/*
sgodup -- File deduplication utility
Copyright (C) 2020-2023 Sergey Matveev <stargrave@stargrave.org>

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, version 3 of the License.

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 main

import (
	"io"
	"log"
	"os"
	"path"
	"syscall"
)

type FileInode struct {
	Path string
	Size int64
	Dev  uint64
	Ino  uint64
}

func walker(c chan FileInode, dirPath string) {
	dirFd, err := os.Open(dirPath)
	if err != nil {
		log.Fatal(err)
	}
	for {
		fis, err := dirFd.Readdir(1 << 10)
		if err != nil {
			if err == io.EOF {
				break
			}
			log.Fatal(err)
		}
		for _, fi := range fis {
			stat := fi.Sys().(*syscall.Stat_t)
			if fi.Mode().IsRegular() {
				c <- FileInode{
					path.Join(dirPath, fi.Name()),
					fi.Size(),
					stat.Dev, stat.Ino,
				}
			} else if fi.IsDir() {
				walker(c, path.Join(dirPath, fi.Name()))
			}
		}
	}
	if err = dirFd.Close(); err != nil {
		log.Fatal(err)
	}
}

func walk(dirPath string) chan FileInode {
	c := make(chan FileInode, 1<<10)
	go func() {
		walker(c, dirPath)
		close(c)
	}()
	return c
}