package notes

import (
	"bufio"
	"bytes"
	"errors"
	"fmt"
	"io"
	"io/ioutil"
	"local/notes-server/filetree"
	"os"
	"path"
	"strings"
)

func (n *Notes) Comment(urlPath string, lineno int, comment string) error {
	p := filetree.NewPathFromURL(urlPath)
	if stat, err := os.Stat(p.Local); err != nil {
		return errors.New("cannot comment as it does not exist")
	} else if stat.IsDir() {
		return errors.New("cannot comment on a dir")
	}
	f, err := os.Open(p.Local)
	if err != nil {
		return err
	}
	defer f.Close()
	f2, err := ioutil.TempFile(os.TempDir(), path.Base(p.Local)+".*")
	if err != nil {
		return err
	}
	defer f2.Close()
	reader := bufio.NewReader(f)
	writer := io.Writer(f2)
	for i := 0; i < lineno+1; i++ {
		line, _, err := reader.ReadLine()
		if err == io.EOF {
			break
		}
		if err != nil {
			return err
		}
		_, err = io.Copy(writer, bytes.NewReader(line))
		if err != nil {
			return err
		}
		_, err = writer.Write([]byte("\n"))
		if err != nil {
			return err
		}
	}
	formatted := fmt.Sprintf("> *%s*\n\n", comment)
	_, err = io.Copy(writer, strings.NewReader(formatted))
	if err != nil {
		return err
	}
	_, err = io.Copy(writer, reader)
	if err != nil && err != io.EOF {
		return err
	}
	f2.Close()
	return os.Rename(f2.Name(), p.Local)
}