package git

import (
	"fmt"
	"os/exec"
	"strings"

	"coopcloud.tech/abra/pkg/log"
)

// getGitDiffArgs builds the `git diff` invocation args. It removes the usage
// of a pager and ensures that colours are specified even when Git might detect
// otherwise.
func getGitDiffArgs(repoPath, fname string) []string {
	args := []string{
		"-C",
		repoPath,
		"--no-pager",
		"-c",
		"color.diff=always",
		"diff",
	}

	if fname != "" {
		args = append(args, fname)
	}

	return args
}

// DiffUnstaged shows a `git diff`. Due to limitations in the underlying go-git
// library, this implementation requires the /usr/bin/git binary.
func DiffUnstaged(path, fname string) (string, error) {
	if _, err := exec.LookPath("git"); err != nil {
		return "", fmt.Errorf("missing /usr/bin/git command? cannot output diff")
	}

	gitDiffArgs := getGitDiffArgs(path, fname)

	log.Debugf("running: git %s", strings.Join(gitDiffArgs, " "))

	diff, err := exec.Command("git", gitDiffArgs...).Output()
	if err != nil {
		return "", err
	}

	return string(diff), nil
}