package grpc

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

	agentv1 "github.com/containarr/server/internal/proto/agentv1"
)

type AgentState struct {
	ID         string
	Hostname   string
	Alias      string
	IPAddress  string
	Arch       string
	OS         string
	LastSeenAt time.Time
	Containers []*agentv1.ContainerInfo
	Images     []*agentv1.ImageInfo
	Volumes    []*agentv1.VolumeInfo
	Networks   []*agentv1.NetworkInfo

	Stats          *agentv1.StatsSnapshot
	cmdCh          chan *agentv1.ServerMessage
	pendingFiles   map[string]chan *agentv1.FileResult
	pendingUpdates map[string]string // commandID → containerID
	pendingMu      sync.Mutex
}

type Registry struct {
	mu     sync.RWMutex
	agents map[string]*AgentState
}

func NewRegistry() *Registry {
	return &Registry{agents: make(map[string]*AgentState)}
}

func (r *Registry) Register(id, hostname, alias, ipAddress, arch, os string) *AgentState {
	state := &AgentState{
		ID:           id,
		Hostname:     hostname,
		Alias:        alias,
		IPAddress:    ipAddress,
		Arch:         arch,
		OS:           os,
		cmdCh:          make(chan *agentv1.ServerMessage, 16),
		pendingFiles:   make(map[string]chan *agentv1.FileResult),
		pendingUpdates: make(map[string]string),
	}
	r.mu.Lock()
	r.agents[id] = state
	r.mu.Unlock()
	return state
}

func (r *Registry) Deregister(id string) {
	r.mu.Lock()
	if s, ok := r.agents[id]; ok {
		close(s.cmdCh)
		delete(r.agents, id)
	}
	r.mu.Unlock()
}

func (r *Registry) Get(id string) (*AgentState, bool) {
	r.mu.RLock()
	defer r.mu.RUnlock()
	s, ok := r.agents[id]
	return s, ok
}

func (r *Registry) List() []*AgentState {
	r.mu.RLock()
	defer r.mu.RUnlock()
	out := make([]*AgentState, 0, len(r.agents))
	for _, s := range r.agents {
		out = append(out, s)
	}
	return out
}

func (r *Registry) UpdateContainers(id string, containers []*agentv1.ContainerInfo) {
	r.mu.Lock()
	defer r.mu.Unlock()
	if s, ok := r.agents[id]; ok {
		s.Containers = containers
		s.LastSeenAt = time.Now()
	}
}

func (r *Registry) UpdateResources(id string, containers []*agentv1.ContainerInfo, images []*agentv1.ImageInfo, volumes []*agentv1.VolumeInfo, networks []*agentv1.NetworkInfo) {
	r.mu.Lock()
	defer r.mu.Unlock()
	if s, ok := r.agents[id]; ok {
		s.Containers = containers
		s.Images = images
		s.Volumes = volumes
		s.Networks = networks
		s.LastSeenAt = time.Now()
	}
}

func (r *Registry) UpdateStats(id string, stats *agentv1.StatsSnapshot) {
	r.mu.Lock()
	defer r.mu.Unlock()
	if s, ok := r.agents[id]; ok {
		s.Stats = stats
		s.LastSeenAt = time.Now()
	}
}

// UpdateAlias refreshes the alias for a live agent (called after an admin update).
func (r *Registry) UpdateAlias(id, alias string) {
	r.mu.Lock()
	defer r.mu.Unlock()
	if s, ok := r.agents[id]; ok {
		s.Alias = alias
	}
}

func (r *Registry) Send(agentID string, msg *agentv1.ServerMessage) bool {
	r.mu.RLock()
	s, ok := r.agents[agentID]
	r.mu.RUnlock()
	if !ok {
		return false
	}
	select {
	case s.cmdCh <- msg:
		return true
	default:
		return false
	}
}

// RegisterPending registers a channel waiting for a FileResult with the given cmdID.
func (r *Registry) RegisterPending(agentID, cmdID string) chan *agentv1.FileResult {
	r.mu.RLock()
	s, ok := r.agents[agentID]
	r.mu.RUnlock()
	if !ok {
		return nil
	}
	ch := make(chan *agentv1.FileResult, 1)
	s.pendingMu.Lock()
	s.pendingFiles[cmdID] = ch
	s.pendingMu.Unlock()
	return ch
}

// ResolvePending sends the FileResult to the waiting channel identified by cmdID.
func (r *Registry) ResolvePending(agentID, cmdID string, result *agentv1.FileResult) {
	r.mu.RLock()
	s, ok := r.agents[agentID]
	r.mu.RUnlock()
	if !ok {
		return
	}
	s.pendingMu.Lock()
	ch, ok := s.pendingFiles[cmdID]
	if ok {
		delete(s.pendingFiles, cmdID)
	}
	s.pendingMu.Unlock()
	if ok {
		select {
		case ch <- result:
		default:
		}
	}
}

// CancelPending removes the pending channel for cmdID (cleanup on timeout).
func (r *Registry) CancelPending(agentID, cmdID string) {
	r.mu.RLock()
	s, ok := r.agents[agentID]
	r.mu.RUnlock()
	if !ok {
		return
	}
	s.pendingMu.Lock()
	delete(s.pendingFiles, cmdID)
	s.pendingMu.Unlock()
}

// SendAndWait registers a pending channel, sends msg to the agent, and waits up
// to 30 seconds for the FileResult response identified by cmdID.
func (r *Registry) SendAndWait(agentID string, msg *agentv1.ServerMessage, cmdID string) (*agentv1.FileResult, error) {
	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
	defer cancel()
	return r.SendAndWaitCtx(ctx, agentID, msg, cmdID)
}

// RegisterPendingUpdate enregistre un commandID en attente de CommandResult pour un UpdateContainer.
func (r *Registry) RegisterPendingUpdate(agentID, cmdID, containerID string) {
	r.mu.RLock()
	s, ok := r.agents[agentID]
	r.mu.RUnlock()
	if !ok {
		return
	}
	s.pendingMu.Lock()
	s.pendingUpdates[cmdID] = containerID
	s.pendingMu.Unlock()
}

// ResolvePendingUpdate retourne le containerID associé au commandID et le supprime de la map.
// Retourne ("", false) si le commandID n'est pas connu.
func (r *Registry) ResolvePendingUpdate(agentID, cmdID string) (string, bool) {
	r.mu.RLock()
	s, ok := r.agents[agentID]
	r.mu.RUnlock()
	if !ok {
		return "", false
	}
	s.pendingMu.Lock()
	containerID, found := s.pendingUpdates[cmdID]
	if found {
		delete(s.pendingUpdates, cmdID)
	}
	s.pendingMu.Unlock()
	return containerID, found
}

// SendAndWaitCtx is like SendAndWait but uses the provided context for timeout control.
func (r *Registry) SendAndWaitCtx(ctx context.Context, agentID string, msg *agentv1.ServerMessage, cmdID string) (*agentv1.FileResult, error) {
	ch := r.RegisterPending(agentID, cmdID)
	if ch == nil {
		return nil, fmt.Errorf("agent not connected")
	}

	if !r.Send(agentID, msg) {
		r.CancelPending(agentID, cmdID)
		return nil, fmt.Errorf("agent not connected")
	}

	select {
	case result := <-ch:
		return result, nil
	case <-ctx.Done():
		r.CancelPending(agentID, cmdID)
		return nil, fmt.Errorf("timeout waiting for agent response")
	}
}