package main
	
	import (
		"fmt"
		"os"
		"path/filepath"
		"sync"
	)
	
	// go-fakedu - toy approximation of the du (disk  usage)
	// toy program to learn go concurrency structures
	
	type FileInfo struct {
		path string
		info os.FileInfo
	}
	
	type SafeArraySlice struct {
		m    sync.Mutex
		data []int64
	}
	
	func NewSafeIntArraySlice() *SafeArraySlice {
		return &SafeArraySlice{
			m:    sync.Mutex{},
			data: make([]int64, 100),
		}
	}
	
	func (a *SafeArraySlice) AppendIntArraySlice(i int64) {
		a.m.Lock()
		defer a.m.Unlock()
		a.data = append(a.data, i)
	}
	
	func enumFiles(dir string) {
		fileCh := make(chan FileInfo)
		errCh := make(chan error, 1) // Buffered channel to prevent blocking
		var wg sync.WaitGroup
	
		file_size_storage := NewSafeIntArraySlice()
	
		// Start a goroutine for walking the file tree
		go func() {
			// Send any errors to the errCh channel
			errCh <- filepath.Walk(dir, func(path string, info os.FileInfo, err error) error {
				if err != nil {
					return err
				}
				if !info.IsDir() {
					fileCh <- FileInfo{path, info}
				}
				return nil
			})
			close(fileCh) // Close the fileCh channel after walking is done
		}()
	
		// Start a goroutine to process files
		go func() {
			for path := range fileCh {
				wg.Add(1)
				go func(fInfo FileInfo) {
					defer wg.Done()
					// Process file (e.g., read, hash, etc.)
					fmt.Println(fInfo.path, fInfo.info.Size())
					file_size_storage.AppendIntArraySlice(fInfo.info.Size())
	
				}(path)
			}
			wg.Wait()
			close(errCh) // Close the errCh channel after all processing is done
		}()
	
		// Check for errors from filepath.Walk
		if err := <-errCh; err != nil {
			fmt.Println("Error walking the file tree:", err)
			return
		}
	
		// Not getting a lock here as by now we know
		// that nothing is currently accessing this  slice
		var size int64 = 0
		for _, value := range file_size_storage.data {
			size = size + value
		}
	
		fmt.Println("Total size: ", float32(size)/(1<<20), "MBs")
	}
	
	func main() {
		args := os.Args
		if len(args) < 2 {
			fmt.Println("Must provide path to directory")
			os.Exit(1)
		}
	
		enumFiles(args[1])
	}