/**
 * HAMi MIG Device Plugin实现
 * 提供MIG实例的自动发现、分配和监控功能
 * 详细架构参见第三部分文档 8.1.1 "HAMi与MIG技术的集成架构"
 */
package main

import (
	"context"
	"fmt"
	"log"
	"time"

	"google.golang.org/grpc"
	pluginapi "k8s.io/kubelet/pkg/apis/deviceplugin/v1beta1"
)

// MIGDevicePlugin HAMi MIG设备插件
// 实现Kubernetes Device Plugin接口，管理MIG资源
type MIGDevicePlugin struct {
	resourceName string                       // 资源名称
	socket       string                       // Unix socket路径
	server       *grpc.Server                 // gRPC服务器
	devices      map[string]*pluginapi.Device // 设备映射表
	migManager   *MIGManager                  // MIG实例管理器
}

// MIGManager MIG实例管理器
// 负责MIG实例的生命周期管理
type MIGManager struct {
	instances map[string]*MIGInstance // MIG实例映射表
}

// MIGInstance MIG实例信息
// 封装单个MIG实例的完整状态信息
type MIGInstance struct {
	ID        string // 实例唯一标识符
	GIID      string // GPU实例ID
	CIID      string // 计算实例ID
	Profile   string // 实例规格(1g.5gb, 2g.10gb等)
	MemoryMB  int64  // 内存大小(MB)
	SMCount   int    // SM数量
	Available bool   // 可用状态
}

// ListAndWatch 实现设备发现和监控
func (m *MIGDevicePlugin) ListAndWatch(e *pluginapi.Empty,
	s pluginapi.DevicePlugin_ListAndWatchServer) error {

	// 初始设备列表发送
	devices := make([]*pluginapi.Device, 0)
	for _, instance := range m.migManager.instances {
		if instance.Available {
			devices = append(devices, &pluginapi.Device{
				ID:     instance.ID,
				Health: pluginapi.Healthy,
				Topology: &pluginapi.TopologyInfo{
					Nodes: []*pluginapi.NUMANode{
						{
							ID: 0,
						},
					},
				},
			})
		}
	}

	resp := &pluginapi.ListAndWatchResponse{Devices: devices}
	if err := s.Send(resp); err != nil {
		return err
	}

	// 持续监控设备状态变化
	ticker := time.NewTicker(10 * time.Second)
	defer ticker.Stop()

	for {
		select {
		case <-ticker.C:
			// 检查MIG实例状态变化
			if m.checkMIGInstancesHealth() {
				// 发送更新的设备列表
				updatedDevices := m.getUpdatedDeviceList()
				resp := &pluginapi.ListAndWatchResponse{
					Devices: updatedDevices,
				}
				if err := s.Send(resp); err != nil {
					return err
				}
			}
		}
	}
}

// Allocate 实现设备分配
func (m *MIGDevicePlugin) Allocate(ctx context.Context,
	reqs *pluginapi.AllocateRequest) (*pluginapi.AllocateResponse, error) {

	responses := make([]*pluginapi.ContainerAllocateResponse, 0)

	for _, req := range reqs.ContainerRequests {
		response := &pluginapi.ContainerAllocateResponse{
			Envs:        make(map[string]string),
			Mounts:      make([]*pluginapi.Mount, 0),
			Devices:     make([]*pluginapi.DeviceSpec, 0),
			Annotations: make(map[string]string),
		}

		for _, deviceID := range req.DevicesIDs {
			instance, exists := m.migManager.instances[deviceID]
			if !exists {
				return nil, fmt.Errorf("MIG实例 %s 不存在", deviceID)
			}

			// 设置MIG相关环境变量
			response.Envs["CUDA_VISIBLE_DEVICES"] = fmt.Sprintf("MIG-%s", instance.ID)
			response.Envs["NVIDIA_MIG_CONFIG_DEVICES"] = instance.ID
			response.Envs["HAMI_MIG_PROFILE"] = instance.Profile
			response.Envs["HAMI_MEMORY_LIMIT"] = fmt.Sprintf("%d", instance.MemoryMB)

			// 添加设备文件
			response.Devices = append(response.Devices, &pluginapi.DeviceSpec{
				ContainerPath: fmt.Sprintf("/dev/nvidia%s", instance.GIID),
				HostPath:      fmt.Sprintf("/dev/nvidia%s", instance.GIID),
				Permissions:   "rwm",
			})

			// 挂载HAMi-core库
			response.Mounts = append(response.Mounts, &pluginapi.Mount{
				ContainerPath: "/usr/local/hami",
				HostPath:      "/usr/local/hami",
				ReadOnly:      true,
			})

			// 标记实例为已分配
			instance.Available = false

			log.Printf("分配MIG实例 %s (Profile: %s) 给容器",
				deviceID, instance.Profile)
		}

		responses = append(responses, response)
	}

	return &pluginapi.AllocateResponse{
		ContainerResponses: responses,
	}, nil
}

// checkMIGInstancesHealth 检查MIG实例健康状态
func (m *MIGDevicePlugin) checkMIGInstancesHealth() bool {
	// 实现MIG实例健康检查逻辑
	return false
}

// getUpdatedDeviceList 获取更新的设备列表
func (m *MIGDevicePlugin) getUpdatedDeviceList() []*pluginapi.Device {
	// 实现设备列表更新逻辑
	return nil
}