package gitlab

import (
	"fmt"
	"time"

	"github.com/xanzy/go-gitlab"

	"github.com/MichaelMure/git-bug/bridge/core"
	"github.com/MichaelMure/git-bug/bug"
	"github.com/MichaelMure/git-bug/cache"
	"github.com/MichaelMure/git-bug/util/text"
)

const (
	keyGitlabLogin = "gitlab-login"
)

type gitlabImporter struct {
	conf core.Configuration

	// iterator
	iterator *iterator

	// number of imported issues
	importedIssues int

	// number of imported identities
	importedIdentities int
}

func (gi *gitlabImporter) Init(conf core.Configuration) error {
	gi.conf = conf
	return nil
}

func (gi *gitlabImporter) ImportAll(repo *cache.RepoCache, since time.Time) error {
	gi.iterator = NewIterator(gi.conf[keyProjectID], gi.conf[keyToken], since)

	// Loop over all matching issues
	for gi.iterator.NextIssue() {
		issue := gi.iterator.IssueValue()
		fmt.Printf("importing issue: %v\n", issue.Title)

		// create issue
		b, err := gi.ensureIssue(repo, issue)
		if err != nil {
			return fmt.Errorf("issue creation: %v", err)
		}

		// Loop over all notes
		for gi.iterator.NextNote() {
			note := gi.iterator.NoteValue()
			if err := gi.ensureNote(repo, b, note); err != nil {
				return fmt.Errorf("note creation: %v", err)
			}
		}

		// Loop over all label events
		for gi.iterator.NextLabelEvent() {
			labelEvent := gi.iterator.LabelEventValue()
			if err := gi.ensureLabelEvent(repo, b, labelEvent); err != nil {
				return fmt.Errorf("label event creation: %v", err)
			}

		}

		// commit bug state
		if err := b.CommitAsNeeded(); err != nil {
			return fmt.Errorf("bug commit: %v", err)
		}
	}

	if err := gi.iterator.Error(); err != nil {
		fmt.Printf("import error: %v\n", err)
		return err
	}

	fmt.Printf("Successfully imported %d issues and %d identities from Gitlab\n", gi.importedIssues, gi.importedIdentities)
	return nil
}

func (gi *gitlabImporter) ensureIssue(repo *cache.RepoCache, issue *gitlab.Issue) (*cache.BugCache, error) {
	// ensure issue author
	author, err := gi.ensurePerson(repo, issue.Author.ID)
	if err != nil {
		return nil, err
	}

	// resolve bug
	b, err := repo.ResolveBugCreateMetadata(keyGitlabUrl, issue.WebURL)
	if err != nil && err != bug.ErrBugNotExist {
		return nil, err
	}

	if err == bug.ErrBugNotExist {
		cleanText, err := text.Cleanup(string(issue.Description))
		if err != nil {
			return nil, err
		}

		// create bug
		b, _, err = repo.NewBugRaw(
			author,
			issue.CreatedAt.Unix(),
			issue.Title,
			cleanText,
			nil,
			map[string]string{
				keyOrigin:    target,
				keyGitlabId:  parseID(issue.ID),
				keyGitlabUrl: issue.WebURL,
			},
		)

		if err != nil {
			return nil, err
		}

		// importing a new bug
		gi.importedIssues++

		return b, nil
	}

	return nil, nil
}

func (gi *gitlabImporter) ensureNote(repo *cache.RepoCache, b *cache.BugCache, note *gitlab.Note) error {
	id := parseID(note.ID)

	hash, err := b.ResolveOperationWithMetadata(keyGitlabId, id)
	if err != cache.ErrNoMatchingOp {
		return err
	}

	// ensure issue author
	author, err := gi.ensurePerson(repo, note.Author.ID)
	if err != nil {
		return err
	}

	noteType, body := GetNoteType(note)
	switch noteType {
	case NOTE_CLOSED:
		_, err = b.CloseRaw(
			author,
			note.CreatedAt.Unix(),
			map[string]string{
				keyGitlabId: id,
			},
		)
		return err

	case NOTE_REOPENED:
		_, err = b.OpenRaw(
			author,
			note.CreatedAt.Unix(),
			map[string]string{
				keyGitlabId: id,
			},
		)
		return err

	case NOTE_DESCRIPTION_CHANGED:
		issue := gi.iterator.IssueValue()

		// since gitlab doesn't provide the issue history
		// we should check for "changed the description" notes and compare issue texts

		if issue.Description != b.Snapshot().Comments[0].Message {
			// comment edition
			_, err = b.EditCommentRaw(
				author,
				note.UpdatedAt.Unix(),
				target,
				issue.Description,
				map[string]string{
					keyGitlabId:  id,
					keyGitlabUrl: "",
				},
			)

			return err

		}

	case NOTE_COMMENT:

		cleanText, err := text.Cleanup(body)
		if err != nil {
			return err
		}

		// if we didn't import the comment
		if err == cache.ErrNoMatchingOp {

			// add comment operation
			_, err = b.AddCommentRaw(
				author,
				note.CreatedAt.Unix(),
				cleanText,
				nil,
				map[string]string{
					keyGitlabId:  id,
					keyGitlabUrl: "",
				},
			)

			return err
		}

		// if comment was already exported

		// if note wasn't updated
		if note.UpdatedAt.Equal(*note.CreatedAt) {
			return nil
		}

		// search for last comment update
		timeline, err := b.Snapshot().SearchTimelineItem(hash)
		if err != nil {
			return err
		}

		item, ok := timeline.(*bug.AddCommentTimelineItem)
		if !ok {
			return fmt.Errorf("expected add comment time line")
		}

		// compare local bug comment with the new note body
		if item.Message != cleanText {
			// comment edition
			_, err = b.EditCommentRaw(
				author,
				note.UpdatedAt.Unix(),
				target,
				cleanText,
				map[string]string{
					// no metadata unique metadata to store
					keyGitlabId:  "",
					keyGitlabUrl: "",
				},
			)

			return err
		}

		return nil

	case NOTE_TITLE_CHANGED:

		_, err = b.SetTitleRaw(
			author,
			note.CreatedAt.Unix(),
			body,
			map[string]string{
				keyGitlabId:  id,
				keyGitlabUrl: "",
			},
		)

		return err

	default:
		// non handled note types

		return nil
	}

	return nil
}

func (gi *gitlabImporter) ensureLabelEvent(repo *cache.RepoCache, b *cache.BugCache, labelEvent *gitlab.LabelEvent) error {
	_, err := b.ResolveOperationWithMetadata(keyGitlabId, parseID(labelEvent.ID))
	if err != cache.ErrNoMatchingOp {
		return err
	}

	// ensure issue author
	author, err := gi.ensurePerson(repo, labelEvent.User.ID)
	if err != nil {
		return err
	}

	switch labelEvent.Action {
	case "add":
		_, err = b.ForceChangeLabelsRaw(
			author,
			labelEvent.CreatedAt.Unix(),
			[]string{labelEvent.Label.Name},
			nil,
			map[string]string{
				keyGitlabId: parseID(labelEvent.ID),
			},
		)

	case "remove":
		_, err = b.ForceChangeLabelsRaw(
			author,
			labelEvent.CreatedAt.Unix(),
			nil,
			[]string{labelEvent.Label.Name},
			map[string]string{
				keyGitlabId: parseID(labelEvent.ID),
			},
		)

	default:
		panic("unexpected label event action")
	}

	return err
}

func (gi *gitlabImporter) ensurePerson(repo *cache.RepoCache, id int) (*cache.IdentityCache, error) {
	client := buildClient(gi.conf["token"])

	user, _, err := client.Users.GetUser(id)
	if err != nil {
		return nil, err
	}

	return repo.NewIdentityRaw(
		user.Name,
		user.PublicEmail,
		user.Username,
		user.AvatarURL,
		map[string]string{
			keyGitlabLogin: user.Username,
		},
	)
}

func parseID(id int) string {
	return fmt.Sprintf("%d", id)
}