package main

import (
	"bufio"
	"fmt"
	"os"
	"path"
	"sync"
)

func oneechan(output chan string) {
	reader := bufio.NewReader(os.Stdin)
	for {
		if text, err := reader.ReadString('\n'); err != nil {
			fmt.Println("[e] Reading from stdin failed, closing: ", err)
			break;
		} else {
			output <- text[:len(text)-1]
		}
	}
	close(output)
}

var shadow bool = false

func worker(from, to string, wg *sync.WaitGroup) {
	defer wg.Done()
	
	if _, err := os.Stat(from); os.IsNotExist(err) {
		fmt.Println("[w] input file does not exist: ",from)
		return
	} else {
		fmt.Printf("[i] %v -> %v\n", from, to)
	}

	if !shadow {
		parent_dir, _ := path.Split(to)

		if _, err := os.Stat(parent_dir); os.IsNotExist(err) {
			if err := os.MkdirAll(parent_dir, os.ModePerm); err != nil {
				fmt.Printf("[e] failed to create structure `%s`: %v\n", parent_dir, err)
				return
			}
		}

		if err := os.Link(from, to); err != nil {
			fmt.Printf("[e] failed to create hardlink `%s`: %v\n", to, err)
		}
	}

}

func imouto(root string, input chan string) {
	var wg sync.WaitGroup
	for from := range input {
		to := path.Join(root, from)

		wg.Add(1)
		go worker(from, to, &wg)
	}
	wg.Wait()
}

func main() {

	if len(os.Args) < 2 {
		fmt.Println("usage: glue [--shadow] <path root>")
		fmt.Println(" -shadow: do not link files or build directory structure")
		return
	}

	i := 1
	if os.Args[1] == "--shadow" {
		shadow = true
		i+=1
	}
	
	paths := make(chan string)
	root := os.Args[i]
	
	go oneechan(paths)
	imouto(root, paths)
}