package gitengine

import (
	"errors"
	"os/exec"
	"strings"
)

var ErrInvalidGitInput = errors.New("invalid git input")

type CommandRunner interface {
	Run(workdir string, args ...string) (string, error)
}

type CLI struct{}

func (CLI) Run(workdir string, args ...string) (string, error) {
	if len(args) == 0 {
		return "", ErrInvalidGitInput
	}
	cmd := exec.Command("git", args...)
	if strings.TrimSpace(workdir) != "" {
		cmd.Dir = workdir
	}
	out, err := cmd.CombinedOutput()
	return string(out), err
}

type StatusResult struct {
	Clean  bool
	Output string
}

func Status(runner CommandRunner, workdir string) (StatusResult, error) {
	output, err := runner.Run(workdir, "status", "--porcelain")
	if err != nil {
		return StatusResult{}, err
	}
	return StatusResult{
		Clean:  strings.TrimSpace(output) == "",
		Output: output,
	}, nil
}

func ChangedFiles(runner CommandRunner, workdir, before, after string) ([]string, error) {
	before = strings.TrimSpace(before)
	after = strings.TrimSpace(after)
	if before == "" || after == "" {
		return nil, ErrInvalidGitInput
	}
	output, err := runner.Run(workdir, "diff", "--name-only", before+".."+after)
	if err != nil {
		return nil, err
	}
	lines := strings.Split(output, "\n")
	files := make([]string, 0, len(lines))
	for _, line := range lines {
		line = strings.TrimSpace(line)
		if line != "" {
			files = append(files, line)
		}
	}
	return files, nil
}