exduckdb

#include "duckdb/planner/joinside.hpp"

#include "duckdb/planner/expression/bound_columnref_expression.hpp"
#include "duckdb/planner/expression/bound_comparison_expression.hpp"
#include "duckdb/planner/expression/bound_subquery_expression.hpp"
#include "duckdb/planner/expression_iterator.hpp"

namespace duckdb {

unique_ptr<Expression> JoinCondition::CreateExpression(JoinCondition cond) {
	return make_unique<BoundComparisonExpression>(cond.comparison, move(cond.left), move(cond.right));
}

JoinSide JoinSide::CombineJoinSide(JoinSide left, JoinSide right) {
	if (left == JoinSide::NONE) {
		return right;
	}
	if (right == JoinSide::NONE) {
		return left;
	}
	if (left != right) {
		return JoinSide::BOTH;
	}
	return left;
}

JoinSide JoinSide::GetJoinSide(idx_t table_binding, unordered_set<idx_t> &left_bindings,
                               unordered_set<idx_t> &right_bindings) {
	if (left_bindings.find(table_binding) != left_bindings.end()) {
		// column references table on left side
		D_ASSERT(right_bindings.find(table_binding) == right_bindings.end());
		return JoinSide::LEFT;
	} else {
		// column references table on right side
		D_ASSERT(right_bindings.find(table_binding) != right_bindings.end());
		return JoinSide::RIGHT;
	}
}

JoinSide JoinSide::GetJoinSide(Expression &expression, unordered_set<idx_t> &left_bindings,
                               unordered_set<idx_t> &right_bindings) {
	if (expression.type == ExpressionType::BOUND_COLUMN_REF) {
		auto &colref = (BoundColumnRefExpression &)expression;
		if (colref.depth > 0) {
			throw Exception("Non-inner join on correlated columns not supported");
		}
		return GetJoinSide(colref.binding.table_index, left_bindings, right_bindings);
	}
	D_ASSERT(expression.type != ExpressionType::BOUND_REF);
	if (expression.type == ExpressionType::SUBQUERY) {
		D_ASSERT(expression.GetExpressionClass() == ExpressionClass::BOUND_SUBQUERY);
		auto &subquery = (BoundSubqueryExpression &)expression;
		JoinSide side = JoinSide::NONE;
		if (subquery.child) {
			side = GetJoinSide(*subquery.child, left_bindings, right_bindings);
		}
		// correlated subquery, check the side of each of correlated columns in the subquery
		for (auto &corr : subquery.binder->correlated_columns) {
			if (corr.depth > 1) {
				// correlated column has depth > 1
				// it does not refer to any table in the current set of bindings
				return JoinSide::BOTH;
			}
			auto correlated_side = GetJoinSide(corr.binding.table_index, left_bindings, right_bindings);
			side = CombineJoinSide(side, correlated_side);
		}
		return side;
	}
	JoinSide join_side = JoinSide::NONE;
	ExpressionIterator::EnumerateChildren(expression, [&](Expression &child) {
		auto child_side = GetJoinSide(child, left_bindings, right_bindings);
		join_side = CombineJoinSide(child_side, join_side);
	});
	return join_side;
}

JoinSide JoinSide::GetJoinSide(const unordered_set<idx_t> &bindings, unordered_set<idx_t> &left_bindings,
                               unordered_set<idx_t> &right_bindings) {
	JoinSide side = JoinSide::NONE;
	for (auto binding : bindings) {
		side = CombineJoinSide(side, GetJoinSide(binding, left_bindings, right_bindings));
	}
	return side;
}

} // namespace duckdb