// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
// See LICENSE.txt for license information.

package sqlstore

import (
	"database/sql"
	"slices"
	"strconv"

	sq "github.com/mattermost/squirrel"
	"github.com/pkg/errors"

	"github.com/mattermost/mattermost/server/public/model"
	"github.com/mattermost/mattermost/server/v8/channels/store"
	"github.com/mattermost/mattermost/server/v8/channels/utils"
)

type SqlViewStore struct {
	*SqlStore
	viewSelect sq.SelectBuilder
}

func newSqlViewStore(sqlStore *SqlStore) store.ViewStore {
	s := &SqlViewStore{
		SqlStore: sqlStore,
	}

	s.viewSelect = s.getQueryBuilder().
		Select(viewColumns()...).
		From("Views")

	return s
}

func viewColumns() []string {
	return []string{
		"Id", "ChannelId", "Type", "CreatorId", "Title",
		"Description", "SortOrder", "Props",
		"CreateAt", "UpdateAt", "DeleteAt",
	}
}

func (s *SqlViewStore) Save(view *model.View) (*model.View, error) {
	if err := s.saveViewT(s.GetMaster(), view); err != nil {
		return nil, err
	}
	return view, nil
}

// saveViewT inserts a view row using the provided executor (either a
// transaction or a regular master DB handle). The caller is responsible for
// setting view.ChannelId before calling. PreSave + IsValid are run here so
// callers can't forget to validate.
func (s *SqlViewStore) saveViewT(ex sqlxExecutor, view *model.View) error {
	view.PreSave()
	if err := view.IsValid(); err != nil {
		return err
	}

	builder := s.getQueryBuilder().
		Insert("Views").
		Columns(viewColumns()...).
		Values(
			view.Id, view.ChannelId, view.Type, view.CreatorId, view.Title,
			view.Description, view.SortOrder, view.Props,
			view.CreateAt, view.UpdateAt, view.DeleteAt,
		)

	if _, err := ex.ExecBuilder(builder); err != nil {
		return errors.Wrap(err, "failed to save view")
	}

	return nil
}

func (s *SqlViewStore) Get(id string) (*model.View, error) {
	builder := s.viewSelect.Where(sq.Eq{"Id": id, "DeleteAt": 0})

	var view model.View
	if err := s.GetReplica().GetBuilder(&view, builder); err != nil {
		if errors.Is(err, sql.ErrNoRows) {
			return nil, store.NewErrNotFound("View", id)
		}
		return nil, errors.Wrapf(err, "failed to get view with id=%s", id)
	}

	return &view, nil
}

func (s *SqlViewStore) GetForChannel(channelID string, opts model.ViewQueryOpts) ([]*model.View, error) {
	if channelID == "" {
		return nil, store.NewErrInvalidInput("View", "channelID", channelID)
	}

	if opts.PerPage <= 0 {
		opts.PerPage = model.ViewQueryDefaultPerPage
	} else if opts.PerPage > model.ViewQueryMaxPerPage {
		opts.PerPage = model.ViewQueryMaxPerPage
	}

	if opts.Page < 0 {
		opts.Page = 0
	}

	builder := s.viewSelect.
		Where(sq.Eq{"ChannelId": channelID, "DeleteAt": 0}).
		OrderBy("SortOrder ASC", "CreateAt ASC", "Id ASC").
		Limit(uint64(opts.PerPage)).
		Offset(uint64(opts.Page * opts.PerPage))

	var rows []model.View
	if err := s.GetReplica().SelectBuilder(&rows, builder); err != nil {
		return nil, errors.Wrapf(err, "failed to get views for channel %s", channelID)
	}

	views := make([]*model.View, len(rows))
	for i := range rows {
		views[i] = &rows[i]
	}

	return views, nil
}

func (s *SqlViewStore) CountForChannel(channelID string, opts model.ViewQueryOpts) (int64, error) {
	if channelID == "" {
		return 0, store.NewErrInvalidInput("View", "channelID", channelID)
	}

	builder := s.getQueryBuilder().
		Select("COUNT(*)").
		From("Views").
		Where(sq.Eq{"ChannelId": channelID, "DeleteAt": 0})

	var count int64
	if err := s.GetReplica().GetBuilder(&count, builder); err != nil {
		return 0, errors.Wrapf(err, "failed to count views for channel %s", channelID)
	}

	return count, nil
}

func (s *SqlViewStore) Update(view *model.View) (*model.View, error) {
	view.PreUpdate()
	if err := view.IsValid(); err != nil {
		return nil, err
	}

	builder := s.getQueryBuilder().
		Update("Views").
		Set("Title", view.Title).
		Set("Description", view.Description).
		Set("SortOrder", view.SortOrder).
		Set("Props", view.Props).
		Set("UpdateAt", view.UpdateAt).
		Where(sq.Eq{"Id": view.Id, "DeleteAt": 0})

	res, err := s.GetMaster().ExecBuilder(builder)
	if err != nil {
		return nil, errors.Wrapf(err, "failed to update view with id=%s", view.Id)
	}

	rowsAffected, err := res.RowsAffected()
	if err != nil {
		return nil, errors.Wrapf(err, "failed to get affected rows after updating view with id=%s", view.Id)
	}
	if rowsAffected == 0 {
		return nil, store.NewErrNotFound("View", view.Id)
	}

	return view, nil
}

func (s *SqlViewStore) Delete(viewID string, deleteAt int64) error {
	builder := s.getQueryBuilder().
		Update("Views").
		Set("DeleteAt", deleteAt).
		Set("UpdateAt", deleteAt).
		Where(sq.Eq{"Id": viewID, "DeleteAt": 0})

	res, err := s.GetMaster().ExecBuilder(builder)
	if err != nil {
		return errors.Wrapf(err, "failed to delete view with id=%s", viewID)
	}

	rowsAffected, err := res.RowsAffected()
	if err != nil {
		return errors.Wrapf(err, "failed to get affected rows after deleting view with id=%s", viewID)
	}
	if rowsAffected == 0 {
		return store.NewErrNotFound("View", viewID)
	}

	return nil
}

func (s *SqlViewStore) UpdateSortOrder(viewID, channelID string, newIndex int64) ([]*model.View, error) {
	if channelID == "" {
		return nil, store.NewErrInvalidInput("View", "channelID", channelID)
	}
	if viewID == "" {
		return nil, store.NewErrInvalidInput("View", "viewID", viewID)
	}
	if newIndex < 0 {
		return nil, store.NewErrInvalidInput("View", "SortOrder", newIndex)
	}

	now := model.GetMillis()
	transaction, err := s.GetMaster().Begin()
	if err != nil {
		return nil, errors.Wrap(err, "failed to begin transaction for UpdateSortOrder")
	}
	defer finalizeTransactionX(transaction, &err)

	builder := s.viewSelect.
		Where(sq.Eq{"ChannelId": channelID, "DeleteAt": 0}).
		OrderBy("SortOrder ASC", "CreateAt ASC", "Id ASC")

	var rows []model.View
	if err = transaction.SelectBuilder(&rows, builder); err != nil {
		return nil, errors.Wrapf(err, "failed to get views for channel %s", channelID)
	}

	views := make([]*model.View, len(rows))
	for i := range rows {
		views[i] = &rows[i]
	}

	if len(views) == 0 || int(newIndex) > len(views)-1 {
		return nil, store.NewErrInvalidInput("View", "SortOrder", newIndex)
	}

	currentIndex := -1
	var current *model.View
	for index, v := range views {
		if v.Id == viewID {
			currentIndex = index
			current = v
			break
		}
	}

	if currentIndex == -1 {
		return nil, store.NewErrNotFound("View", viewID)
	}

	views = utils.RemoveElementFromSliceAtIndex(views, currentIndex)
	views = slices.Insert(views, int(newIndex), current)

	caseStmt := sq.Case()
	query := s.getQueryBuilder().Update("Views")
	ids := make([]string, 0, len(views))
	for index, v := range views {
		v.SortOrder = index
		v.UpdateAt = now
		caseStmt = caseStmt.When(sq.Eq{"Id": v.Id}, strconv.FormatInt(int64(index), 10))
		ids = append(ids, v.Id)
	}
	query = query.Set("SortOrder", caseStmt)
	query = query.Set("UpdateAt", now)
	query = query.Where(sq.Eq{"Id": ids})

	queryStr, args, queryErr := query.ToSql()
	if queryErr != nil {
		return nil, errors.Wrap(queryErr, "failed to build sort order update query for views")
	}

	if _, execErr := transaction.Exec(queryStr, args...); execErr != nil {
		return nil, errors.Wrapf(execErr, "failed to update sort order for views in channel %s", channelID)
	}

	if err = transaction.Commit(); err != nil {
		return nil, errors.Wrap(err, "failed to commit sort order update for views")
	}
	return views, nil
}