package git

import (
	"fmt"
	"os/exec"
	"path/filepath"
	"strings"
)

type RepoInfo struct {
	Root          string
	DefaultBranch string
	Remote        string
}

func Inspect(path string) (RepoInfo, error) {
	abs, err := filepath.Abs(path)
	if err != nil {
		return RepoInfo{}, err
	}

	root, err := run(abs, "rev-parse", "--show-toplevel")
	if err != nil {
		return RepoInfo{}, err
	}

	root, err = filepath.EvalSymlinks(root)
	if err != nil {
		return RepoInfo{}, err
	}

	abs, err = filepath.EvalSymlinks(abs)
	if err != nil {
		return RepoInfo{}, err
	}

	if root != abs {
		return RepoInfo{}, fmt.Errorf("%s is inside the repo at %s; register the repo root", abs, root)
	}

	branch, err := run(root, "symbolic-ref", "--short", "HEAD")
	if err != nil {
		return RepoInfo{}, err
	}

	remote, err := run(root, "remote", "get-url", "origin")
	if err != nil {
		return RepoInfo{}, err
	}

	return RepoInfo{Root: root, DefaultBranch: branch, Remote: remote}, nil
}

func AddWorktree(repo, path, branch, base string) (string, error) {
	sha, err := run(repo, "rev-parse", "--verify", base+"^{commit}")
	if err != nil {
		return "", err
	}

	_, err = run(repo, "worktree", "add", "-b", branch, path, sha)
	if err != nil {
		return "", err
	}

	return sha, nil
}

func RemoveWorktree(repo, path, branch string) error {
	_, err := run(repo, "worktree", "remove", "--force", path)
	if err != nil {
		return err
	}

	_, err = run(repo, "branch", "-D", branch)
	return err
}

func run(dir string, args ...string) (string, error) {
	cmd := exec.Command("git", args...)
	cmd.Dir = dir
	out, err := cmd.CombinedOutput()
	if err != nil {
		return "", fmt.Errorf("git %s: %w: %s", strings.Join(args, " "), err, strings.TrimSpace(string(out)))
	}
	return strings.TrimSpace(string(out)), nil
}