package dht

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

	bzzconfig "chorus.services/bzzz/pkg/config"
)

// RealDHT implements DHT interface - simplified implementation for Phase 2
// In production, this would use libp2p Kademlia DHT
type RealDHT struct {
	config    *bzzconfig.HybridConfig
	ctx       context.Context
	cancel    context.CancelFunc
	
	// Simplified storage for Phase 2
	storage   map[string][]byte
	providers map[string][]string
	storageMu sync.RWMutex
	
	// Statistics
	stats     *RealDHTStats
	statsMu   sync.RWMutex
	
	logger    Logger
}

// RealDHTStats tracks real DHT performance metrics
type RealDHTStats struct {
	ConnectedPeers   int           `json:"connected_peers"`
	TotalKeys        int           `json:"total_keys"`
	TotalProviders   int           `json:"total_providers"`
	BootstrapNodes   []string      `json:"bootstrap_nodes"`
	NodeID           string        `json:"node_id"`
	Addresses        []string      `json:"addresses"`
	Uptime          time.Duration `json:"uptime_seconds"`
	LastBootstrap   time.Time     `json:"last_bootstrap"`
	
	// Operation counters
	PutOperations    uint64        `json:"put_operations"`
	GetOperations    uint64        `json:"get_operations"`
	ProvideOperations uint64       `json:"provide_operations"`
	FindProviderOps  uint64        `json:"find_provider_operations"`
	
	// Performance metrics
	AvgLatency       time.Duration `json:"avg_latency_ms"`
	ErrorCount       uint64        `json:"error_count"`
	ErrorRate        float64       `json:"error_rate"`
}

// NewRealDHT creates a new simplified real DHT implementation for Phase 2
func NewRealDHT(config *bzzconfig.HybridConfig) (DHT, error) {
	ctx, cancel := context.WithCancel(context.Background())
	
	realDHT := &RealDHT{
		config:    config,
		ctx:       ctx,
		cancel:    cancel,
		storage:   make(map[string][]byte),
		providers: make(map[string][]string),
		stats: &RealDHTStats{
			BootstrapNodes: config.GetDHTBootstrapNodes(),
			NodeID:        "real-dht-node-" + fmt.Sprintf("%d", time.Now().Unix()),
			Addresses:     []string{"127.0.0.1:8080"}, // Simplified for Phase 2
			LastBootstrap: time.Now(),
		},
		logger: &defaultLogger{},
	}
	
	// Simulate bootstrap process
	if err := realDHT.bootstrap(); err != nil {
		realDHT.logger.Warn("DHT bootstrap failed", "error", err)
		// Don't fail completely - DHT can still work without bootstrap
	}
	
	realDHT.logger.Info("Real DHT initialized (Phase 2 simplified)",
		"node_id", realDHT.stats.NodeID,
		"bootstrap_nodes", config.GetDHTBootstrapNodes())
	
	return realDHT, nil
}

// PutValue stores a key-value pair in the DHT
func (r *RealDHT) PutValue(ctx context.Context, key string, value []byte) error {
	start := time.Now()
	defer func() {
		r.updateStats("put", time.Since(start), nil)
	}()
	
	// Simulate network latency for real DHT
	time.Sleep(10 * time.Millisecond)
	
	r.storageMu.Lock()
	r.storage[key] = make([]byte, len(value))
	copy(r.storage[key], value)
	r.storageMu.Unlock()
	
	r.logger.Debug("Real DHT PutValue successful", "key", key, "size", len(value))
	return nil
}

// GetValue retrieves a value by key from the DHT
func (r *RealDHT) GetValue(ctx context.Context, key string) ([]byte, error) {
	start := time.Now()
	
	// Simulate network latency for real DHT
	time.Sleep(15 * time.Millisecond)
	
	r.storageMu.RLock()
	value, exists := r.storage[key]
	r.storageMu.RUnlock()
	
	latency := time.Since(start)
	
	if !exists {
		r.updateStats("get", latency, ErrNotFound)
		return nil, ErrNotFound
	}
	
	// Return a copy to avoid data races
	result := make([]byte, len(value))
	copy(result, value)
	
	r.updateStats("get", latency, nil)
	r.logger.Debug("Real DHT GetValue successful", "key", key, "size", len(result))
	return result, nil
}

// Provide announces that this node provides a value for the given key
func (r *RealDHT) Provide(ctx context.Context, key, providerId string) error {
	start := time.Now()
	defer func() {
		r.updateStats("provide", time.Since(start), nil)
	}()
	
	// Simulate network latency for real DHT
	time.Sleep(5 * time.Millisecond)
	
	r.storageMu.Lock()
	if r.providers[key] == nil {
		r.providers[key] = make([]string, 0)
	}
	
	// Add provider if not already present
	found := false
	for _, p := range r.providers[key] {
		if p == providerId {
			found = true
			break
		}
	}
	if !found {
		r.providers[key] = append(r.providers[key], providerId)
	}
	r.storageMu.Unlock()
	
	r.logger.Debug("Real DHT Provide successful", "key", key, "provider_id", providerId)
	return nil
}

// FindProviders finds providers for the given key
func (r *RealDHT) FindProviders(ctx context.Context, key string) ([]string, error) {
	start := time.Now()
	
	// Simulate network latency for real DHT
	time.Sleep(20 * time.Millisecond)
	
	r.storageMu.RLock()
	providers, exists := r.providers[key]
	r.storageMu.RUnlock()
	
	var result []string
	if exists {
		// Return a copy
		result = make([]string, len(providers))
		copy(result, providers)
	} else {
		result = make([]string, 0)
	}
	
	r.updateStats("find_providers", time.Since(start), nil)
	r.logger.Debug("Real DHT FindProviders successful", "key", key, "provider_count", len(result))
	
	return result, nil
}

// GetStats returns current DHT statistics
func (r *RealDHT) GetStats() DHTStats {
	r.statsMu.RLock()
	defer r.statsMu.RUnlock()
	
	// Update stats
	r.storageMu.RLock()
	keyCount := len(r.storage)
	providerCount := len(r.providers)
	r.storageMu.RUnlock()
	
	r.stats.TotalKeys = keyCount
	r.stats.TotalProviders = providerCount
	r.stats.ConnectedPeers = len(r.config.GetDHTBootstrapNodes()) // Simulate connected peers
	r.stats.Uptime = time.Since(r.stats.LastBootstrap)
	
	// Convert to common DHTStats format
	return DHTStats{
		TotalKeys:    r.stats.TotalKeys,
		TotalPeers:   r.stats.ConnectedPeers,
		Latency:      r.stats.AvgLatency,
		ErrorCount:   int(r.stats.ErrorCount),
		ErrorRate:    r.stats.ErrorRate,
		Uptime:       r.stats.Uptime,
	}
}

// GetDetailedStats returns real DHT specific statistics
func (r *RealDHT) GetDetailedStats() *RealDHTStats {
	r.statsMu.RLock()
	defer r.statsMu.RUnlock()
	
	// Update dynamic stats
	r.stats.ConnectedPeers = len(r.host.Network().Peers())
	r.stats.Uptime = time.Since(r.stats.LastBootstrap)
	
	// Return a copy
	stats := *r.stats
	return &stats
}

// Close shuts down the real DHT
func (r *RealDHT) Close() error {
	r.logger.Info("Shutting down real DHT")
	
	r.cancel()
	
	// Clean up storage
	r.storageMu.Lock()
	r.storage = nil
	r.providers = nil
	r.storageMu.Unlock()
	
	return nil
}

// Bootstrap connects to bootstrap nodes and initializes routing table
func (r *RealDHT) bootstrap() error {
	r.logger.Info("Bootstrapping real DHT (Phase 2 simplified)", "bootstrap_nodes", r.config.GetDHTBootstrapNodes())
	
	// Simulate bootstrap process
	bootstrapNodes := r.config.GetDHTBootstrapNodes()
	if len(bootstrapNodes) == 0 {
		r.logger.Warn("No bootstrap nodes configured")
	}
	
	// Simulate connecting to bootstrap nodes
	time.Sleep(100 * time.Millisecond) // Simulate bootstrap time
	
	r.statsMu.Lock()
	r.stats.LastBootstrap = time.Now()
	r.stats.ConnectedPeers = len(bootstrapNodes)
	r.statsMu.Unlock()
	
	r.logger.Info("Real DHT bootstrap completed (simulated)", "connected_peers", len(bootstrapNodes))
	return nil
}

// updateStats updates internal performance statistics
func (r *RealDHT) updateStats(operation string, latency time.Duration, err error) {
	r.statsMu.Lock()
	defer r.statsMu.Unlock()
	
	// Update operation counters
	switch operation {
	case "put":
		r.stats.PutOperations++
	case "get":
		r.stats.GetOperations++
	case "provide":
		r.stats.ProvideOperations++
	case "find_providers":
		r.stats.FindProviderOps++
	}
	
	// Update latency (exponential moving average)
	totalOps := r.stats.PutOperations + r.stats.GetOperations + r.stats.ProvideOperations + r.stats.FindProviderOps
	if totalOps > 0 {
		weight := 1.0 / float64(totalOps)
		r.stats.AvgLatency = time.Duration(float64(r.stats.AvgLatency)*(1-weight) + float64(latency)*weight)
	}
	
	// Update error statistics
	if err != nil {
		r.stats.ErrorCount++
		if totalOps > 0 {
			r.stats.ErrorRate = float64(r.stats.ErrorCount) / float64(totalOps)
		}
	}
}

// defaultLogger provides a basic logger implementation
type defaultLogger struct{}

func (l *defaultLogger) Info(msg string, fields ...interface{}) {
	fmt.Printf("[INFO] %s %v\n", msg, fields)
}

func (l *defaultLogger) Warn(msg string, fields ...interface{}) {
	fmt.Printf("[WARN] %s %v\n", msg, fields)
}

func (l *defaultLogger) Error(msg string, fields ...interface{}) {
	fmt.Printf("[ERROR] %s %v\n", msg, fields)
}

func (l *defaultLogger) Debug(msg string, fields ...interface{}) {
	fmt.Printf("[DEBUG] %s %v\n", msg, fields)
}

// ErrNotFound indicates a key was not found in the DHT
var ErrNotFound = fmt.Errorf("key not found")