package main

import (
	"errors"
	"flag"
	"fmt"
	"io/fs"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
)

const codeDir = "/nezuko/code/"

func checkRepoName(name string) (string, error) {
	if strings.Contains(name, "/") {
		return "", fmt.Errorf("invalid name %q: contains slashes", name)
	}
	if !strings.HasSuffix(name, ".git") {
		name += ".git"
	}
	return name, nil
}

func checkRepoNames(args []string) ([]string, error) {
	if len(args) == 0 {
		return nil, fmt.Errorf("missing operand\nUse %s -help for usage info", filepath.Base(os.Args[0]))
	}
	names := make([]string, len(args))
	var errs []error
	for i, arg := range args {
		var err error
		names[i], err = checkRepoName(arg)
		if err != nil {
			errs = append(errs, err)
		}
	}
	if len(errs) > 0 {
		return nil, errors.Join(errs...)
	}
	return names, nil
}

func createRepo(name string) error {
	dir := filepath.Join(codeDir, name)
	fmt.Printf("mkdir %s\n", dir)
	if err := os.Mkdir(dir, 0755); err != nil {
		return err
	}
	fmt.Printf("cd %s && git init --bare\n", dir)
	git := exec.Command("git", "init", "--bare")
	git.Dir = dir
	git.Stdout = os.Stdout
	git.Stderr = os.Stderr
	if err := git.Run(); err != nil {
		return err
	}
	hook := filepath.Join(dir, "hooks/post-update")
	hookSample := hook + ".sample"
	fmt.Printf("mv %s %s\n", hookSample, hook)
	if err := os.Rename(hookSample, hook); err != nil {
		return err
	}
	return nil
}

func create() {
	flag.Usage = func() {
		fmt.Fprintf(os.Stderr, `Usage: create [REPO]...
Create a new git repo named REPO.
`)
	}
	flag.Parse()
	names, err := checkRepoNames(flag.Args())
	if err != nil {
		fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}
	exitCode := 0
	for _, name := range names {
		if err := createRepo(name); err != nil {
			fmt.Fprintln(os.Stderr, err)
			exitCode = 1
		}
	}
	os.Exit(exitCode)
}

func fileExists(path string) bool {
	_, err := os.Stat(path)
	return !errors.Is(err, fs.ErrNotExist)
}

func deleteRepo(name string) error {
	dir := filepath.Join(codeDir, name)
	fmt.Printf("rm -rf %s\n", dir)
	if !fileExists(dir) {
		return fmt.Errorf("repo %q does not exist", name)
	}
	if err := os.RemoveAll(dir); err != nil {
		return err
	}
	return nil
}

func delete() {
	flag.Usage = func() {
		fmt.Fprintf(os.Stderr, `Usage: delete [REPO]...
Delete the git repo named REPO.
`)
	}
	flag.Parse()
	names, err := checkRepoNames(flag.Args())
	if err != nil {
		fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}
	exitCode := 0
	for _, name := range names {
		if err := deleteRepo(name); err != nil {
			fmt.Fprintln(os.Stderr, err)
			exitCode = 1
		}
	}
	os.Exit(exitCode)
}

func help() {
	fmt.Printf(`Available commands:
	create	create a new git repo
	delete	delete a git repo
	help	print this message
`)
}

func main() {
	switch filepath.Base(os.Args[0]) {
	case "create":
		create()
	case "delete":
		delete()
	default:
		help()
	}
}