package db

import (
	"context"
	"slices"

	"github.com/bluesky-social/indigo/atproto/syntax"
	"tangled.org/core/api/tangled"
	"tangled.org/core/appview/db"
	"tangled.org/core/appview/models"
	"tangled.org/core/appview/notify"
	"tangled.org/core/idresolver"
	"tangled.org/core/log"
	"tangled.org/core/orm"
	"tangled.org/core/sets"
)

const (
	maxMentions     = 8
	assigneeLabelAt = "at://did:plc:wshs7t2adsemcrrd4snkeqli/sh.tangled.label.definition/assignee"
)

type databaseNotifier struct {
	db  *db.DB
	res *idresolver.Resolver
}

func NewDatabaseNotifier(database *db.DB, resolver *idresolver.Resolver) notify.Notifier {
	return &databaseNotifier{
		db:  database,
		res: resolver,
	}
}

var _ notify.Notifier = &databaseNotifier{}

func (n *databaseNotifier) NewRepo(ctx context.Context, repo *models.Repo) {
	// no-op for now
}
func (n *databaseNotifier) DeleteRepo(ctx context.Context, repo *models.Repo) {
	// no-op for now
}

func (n *databaseNotifier) RenameRepo(ctx context.Context, actor syntax.DID, oldRepo, newRepo *models.Repo) {
}

func (n *databaseNotifier) NewStar(ctx context.Context, star *models.Star) {
	l := log.FromContext(ctx)

	if star.SubjectType != models.StarSubjectRepo {
		return
	}

	repo, err := db.GetRepo(n.db, orm.FilterEq("repo_did", star.Subject))
	if err != nil {
		l.Error("failed to get repos", "err", err)
		return
	}

	actorDid := syntax.DID(star.Did)
	recipients := sets.Singleton(syntax.DID(repo.Did))
	eventType := models.NotificationTypeRepoStarred
	entityType := "repo"
	entityId := star.Subject
	repoId := &repo.Id
	var issueId *int64
	var pullId *int64

	n.notifyEvent(
		ctx,
		actorDid,
		recipients,
		eventType,
		entityType,
		entityId,
		repoId,
		issueId,
		pullId,
	)
}

func (n *databaseNotifier) DeleteStar(ctx context.Context, star *models.Star) {
	// no-op
}

func (n *databaseNotifier) NewComment(ctx context.Context, comment *models.Comment, mentions []syntax.DID) {
	l := log.FromContext(ctx)

	var (
		// built the recipients list:
		// - the owner of the repo
		// - | if the comment is a reply -> everybody on that thread
		//   | if the comment is a top level -> just the issue owner
		// - remove mentioned users from the recipients list
		recipients = sets.New[syntax.DID]()
		entityType string
		entityId   string
		repoId     *int64
		issueId    *int64
		pullId     *int64
	)

	subjectAt := syntax.ATURI(comment.Subject.Uri)

	switch subjectAt.Collection() {
	case tangled.RepoIssueNSID:
		issues, err := db.GetIssues(
			n.db,
			orm.FilterEq("at_uri", subjectAt),
		)
		if err != nil {
			l.Error("failed to get issues", "err", err)
			return
		}
		if len(issues) == 0 {
			l.Error("no issue found", "subject", comment.Subject)
			return
		}
		issue := issues[0]

		recipients.Insert(syntax.DID(issue.Repo.Did))
		if comment.IsReply() {
			// if this comment is a reply, then notify everybody in that thread
			parent := *comment.ReplyTo

			// find the parent thread, and add all DIDs from here to the recipient list
			for _, t := range models.NewCommentList(issue.Comments) {
				if t.Self.AtUri() == syntax.ATURI(parent.Uri) {
					for _, p := range t.Participants() {
						recipients.Insert(p)
					}
				}
			}
		} else {
			// not a reply, notify just the issue author
			recipients.Insert(syntax.DID(issue.Did))
		}

		entityType = "issue"
		entityId = issue.AtUri().String()
		repoId = &issue.Repo.Id
		issueId = &issue.Id

		for _, m := range mentions {
			recipients.Remove(m)
		}

		n.notifyEvent(
			ctx,
			comment.Did,
			recipients,
			models.NotificationTypeIssueCommented,
			entityType,
			entityId,
			repoId,
			issueId,
			pullId,
		)

	case tangled.RepoPullNSID:
		pull, err := db.GetPull(
			n.db,
			orm.FilterEq("owner_did", subjectAt.Authority()),
			orm.FilterEq("rkey", subjectAt.RecordKey()),
		)
		if err != nil {
			l.Error("NewComment: failed to get pull", "err", err)
			return
		}

		pull.Repo, err = db.GetRepo(n.db, orm.FilterEq("repo_did", pull.RepoDid))
		if err != nil {
			l.Error("NewComment: failed to get repo", "err", err)
			return
		}

		recipients.Insert(syntax.DID(pull.Repo.Did))
		for _, p := range pull.Participants() {
			recipients.Insert(syntax.DID(p))
		}

		entityType = "pull"
		entityId = pull.AtUri().String()
		repoId = &pull.Repo.Id
		p := int64(pull.ID)
		pullId = &p

		for _, m := range mentions {
			recipients.Remove(m)
		}

		n.notifyEvent(
			ctx,
			comment.Did,
			recipients,
			models.NotificationTypePullCommented,
			entityType,
			entityId,
			repoId,
			issueId,
			pullId,
		)
	default:
		return // no-op
	}

	n.notifyEvent(
		ctx,
		comment.Did,
		sets.Collect(slices.Values(mentions)),
		models.NotificationTypeUserMentioned,
		entityType,
		entityId,
		repoId,
		issueId,
		pullId,
	)
}

func (n *databaseNotifier) DeleteComment(ctx context.Context, comment *models.Comment) {
	// no-op
}

func (n *databaseNotifier) NewIssue(ctx context.Context, issue *models.Issue, mentions []syntax.DID) {
	l := log.FromContext(ctx)

	collaborators, err := db.GetCollaborators(n.db, orm.FilterEq("repo_did", string(issue.RepoDid)))
	if err != nil {
		l.Error("failed to fetch collaborators", "err", err)
		return
	}

	// build the recipients list
	// - owner of the repo
	// - collaborators in the repo
	// - remove users already mentioned
	recipients := sets.Singleton(syntax.DID(issue.Repo.Did))
	for _, c := range collaborators {
		recipients.Insert(c.SubjectDid)
	}
	for _, m := range mentions {
		recipients.Remove(m)
	}

	actorDid := syntax.DID(issue.Did)
	entityType := "issue"
	entityId := issue.AtUri().String()
	repoId := &issue.Repo.Id
	issueId := &issue.Id
	var pullId *int64

	n.notifyEvent(
		ctx,
		actorDid,
		recipients,
		models.NotificationTypeIssueCreated,
		entityType,
		entityId,
		repoId,
		issueId,
		pullId,
	)
	n.notifyEvent(
		ctx,
		actorDid,
		sets.Collect(slices.Values(mentions)),
		models.NotificationTypeUserMentioned,
		entityType,
		entityId,
		repoId,
		issueId,
		pullId,
	)
}

func (n *databaseNotifier) DeleteIssue(ctx context.Context, issue *models.Issue) {
	// no-op for now
}

func (n *databaseNotifier) NewIssueLabelOp(ctx context.Context, actor syntax.DID, issue *models.Issue, ops []models.LabelOp) {
	entityType := "issue"
	entityId := issue.AtUri().String()
	repoId := &issue.Repo.Id
	issueId := &issue.Id
	var pullId *int64

	assigned := sets.New[syntax.DID]()
	unassigned := sets.New[syntax.DID]()
	for _, op := range ops {
		if op.OperandKey != assigneeLabelAt {
			continue
		}
		assignee := syntax.DID(op.OperandValue)
		switch op.Operation {
		case models.LabelOperationAdd:
			assigned.Insert(assignee)
		case models.LabelOperationDel:
			unassigned.Insert(assignee)
		default:
			continue
		}
	}

	n.notifyEvent(ctx, actor, assigned, models.NotificationTypeIssueAssigned, entityType, entityId, repoId, issueId, pullId)
	n.notifyEvent(ctx, actor, unassigned, models.NotificationTypeIssueUnassigned, entityType, entityId, repoId, issueId, pullId)
}

func (n *databaseNotifier) NewPullLabelOp(ctx context.Context, actor syntax.DID, pull *models.Pull, ops []models.LabelOp) {
	entityType := "pull"
	entityId := pull.AtUri().String()
	repoId := &pull.Repo.Id
	var issueId *int64
	p := int64(pull.ID)
	pullId := &p

	assigned := sets.New[syntax.DID]()
	unassigned := sets.New[syntax.DID]()
	for _, op := range ops {
		if op.OperandKey != assigneeLabelAt {
			continue
		}
		assignee := syntax.DID(op.OperandValue)
		switch op.Operation {
		case models.LabelOperationAdd:
			assigned.Insert(assignee)
		case models.LabelOperationDel:
			unassigned.Insert(assignee)
		default:
			continue
		}
	}

	n.notifyEvent(ctx, actor, assigned, models.NotificationTypePullAssigned, entityType, entityId, repoId, issueId, pullId)
	n.notifyEvent(ctx, actor, unassigned, models.NotificationTypePullUnassigned, entityType, entityId, repoId, issueId, pullId)
}

func (n *databaseNotifier) NewFollow(ctx context.Context, follow *models.Follow) {
	actorDid := syntax.DID(follow.UserDid)
	recipients := sets.Singleton(syntax.DID(follow.SubjectDid))
	eventType := models.NotificationTypeFollowed
	entityType := "follow"
	entityId := follow.UserDid
	var repoId, issueId, pullId *int64

	n.notifyEvent(
		ctx,
		actorDid,
		recipients,
		eventType,
		entityType,
		entityId,
		repoId,
		issueId,
		pullId,
	)
}

func (n *databaseNotifier) DeleteFollow(ctx context.Context, follow *models.Follow) {
	// no-op
}

func (n *databaseNotifier) NewPull(ctx context.Context, pull *models.Pull) {
	l := log.FromContext(ctx)

	repo, err := db.GetRepo(n.db, orm.FilterEq("repo_did", string(pull.RepoDid)))
	if err != nil {
		l.Error("failed to get repos", "err", err)
		return
	}
	collaborators, err := db.GetCollaborators(n.db, orm.FilterEq("repo_did", string(pull.RepoDid)))
	if err != nil {
		l.Error("failed to fetch collaborators", "err", err)
		return
	}

	// build the recipients list
	// - owner of the repo
	// - collaborators in the repo
	recipients := sets.Singleton(syntax.DID(repo.Did))
	for _, c := range collaborators {
		recipients.Insert(c.SubjectDid)
	}

	actorDid := syntax.DID(pull.OwnerDid)
	eventType := models.NotificationTypePullCreated
	entityType := "pull"
	entityId := pull.AtUri().String()
	repoId := &repo.Id
	var issueId *int64
	p := int64(pull.ID)
	pullId := &p

	n.notifyEvent(
		ctx,
		actorDid,
		recipients,
		eventType,
		entityType,
		entityId,
		repoId,
		issueId,
		pullId,
	)
}

func (n *databaseNotifier) UpdateProfile(ctx context.Context, profile *models.Profile) {
	// no-op
}

func (n *databaseNotifier) DeleteString(ctx context.Context, did, rkey string) {
	// no-op
}

func (n *databaseNotifier) EditString(ctx context.Context, string *models.String) {
	// no-op
}

func (n *databaseNotifier) NewString(ctx context.Context, string *models.String) {
	// no-op
}

func (n *databaseNotifier) Push(ctx context.Context, repo *models.Repo, ref, oldSha, newSha, committerDid string) {
	// no-op for now; webhooks are handled by the webhook notifier
}

func (n *databaseNotifier) Clone(ctx context.Context, repo *models.Repo) {
	// no-op
}

func (n *databaseNotifier) NewIssueState(ctx context.Context, actor syntax.DID, issue *models.Issue) {
	l := log.FromContext(ctx)

	collaborators, err := db.GetCollaborators(n.db, orm.FilterEq("repo_did", string(issue.RepoDid)))
	if err != nil {
		l.Error("failed to fetch collaborators", "err", err)
		return
	}

	// build up the recipients list:
	// - repo owner
	// - repo collaborators
	// - all issue participants
	recipients := sets.Singleton(syntax.DID(issue.Repo.Did))
	for _, c := range collaborators {
		recipients.Insert(c.SubjectDid)
	}
	for _, p := range issue.Participants() {
		recipients.Insert(syntax.DID(p))
	}

	entityType := "issue"
	entityId := issue.AtUri().String()
	repoId := &issue.Repo.Id
	issueId := &issue.Id
	var pullId *int64
	var eventType models.NotificationType

	if issue.Open {
		eventType = models.NotificationTypeIssueReopen
	} else {
		eventType = models.NotificationTypeIssueClosed
	}

	n.notifyEvent(
		ctx,
		actor,
		recipients,
		eventType,
		entityType,
		entityId,
		repoId,
		issueId,
		pullId,
	)
}

func (n *databaseNotifier) ResubmitPull(ctx context.Context, pull *models.Pull) {
	// no-op for now
}

func (n *databaseNotifier) NewPullState(ctx context.Context, actor syntax.DID, pull *models.Pull) {
	l := log.FromContext(ctx)

	// Get repo details
	repo, err := db.GetRepo(n.db, orm.FilterEq("repo_did", string(pull.RepoDid)))
	if err != nil {
		l.Error("failed to get repos", "err", err)
		return
	}

	collaborators, err := db.GetCollaborators(n.db, orm.FilterEq("repo_did", string(pull.RepoDid)))
	if err != nil {
		l.Error("failed to fetch collaborators", "err", err)
		return
	}

	// build up the recipients list:
	// - repo owner
	// - all pull participants
	recipients := sets.Singleton(syntax.DID(repo.Did))
	for _, c := range collaborators {
		recipients.Insert(c.SubjectDid)
	}
	for _, p := range pull.Participants() {
		recipients.Insert(p)
	}

	entityType := "pull"
	entityId := pull.AtUri().String()
	repoId := &repo.Id
	var issueId *int64
	var eventType models.NotificationType
	switch pull.State {
	case models.PullClosed:
		eventType = models.NotificationTypePullClosed
	case models.PullOpen:
		eventType = models.NotificationTypePullReopen
	case models.PullMerged:
		eventType = models.NotificationTypePullMerged
	default:
		l.Error("unexpected new PR state", "state", pull.State)
		return
	}
	p := int64(pull.ID)
	pullId := &p

	n.notifyEvent(
		ctx,
		actor,
		recipients,
		eventType,
		entityType,
		entityId,
		repoId,
		issueId,
		pullId,
	)
}

func (n *databaseNotifier) notifyEvent(
	ctx context.Context,
	actorDid syntax.DID,
	recipients sets.Set[syntax.DID],
	eventType models.NotificationType,
	entityType string,
	entityId string,
	repoId *int64,
	issueId *int64,
	pullId *int64,
) {
	l := log.FromContext(ctx)

	// if the user is attempting to mention >maxMentions users, this is probably spam, do not mention anybody
	if eventType == models.NotificationTypeUserMentioned && recipients.Len() > maxMentions {
		return
	}

	// Apply subscription overrides for thread-activity events only.
	// Mention and assignment events are targeted at specific users and should
	// not be broadcast to all thread subscribers.
	isThreadEvent := eventType != models.NotificationTypeUserMentioned &&
		eventType != models.NotificationTypeIssueAssigned &&
		eventType != models.NotificationTypeIssueUnassigned &&
		eventType != models.NotificationTypePullAssigned &&
		eventType != models.NotificationTypePullUnassigned

	switch {
	case issueId != nil && isThreadEvent:
		if subs, err := db.GetIssueSubscribers(n.db, *issueId); err == nil {
			for _, did := range subs {
				recipients.Insert(syntax.DID(did))
			}
		}
		if unsubs, err := db.GetIssueUnsubscribers(n.db, *issueId); err == nil {
			for _, did := range unsubs {
				recipients.Remove(syntax.DID(did))
			}
		}
	case pullId != nil && isThreadEvent:
		if subs, err := db.GetPullSubscribers(n.db, *pullId); err == nil {
			for _, did := range subs {
				recipients.Insert(syntax.DID(did))
			}
		}
		if unsubs, err := db.GetPullUnsubscribers(n.db, *pullId); err == nil {
			for _, did := range unsubs {
				recipients.Remove(syntax.DID(did))
			}
		}
	}

	recipients.Remove(actorDid)

	// Auto-subscribe the actor to this issue/pull when they interact with it.
	// This happens outside the transaction since it’s best-effort.
	switch {
	case issueId != nil:
		if err := db.UpsertIssueSubscription(n.db, actorDid.String(), *issueId, true); err != nil {
			l.Warn("failed to auto-subscribe actor to issue", "actor", actorDid, "issueId", *issueId, "err", err)
		}
	case pullId != nil:
		if err := db.UpsertPullSubscription(n.db, actorDid.String(), *pullId, true); err != nil {
			l.Warn("failed to auto-subscribe actor to pull", "actor", actorDid, "pullId", *pullId, "err", err)
		}
	}

	prefMap, err := db.GetNotificationPreferences(
		n.db,
		orm.FilterIn("user_did", slices.Collect(recipients.All())),
	)
	if err != nil {
		// failed to get prefs for users
		return
	}

	// create a transaction for bulk notification storage
	tx, err := n.db.Begin()
	if err != nil {
		// failed to start tx
		return
	}
	defer tx.Rollback()

	// filter based on preferences
	for recipientDid := range recipients.All() {
		prefs, ok := prefMap[recipientDid]
		if !ok {
			prefs = models.DefaultNotificationPreferences(recipientDid)
		}

		// skip users who don’t want this type
		if !prefs.ShouldNotify(eventType) {
			continue
		}

		// create notification
		notif := &models.Notification{
			RecipientDid: recipientDid.String(),
			ActorDid:     actorDid.String(),
			Type:         eventType,
			EntityType:   entityType,
			EntityId:     entityId,
			RepoId:       repoId,
			IssueId:      issueId,
			PullId:       pullId,
		}

		if err := db.CreateNotification(tx, notif); err != nil {
			l.Error("failed to create notification", "recipientDid", recipientDid, "err", err)
		}
	}

	if err := tx.Commit(); err != nil {
		// failed to commit
		return
	}
}