package main

import (
	"io/ioutil"
	"os"
	"log"
	"bufio"
	"fmt"
	"strings"
	"path/filepath"
	"io"
	"flag"
)

func main() {
	sourceDir := flag.String("dir", "", "directory where to search")
	fileType := flag.String("type", "", "type of files to search in")
	textToSearch := flag.String("text", "", "text to search")

	flag.Parse()
	if *sourceDir == "" || *fileType == "" || *textToSearch == "" {
		flag.PrintDefaults()
		os.Exit(1)
	}

	allFiles, _ := ioutil.ReadDir(*sourceDir)
	for _, f := range allFiles {
		if !f.IsDir() && strings.HasSuffix(f.Name(), *fileType) {
			//fmt.Println("searching file ", f.Name())
			fullFilePath := filepath.Join(*sourceDir, f.Name())
			file, err := os.Open(fullFilePath)
			if err != nil {
				log.Printf("Error reading %s", fullFilePath)
				continue
			}
			func() {
				defer file.Close()
				searchText(file, *textToSearch)
			}()
		}
	}

}
func searchText(rd io.Reader, textToSearch string) {
	scanner := bufio.NewScanner(rd)
	for scanner.Scan() {
		if strings.Contains(scanner.Text(), textToSearch) {
			fmt.Println(scanner.Text())
		}
	}

	if err := scanner.Err(); err != nil {
		log.Fatal("scanner error ", err)
	}
}