package sync

import (
	"bufio"
	"os"

	"github.com/go-git/go-git/v5"
	"github.com/go-git/go-git/v5/config"
)

// GitImporter implements an Importer, where files to imports are located
// inside a local directory from your filesystem, backed by git.
type GitImporter struct {
	li     LocalImporter
	Remote string
}

func NewGitImporter(li LocalImporter, remote string) GitImporter {
	return GitImporter{
		li:     li,
		Remote: remote,
	}
}

func (i GitImporter) Kind() string {
	var gitinfo string
	r, err := git.PlainOpen(i.li.Base)
	if err == nil {
		ref, err := r.Head()
		if err == nil {
			gitinfo = ref.Hash().String()
		}
	}

	return "git originated from " + i.Remote + " on " + i.li.Kind() + ", currently on commit " + gitinfo
}

func countFileInDir(dirname string) (int, error) {
	files, err := os.ReadDir(dirname)
	if err != nil {
		return 0, err
	}

	return len(files), nil
}

func (i GitImporter) Init() error {
	// Check if the directory exists, create it if needed
	if err := i.li.Init(); err != nil {
		return err
	}

	// If the directory is empty, clone it
	if n, err := countFileInDir(i.li.Base); err != nil {
		return err
	} else if n == 0 {
		_, err = git.PlainClone(i.li.Base, false, &git.CloneOptions{
			URL:               i.Remote,
			RecurseSubmodules: git.DefaultSubmoduleRecursionDepth,
		})
		if err != nil {
			return err
		}
	}

	// Check if the .git directory exists, change the origin remote to our
	r, err := git.PlainOpen(i.li.Base)
	if err != nil {
		return err
	}

	r.DeleteRemote("origin")
	_, err = r.CreateRemote(&config.RemoteConfig{
		Name: "origin",
		URLs: []string{i.Remote},
	})
	if err != nil {
		return err
	}

	return nil
}

func (i GitImporter) Sync() error {
	r, err := git.PlainOpen(i.li.Base)
	if err != nil {
		return err
	}

	w, err := r.Worktree()
	if err != nil {
		return err
	}

	// Perform a git pull --rebase origin/master
	err = w.Pull(&git.PullOptions{
		RemoteName:        "origin",
		Depth:             1,
		RecurseSubmodules: git.DefaultSubmoduleRecursionDepth,
		Force:             true,
	})
	return err
}

func (i GitImporter) exists(filename string) bool {
	return i.li.exists(filename)
}

func (i GitImporter) toURL(filename string) string {
	return i.li.toURL(filename)
}

func (i GitImporter) importFile(URI string, next func(string, string) (interface{}, error)) (interface{}, error) {
	return i.li.importFile(URI, next)
}

func (i GitImporter) getFile(filename string, writer *bufio.Writer) error {
	return i.li.getFile(filename, writer)
}

func (i GitImporter) listDir(filename string) ([]string, error) {
	return i.li.listDir(filename)
}

func (i GitImporter) stat(filename string) (os.FileInfo, error) {
	return i.li.stat(filename)
}