package monitoring

import (
	"context"
	"fmt"
	"strings"
	"sync"
	"time"

	"github.com/rcourtman/pulse-go-rewrite/internal/config"
	recoverymanager "github.com/rcourtman/pulse-go-rewrite/internal/recovery/manager"
	"github.com/rcourtman/pulse-go-rewrite/internal/websocket"
	"github.com/rs/zerolog/log"
)

// MultiTenantMonitor manages a dedicated Monitor instance for each organization.
type MultiTenantMonitor struct {
	mu           sync.RWMutex
	monitors     map[string]*Monitor
	tenantCancel map[string]context.CancelFunc
	tenantDone   map[string]chan struct{}
	persistence  *config.MultiTenantPersistence
	baseConfig   *config.Config
	wsHub        *websocket.Hub
	recoveryMgr  *recoverymanager.Manager
	initializer  func(*Monitor)
	globalCtx    context.Context
	globalCancel context.CancelFunc
}

// NewMultiTenantMonitor creates a new multi-tenant monitor manager.
func NewMultiTenantMonitor(baseCfg *config.Config, persistence *config.MultiTenantPersistence, wsHub *websocket.Hub) *MultiTenantMonitor {
	ctx, cancel := context.WithCancel(context.Background())
	return &MultiTenantMonitor{
		monitors:     make(map[string]*Monitor),
		tenantCancel: make(map[string]context.CancelFunc),
		tenantDone:   make(map[string]chan struct{}),
		persistence:  persistence,
		baseConfig:   baseCfg, // Used as a template or for global settings
		wsHub:        wsHub,
		globalCtx:    ctx,
		globalCancel: cancel,
	}
}

const tenantMonitorShutdownTimeout = 2 * time.Second

// SetRecoveryManager wires a recovery store manager into all existing and future tenant monitors.
func (mtm *MultiTenantMonitor) SetRecoveryManager(manager *recoverymanager.Manager) {
	mtm.mu.Lock()
	defer mtm.mu.Unlock()
	mtm.recoveryMgr = manager
	for _, monitor := range mtm.monitors {
		if monitor == nil {
			continue
		}
		monitor.SetRecoveryManager(manager)
	}
}

// SetMonitorInitializer configures a callback that is applied to all existing
// and future tenant monitors after creation.
func (mtm *MultiTenantMonitor) SetMonitorInitializer(initializer func(*Monitor)) {
	if mtm == nil {
		return
	}

	mtm.mu.Lock()
	mtm.initializer = initializer
	monitors := make([]*Monitor, 0, len(mtm.monitors))
	for _, monitor := range mtm.monitors {
		if monitor == nil {
			continue
		}
		monitors = append(monitors, monitor)
	}
	mtm.mu.Unlock()

	if initializer == nil {
		return
	}
	for _, monitor := range monitors {
		initializer(monitor)
	}
}

// GetMonitor returns the monitor instance for a specific organization.
// It lazily initializes the monitor if it doesn't exist.
func (mtm *MultiTenantMonitor) GetMonitor(orgID string) (*Monitor, error) {
	orgID = strings.TrimSpace(orgID)
	if orgID == "" {
		return nil, fmt.Errorf("organization ID is required")
	}

	mtm.mu.RLock()
	monitor, exists := mtm.monitors[orgID]
	mtm.mu.RUnlock()

	if exists {
		return monitor, nil
	}

	mtm.mu.Lock()
	defer mtm.mu.Unlock()

	if mtm.monitors == nil {
		mtm.monitors = make(map[string]*Monitor)
	}
	if mtm.tenantCancel == nil {
		mtm.tenantCancel = make(map[string]context.CancelFunc)
	}
	if mtm.tenantDone == nil {
		mtm.tenantDone = make(map[string]chan struct{})
	}

	// Double-check locking pattern
	if monitor, exists = mtm.monitors[orgID]; exists {
		return monitor, nil
	}

	if mtm.persistence == nil {
		return nil, fmt.Errorf("tenant persistence is not configured")
	}
	if orgID != "default" && !mtm.persistence.OrgExists(orgID) {
		return nil, fmt.Errorf("organization %q is not provisioned", orgID)
	}

	// Initialize new monitor for this tenant
	log.Info().Str("org_id", orgID).Msg("initializing tenant monitor")

	// 1. Load Tenant Config
	// Deep copy the base config to ensure tenant isolation.
	// Each tenant gets its own independent config that won't share
	// credential slices or other mutable state with other tenants.
	tenantConfig := mtm.baseConfig.DeepCopy()

	// Clear inherited credentials - tenants must load their own
	// This prevents credential leakage between tenants
	tenantConfig.PVEInstances = nil
	tenantConfig.PBSInstances = nil
	tenantConfig.PMGInstances = nil

	// Ensure the DataPath is correct for this tenant to isolate storage (sqlite, etc)
	tenantPersistence, err := mtm.persistence.GetPersistence(orgID)
	if err != nil {
		return nil, fmt.Errorf("failed to get persistence for org %s: %w", orgID, err)
	}
	tenantConfig.DataPath = tenantPersistence.GetConfigDir()

	// Load tenant-specific nodes from <orgDir>/nodes.enc
	nodesConfig, err := tenantPersistence.LoadNodesConfig()
	if err != nil {
		log.Warn().Err(err).Str("org_id", orgID).Msg("failed to load tenant nodes config, starting with empty config")
		// Not a fatal error - tenant may not have configured any nodes yet
	} else if nodesConfig != nil {
		tenantConfig.PVEInstances = nodesConfig.PVEInstances
		tenantConfig.PBSInstances = nodesConfig.PBSInstances
		tenantConfig.PMGInstances = nodesConfig.PMGInstances
		log.Info().
			Str("org_id", orgID).
			Int("pve_count", len(nodesConfig.PVEInstances)).
			Int("pbs_count", len(nodesConfig.PBSInstances)).
			Int("pmg_count", len(nodesConfig.PMGInstances)).
			Msg("Loaded tenant nodes config")
	}

	// 2. Create Monitor
	// Usage of internal New constructor
	monitor, err = New(tenantConfig)
	if err != nil {
		return nil, fmt.Errorf("failed to create monitor for org %s: %w", orgID, err)
	}

	// Set org ID for tenant isolation
	// This enables tenant-scoped WebSocket broadcasts
	monitor.SetOrgID(orgID)
	if mtm.recoveryMgr != nil {
		monitor.SetRecoveryManager(mtm.recoveryMgr)
	}
	if mtm.initializer != nil {
		mtm.initializer(monitor)
	}

	// 3. Start Monitor with a tenant-scoped runtime so RemoveTenant can stop it cleanly.
	tenantCtx, tenantCancel := context.WithCancel(mtm.globalCtx)
	tenantDone := make(chan struct{})
	go func() {
		defer close(tenantDone)
		monitor.Start(tenantCtx, mtm.wsHub)
	}()

	mtm.monitors[orgID] = monitor
	mtm.tenantCancel[orgID] = tenantCancel
	mtm.tenantDone[orgID] = tenantDone
	return monitor, nil
}

// PeekMonitor returns the tenant monitor instance if it is already initialized.
// It does not create a new monitor.
func (mtm *MultiTenantMonitor) PeekMonitor(orgID string) (*Monitor, bool) {
	orgID = strings.TrimSpace(orgID)
	if orgID == "" {
		return nil, false
	}

	mtm.mu.RLock()
	defer mtm.mu.RUnlock()
	monitor, exists := mtm.monitors[orgID]
	return monitor, exists
}

// Stop stops all tenant monitors.
func (mtm *MultiTenantMonitor) Stop() {
	log.Info().Msg("stopping MultiTenantMonitor and all tenant instances")

	mtm.mu.Lock()
	mtm.globalCancel()

	monitors := make([]*Monitor, 0, len(mtm.monitors))
	cancels := make([]context.CancelFunc, 0, len(mtm.tenantCancel))
	doneSignals := make([]chan struct{}, 0, len(mtm.tenantDone))
	for orgID, monitor := range mtm.monitors {
		if cancel := mtm.tenantCancel[orgID]; cancel != nil {
			cancels = append(cancels, cancel)
		}
		if done := mtm.tenantDone[orgID]; done != nil {
			doneSignals = append(doneSignals, done)
		}
		monitors = append(monitors, monitor)
	}
	mtm.tenantCancel = make(map[string]context.CancelFunc)
	mtm.tenantDone = make(map[string]chan struct{})
	mtm.monitors = make(map[string]*Monitor)
	mtm.mu.Unlock()

	for _, cancel := range cancels {
		cancel()
	}
	for _, done := range doneSignals {
		waitForTenantMonitorShutdown("", done)
	}
	for _, monitor := range monitors {
		monitor.Stop()
	}
}

// RemoveTenant stops and removes a specific tenant's monitor.
// Useful for offboarding or manual reloading.
func (mtm *MultiTenantMonitor) RemoveTenant(orgID string) {
	orgID = strings.TrimSpace(orgID)
	if orgID == "" {
		return
	}

	mtm.mu.Lock()
	monitor, exists := mtm.monitors[orgID]
	cancel := mtm.tenantCancel[orgID]
	done := mtm.tenantDone[orgID]
	delete(mtm.monitors, orgID)
	delete(mtm.tenantCancel, orgID)
	delete(mtm.tenantDone, orgID)
	mtm.mu.Unlock()

	if !exists {
		return
	}

	log.Info().Str("org_id", orgID).Msg("stopping and removing tenant monitor")
	if cancel != nil {
		cancel()
	}
	waitForTenantMonitorShutdown(orgID, done)
	monitor.Stop()
}

func waitForTenantMonitorShutdown(orgID string, done <-chan struct{}) {
	if done == nil {
		return
	}

	timer := time.NewTimer(tenantMonitorShutdownTimeout)
	defer timer.Stop()

	select {
	case <-done:
	case <-timer.C:
		logger := log.Warn().Dur("timeout", tenantMonitorShutdownTimeout)
		if orgID != "" {
			logger = logger.Str("org_id", orgID)
		}
		logger.Msg("timed out waiting for tenant monitor loop to exit")
	}
}

// OrgExists checks if an organization exists (directory exists) without creating it.
func (mtm *MultiTenantMonitor) OrgExists(orgID string) bool {
	orgID = strings.TrimSpace(orgID)
	if orgID == "" {
		return false
	}

	if mtm.persistence == nil {
		return false
	}
	return mtm.persistence.OrgExists(orgID)
}