package app

import (
	"context"
	"sync"
	"time"

	"github.com/bwmarrin/snowflake"
)

var SnowFlakeNode *snowflake.Node
var SnowFlake11Node *snowflake11
var NodeId int64

func InitNode() (err error) {
	NodeId, err = Redis.Incr(context.Background(), "joybuywork:snow_flake_node")
	if err != nil {
		return
	}
	NodeId = NodeId % 1000
	snowflake.Epoch = 1687190400000
	SnowFlakeNode, _ = snowflake.NewNode(NodeId)

	SnowFlake11Node = newSnowflake11(NodeId)
	return
}

const (
	epoch    = 1609459200000 // 2021-01-01 00:00:00 UTC
	nodeBits = 4             // 节点ID位数
	stepBits = 7             // 序列号位数
)

type snowflake11 struct {
	mu   sync.Mutex
	node int64
	step int64
	time int64
}

func newSnowflake11(node int64) *snowflake11 {
	return &snowflake11{
		node: node % (1 << nodeBits),
	}
}

func (s *snowflake11) ID() int64 {
	s.mu.Lock()
	defer s.mu.Unlock()

	now := time.Now().UnixNano() / 1e6 // 毫秒时间戳

	if s.time == now {
		s.step = (s.step + 1) & ((1 << stepBits) - 1)
		if s.step == 0 {
			for now <= s.time {
				now = time.Now().UnixNano() / 1e6
			}
		}
	} else {
		s.step = 0
	}

	s.time = now

	// 组成11位ID: 时间差(24位) + 节点(4位) + 序列号(7位)
	// 但实际计算会压缩到11位十进制
	id := (now-epoch)<<(nodeBits+stepBits) | (s.node << stepBits) | s.step

	// 转换为11位十进制数
	return id % 1e11
}