package main

import (
	"bufio"
	"bytes"
	"errors"
	"fmt"
	"os"
	"os/exec"
	"strings"

	"github.com/logrusorgru/aurora"
)

// goFmt checks for bad formatting. It uses the "goimports" command. As of
// 2020-02, the command "goimports ." recurses and ignores module boundaries and
// non-go directories. It can therefore be run from the root of the git repo.
func goFmt() error {
	// execute goimports
	wbuf := bytes.NewBuffer(nil)
	cmd := exec.Command("goimports", "-l", ".")
	cmd.Stdout = wbuf
	cmd.Stderr = os.Stderr
	if err := cmd.Run(); err != nil {
		// non-zero return code = program error (not bad formatting)
		return fmt.Errorf("%s: %v", aurora.Blue("goimports -l"), aurora.Red(err))
	}

	// iterate over list of changed files, may be empty
	var (
		scanner = bufio.NewScanner(wbuf)
		werr    strings.Builder
		ok      = true
	)
	fmt.Fprintln(&werr, aurora.Red("The following files need reformatting:"))
	for scanner.Scan() {
		// ignore generated .pb.go files
		if strings.HasSuffix(scanner.Text(), ".pb.go") {
			continue
		}

		ok = false
		werr.WriteByte('\t')
		werr.WriteString(scanner.Text())
		werr.WriteByte('\n')
	}

	if ok {
		return nil
	}
	return errors.New(werr.String())
}