package web

import (
	"fmt"
	"log"
	"strings"
	"sync"

	"gitea.dooplex.hu/admin/felhom-controller/internal/backup"
	"gitea.dooplex.hu/admin/felhom-controller/internal/config"
	"gitea.dooplex.hu/admin/felhom-controller/internal/monitor"
)

// Alert represents a persistent dashboard alert banner.
type Alert struct {
	ID       string   // unique identifier for filtering
	Level    string   // "error", "warning", "info"
	Message  string   // Hungarian display text
	Link     string   // optional link to relevant page
	LinkText string   // link display text
	PageOnly []string // if non-empty, only show on these pages (e.g., ["dashboard", "monitoring"])
}

// AlertManager generates and stores dashboard alerts from health check results.
// Alerts are state-based (not event-based) — they reflect current system state
// and are regenerated after each health check cycle.
type AlertManager struct {
	mu     sync.RWMutex
	alerts []Alert
	logger *log.Logger
}

// NewAlertManager creates a new AlertManager.
func NewAlertManager(logger *log.Logger) *AlertManager {
	return &AlertManager{
		logger: logger,
	}
}

// Refresh regenerates alerts from the latest health check report and config state.
// Called after each health check cycle (every 5 minutes).
func (am *AlertManager) Refresh(report *monitor.HealthReport, cfg *config.Config, backupMgr *backup.Manager) {
	var alerts []Alert

	// From health check issues (critical)
	for _, issue := range report.Issues {
		alerts = append(alerts, Alert{
			ID:       "health-" + simpleHash(issue),
			Level:    "error",
			Message:  issue,
			Link:     "/monitoring",
			LinkText: "Rendszermonitor",
		})
	}

	// From health check warnings
	for _, w := range report.Warnings {
		alert := Alert{
			ID:       "health-" + simpleHash(w),
			Level:    "warning",
			Message:  w,
			Link:     "/monitoring",
			LinkText: "Rendszermonitor",
		}
		// Disk-related warnings only relevant on dashboard and monitoring pages
		if strings.Contains(w, "meghajtón") || strings.Contains(w, "adattároló") || strings.Contains(w, "meghajtó") {
			alert.ID = "disk-not-separate"
			alert.PageOnly = []string{"dashboard", "monitoring"}
		}
		alerts = append(alerts, alert)
	}

	// Missing ping UUIDs
	if cfg.Monitoring.Enabled {
		missing := countMissingPings(cfg)
		if missing > 0 {
			alerts = append(alerts, Alert{
				ID:       "pings-missing",
				Level:    "warning",
				Message:  fmt.Sprintf("%d monitoring ellenőrzés nincs beállítva", missing),
				Link:     "/monitoring",
				LinkText: "Rendszermonitor",
			})
		}
	}

	// Backup disabled
	if !cfg.Backup.Enabled {
		alerts = append(alerts, Alert{
			ID:       "backup-disabled",
			Level:    "warning",
			Message:  "A biztonsági mentés nincs bekapcsolva",
			Link:     "/settings",
			LinkText: "Beállítások",
		})
	}

	// Sort: errors first, then warnings, then info
	sortAlerts(alerts)

	am.mu.Lock()
	am.alerts = alerts
	am.mu.Unlock()

	am.logger.Printf("[DEBUG] AlertManager refreshed: %d alerts (%d error, %d warning)",
		len(alerts), countLevel(alerts, "error"), countLevel(alerts, "warning"))
}

// GetAlerts returns a copy of the current alerts, optionally excluding specific IDs.
func (am *AlertManager) GetAlerts(excludeIDs ...string) []Alert {
	am.mu.RLock()
	defer am.mu.RUnlock()

	if len(am.alerts) == 0 {
		return nil
	}

	exclude := make(map[string]bool, len(excludeIDs))
	for _, id := range excludeIDs {
		exclude[id] = true
	}

	var result []Alert
	for _, a := range am.alerts {
		if exclude[a.ID] {
			continue
		}
		result = append(result, a)
	}

	// Cap at 5 visible alerts
	if len(result) > 5 {
		overflow := len(result) - 5
		result = result[:5]
		result = append(result, Alert{
			ID:      "overflow",
			Level:   "info",
			Message: fmt.Sprintf("+ %d további figyelmeztetés", overflow),
			Link:    "/monitoring",
		})
	}

	return result
}

// countMissingPings counts how many ping UUIDs are not configured.
func countMissingPings(cfg *config.Config) int {
	count := 0
	uuids := []string{
		cfg.Monitoring.PingUUIDs.Heartbeat,
		cfg.Monitoring.PingUUIDs.SystemHealth,
		cfg.Monitoring.PingUUIDs.DBDump,
		cfg.Monitoring.PingUUIDs.Backup,
		cfg.Monitoring.PingUUIDs.BackupIntegrity,
	}
	for _, uuid := range uuids {
		if !isPingConfigured(uuid) {
			count++
		}
	}
	return count
}

// simpleHash returns a short deterministic hash for deduplication.
func simpleHash(s string) string {
	h := uint32(0)
	for _, c := range s {
		h = h*31 + uint32(c)
	}
	return fmt.Sprintf("%08x", h)
}

// sortAlerts sorts alerts by severity: error > warning > info.
func sortAlerts(alerts []Alert) {
	levelOrder := map[string]int{"error": 0, "warning": 1, "info": 2}
	for i := 1; i < len(alerts); i++ {
		for j := i; j > 0 && levelOrder[alerts[j].Level] < levelOrder[alerts[j-1].Level]; j-- {
			alerts[j], alerts[j-1] = alerts[j-1], alerts[j]
		}
	}
}

func countLevel(alerts []Alert, level string) int {
	n := 0
	for _, a := range alerts {
		if a.Level == level {
			n++
		}
	}
	return n
}