notes.go

package main

import (
	"bufio"
	"context"
	"fmt"
	"io"
	"os"
	"os/exec"
	"strings"
	"time"
)

type NoteList map[string]string

func show(w io.Writer, notes NoteList) {
	if len(notes) == 0 {
		fmt.Fprintln(w, "No notes yet")
		return
	}
	for key, value := range notes {
		fmt.Fprintf(w, "%s: %v\n", key, len(value))
	}
}

func FileChanged(initialStat os.FileInfo, file *os.File, c chan<- bool) {
	for {
		stat, err := file.Stat()
		if err != nil {
			return
		}

		if stat.Size() != initialStat.Size() || stat.ModTime() != initialStat.ModTime() {
			c <- true
		}

		time.Sleep(10 * time.Millisecond)
	}
}

func ProgramClosed(c chan<- bool, command *exec.Cmd) {
	command.Wait()
	// Wait for program termination signal
	c <- true
}

const EDITOR_FILENAME = "./RAGADSFILE"

func addNew(w io.Writer, r io.Reader, notes NoteList, editorCommand string, editorArgs ...string) error {
	//print request for input for title
	reader := bufio.NewReader(r)
	fmt.Fprintln(w, "Enter note title: ")
	// read input and store in variable for title
	input, _ := reader.ReadString('\n')
	noteTitle := strings.TrimSpace(input)

	//make a temp file
	file, err := os.Create(EDITOR_FILENAME)
	if err != nil {
		return err
	}
	if err := file.Sync(); err != nil {
		return err
	}

	//print request for input for text
	fmt.Fprintln(w, "Enter lines of text:")
	contents, err := editFile(file, editorCommand, editorArgs)
	if err != nil {
		return err
	}
	notes[noteTitle] = contents
	return nil
}

// edits a temp file with the given editor and returns the contents or an error
func editFile(file *os.File, editorCommand string, editorArgs []string) (string, error) {
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()
	// spawn a editor for the file
	cmd := exec.CommandContext(ctx, editorCommand, append(editorArgs, file.Name())...)
	// watch the file for edits
	initialStat, err := file.Stat()
	if err != nil {
		return "", err
	}

	cmd.Start()

	c := make(chan bool)
	go FileChanged(initialStat, file, c)
	go ProgramClosed(c, cmd)

	<-c

	// when saved copy the contents to the storage at the `title`
	contents, err := os.ReadFile(file.Name())
	if err != nil {
		return "", err
	}

	// clear the contents of the temp file (or destroy it)
	err = os.Remove(file.Name())
	if err != nil {
		return "", err
	}
	// TODO: close the spawned program
	return string(contents), nil
}

func deleteFileName(w io.Writer, r io.Reader, notes NoteList) {
	show(w, notes)
	reader := bufio.NewReader(r)
	fmt.Fprint(w, "Enter the file name of the note you want to delete: ")
	input, _ := reader.ReadString('\n')
	input = strings.TrimSpace(input)
	delete(notes, input)
	show(w, notes)
}

func edit(w io.Writer, r io.Reader, notes NoteList, editorCommand string, editorArgs ...string) error {
	show(w, notes)
	reader := bufio.NewReader(r)
	fmt.Fprint(w, "Enter the file name of the note you want to edit: ")
	input, _ := reader.ReadString('\n')
	noteTitle := strings.TrimSpace(input)
	value, ok := notes[noteTitle]
	if !ok {
		return fmt.Errorf("no note found called %s", noteTitle)
	}
	//make a temp file
	file, err := os.Create(EDITOR_FILENAME)
	if err != nil {
		return err
	}
	_, err = file.WriteString(value)
	if err != nil {
		return err
	}
	contents, err := editFile(file, editorCommand, editorArgs)
	if err != nil {
		return err
	}
	notes[noteTitle] = contents
	return nil
}

const DEFAULT_EDITOR = "code"
const DEFAULT_EDITOR_ARGS = "--wait"

const EDITOR_ENV_VAR = "EDITOR"
const EDITOR_ARGS_ENV_VAR = "EDITOR_ARGS"

func getVarOrDefault(envVar, defaultValue string) string {
	value, set := os.LookupEnv(envVar)
	value = strings.TrimSpace(value)
	if value == "" || !set {
		value = defaultValue
	}
	return value
}

func getEditor() string {
	return getVarOrDefault(EDITOR_ENV_VAR, DEFAULT_EDITOR)
}

func getEditorArgs() []string {
	args := getVarOrDefault(EDITOR_ARGS_ENV_VAR, DEFAULT_EDITOR_ARGS)
	splitArgs := strings.Split(args, " ")
	return splitArgs
}

func main() {
	notes := make(map[string]string)
	editor := getEditor()
	editorArgs := getEditorArgs()
	for {
		var i int
		fmt.Println("select an option by the number: \n1. show all notes \n2. add a note\n3. delete a note \n4. edit  a note")
		fmt.Scan(&i)
		switch i {
		case 1:
			fmt.Println("You want to see your notes")
			show(os.Stdout, notes)
		case 2:
			fmt.Println("You want to add a note")
			addNew(os.Stdin, os.Stdout, notes, editor, editorArgs...)
		case 3:
			fmt.Println("You want to delete a note")
			deleteFileName(os.Stdin, os.Stdout, notes)
		case 4:
			fmt.Println("You want edit a note")
			edit(os.Stdin, os.Stdout, notes, editor, editorArgs...)
		default:
			fmt.Println("Choose between 1-4")
		}
	}

}