/*
Copyright © 2025 filifa

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package cmd

import (
	"fmt"

	"github.com/spf13/cobra"
)

var primeOmegaN uint

func primeOmegaUpdateMultiples(sieve []uint, p uint, n uint) {
	for q := p; ; q *= p {
		// omega(a*b) = omega(a) + omega(b) if gcd(a,b) = 1
		for i := 2 * q; i < n; i += q {
			if i%(p*q) != 0 {
				sieve[i] += sieve[q]
			}
		}

		if p*q >= n {
			break
		}
	}
}

func primeOmegaSieve(n uint) chan uint {
	sieve := make([]uint, n)
	for i := uint(0); i < n; i++ {
		sieve[i] = 0
	}

	ch := make(chan uint)
	go func() {
		for i := uint(0); i < n; i++ {
			if i == 0 || i == 1 || sieve[i] != 0 {
				ch <- sieve[i]
				continue
			}

			sieve[i] = 1
			primeOmegaUpdateMultiples(sieve, i, n)
			ch <- sieve[i]
		}

		close(ch)
	}()

	return ch
}

func primeOmega(cmd *cobra.Command, args []string) {
	ch := primeOmegaSieve(primeOmegaN)
	for i := 0; ; i++ {
		v, ok := <-ch
		if !ok {
			break
		}

		if i == 0 {
			continue
		}

		fmt.Println(v)
	}
}

// primeOmegaCmd represents the primeOmega command
var primeOmegaCmd = &cobra.Command{
	Use:   "prime-omega -n N",
	Short: "",
	Long:  ``,
	Run:   primeOmega,
}

func init() {
	sieveCmd.AddCommand(primeOmegaCmd)

	// Here you will define your flags and configuration settings.

	// Cobra supports Persistent Flags which will work for this command
	// and all subcommands, e.g.:
	// primeOmegaCmd.PersistentFlags().String("foo", "", "A help for foo")

	// Cobra supports local flags which will only run when this command
	// is called directly, e.g.:
	// primeOmegaCmd.Flags().BoolP("toggle", "t", false, "Help message for toggle")

	primeOmegaCmd.Flags().UintVarP(&primeOmegaN, "limit", "n", 0, "upper limit")
	primeOmegaCmd.MarkFlagRequired("limit")
}