// CheckAndUpdateSelectList checks order by fields validity and set hidden fields to selectList.
func (r *OrderByRset) CheckAndUpdateSelectList(selectList *plans.SelectList, tableFields []*field.ResultField) error {
	for i, v := range r.By {
		if expressions.ContainAggregateFunc(v.Expr) {
			expr, err := selectList.UpdateAggFields(v.Expr, tableFields)
			if err != nil {
				return errors.Errorf("%s in 'order clause'", err.Error())
			}

			r.By[i].Expr = expr
		} else {
			names := expressions.MentionedColumns(v.Expr)
			for _, name := range names {
				// try to find in select list
				// TODO: mysql has confused result for this, see #555.
				// now we use select list then order by, later we should make it easier.
				if field.ContainFieldName(name, selectList.ResultFields, field.CheckFieldFlag) {
					// check ambiguous fields, like `select c1 as c2, c2 from t order by c2`.
					if err := field.CheckAmbiguousField(name, selectList.ResultFields, field.DefaultFieldFlag); err != nil {
						return errors.Errorf("Column '%s' in order statement is ambiguous", name)
					}
					continue
				}

				if !selectList.CloneHiddenField(name, tableFields) {
					return errors.Errorf("Unknown column '%s' in 'order clause'", name)
				}
			}
		}
	}

	return nil
}

func checkIdentAmbiguous(i *expression.Ident, selectList *plans.SelectList, clause clauseType) (int, error) {
	index, err := selectList.CheckAmbiguous(i)
	if err != nil {
		return -1, errors.Errorf("Column '%s' in %s is ambiguous", i, clause)
	} else if index == -1 {
		return -1, nil
	}

	return index, nil
}

// CheckAggregate will check whether order by has aggregate function or not,
// if has, we will add it to select list hidden field.
func (r *HavingRset) CheckAggregate(selectList *plans.SelectList) error {
	if expression.ContainAggregateFunc(r.Expr) {
		expr, err := selectList.UpdateAggFields(r.Expr)
		if err != nil {
			return errors.Errorf("%s in 'having clause'", err.Error())
		}

		r.Expr = expr
	}

	return nil
}

// CheckAggregate will check whether order by has aggregate function or not,
// if has, we will add it to select list hidden field.
func (r *OrderByRset) CheckAggregate(selectList *plans.SelectList) error {
	for i, v := range r.By {
		if expression.ContainAggregateFunc(v.Expr) {
			expr, err := selectList.UpdateAggFields(v.Expr)
			if err != nil {
				return errors.Errorf("%s in 'order clause'", err.Error())
			}

			r.By[i].Expr = expr
		}
	}
	return nil
}

// CheckAndUpdateSelectList checks having fields validity and set hidden fields to selectList.
func (r *HavingRset) CheckAndUpdateSelectList(selectList *plans.SelectList, groupBy []expression.Expression, tableFields []*field.ResultField) error {
	if err := expressions.CheckOneColumn(r.Expr); err != nil {
		return errors.Trace(err)
	}

	if expressions.ContainAggregateFunc(r.Expr) {
		expr, err := selectList.UpdateAggFields(r.Expr, tableFields)
		if err != nil {
			return errors.Errorf("%s in 'having clause'", err.Error())
		}

		r.Expr = expr
	} else {
		// having can only contain group by column and select list, e.g,
		// `select c1 from t group by c2 having c3 > 0` is invalid,
		// because c3 is not in group by and select list.
		names := expressions.MentionedColumns(r.Expr)
		for _, name := range names {
			found := false

			// check name whether in select list.
			// notice that `select c1 as c2 from t group by c1, c2, c3 having c2 > c3`,
			// will use t.c2 not t.c1 here.
			if field.ContainFieldName(name, selectList.ResultFields, field.OrgFieldNameFlag) {
				continue
			}
			if field.ContainFieldName(name, selectList.ResultFields, field.FieldNameFlag) {
				if field.ContainFieldName(name, tableFields, field.OrgFieldNameFlag) {
					selectList.CloneHiddenField(name, tableFields)
				}
				continue
			}

			// check name whether in group by.
			// group by must only have column name, e.g,
			// `select c1 from t group by c2 having c2 > 0` is valid,
			// but `select c1 from t group by c2 + 1 having c2 > 0` is invalid.
			for _, by := range groupBy {
				if !field.CheckFieldsEqual(name, by.String()) {
					continue
				}

				// if name is not in table fields, it will get an unknown field error in GroupByRset,
				// so no need to check return value.
				selectList.CloneHiddenField(name, tableFields)

				found = true
				break
			}

			if !found {
				return errors.Errorf("Unknown column '%s' in 'having clause'", name)
			}
		}
	}

	return nil
}

// CheckAndUpdateSelectList checks order by fields validity and set hidden fields to selectList.
func (r *OrderByRset) CheckAndUpdateSelectList(selectList *plans.SelectList, tableFields []*field.ResultField) error {
	for i, v := range r.By {
		if expression.ContainAggregateFunc(v.Expr) {
			expr, err := selectList.UpdateAggFields(v.Expr, tableFields)
			if err != nil {
				return errors.Errorf("%s in 'order clause'", err.Error())
			}

			r.By[i].Expr = expr
		} else {
			if _, err := selectList.CheckReferAmbiguous(v.Expr); err != nil {
				return errors.Errorf("Column '%s' in order statement is ambiguous", v.Expr)
			}

			// TODO: check more ambiguous case
			// Order by ambiguous rule:
			//	select c1 as a, c2 as a from t order by a is ambiguous
			//	select c1 as a, c2 as a from t order by a + 1 is ambiguous
			//	select c1 as c2, c2 from t order by c2 is ambiguous
			//	select c1 as c2, c2 from t order by c2 + 1 is ambiguous

			// TODO: use vistor to refactor all and combine following plan check.
			names := expression.MentionedColumns(v.Expr)
			for _, name := range names {
				// try to find in select list
				// TODO: mysql has confused result for this, see #555.
				// now we use select list then order by, later we should make it easier.
				if field.ContainFieldName(name, selectList.ResultFields, field.CheckFieldFlag) {
					continue
				}

				if !selectList.CloneHiddenField(name, tableFields) {
					return errors.Errorf("Unknown column '%s' in 'order clause'", name)
				}
			}
		}
	}

	return nil
}

func resetAggFields(selectList *plans.SelectList) {
	fields := selectList.Fields
	selectList.AggFields = GetAggFields(fields)
}