package statistic

import (
	"os"
	"sync"
	"time"

	"github.com/shirou/gopsutil/v3/process"
	"go.uber.org/atomic"
)

var DefaultManager *Manager

func init() {
	DefaultManager = &Manager{
		uploadTemp:    atomic.NewInt64(0),
		downloadTemp:  atomic.NewInt64(0),
		uploadBlip:    atomic.NewInt64(0),
		downloadBlip:  atomic.NewInt64(0),
		uploadTotal:   atomic.NewInt64(0),
		downloadTotal: atomic.NewInt64(0),
		pid:           os.Getpid(),
	}

	go DefaultManager.handle()
}

type Manager struct {
	connections   sync.Map
	uploadTemp    *atomic.Int64
	downloadTemp  *atomic.Int64
	uploadBlip    *atomic.Int64
	downloadBlip  *atomic.Int64
	uploadTotal   *atomic.Int64
	downloadTotal *atomic.Int64
	pid           int
}

func (m *Manager) Join(c tracker) {
	m.connections.Store(c.ID(), c)
}

func (m *Manager) Leave(c tracker) {
	m.connections.Delete(c.ID())
}

func (m *Manager) PushUploaded(size int64) {
	m.uploadTemp.Add(size)
	m.uploadTotal.Add(size)
}

func (m *Manager) PushDownloaded(size int64) {
	m.downloadTemp.Add(size)
	m.downloadTotal.Add(size)
}

func (m *Manager) Now() (up int64, down int64) {
	return m.uploadBlip.Load(), m.downloadBlip.Load()
}

func (m *Manager) Snapshot() *Snapshot {
	connections := []tracker{}
	m.connections.Range(func(key, value any) bool {
		connections = append(connections, value.(tracker))
		return true
	})

	getMem := func() uint64 {
		p, err := process.NewProcess(int32(m.pid))
		if err != nil {
			return 0
		}
		stat, err := p.MemoryInfo()
		if err != nil {
			return 0
		}
		return stat.RSS
	}

	return &Snapshot{
		UploadTotal:   m.uploadTotal.Load(),
		DownloadTotal: m.downloadTotal.Load(),
		Connections:   connections,
		Memory:        getMem(),
	}
}

func (m *Manager) ResetStatistic() {
	m.uploadTemp.Store(0)
	m.uploadBlip.Store(0)
	m.uploadTotal.Store(0)
	m.downloadTemp.Store(0)
	m.downloadBlip.Store(0)
	m.downloadTotal.Store(0)
}

func (m *Manager) handle() {
	ticker := time.NewTicker(time.Second)

	for range ticker.C {
		m.uploadBlip.Store(m.uploadTemp.Load())
		m.uploadTemp.Store(0)
		m.downloadBlip.Store(m.downloadTemp.Load())
		m.downloadTemp.Store(0)
	}
}

type Snapshot struct {
	DownloadTotal int64     `json:"downloadTotal"`
	UploadTotal   int64     `json:"uploadTotal"`
	Connections   []tracker `json:"connections"`
	Memory        uint64    `json:"memory"`
}