package main

import (
	"context"
	"fmt"
	"log"
	"os"
	"os/exec"
	"path/filepath"
	"strings"

	"github.com/urfave/cli/v3"
)

func exists(path string) bool {
	_, err := os.Stat(path)
	return !os.IsNotExist(err)
}

func Getwtd() (string, error) {
	hd, err := os.UserHomeDir()
	if err != nil {
		return "", err
	}
	wtd := filepath.Join(hd, ".wt")
	if !exists(wtd) {
		if err := os.Mkdir(wtd, 0o755); err != nil {
			return "", err
		}
	}

	return wtd, nil
}

func GetWorktree(cwd string, name string) (string, error) {
	wtd, err := Getwtd()
	if err != nil {
		return "", err
	}
	project := filepath.Base(cwd)

	return filepath.Join(wtd, project, name), nil
}

func Init(ctx context.Context, cmd *cli.Command) error {
	fmt.Println("init")
	cwd, err := os.Getwd()
	if err != nil {
		return err
	}
	wtd, err := Getwtd()
	if err != nil {
		return err
	}
	if cmd.Args().Get(0) != "" {
		cwd, err = filepath.Abs(cmd.Args().Get(0))
		if err != nil {
			return err
		}
	}
	if !exists(cwd) {
		return fmt.Errorf("%s does not exists", cwd)
	}
	project := filepath.Join(wtd, filepath.Base(cwd))
	if !exists(project) {
		if err := os.Mkdir(project, 0o755); err != nil {
			return err
		}
		c := exec.Command("git", "branch", "--show-current")
		c.Dir = cwd
		out, err := c.Output()
		if err != nil {
			return err
		}
		branch := strings.TrimSpace(string(out))
		worktree := filepath.Join(project, branch)
		if err := os.Rename(cwd, worktree); err != nil {
			return err
		}
		if err := os.Symlink(worktree, cwd); err != nil {
			return err
		}
	}

	return nil
}

func Switch(ctx context.Context, cmd *cli.Command) error {
	branch := strings.TrimSpace(cmd.Args().Get(0))
	if len(branch) == 0 {
		return fmt.Errorf("no worktree name given")
	}
	cwd, err := os.Getwd()
	if err != nil {
		return err
	}
	worktree, err := GetWorktree(cwd, branch)
	if err != nil {
		return err
	}

	if !exists(worktree) {
		if err := exec.Command("git", "worktree", "add", worktree, branch).Run(); err != nil {
			return err
		}
	}

	if _, err := os.Lstat(cwd); err == nil {
		if err := os.Remove(cwd); err != nil {
			return err
		}
	}
	return os.Symlink(worktree, cwd)
}

func List(ctx context.Context, cmd *cli.Command) error {
	wtd, err := Getwtd()
	if err != nil {
		return err
	}
	project, err := os.Getwd()
	if err != nil {
		return err
	}
	dirs, err := os.ReadDir(filepath.Join(wtd, filepath.Base(project)))
	if err != nil {
		return err
	}

	for i := range dirs {
		fmt.Println(dirs[i].Name())
	}
	return nil
}

func main() {
	cmd := cli.Command{
		Name: "wt",
		Commands: []*cli.Command{
			{
				Name:   "init",
				Action: Init,
			},
			{
				Name: "clone",
			},
			{
				Name:   "list",
				Action: List,
			},
			{
				Name:   "switch",
				Action: Switch,
			},
		},
	}

	if err := cmd.Run(context.Background(), os.Args); err != nil {
		log.Fatal(err)
	}
}