// GoToSocial
// Copyright (C) GoToSocial Authors admin@gotosocial.org
// SPDX-License-Identifier: AGPL-3.0-or-later
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

package bundb

import (
	"context"
	"errors"
	"fmt"

	"github.com/superseriousbusiness/gotosocial/internal/db"
	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
	"github.com/superseriousbusiness/gotosocial/internal/log"
	"github.com/superseriousbusiness/gotosocial/internal/state"
	"github.com/uptrace/bun"
)

type relationshipDB struct {
	conn  *DBConn
	state *state.State
}

func (r *relationshipDB) IsBlocked(ctx context.Context, account1 string, account2 string, eitherDirection bool) (bool, db.Error) {
	// Look for a block in direction of account1->account2
	block1, err := r.getBlock(ctx, account1, account2)
	if err != nil && !errors.Is(err, db.ErrNoEntries) {
		return false, err
	}

	if block1 != nil {
		// account1 blocks account2
		return true, nil
	} else if !eitherDirection {
		// Don't check for mutli-directional
		return false, nil
	}

	// Look for a block in direction of account2->account1
	block2, err := r.getBlock(ctx, account2, account1)
	if err != nil && !errors.Is(err, db.ErrNoEntries) {
		return false, err
	}

	return (block2 != nil), nil
}

func (r *relationshipDB) GetBlock(ctx context.Context, account1 string, account2 string) (*gtsmodel.Block, db.Error) {
	// Fetch block from database
	block, err := r.getBlock(ctx, account1, account2)
	if err != nil {
		return nil, err
	}

	// Set the block originating account
	block.Account, err = r.state.DB.GetAccountByID(ctx, block.AccountID)
	if err != nil {
		return nil, err
	}

	// Set the block target account
	block.TargetAccount, err = r.state.DB.GetAccountByID(ctx, block.TargetAccountID)
	if err != nil {
		return nil, err
	}

	return block, nil
}

func (r *relationshipDB) getBlock(ctx context.Context, account1 string, account2 string) (*gtsmodel.Block, db.Error) {
	return r.state.Caches.GTS.Block().Load("AccountID.TargetAccountID", func() (*gtsmodel.Block, error) {
		var block gtsmodel.Block

		q := r.conn.NewSelect().Model(&block).
			Where("? = ?", bun.Ident("block.account_id"), account1).
			Where("? = ?", bun.Ident("block.target_account_id"), account2)
		if err := q.Scan(ctx); err != nil {
			return nil, r.conn.ProcessError(err)
		}

		return &block, nil
	}, account1, account2)
}

func (r *relationshipDB) PutBlock(ctx context.Context, block *gtsmodel.Block) db.Error {
	return r.state.Caches.GTS.Block().Store(block, func() error {
		_, err := r.conn.NewInsert().Model(block).Exec(ctx)
		return r.conn.ProcessError(err)
	})
}

func (r *relationshipDB) DeleteBlockByID(ctx context.Context, id string) db.Error {
	if _, err := r.conn.
		NewDelete().
		TableExpr("? AS ?", bun.Ident("blocks"), bun.Ident("block")).
		Where("? = ?", bun.Ident("block.id"), id).
		Exec(ctx); err != nil {
		return r.conn.ProcessError(err)
	}

	// Drop any old value from cache by this ID
	r.state.Caches.GTS.Block().Invalidate("ID", id)
	return nil
}

func (r *relationshipDB) DeleteBlockByURI(ctx context.Context, uri string) db.Error {
	if _, err := r.conn.
		NewDelete().
		TableExpr("? AS ?", bun.Ident("blocks"), bun.Ident("block")).
		Where("? = ?", bun.Ident("block.uri"), uri).
		Exec(ctx); err != nil {
		return r.conn.ProcessError(err)
	}

	// Drop any old value from cache by this URI
	r.state.Caches.GTS.Block().Invalidate("URI", uri)
	return nil
}

func (r *relationshipDB) DeleteBlocksByOriginAccountID(ctx context.Context, originAccountID string) db.Error {
	blockIDs := []string{}

	q := r.conn.
		NewSelect().
		TableExpr("? AS ?", bun.Ident("blocks"), bun.Ident("block")).
		Column("block.id").
		Where("? = ?", bun.Ident("block.account_id"), originAccountID)

	if err := q.Scan(ctx, &blockIDs); err != nil {
		return r.conn.ProcessError(err)
	}

	for _, blockID := range blockIDs {
		if err := r.DeleteBlockByID(ctx, blockID); err != nil {
			return err
		}
	}

	return nil
}

func (r *relationshipDB) DeleteBlocksByTargetAccountID(ctx context.Context, targetAccountID string) db.Error {
	blockIDs := []string{}

	q := r.conn.
		NewSelect().
		TableExpr("? AS ?", bun.Ident("blocks"), bun.Ident("block")).
		Column("block.id").
		Where("? = ?", bun.Ident("block.target_account_id"), targetAccountID)

	if err := q.Scan(ctx, &blockIDs); err != nil {
		return r.conn.ProcessError(err)
	}

	for _, blockID := range blockIDs {
		if err := r.DeleteBlockByID(ctx, blockID); err != nil {
			return err
		}
	}

	return nil
}

func (r *relationshipDB) GetRelationship(ctx context.Context, requestingAccount string, targetAccount string) (*gtsmodel.Relationship, db.Error) {
	rel := &gtsmodel.Relationship{
		ID: targetAccount,
	}

	// check if the requesting account follows the target account
	follow := &gtsmodel.Follow{}
	if err := r.conn.
		NewSelect().
		Model(follow).
		Column("follow.show_reblogs", "follow.notify").
		Where("? = ?", bun.Ident("follow.account_id"), requestingAccount).
		Where("? = ?", bun.Ident("follow.target_account_id"), targetAccount).
		Limit(1).
		Scan(ctx); err != nil {
		if err := r.conn.ProcessError(err); err != db.ErrNoEntries {
			return nil, fmt.Errorf("GetRelationship: error fetching follow: %s", err)
		}
		// no follow exists so these are all false
		rel.Following = false
		rel.ShowingReblogs = false
		rel.Notifying = false
	} else {
		// follow exists so we can fill these fields out...
		rel.Following = true
		rel.ShowingReblogs = *follow.ShowReblogs
		rel.Notifying = *follow.Notify
	}

	// check if the target account follows the requesting account
	followedByQ := r.conn.
		NewSelect().
		TableExpr("? AS ?", bun.Ident("follows"), bun.Ident("follow")).
		Column("follow.id").
		Where("? = ?", bun.Ident("follow.account_id"), targetAccount).
		Where("? = ?", bun.Ident("follow.target_account_id"), requestingAccount)
	followedBy, err := r.conn.Exists(ctx, followedByQ)
	if err != nil {
		return nil, fmt.Errorf("GetRelationship: error checking followedBy: %s", err)
	}
	rel.FollowedBy = followedBy

	// check if there's a pending following request from requesting account to target account
	requestedQ := r.conn.
		NewSelect().
		TableExpr("? AS ?", bun.Ident("follow_requests"), bun.Ident("follow_request")).
		Column("follow_request.id").
		Where("? = ?", bun.Ident("follow_request.account_id"), requestingAccount).
		Where("? = ?", bun.Ident("follow_request.target_account_id"), targetAccount)
	requested, err := r.conn.Exists(ctx, requestedQ)
	if err != nil {
		return nil, fmt.Errorf("GetRelationship: error checking requested: %s", err)
	}
	rel.Requested = requested

	// check if the requesting account is blocking the target account
	blockA2T, err := r.getBlock(ctx, requestingAccount, targetAccount)
	if err != nil && !errors.Is(err, db.ErrNoEntries) {
		return nil, fmt.Errorf("GetRelationship: error checking blocking: %s", err)
	}
	rel.Blocking = (blockA2T != nil)

	// check if the requesting account is blocked by the target account
	blockT2A, err := r.getBlock(ctx, targetAccount, requestingAccount)
	if err != nil && !errors.Is(err, db.ErrNoEntries) {
		return nil, fmt.Errorf("GetRelationship: error checking blockedBy: %s", err)
	}
	rel.BlockedBy = (blockT2A != nil)

	return rel, nil
}

func (r *relationshipDB) IsFollowing(ctx context.Context, sourceAccount *gtsmodel.Account, targetAccount *gtsmodel.Account) (bool, db.Error) {
	if sourceAccount == nil || targetAccount == nil {
		return false, nil
	}

	q := r.conn.
		NewSelect().
		TableExpr("? AS ?", bun.Ident("follows"), bun.Ident("follow")).
		Column("follow.id").
		Where("? = ?", bun.Ident("follow.account_id"), sourceAccount.ID).
		Where("? = ?", bun.Ident("follow.target_account_id"), targetAccount.ID)

	return r.conn.Exists(ctx, q)
}

func (r *relationshipDB) IsFollowRequested(ctx context.Context, sourceAccount *gtsmodel.Account, targetAccount *gtsmodel.Account) (bool, db.Error) {
	if sourceAccount == nil || targetAccount == nil {
		return false, nil
	}

	q := r.conn.
		NewSelect().
		TableExpr("? AS ?", bun.Ident("follow_requests"), bun.Ident("follow_request")).
		Column("follow_request.id").
		Where("? = ?", bun.Ident("follow_request.account_id"), sourceAccount.ID).
		Where("? = ?", bun.Ident("follow_request.target_account_id"), targetAccount.ID)

	return r.conn.Exists(ctx, q)
}

func (r *relationshipDB) IsMutualFollowing(ctx context.Context, account1 *gtsmodel.Account, account2 *gtsmodel.Account) (bool, db.Error) {
	if account1 == nil || account2 == nil {
		return false, nil
	}

	// make sure account 1 follows account 2
	f1, err := r.IsFollowing(ctx, account1, account2)
	if err != nil {
		return false, err
	}

	// make sure account 2 follows account 1
	f2, err := r.IsFollowing(ctx, account2, account1)
	if err != nil {
		return false, err
	}

	return f1 && f2, nil
}

func (r *relationshipDB) AcceptFollowRequest(ctx context.Context, originAccountID string, targetAccountID string) (*gtsmodel.Follow, db.Error) {
	// Get original follow request.
	var followRequestID string
	if err := r.conn.
		NewSelect().
		TableExpr("? AS ?", bun.Ident("follow_requests"), bun.Ident("follow_request")).
		Column("follow_request.id").
		Where("? = ?", bun.Ident("follow_request.account_id"), originAccountID).
		Where("? = ?", bun.Ident("follow_request.target_account_id"), targetAccountID).
		Scan(ctx, &followRequestID); err != nil {
		return nil, r.conn.ProcessError(err)
	}

	followRequest, err := r.getFollowRequest(ctx, followRequestID)
	if err != nil {
		return nil, r.conn.ProcessError(err)
	}

	// Create a new follow to 'replace'
	// the original follow request with.
	follow := &gtsmodel.Follow{
		ID:              followRequest.ID,
		AccountID:       originAccountID,
		Account:         followRequest.Account,
		TargetAccountID: targetAccountID,
		TargetAccount:   followRequest.TargetAccount,
		URI:             followRequest.URI,
	}

	// If the follow already exists, just
	// replace the URI with the new one.
	if _, err := r.conn.
		NewInsert().
		Model(follow).
		On("CONFLICT (?,?) DO UPDATE set ? = ?", bun.Ident("account_id"), bun.Ident("target_account_id"), bun.Ident("uri"), follow.URI).
		Exec(ctx); err != nil {
		return nil, r.conn.ProcessError(err)
	}

	// Delete original follow request.
	if _, err := r.conn.
		NewDelete().
		TableExpr("? AS ?", bun.Ident("follow_requests"), bun.Ident("follow_request")).
		Where("? = ?", bun.Ident("follow_request.id"), followRequest.ID).
		Exec(ctx); err != nil {
		return nil, r.conn.ProcessError(err)
	}

	// Delete original follow request notification.
	if err := r.deleteFollowRequestNotif(ctx, originAccountID, targetAccountID); err != nil {
		return nil, err
	}

	// return the new follow
	return follow, nil
}

func (r *relationshipDB) RejectFollowRequest(ctx context.Context, originAccountID string, targetAccountID string) (*gtsmodel.FollowRequest, db.Error) {
	// Get original follow request.
	var followRequestID string
	if err := r.conn.
		NewSelect().
		TableExpr("? AS ?", bun.Ident("follow_requests"), bun.Ident("follow_request")).
		Column("follow_request.id").
		Where("? = ?", bun.Ident("follow_request.account_id"), originAccountID).
		Where("? = ?", bun.Ident("follow_request.target_account_id"), targetAccountID).
		Scan(ctx, &followRequestID); err != nil {
		return nil, r.conn.ProcessError(err)
	}

	followRequest, err := r.getFollowRequest(ctx, followRequestID)
	if err != nil {
		return nil, r.conn.ProcessError(err)
	}

	// Delete original follow request.
	if _, err := r.conn.
		NewDelete().
		TableExpr("? AS ?", bun.Ident("follow_requests"), bun.Ident("follow_request")).
		Where("? = ?", bun.Ident("follow_request.id"), followRequest.ID).
		Exec(ctx); err != nil {
		return nil, r.conn.ProcessError(err)
	}

	// Delete original follow request notification.
	if err := r.deleteFollowRequestNotif(ctx, originAccountID, targetAccountID); err != nil {
		return nil, err
	}

	// Return the now deleted follow request.
	return followRequest, nil
}

func (r *relationshipDB) deleteFollowRequestNotif(ctx context.Context, originAccountID string, targetAccountID string) db.Error {
	var id string
	if err := r.conn.
		NewSelect().
		TableExpr("? AS ?", bun.Ident("notifications"), bun.Ident("notification")).
		Column("notification.id").
		Where("? = ?", bun.Ident("notification.origin_account_id"), originAccountID).
		Where("? = ?", bun.Ident("notification.target_account_id"), targetAccountID).
		Where("? = ?", bun.Ident("notification.notification_type"), gtsmodel.NotificationFollowRequest).
		Limit(1). // There should only be one!
		Scan(ctx, &id); err != nil {
		err = r.conn.ProcessError(err)
		if errors.Is(err, db.ErrNoEntries) {
			// If no entries, the notif didn't
			// exist anyway so nothing to do here.
			return nil
		}
		// Return on real error.
		return err
	}

	return r.state.DB.DeleteNotification(ctx, id)
}

func (r *relationshipDB) getFollow(ctx context.Context, id string) (*gtsmodel.Follow, db.Error) {
	follow := &gtsmodel.Follow{}

	err := r.conn.
		NewSelect().
		Model(follow).
		Where("? = ?", bun.Ident("follow.id"), id).
		Scan(ctx)
	if err != nil {
		return nil, r.conn.ProcessError(err)
	}

	follow.Account, err = r.state.DB.GetAccountByID(ctx, follow.AccountID)
	if err != nil {
		log.Errorf(ctx, "error getting follow account %q: %v", follow.AccountID, err)
	}

	follow.TargetAccount, err = r.state.DB.GetAccountByID(ctx, follow.TargetAccountID)
	if err != nil {
		log.Errorf(ctx, "error getting follow target account %q: %v", follow.TargetAccountID, err)
	}

	return follow, nil
}

func (r *relationshipDB) GetLocalFollowersIDs(ctx context.Context, targetAccountID string) ([]string, db.Error) {
	accountIDs := []string{}

	// Select only the account ID of each follow.
	q := r.conn.
		NewSelect().
		TableExpr("? AS ?", bun.Ident("follows"), bun.Ident("follow")).
		ColumnExpr("? AS ?", bun.Ident("follow.account_id"), bun.Ident("account_id")).
		Where("? = ?", bun.Ident("follow.target_account_id"), targetAccountID)

	// Join on accounts table to select only
	// those with NULL domain (local accounts).
	q = q.
		Join("JOIN ? AS ? ON ? = ?",
			bun.Ident("accounts"),
			bun.Ident("account"),
			bun.Ident("follow.account_id"),
			bun.Ident("account.id"),
		).
		Where("? IS NULL", bun.Ident("account.domain"))

	// We don't *really* need to order these,
	// but it makes it more consistent to do so.
	q = q.Order("account_id DESC")

	if err := q.Scan(ctx, &accountIDs); err != nil {
		return nil, r.conn.ProcessError(err)
	}

	return accountIDs, nil
}

func (r *relationshipDB) GetFollows(ctx context.Context, accountID string, targetAccountID string) ([]*gtsmodel.Follow, db.Error) {
	ids := []string{}

	q := r.conn.
		NewSelect().
		TableExpr("? AS ?", bun.Ident("follows"), bun.Ident("follow")).
		Column("follow.id").
		Order("follow.updated_at DESC")

	if accountID != "" {
		q = q.Where("? = ?", bun.Ident("follow.account_id"), accountID)
	}

	if targetAccountID != "" {
		q = q.Where("? = ?", bun.Ident("follow.target_account_id"), targetAccountID)
	}

	if err := q.Scan(ctx, &ids); err != nil {
		return nil, r.conn.ProcessError(err)
	}

	follows := make([]*gtsmodel.Follow, 0, len(ids))
	for _, id := range ids {
		follow, err := r.getFollow(ctx, id)
		if err != nil {
			log.Errorf(ctx, "error getting follow %q: %v", id, err)
			continue
		}

		follows = append(follows, follow)
	}

	return follows, nil
}

func (r *relationshipDB) CountFollows(ctx context.Context, accountID string, targetAccountID string) (int, db.Error) {
	q := r.conn.
		NewSelect().
		TableExpr("? AS ?", bun.Ident("follows"), bun.Ident("follow")).
		Column("follow.id")

	if accountID != "" {
		q = q.Where("? = ?", bun.Ident("follow.account_id"), accountID)
	}

	if targetAccountID != "" {
		q = q.Where("? = ?", bun.Ident("follow.target_account_id"), targetAccountID)
	}

	return q.Count(ctx)
}

func (r *relationshipDB) getFollowRequest(ctx context.Context, id string) (*gtsmodel.FollowRequest, db.Error) {
	followRequest := &gtsmodel.FollowRequest{}

	err := r.conn.
		NewSelect().
		Model(followRequest).
		Where("? = ?", bun.Ident("follow_request.id"), id).
		Scan(ctx)
	if err != nil {
		return nil, r.conn.ProcessError(err)
	}

	followRequest.Account, err = r.state.DB.GetAccountByID(ctx, followRequest.AccountID)
	if err != nil {
		log.Errorf(ctx, "error getting follow request account %q: %v", followRequest.AccountID, err)
	}

	followRequest.TargetAccount, err = r.state.DB.GetAccountByID(ctx, followRequest.TargetAccountID)
	if err != nil {
		log.Errorf(ctx, "error getting follow request target account %q: %v", followRequest.TargetAccountID, err)
	}

	return followRequest, nil
}

func (r *relationshipDB) GetFollowRequests(ctx context.Context, accountID string, targetAccountID string) ([]*gtsmodel.FollowRequest, db.Error) {
	ids := []string{}

	q := r.conn.
		NewSelect().
		TableExpr("? AS ?", bun.Ident("follow_requests"), bun.Ident("follow_request")).
		Column("follow_request.id")

	if accountID != "" {
		q = q.Where("? = ?", bun.Ident("follow_request.account_id"), accountID)
	}

	if targetAccountID != "" {
		q = q.Where("? = ?", bun.Ident("follow_request.target_account_id"), targetAccountID)
	}

	if err := q.Scan(ctx, &ids); err != nil {
		return nil, r.conn.ProcessError(err)
	}

	followRequests := make([]*gtsmodel.FollowRequest, 0, len(ids))
	for _, id := range ids {
		followRequest, err := r.getFollowRequest(ctx, id)
		if err != nil {
			log.Errorf(ctx, "error getting follow request %q: %v", id, err)
			continue
		}

		followRequests = append(followRequests, followRequest)
	}

	return followRequests, nil
}

func (r *relationshipDB) CountFollowRequests(ctx context.Context, accountID string, targetAccountID string) (int, db.Error) {
	q := r.conn.
		NewSelect().
		TableExpr("? AS ?", bun.Ident("follow_requests"), bun.Ident("follow_request")).
		Column("follow_request.id").
		Order("follow_request.updated_at DESC")

	if accountID != "" {
		q = q.Where("? = ?", bun.Ident("follow_request.account_id"), accountID)
	}

	if targetAccountID != "" {
		q = q.Where("? = ?", bun.Ident("follow_request.target_account_id"), targetAccountID)
	}

	return q.Count(ctx)
}

func (r *relationshipDB) Unfollow(ctx context.Context, originAccountID string, targetAccountID string) (string, db.Error) {
	uri := new(string)

	_, err := r.conn.
		NewDelete().
		TableExpr("? AS ?", bun.Ident("follows"), bun.Ident("follow")).
		Where("? = ?", bun.Ident("follow.target_account_id"), targetAccountID).
		Where("? = ?", bun.Ident("follow.account_id"), originAccountID).
		Returning("?", bun.Ident("uri")).Exec(ctx, uri)

	// Only return proper errors.
	if err = r.conn.ProcessError(err); err != db.ErrNoEntries {
		return *uri, err
	}

	return *uri, nil
}

func (r *relationshipDB) UnfollowRequest(ctx context.Context, originAccountID string, targetAccountID string) (string, db.Error) {
	uri := new(string)

	_, err := r.conn.
		NewDelete().
		TableExpr("? AS ?", bun.Ident("follow_requests"), bun.Ident("follow_request")).
		Where("? = ?", bun.Ident("follow_request.target_account_id"), targetAccountID).
		Where("? = ?", bun.Ident("follow_request.account_id"), originAccountID).
		Returning("?", bun.Ident("uri")).Exec(ctx, uri)

	// Only return proper errors.
	if err = r.conn.ProcessError(err); err != db.ErrNoEntries {
		return *uri, err
	}

	return *uri, nil
}