical") || contains(message, "Critical") {
			return "disk_critical"
		}
		return "disk_warning"
	case contains(message, "Memory") || contains(message, "memory"):
		return "disk_warning" // group memory under system warnings
	case contains(message, "Temperature") || contains(message, "temperature"):
		return "disk_warning" // group temp under system warnings
	case contains(message, "container") || contains(message, "Container"):
		return "container_unhealthy"
	default:
		return "disk_warning" // fallback to generic system warning
	}
}

func contains(s, substr string) bool {
	return strings.Contains(s, substr)
}