package main

import (
	"bufio"
	"fmt"
	"io/fs"
	"log"
	"os"
	"path/filepath"
	"regexp"
)

const CHANNEL_BUFFERING = 10

type FileMatchData struct {
	Path        string
	LineIndexes []int
	Lines       []string
}

func ProcessSingleFile(re_pattern regexp.Regexp, path string, out chan FileMatchData) error {
	file, err := os.Open(path)
	if err != nil {
		log.Fatal(err)
	}
	defer file.Close()

	res := FileMatchData{Path: path, LineIndexes: make([]int, 0), Lines: make([]string, 0)}
	scanner := bufio.NewScanner(file)
	// optionally, resize scanner's capacity for lines over 64K, see next example
	cur_line_ind := 1
	for scanner.Scan() {
		line_text := scanner.Text()
		if re_pattern.FindString(line_text) != "" {
			res.LineIndexes = append(res.LineIndexes, cur_line_ind)
			res.Lines = append(res.Lines, line_text)
		}
		cur_line_ind++
	}

	if err := scanner.Err(); err != nil {
		log.Fatal(err)
	}
	out <- res
	return nil
}

func main() {
	path_pattern := "git/hook"
	re_path_pattern, err := regexp.Compile(path_pattern)
	if err != nil {
		fmt.Printf("Unable to compile path pattern Regexp: %v\n", path_pattern)
		return
	}

	text_pattern := "the commit"
	re_text_pattern, err := regexp.Compile(text_pattern)
	if err != nil {
		fmt.Printf("Unable to compile text pattern Regexp: %v\n", text_pattern)
		return
	}
	processed_channel := make(chan FileMatchData, CHANNEL_BUFFERING)
	total_files := 0
	err = filepath.Walk(".", func(path string, info fs.FileInfo, err error) error {
		if err != nil {
			fmt.Printf("prevent panic by handling failure accessing a path %q: %v\n", path, err)
			return err
		}
		if re_path_pattern.FindString(path) == "" {
			return nil
		}
		// if info.IsDir() && info.Name() == subDirToSkip {
		// 	fmt.Printf("skipping a dir without errors: %+v \n", info.Name())
		// 	return filepath.SkipDir
		// }
		if info.IsDir() {
			return nil
		}
		go ProcessSingleFile(*re_text_pattern, path, processed_channel)
		total_files++

		return nil
	})
	for ; total_files > 0; total_files-- {
		cur_processed := <-processed_channel
		if len(cur_processed.Lines) == 0 {
			continue
		}
		fmt.Printf("%s:\n", cur_processed.Path)
		for i := 0; i < len(cur_processed.Lines); i++ {
			fmt.Printf("%d:%s\n", cur_processed.LineIndexes[i], cur_processed.Lines[i])
		}
		fmt.Print("\n")
	}

	if err != nil {
		fmt.Printf("error walking the path %q: %v\n", path_pattern, err)
		return
	}
}