package routing

import (
	"context"
	"encoding/json"
	"fmt"
	"log"
	"strings"
	"sync"

	"synapse/internal/agent/group"
	"synapse/internal/agent/p2p"
	"synapse/internal/hil"
	"synapse/pkg/types"
)

// =============================================================================
// Message Router
// =============================================================================

// Router handles routing of Synapse messages
type Router struct {
	mu sync.RWMutex

	// Protocols
	p2pProtocol   *p2p.P2PProtocol
	groupProtocol *group.GroupProtocol
	hilProtocol   *hil.HILProtocol

	// External routing
	externalRoutes map[string]string // system_id -> gateway endpoint

	// Configuration
	config *RouterConfig
}

// RouterConfig holds router configuration
type RouterConfig struct {
	MaxHops       int
	EnableCaching bool
}

// DefaultRouterConfig returns default router configuration
func DefaultRouterConfig() *RouterConfig {
	return &RouterConfig{
		MaxHops:       10,
		EnableCaching: true,
	}
}

// =============================================================================
// NewRouter creates a new message router
// =============================================================================

func NewRouter(config *RouterConfig) *Router {
	if config == nil {
		config = DefaultRouterConfig()
	}
	return &Router{
		externalRoutes: make(map[string]string),
		config:         config,
	}
}

// SetP2PProtocol sets the P2P protocol handler
func (r *Router) SetP2PProtocol(p *p2p.P2PProtocol) {
	r.mu.Lock()
	defer r.mu.Unlock()
	r.p2pProtocol = p
}

// SetGroupProtocol sets the Group protocol handler
func (r *Router) SetGroupProtocol(g *group.GroupProtocol) {
	r.mu.Lock()
	defer r.mu.Unlock()
	r.groupProtocol = g
}

// SetHILProtocol sets the HiL protocol handler
func (r *Router) SetHILProtocol(h *hil.HILProtocol) {
	r.mu.Lock()
	defer r.mu.Unlock()
	r.hilProtocol = h
}

// RegisterExternalRoute registers an external system gateway
func (r *Router) RegisterExternalRoute(systemID, endpoint string) {
	r.mu.Lock()
	defer r.mu.Unlock()
	r.externalRoutes[systemID] = endpoint
}

// =============================================================================
// RouteMessage routes an incoming message to the appropriate handler
// =============================================================================

func (r *Router) RouteMessage(ctx context.Context, msg *types.UnifiedSynapseMessage) (*types.UnifiedSynapseMessage, error) {
	r.mu.RLock()
	defer r.mu.RUnlock()

	// Validate message
	if err := r.validateMessage(msg); err != nil {
		return nil, err
	}

	// Route based on message category
	if isGroupMessage(msg.Type) {
		if r.groupProtocol == nil {
			return nil, fmt.Errorf("group protocol not configured")
		}
		return r.groupProtocol.HandleMessage(ctx, msg)
	}

	if isP2PMessage(msg.Type) {
		if r.p2pProtocol == nil {
			return nil, fmt.Errorf("p2p protocol not configured")
		}
		return r.p2pProtocol.HandleMessage(ctx, msg)
	}

	return nil, fmt.Errorf("unknown message type: %s", msg.Type)
}

// =============================================================================
// SendMessage sends a message to a destination
// =============================================================================

// MessageSender is the interface for sending messages
type MessageSender interface {
	Send(ctx context.Context, endpoint string, msg *types.UnifiedSynapseMessage) error
}

// TransportSender is used by the router to send messages
var _ MessageSender = (*TransportSender)(nil)

// TransportSender is a placeholder for actual transport implementation
type TransportSender struct {
	httpClient *HTTPClient
}

// HTTPClient is a simple HTTP client for sending messages
type HTTPClient struct {
	baseURL   string
	timeoutMs int
}

// Send sends a message via HTTP
func (t *TransportSender) Send(ctx context.Context, endpoint string, msg *types.UnifiedSynapseMessage) error {
	if endpoint == "" {
		return fmt.Errorf("endpoint is required")
	}

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

	// In a real implementation, this would use net/http to send the message
	log.Printf("[Router] Sending message to %s: type=%s, id=%s", endpoint, msg.Type, msg.ID)

	return nil // Placeholder - actual HTTP call would go here
}

// =============================================================================
// CreateOutboundMessage creates a message for sending to a remote agent
// =============================================================================

func (r *Router) CreateOutboundMessage(
	msgType string,
	sender types.AgentEndpoint,
	receiver *types.AgentEndpoint,
	payload any,
	correlationID string,
) (*types.UnifiedSynapseMessage, error) {
	payloadBytes, err := json.Marshal(payload)
	if err != nil {
		return nil, fmt.Errorf("failed to marshal payload: %w", err)
	}

	msg := &types.UnifiedSynapseMessage{
		ID:            types.GenerateMessageID(),
		Version:       "1.0.0",
		Type:          msgType,
		Sender:        sender,
		Receiver:      receiver,
		CorrelationID: correlationID,
		Payload:       payloadBytes,
		Timestamp:     types.NowTimestamp(),
	}

	return msg, nil
}

// =============================================================================
// CreateTaskRequest creates a task request message
// =============================================================================

func (r *Router) CreateTaskRequest(
	sender types.AgentEndpoint,
	receiver types.AgentEndpoint,
	taskID string,
	taskType string,
	taskPayload map[string]interface{},
	priority types.Priority,
	correlationID string,
) (*types.UnifiedSynapseMessage, error) {
	payload := types.TaskRequestPayload{}
	payload.Task.ID = taskID
	payload.Task.Type = taskType
	payload.Task.Priority = priority
	payload.Task.Payload = taskPayload

	return r.CreateOutboundMessage(
		string(types.P2PTaskRequest),
		sender,
		&receiver,
		payload,
		correlationID,
	)
}

// =============================================================================
// CreateTaskNeedHuman creates a need human message
// =============================================================================

func (r *Router) CreateTaskNeedHuman(
	sender types.AgentEndpoint,
	receiver types.AgentEndpoint,
	taskID string,
	reasonCode, reasonMessage string,
	context struct {
		TaskSummary     string
		CurrentProgress int
		BlockedReason   string
		RelevantHistory []any
	},
	options []struct {
		Field      string
		Value      any
		ProsCons   string
		Confidence int
	},
	suggestedValue any,
	escalationLevel int,
	correlationID string,
) (*types.UnifiedSynapseMessage, error) {
	payload := types.TaskNeedHumanPayload{}
	payload.TaskID = taskID
	payload.Reason.Code = reasonCode
	payload.Reason.Message = reasonMessage
	payload.Context.TaskSummary = context.TaskSummary
	payload.Context.CurrentProgress = context.CurrentProgress
	payload.Context.BlockedReason = context.BlockedReason
	payload.Context.RelevantHistory = context.RelevantHistory

	// Copy options
	payload.Options = make([]struct {
		Field      string `json:"field"`
		Value      any    `json:"value"`
		ProsCons   string `json:"pros_cons,omitempty"`
		Confidence int    `json:"confidence,omitempty"`
	}, len(options))
	for i, opt := range options {
		payload.Options[i].Field = opt.Field
		payload.Options[i].Value = opt.Value
		payload.Options[i].ProsCons = opt.ProsCons
		payload.Options[i].Confidence = opt.Confidence
	}

	payload.SuggestedValue = suggestedValue
	payload.EscalationLevel = escalationLevel

	return r.CreateOutboundMessage(
		string(types.P2PTaskNeedHuman),
		sender,
		&receiver,
		payload,
		correlationID,
	)
}

// =============================================================================
// CreateGroupTaskSplit creates a group task split message
// =============================================================================

func (r *Router) CreateGroupTaskSplit(
	sender types.AgentEndpoint,
	groupID string,
	originalTask struct {
		ID           string
		Type         string
		Requirements map[string]interface{}
		Deadline     *types.Timestamp
	},
	subtasks []types.Subtask,
	mergeStrategy types.MergeStrategy,
	correlationID string,
) (*types.UnifiedSynapseMessage, error) {
	payload := types.GroupTaskSplitPayload{}
	payload.OriginalTask.ID = originalTask.ID
	payload.OriginalTask.Type = originalTask.Type
	payload.OriginalTask.Requirements = originalTask.Requirements
	payload.OriginalTask.Deadline = originalTask.Deadline
	payload.Subtasks = subtasks
	payload.MergeStrategy = mergeStrategy

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

	msg := &types.UnifiedSynapseMessage{
		ID:            types.GenerateMessageID(),
		Version:       "1.0.0",
		Type:          string(types.GroupTaskSplit),
		Sender:        sender,
		GroupID:       groupID,
		Broadcast:     false,
		CorrelationID: correlationID,
		Payload:       payloadBytes,
		Timestamp:     types.NowTimestamp(),
	}

	return msg, nil
}

// =============================================================================
// CreateGroupBroadcast creates a group broadcast message
// =============================================================================

func (r *Router) CreateGroupBroadcast(
	sender types.AgentEndpoint,
	groupID string,
	msgType string,
	payload any,
	correlationID string,
) (*types.UnifiedSynapseMessage, error) {
	payloadBytes, err := json.Marshal(payload)
	if err != nil {
		return nil, fmt.Errorf("failed to marshal payload: %w", err)
	}

	msg := &types.UnifiedSynapseMessage{
		ID:            types.GenerateMessageID(),
		Version:       "1.0.0",
		Type:          msgType,
		Sender:        sender,
		GroupID:       groupID,
		Broadcast:     true,
		CorrelationID: correlationID,
		Payload:       payloadBytes,
		Timestamp:     types.NowTimestamp(),
	}

	return msg, nil
}

// =============================================================================
// CreateGroupVote creates a group vote message
// =============================================================================

func (r *Router) CreateGroupVote(
	sender types.AgentEndpoint,
	groupID string,
	voteID string,
	question string,
	options []string,
	voters []string,
	threshold float64,
	deadline types.Timestamp,
	correlationID string,
) (*types.UnifiedSynapseMessage, error) {
	payload := types.GroupVotePayload{}
	payload.VoteID = voteID
	payload.Question = question
	payload.Options = options
	payload.Voters = voters
	payload.Threshold = threshold
	payload.Deadline = deadline
	payload.Status = "open"

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

	msg := &types.UnifiedSynapseMessage{
		ID:            types.GenerateMessageID(),
		Version:       "1.0.0",
		Type:          string(types.GroupVote),
		Sender:        sender,
		GroupID:       groupID,
		Broadcast:     true,
		CorrelationID: correlationID,
		Payload:       payloadBytes,
		Timestamp:     types.NowTimestamp(),
	}

	return msg, nil
}

// =============================================================================
// Validation
// =============================================================================

func (r *Router) validateMessage(msg *types.UnifiedSynapseMessage) error {
	if msg.ID == "" {
		return types.ErrMessageFormatInvalidError
	}
	if msg.Sender.AgentID == "" {
		return types.NewSynapseError(types.ErrMessageFormatInvalid, "Missing sender agent_id", nil)
	}
	if msg.Sender.Endpoint == "" {
		return types.NewSynapseError(types.ErrMessageFormatInvalid, "Missing sender endpoint", nil)
	}
	return nil
}

// =============================================================================
// Helper Functions
// =============================================================================

func isP2PMessage(msgType string) bool {
	return strings.HasPrefix(msgType, "p2p:")
}

func isGroupMessage(msgType string) bool {
	return strings.HasPrefix(msgType, "group:") || strings.HasPrefix(msgType, "inter_group:")
}

// GetRoute determines the route for a message
func (r *Router) GetRoute(msg *types.UnifiedSynapseMessage) (routeType string, target string, err error) {
	// P2P messages
	if msg.Receiver != nil {
		if msg.Receiver.SystemID != r.p2pProtocol.AgentEndpoint().SystemID {
			// External system
			if endpoint, ok := r.externalRoutes[msg.Receiver.SystemID]; ok {
				return "external", endpoint, nil
			}
			return "unknown", "", fmt.Errorf("no route for system: %s", msg.Receiver.SystemID)
		}
		return "local", msg.Receiver.AgentID, nil
	}

	// Group messages
	if msg.GroupID != "" {
		return "group", msg.GroupID, nil
	}

	return "unknown", "", fmt.Errorf("no route found for message")
}