package main

import (
	"fmt"
	"math/rand"
	"time"
)

// Base-62 encoding characters
const base62 = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"

// Convert a number to Base-62
func toBase62(num int64) string {
	var encoded string
	for num > 0 {
		remainder := num % 62
		encoded = string(base62[remainder]) + encoded
		num /= 62
	}
	return encoded
}

func generateID() string {
	epochStart := time.Date(2020, 1, 1, 0, 0, 0, 0, time.UTC).UnixMilli()
	now := time.Now().UTC().UnixMilli()
	timestamp := now - epochStart // Get milliseconds since 2020
	timestamp %= 1_000_000_000_000 // Keep only 12 digits

	randomNum := rand.Intn(100) // Random 2-digit number (00-99)
	finalNum := timestamp*100 + int64(randomNum)

	return fmt.Sprintf("%08s", toBase62(finalNum)) // Ensure 8-char output
}

func main() {
	fmt.Println(generateID()) // Example output: "A1b2C3D4"
}