package main

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

type Attachment struct {
	Filename string
	Note     string
}

type matches chan Attachment

func scanReader(r io.Reader, path string, matchChan matches) {

	log.Printf("scanning markdown file: %s", path)
	pat := regexp.MustCompile(`\[\[(Resources\/attachments\/.*?)\]\]`)

	s := bufio.NewScanner(r)
	for s.Scan() {
		tok := s.Text()
		matches := pat.FindAllStringSubmatch(tok, -1)
		if len(matches) > 0 {
			log.Printf("media found in %s: %#+v\n", path, matches)
			for _, match := range matches {
				dirs := strings.Split(path, "/")
				noteFilename := dirs[len(dirs)-2]
				matchChan <- Attachment{Filename: match[1], Note: noteFilename}
			}
		}
	}
}

func walkFunc(matchChan matches) filepath.WalkFunc {
	return func(path string, info fs.FileInfo, err error) error {
		if err != nil {
			return nil
		}
		if info.IsDir() {
			return nil
		}
		f, err := os.Open(path)
		if err != nil {
			return err
		}

		if strings.HasSuffix(path, "index.md") {
			scanReader(f, path, matchChan)
		}
		return nil
	}
}

func moveAttachment(att Attachment, dest string) error {
	destPath := filepath.Join(dest, strings.Split(att.Note, ".")[0])
	log.Println("moving files into:", destPath)
	_, err := copy(att.Filename, filepath.Join(destPath, filepath.Base(att.Filename)))
	return err
}

func copy(src, dst string) (int64, error) {
	sourceFileStat, err := os.Stat(src)
	if err != nil {
		return 0, err
	}

	if !sourceFileStat.Mode().IsRegular() {
		return 0, fmt.Errorf("%s is not a regular file", src)
	}

	source, err := os.Open(src)
	if err != nil {
		return 0, err
	}
	defer source.Close()

	destination, err := os.Create(dst)
	if err != nil {
		return 0, err
	}
	defer destination.Close()
	nBytes, err := io.Copy(destination, source)
	return nBytes, err
}

func main() {
	var (
		target string
	)
	flag.StringVar(&target, "target", "/tmp/blog/content/posts/", "target for posts and their attachments")

	flag.Parse()

	attachments := make(matches)

	// for i := 0; i < 5; i++ {
	go func() {
		for match := range attachments {
			err := moveAttachment(match, target)
			if err != nil {
				log.Fatalf("error moving attachment: %s\n", err)
			}
		}
	}()
	// }

	err := filepath.Walk(target, walkFunc(attachments))
	if err != nil {
		log.Fatalf("error walking %s", err)
	}

}