package lib

import (
	"fmt"
	"io/ioutil"
	"os"
	"os/exec"
	"strings"
)

const (
	DefaultEditor = "nano"
	DefaultShell  = "sh"
	DefaultPager  = "less"
)

func getEditor() string {
	editor := os.Getenv("EDITOR")
	if editor == "" {
		editor = DefaultEditor
	}

	return editor
}

func getShell() string {
	shell := os.Getenv("SHELL")
	if shell == "" {
		shell = DefaultShell
	}

	return shell
}

func getPager() string {
	return DefaultPager
}

// OpenInEditor opens the passed body text in an editor and returns it after.
func OpenInEditor(body string) (string, error) {
	tmpfile, err := ioutil.TempFile("", "imap-note-*.md")
	if err != nil {
		return "", fmt.Errorf("failed to create tempfile: %w", err)
	}
	// Cleanup on exit
	defer os.Remove(tmpfile.Name())

	if _, err = tmpfile.WriteString(body); err != nil {
		return "", fmt.Errorf("failed to write note to tempfile: %w", err)
	}

	if err = tmpfile.Close(); err != nil {
		return "", fmt.Errorf("failed to close file after writing original content: %w", err)
	}

	editor := getEditor()
	shell := getShell()

	cmd := exec.Command(shell, "-c", editor+" "+tmpfile.Name())
	cmd.Stdin = os.Stdin
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr

	err = cmd.Run()
	if err != nil {
		return "", fmt.Errorf("failed running editor command: %w", err)
	}

	newBytes, err := os.ReadFile(tmpfile.Name())
	if err != nil {
		return "", fmt.Errorf("failed to read new contents from tmp file: %w", err)
	}

	return string(newBytes), nil
}

// OpenInPager opens the passed body text in a pager.
func OpenInPager(body string) error {
	pager := getPager()
	cmd := exec.Command(pager)

	cmd.Stdin = strings.NewReader(body)
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr

	if err := cmd.Run(); err != nil {
		return fmt.Errorf("failed to run pager: %w", err)
	}

	return nil
}