package login

import (
	"sync"
	"time"

	"eq2emu/internal/udp"
)

// ClientList manages connected login clients
type ClientList struct {
	clients     map[*udp.Connection]*Client
	byAccountID map[int32]*Client
	mu          sync.RWMutex
}

// NewClientList creates a new client list
func NewClientList() *ClientList {
	return &ClientList{
		clients:     make(map[*udp.Connection]*Client),
		byAccountID: make(map[int32]*Client),
	}
}

// Add adds a client to the list
func (cl *ClientList) Add(client *Client) {
	if client == nil || client.GetConnection() == nil {
		return
	}

	cl.mu.Lock()
	defer cl.mu.Unlock()

	// Remove any existing client for this connection
	if existing, exists := cl.clients[client.GetConnection()]; exists {
		existing.Disconnect("Replaced by new connection")
		if existing.GetAccountID() > 0 {
			delete(cl.byAccountID, existing.GetAccountID())
		}
	}

	cl.clients[client.GetConnection()] = client
}

// Remove removes a client from the list
func (cl *ClientList) Remove(client *Client) {
	if client == nil {
		return
	}

	cl.mu.Lock()
	defer cl.mu.Unlock()

	conn := client.GetConnection()
	if conn != nil {
		delete(cl.clients, conn)
	}

	if client.GetAccountID() > 0 {
		delete(cl.byAccountID, client.GetAccountID())
	}
}

// GetByConnection returns a client by connection
func (cl *ClientList) GetByConnection(conn *udp.Connection) *Client {
	if conn == nil {
		return nil
	}

	cl.mu.RLock()
	defer cl.mu.RUnlock()

	return cl.clients[conn]
}

// GetByAccountID returns a client by account ID
func (cl *ClientList) GetByAccountID(accountID int32) *Client {
	if accountID <= 0 {
		return nil
	}

	cl.mu.RLock()
	defer cl.mu.RUnlock()

	return cl.byAccountID[accountID]
}

// UpdateAccountMapping updates the account ID mapping for a client
func (cl *ClientList) UpdateAccountMapping(client *Client) {
	if client == nil {
		return
	}

	cl.mu.Lock()
	defer cl.mu.Unlock()

	accountID := client.GetAccountID()
	if accountID > 0 {
		// Remove any existing mapping for this account
		if existing, exists := cl.byAccountID[accountID]; exists && existing != client {
			existing.Disconnect("Account logged in elsewhere")
			delete(cl.clients, existing.GetConnection())
		}

		cl.byAccountID[accountID] = client
	}
}

// Process processes all clients
func (cl *ClientList) Process() {
	cl.mu.Lock()
	defer cl.mu.Unlock()

	// Check for timed out clients
	timeout := 5 * time.Minute
	var toRemove []*Client

	for _, client := range cl.clients {
		if client.IsTimedOut(timeout) {
			toRemove = append(toRemove, client)
		}
	}

	// Remove timed out clients
	for _, client := range toRemove {
		client.Disconnect("Connection timeout")
		delete(cl.clients, client.GetConnection())
		
		if client.GetAccountID() > 0 {
			delete(cl.byAccountID, client.GetAccountID())
		}
	}
}

// Count returns the number of connected clients
func (cl *ClientList) Count() int {
	cl.mu.RLock()
	defer cl.mu.RUnlock()
	return len(cl.clients)
}

// GetClients returns a slice of all clients (snapshot)
func (cl *ClientList) GetClients() []*Client {
	cl.mu.RLock()
	defer cl.mu.RUnlock()

	clients := make([]*Client, 0, len(cl.clients))
	for _, client := range cl.clients {
		clients = append(clients, client)
	}

	return clients
}

// GetClientsByState returns clients in a specific state
func (cl *ClientList) GetClientsByState(state ClientState) []*Client {
	cl.mu.RLock()
	defer cl.mu.RUnlock()

	var clients []*Client
	for _, client := range cl.clients {
		if client.GetState() == state {
			clients = append(clients, client)
		}
	}

	return clients
}

// DisconnectAll disconnects all clients
func (cl *ClientList) DisconnectAll(reason string) {
	cl.mu.Lock()
	defer cl.mu.Unlock()

	for _, client := range cl.clients {
		client.Disconnect(reason)
	}

	// Clear maps
	cl.clients = make(map[*udp.Connection]*Client)
	cl.byAccountID = make(map[int32]*Client)
}

// DisconnectByAccountID disconnects a client by account ID
func (cl *ClientList) DisconnectByAccountID(accountID int32, reason string) bool {
	client := cl.GetByAccountID(accountID)
	if client == nil {
		return false
	}

	client.Disconnect(reason)
	cl.Remove(client)
	return true
}

// GetStats returns client list statistics
func (cl *ClientList) GetStats() ClientListStats {
	cl.mu.RLock()
	defer cl.mu.RUnlock()

	stats := ClientListStats{
		Total: len(cl.clients),
		States: make(map[ClientState]int),
	}

	for _, client := range cl.clients {
		state := client.GetState()
		stats.States[state]++
	}

	return stats
}

// ClientListStats represents statistics about the client list
type ClientListStats struct {
	Total  int                    `json:"total"`
	States map[ClientState]int    `json:"states"`
}

// ForEach executes a function for each client (thread-safe)
func (cl *ClientList) ForEach(fn func(*Client)) {
	clients := cl.GetClients()
	for _, client := range clients {
		fn(client)
	}
}