package pubsub

import (
	"context"
	"encoding/json"
	"fmt"
	"time"

	"github.com/libp2p/go-libp2p/core/host"
	"github.com/libp2p/go-libp2p/core/peer"
	pubsub "github.com/libp2p/go-libp2p-pubsub"
)

// PubSub handles publish/subscribe messaging for Bzzz coordination and Antennae meta-discussion
type PubSub struct {
	ps     *pubsub.PubSub
	host   host.Host
	ctx    context.Context
	cancel context.CancelFunc
	
	// Topic subscriptions
	bzzzTopic     *pubsub.Topic
	antennaeTopic *pubsub.Topic
	
	// Message subscriptions
	bzzzSub     *pubsub.Subscription
	antennaeSub *pubsub.Subscription
	
	// Configuration
	bzzzTopicName     string
	antennaeTopicName string

	// External message handler for Antennae messages
	AntennaeMessageHandler func(msg Message, from peer.ID)
}

// MessageType represents different types of messages
type MessageType string

const (
	// Bzzz coordination messages
	TaskAnnouncement MessageType = "task_announcement"
	TaskClaim        MessageType = "task_claim"
	TaskProgress     MessageType = "task_progress"
	TaskComplete     MessageType = "task_complete"
	CapabilityBcast  MessageType = "capability_broadcast"
	
	// Antennae meta-discussion messages
	MetaDiscussion MessageType = "meta_discussion" // Generic type for all discussion
)

// Message represents a Bzzz/Antennae message
type Message struct {
	Type      MessageType            `json:"type"`
	From      string                 `json:"from"`
	Timestamp time.Time              `json:"timestamp"`
	Data      map[string]interface{} `json:"data"`
	HopCount  int                    `json:"hop_count,omitempty"` // For Antennae hop limiting
}

// NewPubSub creates a new PubSub instance for Bzzz coordination and Antennae meta-discussion
func NewPubSub(ctx context.Context, h host.Host, bzzzTopic, antennaeTopic string) (*PubSub, error) {
	if bzzzTopic == "" {
		bzzzTopic = "bzzz/coordination/v1"
	}
	if antennaeTopic == "" {
		antennaeTopic = "antennae/meta-discussion/v1"
	}

	pubsubCtx, cancel := context.WithCancel(ctx)

	// Create gossipsub instance with message validation
	ps, err := pubsub.NewGossipSub(pubsubCtx, h,
		pubsub.WithMessageSigning(true),
		pubsub.WithStrictSignatureVerification(true),
		pubsub.WithValidateQueueSize(256),
		pubsub.WithValidateThrottle(1024),
	)
	if err != nil {
		cancel()
		return nil, fmt.Errorf("failed to create gossipsub: %w", err)
	}

	p := &PubSub{
		ps:                ps,
		host:              h,
		ctx:               pubsubCtx,
		cancel:            cancel,
		bzzzTopicName:     bzzzTopic,
		antennaeTopicName: antennaeTopic,
	}

	// Join topics
	if err := p.joinTopics(); err != nil {
		cancel()
		return nil, err
	}

	// Start message handlers
	go p.handleBzzzMessages()
	go p.handleAntennaeMessages()

	fmt.Printf("📡 PubSub initialized - Bzzz: %s, Antennae: %s\n", bzzzTopic, antennaeTopic)
	return p, nil
}

// SetAntennaeMessageHandler sets the handler for incoming Antennae messages.
// This allows the business logic (e.g., in the github module) to process messages.
func (p *PubSub) SetAntennaeMessageHandler(handler func(msg Message, from peer.ID)) {
	p.AntennaeMessageHandler = handler
}

// joinTopics joins the Bzzz coordination and Antennae meta-discussion topics
func (p *PubSub) joinTopics() error {
	// Join Bzzz coordination topic
	bzzzTopic, err := p.ps.Join(p.bzzzTopicName)
	if err != nil {
		return fmt.Errorf("failed to join Bzzz topic: %w", err)
	}
	p.bzzzTopic = bzzzTopic

	// Subscribe to Bzzz messages
	bzzzSub, err := bzzzTopic.Subscribe()
	if err != nil {
		return fmt.Errorf("failed to subscribe to Bzzz topic: %w", err)
	}
	p.bzzzSub = bzzzSub

	// Join Antennae meta-discussion topic
	antennaeTopic, err := p.ps.Join(p.antennaeTopicName)
	if err != nil {
		return fmt.Errorf("failed to join Antennae topic: %w", err)
	}
	p.antennaeTopic = antennaeTopic

	// Subscribe to Antennae messages
	antennaeSub, err := antennaeTopic.Subscribe()
	if err != nil {
		return fmt.Errorf("failed to subscribe to Antennae topic: %w", err)
	}
	p.antennaeSub = antennaeSub

	return nil
}

// PublishBzzzMessage publishes a message to the Bzzz coordination topic
func (p *PubSub) PublishBzzzMessage(msgType MessageType, data map[string]interface{}) error {
	msg := Message{
		Type:      msgType,
		From:      p.host.ID().String(),
		Timestamp: time.Now(),
		Data:      data,
	}

	msgBytes, err := json.Marshal(msg)
	if err != nil {
		return fmt.Errorf("failed to marshal message: %w", err)
	}

	return p.bzzzTopic.Publish(p.ctx, msgBytes)
}

// PublishAntennaeMessage publishes a message to the Antennae meta-discussion topic
func (p *PubSub) PublishAntennaeMessage(msgType MessageType, data map[string]interface{}) error {
	msg := Message{
		Type:      msgType,
		From:      p.host.ID().String(),
		Timestamp: time.Now(),
		Data:      data,
	}

	msgBytes, err := json.Marshal(msg)
	if err != nil {
		return fmt.Errorf("failed to marshal message: %w", err)
	}

	return p.antennaeTopic.Publish(p.ctx, msgBytes)
}

// handleBzzzMessages processes incoming Bzzz coordination messages
func (p *PubSub) handleBzzzMessages() {
	for {
		msg, err := p.bzzzSub.Next(p.ctx)
		if err != nil {
			if p.ctx.Err() != nil {
				return // Context cancelled
			}
			fmt.Printf("❌ Error receiving Bzzz message: %v\n", err)
			continue
		}

		// Skip our own messages
		if msg.ReceivedFrom == p.host.ID() {
			continue
		}

		var bzzzMsg Message
		if err := json.Unmarshal(msg.Data, &bzzzMsg); err != nil {
			fmt.Printf("❌ Failed to unmarshal Bzzz message: %v\n", err)
			continue
		}

		p.processBzzzMessage(bzzzMsg, msg.ReceivedFrom)
	}
}

// handleAntennaeMessages processes incoming Antennae meta-discussion messages
func (p *PubSub) handleAntennaeMessages() {
	for {
		msg, err := p.antennaeSub.Next(p.ctx)
		if err != nil {
			if p.ctx.Err() != nil {
				return // Context cancelled
			}
			fmt.Printf("❌ Error receiving Antennae message: %v\n", err)
			continue
		}

		// Skip our own messages
		if msg.ReceivedFrom == p.host.ID() {
			continue
		}

		var antennaeMsg Message
		if err := json.Unmarshal(msg.Data, &antennaeMsg); err != nil {
			fmt.Printf("❌ Failed to unmarshal Antennae message: %v\n", err)
			continue
		}

		// If an external handler is registered, use it.
		if p.AntennaeMessageHandler != nil {
			p.AntennaeMessageHandler(antennaeMsg, msg.ReceivedFrom)
		} else {
			// Default processing if no handler is set
			p.processAntennaeMessage(antennaeMsg, msg.ReceivedFrom)
		}
	}
}

// processBzzzMessage handles different types of Bzzz coordination messages
func (p *PubSub) processBzzzMessage(msg Message, from peer.ID) {
	fmt.Printf("🐝 Bzzz [%s] from %s: %v\n", msg.Type, from.ShortString(), msg.Data)
}

// processAntennaeMessage provides default handling for Antennae messages if no external handler is set
func (p *PubSub) processAntennaeMessage(msg Message, from peer.ID) {
	fmt.Printf("🎯 Default Antennae Handler [%s] from %s: %v\n", 
		msg.Type, from.ShortString(), msg.Data)
}

// GetConnectedPeers returns the number of connected peers
func (p *PubSub) GetConnectedPeers() int {
	return len(p.host.Network().Peers())
}

// Close shuts down the PubSub instance
func (p *PubSub) Close() error {
	p.cancel()
	
	if p.bzzzSub != nil {
		p.bzzzSub.Cancel()
	}
	if p.antennaeSub != nil {
		p.antennaeSub.Cancel()
	}
	
	if p.bzzzTopic != nil {
		p.bzzzTopic.Close()
	}
	if p.antennaeTopic != nil {
		p.antennaeTopic.Close()
	}
	
	return nil
}