// GetColumns returns all columns from a table. It discards the column entity_type_id from some
// entity tables.
func GetColumns(dbrSess dbr.SessionRunner, table string) (Columns, error) {
	var cols = make(Columns, 0, 100)

	sel := dbrSess.SelectBySql("SHOW COLUMNS FROM " + dbr.Quoter.Table(table))
	selSql, selArg := sel.ToSql()
	rows, err := sel.Query(selSql, selArg...)

	if err != nil {
		return nil, log.Error("csdb.GetColumns.Query", "err", err, "query", selSql, "args", selArg)
	}
	defer rows.Close()

	col := Column{}
	for rows.Next() {
		err := rows.Scan(&col.Field, &col.Type, &col.Null, &col.Key, &col.Default, &col.Extra)
		if err != nil {
			return nil, log.Error("csdb.GetColumns.Rows.Scan", "err", err, "query", selSql, "args", selArg)
		}
		cols = append(cols, col)
	}
	err = rows.Err()
	if err != nil {
		return nil, log.Error("csdb.GetColumns.Rows.Err", "err", err, "query", selSql, "args", selArg)
	}
	return cols, nil
}

// Select generates a SELECT * FROM tableName statement
func (ts *Table) Select(dbrSess dbr.SessionRunner) (*dbr.SelectBuilder, error) {
	if ts == nil {
		return nil, ErrTableNotFound
	}
	return dbrSess.
		Select(ts.AllColumnAliasQuote("main_table")...).
		From(ts.Name, "main_table"), nil
}

// GetTables returns all tables from a database. AndWhere can be optionally applied.
// Only first index (0) will be added.
func GetTables(dbrSess dbr.SessionRunner, sql ...string) ([]string, error) {

	qry := "SHOW TABLES"
	if len(sql) > 0 && sql[0] != "" {
		if false == dbr.Stmt.IsSelect(sql[0]) {
			qry = qry + " LIKE '" + sql[0] + "'"
		} else {
			qry = sql[0]
		}
	}
	if PkgLog.IsDebug() { // this if reduces 9 allocs ...
		defer log.WhenDone(PkgLog).Debug("Stats", "Package", "codegen", "Step", "GetTables", "query", qry)
	}

	sb := dbrSess.SelectBySql(qry)
	query, args, err := sb.ToSql()
	if err != nil {
		return nil, errgo.Mask(err)
	}
	rows, err := sb.Query(query, args...)
	if err != nil {
		return nil, errgo.Mask(err)
	}
	defer rows.Close()

	var tableName string
	var tableNames = make([]string, 0, 200)
	for rows.Next() {
		if err := rows.Scan(&tableName); err != nil {
			return nil, errgo.Mask(err)
		}
		tableNames = append(tableNames, tableName)
	}

	if err = rows.Err(); err != nil {
		return nil, errgo.Mask(err)
	}
	return tableNames, nil
}

// GetAttributeSelectSql generates the select query to retrieve full attribute configuration
// Implements the scope on a SQL query basis so that attribute functions does not need to deal with it.
// Tests see the tools package
// @see magento2/app/code/Magento/Eav/Model/Resource/Attribute/Collection.php::_initSelect()
func GetAttributeSelectSql(dbrSess dbr.SessionRunner, aat EntityTypeAdditionalAttributeTabler, entityTypeID, websiteID int64) (*dbr.SelectBuilder, error) {

	ta, err := TableCollection.Structure(TableIndexAttribute)
	if err != nil {
		return nil, log.Error("eav.GetAttributeSelectSql.TableCollection.Structure", "err", err, "entityTypeID", entityTypeID, "websiteID", websiteID)
	}
	taa, err := aat.TableAdditionalAttribute()
	if err != nil {
		return nil, log.Error("eav.GetAttributeSelectSql.TableAdditionalAttribute", "err", err, "ta", ta, "entityTypeID", entityTypeID, "websiteID", websiteID)
	}
	tew, err := aat.TableEavWebsite()
	if err != nil {
		return nil, log.Error("eav.GetAttributeSelectSql.TableEavWebsite", "err", err, "ta", ta, "taa", taa, "entityTypeID", entityTypeID, "websiteID", websiteID)
	}
	// tew table can now contains columns names which can occur in table eav_attribute and
	// or [catalog|customer|entity]_eav_attribute
	var (
		ifnull           []string
		tewAddedCols     []string
		taColumnsQuoted  = utils.StringSlice(ta.AllColumnAliasQuote(csdb.MainTable))
		taaColumnsQuoted = utils.StringSlice(taa.ColumnAliasQuote(csdb.AdditionalTable))
	)

	if tew != nil {
		ifnull = make([]string, len(tew.Columns))
		for i, tewC := range tew.Columns.ColumnsNoPK().FieldNames() {
			t := ""
			switch {
			case ta.In(tewC):
				t = csdb.MainTable
				break
			case taa.In(tewC):
				t = csdb.AdditionalTable
				break
			default:
				return nil, log.Error("eav.GetAttributeSelectSql.Columns.FieldNames.default", "err",
					fmt.Errorf("Cannot find column name %s.%s neither in table %s nor in %s.", tew.Name, tewC, ta.Name, taa.Name),
					"ta", ta, "taa", taa,
					"entityTypeID", entityTypeID, "websiteID", websiteID)
			}
			ifnull[i] = dbr.IfNullAs(csdb.ScopeTable, tewC, t, tewC, tewC)
			tewAddedCols = append(tewAddedCols, tewC)
		}
		taColumnsQuoted.ReduceContains(tewAddedCols...)
		taaColumnsQuoted.ReduceContains(tewAddedCols...)
	}

	selectSql := dbrSess.
		Select(taColumnsQuoted...).
		From(ta.Name, csdb.MainTable).
		Join(
			dbr.JoinTable(taa.Name, csdb.AdditionalTable),
			taaColumnsQuoted,
			dbr.JoinOn(dbr.Quote+csdb.AdditionalTable+"`.`attribute_id` = `"+csdb.MainTable+"`.`attribute_id`"),
			dbr.JoinOn(dbr.Quote+csdb.MainTable+"`.`entity_type_id` = ?", entityTypeID),
		)

	if len(tewAddedCols) > 0 {
		selectSql.
			LeftJoin(
				dbr.JoinTable(tew.Name, csdb.ScopeTable),
				append(ifnull),
				dbr.JoinOn(dbr.Quote+csdb.ScopeTable+dbr.Quote+"."+dbr.Quote+"attribute_id"+dbr.Quote+" = "+dbr.Quote+csdb.MainTable+dbr.Quote+"."+dbr.Quote+"attribute_id"+dbr.Quote),
				dbr.JoinOn(dbr.Quote+csdb.ScopeTable+dbr.Quote+"."+dbr.Quote+"website_id"+dbr.Quote+" = ?", websiteID),
			)
	}
	return selectSql, nil
}