package sipguardian

import (
	"net"
	"sync"
	"time"

	"github.com/caddyserver/caddy/v2"
	"go.uber.org/zap"
)

// Global registry to share guardian instances across modules
var (
	guardianRegistry = make(map[string]*SIPGuardian)
	registryMu       sync.RWMutex
)

// GetOrCreateGuardian returns a shared guardian instance by name (backward compat)
func GetOrCreateGuardian(ctx caddy.Context, name string) (*SIPGuardian, error) {
	return GetOrCreateGuardianWithConfig(ctx, name, nil)
}

// GetOrCreateGuardianWithConfig returns a shared guardian instance, merging config if provided
func GetOrCreateGuardianWithConfig(ctx caddy.Context, name string, config *SIPGuardian) (*SIPGuardian, error) {
	if name == "" {
		name = "default"
	}

	registryMu.Lock()
	defer registryMu.Unlock()

	if g, exists := guardianRegistry[name]; exists {
		// Guardian exists - merge any new config
		if config != nil {
			mergeGuardianConfig(ctx, g, config)
		}
		return g, nil
	}

	// Create new guardian with config
	var g *SIPGuardian
	if config != nil {
		// Copy config values to a new guardian
		g = &SIPGuardian{
			MaxFailures:      config.MaxFailures,
			FindTime:         config.FindTime,
			BanTime:          config.BanTime,
			WhitelistCIDR:    config.WhitelistCIDR,
			Webhooks:         config.Webhooks,
			StoragePath:      config.StoragePath,
			GeoIPPath:        config.GeoIPPath,
			BlockedCountries: config.BlockedCountries,
			AllowedCountries: config.AllowedCountries,
			Enumeration:      config.Enumeration,
		}
	} else {
		g = &SIPGuardian{}
	}

	if err := g.Provision(ctx); err != nil {
		return nil, err
	}

	guardianRegistry[name] = g
	return g, nil
}

// mergeGuardianConfig merges new config into an existing guardian
// This handles cases where multiple handlers might specify overlapping config
func mergeGuardianConfig(ctx caddy.Context, g *SIPGuardian, config *SIPGuardian) {
	g.mu.Lock()
	defer g.mu.Unlock()

	logger := ctx.Logger()

	// Merge whitelist CIDRs (add new ones, avoid duplicates)
	for _, cidr := range config.WhitelistCIDR {
		found := false
		for _, existing := range g.WhitelistCIDR {
			if existing == cidr {
				found = true
				break
			}
		}
		if !found {
			g.WhitelistCIDR = append(g.WhitelistCIDR, cidr)
			// Parse and add to whitelistNets
			if _, network, err := net.ParseCIDR(cidr); err == nil {
				g.whitelistNets = append(g.whitelistNets, network)
				logger.Debug("Added whitelist CIDR from handler config",
					zap.String("cidr", cidr),
				)
			}
		}
	}

	// Override numeric values if they're non-zero (handler specified them)
	if config.MaxFailures > 0 && config.MaxFailures != g.MaxFailures {
		g.MaxFailures = config.MaxFailures
	}
	if config.FindTime > 0 && config.FindTime != g.FindTime {
		g.FindTime = config.FindTime
	}
	if config.BanTime > 0 && config.BanTime != g.BanTime {
		g.BanTime = config.BanTime
	}

	// Initialize storage if specified and not yet initialized
	if config.StoragePath != "" && g.storage == nil {
		storage, err := InitStorage(logger, StorageConfig{
			Path: config.StoragePath,
		})
		if err != nil {
			logger.Warn("Failed to initialize storage from handler config",
				zap.Error(err),
			)
		} else {
			g.storage = storage
			g.StoragePath = config.StoragePath
			// Load existing bans from storage
			if bans, err := storage.LoadActiveBans(); err == nil {
				for _, ban := range bans {
					entry := ban
					g.bannedIPs[entry.IP] = &entry
				}
				logger.Info("Loaded bans from storage", zap.Int("count", len(bans)))
			}
		}
	}

	// Initialize GeoIP if specified and not yet initialized
	if config.GeoIPPath != "" && g.geoIP == nil {
		geoIP, err := NewGeoIPLookup(config.GeoIPPath)
		if err != nil {
			logger.Warn("Failed to initialize GeoIP from handler config",
				zap.Error(err),
			)
		} else {
			g.geoIP = geoIP
			g.GeoIPPath = config.GeoIPPath
		}
	}

	// Merge blocked/allowed countries
	for _, country := range config.BlockedCountries {
		found := false
		for _, existing := range g.BlockedCountries {
			if existing == country {
				found = true
				break
			}
		}
		if !found {
			g.BlockedCountries = append(g.BlockedCountries, country)
		}
	}
	for _, country := range config.AllowedCountries {
		found := false
		for _, existing := range g.AllowedCountries {
			if existing == country {
				found = true
				break
			}
		}
		if !found {
			g.AllowedCountries = append(g.AllowedCountries, country)
		}
	}

	// Merge webhooks (add new ones by URL)
	for _, webhook := range config.Webhooks {
		found := false
		for _, existing := range g.Webhooks {
			if existing.URL == webhook.URL {
				found = true
				break
			}
		}
		if !found {
			g.Webhooks = append(g.Webhooks, webhook)
			// Register with webhook manager
			if enableWebhooks {
				wm := GetWebhookManager(logger)
				wm.AddWebhook(webhook)
			}
		}
	}

	// Apply enumeration config if specified
	if config.Enumeration != nil && g.Enumeration == nil {
		g.Enumeration = config.Enumeration
		// Apply to global detector
		SetEnumerationConfig(*config.Enumeration)
		logger.Debug("Applied enumeration config from handler")
	}

	logger.Debug("Merged guardian config",
		zap.Int("whitelist_count", len(g.whitelistNets)),
		zap.Int("webhook_count", len(g.Webhooks)),
		zap.Duration("ban_time", time.Duration(g.BanTime)),
	)
}

// GetGuardian returns an existing guardian instance
func GetGuardian(name string) *SIPGuardian {
	if name == "" {
		name = "default"
	}

	registryMu.RLock()
	defer registryMu.RUnlock()

	return guardianRegistry[name]
}

// ListGuardians returns all guardian names
func ListGuardians() []string {
	registryMu.RLock()
	defer registryMu.RUnlock()

	names := make([]string, 0, len(guardianRegistry))
	for name := range guardianRegistry {
		names = append(names, name)
	}
	return names
}