package vcs

import (
	"io/fs"
	"os"

	"go.alanpearce.eu/website/internal/config"
	"go.alanpearce.eu/x/log"

	"github.com/go-git/go-git/v5"
	"github.com/go-git/go-git/v5/plumbing"
	"gitlab.com/tozd/go/errors"
)

type Options struct {
	LocalPath string
	RemoteURL config.URL
	Branch    string
}

type Repository struct {
	repo      *git.Repository
	log       *log.Logger
	remoteURL config.URL
}

func CloneOrOpen(cfg *Options, log *log.Logger) (repo *Repository, exists bool, err error) {
	stat, err := os.Stat(cfg.LocalPath)
	exists = err == nil
	if err != nil && !errors.Is(err, fs.ErrNotExist) {
		return
	}
	repo = &Repository{
		log:       log,
		remoteURL: cfg.RemoteURL,
	}
	if stat == nil {
		repo.repo, err = git.PlainClone(cfg.LocalPath, false, &git.CloneOptions{
			URL:      cfg.RemoteURL.String(),
			Progress: os.Stdout,
		})
	} else {
		repo.repo, err = git.PlainOpen(cfg.LocalPath)
	}

	return
}

func (r *Repository) Update() (updated bool, err error) {
	r.log.Info("updating repository", "from", r.headSHA())
	err = r.repo.Fetch(&git.FetchOptions{
		Prune: true,
	})
	if err != nil {
		if errors.Is(err, git.NoErrAlreadyUpToDate) {
			r.log.Info("already up-to-date")

			return true, nil
		}

		return false, err
	}

	rem, err := r.repo.Remote("origin")
	if err != nil {
		return false, err
	}
	refs, err := rem.List(&git.ListOptions{
		Timeout: 5,
	})
	if err != nil {
		return false, err
	}

	var hash plumbing.Hash
	for _, ref := range refs {
		if ref.Name() == plumbing.Main {
			hash = ref.Hash()

			break
		}
	}

	wt, err := r.repo.Worktree()
	if err != nil {
		return false, err
	}
	err = wt.Checkout(&git.CheckoutOptions{
		Hash:  hash,
		Force: true,
	})
	if err != nil {
		return false, err
	}

	r.log.Info("updated to", "rev", hash)

	return true, r.Clean(wt)
}

func (r *Repository) Clean(wt *git.Worktree) error {
	st, err := wt.Status()
	if err != nil {
		return err
	}

	if !st.IsClean() {
		err = wt.Clean(&git.CleanOptions{
			Dir: true,
		})
		if err != nil {
			return err
		}
	}

	return nil
}

func (r *Repository) headSHA() string {
	head, err := r.repo.Head()
	if err != nil {
		return ""
	}

	return head.Hash().String()
}