/* Copyright (c) 2011, 2025, Oracle and/or its affiliates.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License, version 2.0,
   as published by the Free Software Foundation.

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   This program is distributed in the hope that it will be useful,
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   GNU General Public License, version 2.0, for more details.

   You should have received a copy of the GNU General Public License
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#include <assert.h>
#include <gtest/gtest.h>
#include <stddef.h>

#include <string>

#include "sql/sql_lex.h"
#include "thr_lock.h"
#include "unittest/gunit/parsertest.h"
#include "unittest/gunit/test_utils.h"

namespace union_syntax_unittest {

using my_testing::Mock_error_handler;
using my_testing::Server_initializer;

class UnionSyntaxTest : public ParserTest {
 protected:
  void test_union_syntax(const char *query, int num_terms,
                         bool expect_syntax_error = false) {
    Query_block *term1 = parse(query, expect_syntax_error ? ER_PARSE_ERROR : 0);
    EXPECT_EQ(nullptr, term1->first_inner_query_expression());
    EXPECT_EQ(nullptr, term1->next_select_in_list());
    EXPECT_EQ(1, term1->get_fields_list()->front()->val_int());

    Query_expression *top_union = term1->master_query_expression();
    EXPECT_EQ(nullptr, top_union->outer_query_block());

    if (num_terms > 1) {
      Query_block *term2 = term1->next_query_block();
      ASSERT_FALSE(term2 == nullptr);

      EXPECT_EQ(nullptr, term2->first_inner_query_expression());
      EXPECT_EQ(term1, term2->next_select_in_list());
      EXPECT_EQ(2, term2->get_fields_list()->front()->val_int());

      if (num_terms > 2) {
      } else
        EXPECT_EQ(nullptr, term2->next_query_block());

      EXPECT_EQ(top_union, term2->master_query_expression());
    }
  }

  Query_block *test_ignored_trailing_limit_on_query_term(const char *query) {
    Query_block *term1 = parse(query);

    EXPECT_EQ(nullptr, term1->select_limit);

    Query_expression *top_union = term1->master_query_expression();

    EXPECT_EQ(4,
              top_union->query_term()->query_block()->select_limit->val_int());

    EXPECT_EQ(nullptr, top_union->outer_query_block());

    Query_block *term2 = term1->next_query_block();

    EXPECT_EQ(nullptr, term2->first_inner_query_expression());
    EXPECT_EQ(term1, term2->next_select_in_list());
    EXPECT_EQ(2, term2->get_fields_list()->front()->val_int());

    return term1;
  }

  void test_ignored_trailing_limit_on_query_term(const char *query,
                                                 int expected_limit) {
    Query_block *term1 = test_ignored_trailing_limit_on_query_term(query);
    EXPECT_EQ(expected_limit,
              term1->next_query_block()->select_limit->val_int())
        << " Outer limit clause should be ignored.";
  }
};

TEST_F(UnionSyntaxTest, First) {
  Query_block *top = parse("SELECT 1");
  Query_expression *top_union = top->master_query_expression();

  EXPECT_EQ(nullptr, top->outer_query_block());
  EXPECT_EQ(top, top_union->first_query_block());
}

using std::string;

string parenthesize(string query, int n) {
  string new_query(n, '(');
  new_query += query;
  new_query.append(n, ')');
  return new_query;
}

TEST_F(UnionSyntaxTest, QueryExpParensDualOrder) {
  Query_block *term = parse("( SELECT 1 FROM t1 ORDER BY 2 ) ORDER BY 3");
  ASSERT_FALSE(term == nullptr);
  EXPECT_EQ(nullptr, term->next_query_block());
  EXPECT_EQ(nullptr, term->first_inner_query_expression());

  // The query expression.
  Query_expression *exp = term->master_query_expression();
  ASSERT_FALSE(exp == nullptr);
  EXPECT_EQ(term, exp->first_query_block());

  // Table expression
  EXPECT_EQ(1U, term->m_table_list.elements);
  Table_ref *table_list = term->get_table_list();
  EXPECT_STREQ("t1", table_list->alias);

  // Inner order clause, outer is ignored
  EXPECT_EQ(1U, term->order_list.elements);
  ORDER *inner_order = term->order_list.first;
  Item *order_exp = *inner_order->item;
  EXPECT_EQ(2, order_exp->val_int());
}

TEST_F(UnionSyntaxTest, QueryExpParensOrder) {
  Query_block *term = parse("(SELECT 1 FROM t1) ORDER BY 3");
  ASSERT_FALSE(term == nullptr);
  EXPECT_EQ(nullptr, term->next_query_block());
  EXPECT_EQ(nullptr, term->first_inner_query_expression());

  // The query expression.
  Query_expression *exp = term->master_query_expression();
  ASSERT_FALSE(exp == nullptr);
  EXPECT_EQ(term, exp->first_query_block());

  // Table expression
  EXPECT_EQ(1U, term->m_table_list.elements);
  Table_ref *table_list = term->get_table_list();
  EXPECT_STREQ("t1", table_list->alias);

  // Inner order clause, outer is used when inner is missing
  EXPECT_EQ(1U, term->order_list.elements);
  ORDER *inner_order = term->order_list.first;
  ASSERT_FALSE(inner_order == nullptr);
  Item *order_exp = *inner_order->item;
  EXPECT_EQ(3, order_exp->val_int());
}

TEST_F(UnionSyntaxTest, QueryExpParensLimit1) {
  Query_block *term = parse("(SELECT 1 FROM t1 LIMIT 2) LIMIT 3");
  ASSERT_FALSE(term == nullptr);
  EXPECT_EQ(nullptr, term->next_query_block());
  EXPECT_EQ(nullptr, term->first_inner_query_expression());

  // The query expression.
  Query_expression *exp = term->master_query_expression();
  ASSERT_FALSE(exp == nullptr);
  EXPECT_EQ(term, exp->first_query_block());

  // Table expression
  EXPECT_EQ(1U, term->m_table_list.elements);
  Table_ref *table_list = term->get_table_list();
  EXPECT_STREQ("t1", table_list->alias);

  EXPECT_EQ(2, term->select_limit->val_int())
      << " Smaller limit always override larger value";

  term = parse("(SELECT 1 FROM t1 LIMIT 3) LIMIT 2");
  EXPECT_EQ(2, term->select_limit->val_int())
      << " Smaller limit always override larger value";
}

TEST_F(UnionSyntaxTest, Simple) {
  Query_block *block1 = parse("SELECT 1 UNION SELECT 2 UNION SELECT 3");
  Query_block *block2 = block1->next_query_block();
  Query_block *block3 = block2->next_query_block();

  EXPECT_EQ(1, block1->get_fields_list()->front()->val_int());
  EXPECT_EQ(2, block2->get_fields_list()->front()->val_int());
  EXPECT_EQ(3, block3->get_fields_list()->front()->val_int());
}

TEST_F(UnionSyntaxTest, ThreeWay) {
  const int max_parens = 2;

  for (int top_parens = 0; top_parens <= max_parens; ++top_parens)
    for (int u1parens = 0; u1parens <= max_parens; ++u1parens)
      for (int u2parens = 0; u2parens <= max_parens; ++u2parens)
        for (int u3parens = 0; u3parens <= max_parens; ++u3parens) {
          string query = parenthesize("SELECT 1", u1parens) + " UNION " +
                         parenthesize("SELECT 2", u2parens) + " UNION " +
                         parenthesize("SELECT 3", u3parens);

          query = parenthesize(query, top_parens);
          test_union_syntax(query.c_str(), 3);
        }
}

const char *get_order_by_column_name(Query_block *query_block, int index = 0) {
  EXPECT_EQ(nullptr, *query_block->order_list.next);
  ORDER *current = query_block->order_list.first;
  for (int i = 0; i < index; ++i) current = current->next;
  Item *order_expression = current->item[0];
  EXPECT_EQ(Item::FIELD_ITEM, order_expression->type());
  //  ASSERT_EQ(Item::FIELD_ITEM, order_expression->type());
  assert(Item::FIELD_ITEM == order_expression->type());
  return order_expression->item_name.ptr();
}

const char *get_order_by_column_name(Query_expression *query_expression,
                                     int index = 0) {
  Query_block *top_qb = query_expression->query_term()->query_block();
  // Why can't I use ASSERT_FALSE here?!
  EXPECT_FALSE(top_qb == nullptr);
  return get_order_by_column_name(top_qb, index);
}

int get_limit(Query_block *query_block) {
  return query_block->select_limit->val_int();
}

TEST_F(UnionSyntaxTest, UnionOrderLimit) {
  Query_block *block1 =
      parse("SELECT 1 UNION SELECT 2 FROM t1 ORDER BY a LIMIT 123");
  Query_block *block2 = block1->next_query_block();

  EXPECT_EQ(nullptr, block1->select_limit)
      << "First query block should not have a limit clause.";

  EXPECT_EQ(nullptr, block2->select_limit)
      << "Second query block should not have a limit clause.";

  EXPECT_EQ(0U, block1->order_list.elements)
      << "First query block should not have an order by clause.";

  EXPECT_EQ(0U, block2->order_list.elements)
      << "Second query block should not have an order by clause.";

  Query_expression *query_expression = block1->master_query_expression();

  // The limit and order by clauses should belong to the whole query
  // expression, i.e. the top level post processing query block.
  Query_block *top_qb = query_expression->query_term()->query_block();
  EXPECT_EQ(123, get_limit(top_qb));
  EXPECT_STREQ("a", get_order_by_column_name(top_qb));
}

TEST_F(UnionSyntaxTest, UnionNestedQueryBlock) {
  Query_block *block1 =
      parse("SELECT 1 UNION (SELECT 2 FROM t1 ORDER BY a LIMIT 123)");
  Query_block *block2 = block1->next_query_block();

  EXPECT_EQ(nullptr, block1->select_limit)
      << "First query block should not have a limit clause.";

  EXPECT_EQ(0U, block1->order_list.elements)
      << "First query block should not have an order by clause.";

  EXPECT_EQ(123, get_limit(block2));
  EXPECT_STREQ("a", get_order_by_column_name(block2));

  Query_expression *query_expression = block1->master_query_expression();

  // The limit and order by clauses should not belong to the whole query
  // expression, i.e. the top level post processing query block
  Query_block *top_qb = query_expression->query_term()->query_block();
  EXPECT_EQ(nullptr, top_qb->select_limit)
      << "The union should not have a LIMIT/OFFSET clause.";
  EXPECT_EQ(0U, top_qb->order_list.elements)
      << "The union should not have an order by clause.";
}

TEST_F(UnionSyntaxTest, NestedQueryExpWithLimit) {
  Query_block *block1 =
      parse("(SELECT 1 ORDER BY a LIMIT 5) UNION SELECT 2 ORDER BY b LIMIT 8");

  Query_expression *query_expression = block1->master_query_expression();

  EXPECT_STREQ("a", get_order_by_column_name(block1, 0));
  EXPECT_EQ(5, block1->select_limit->val_int());

  Query_block *fake = query_expression->query_term()->query_block();
  EXPECT_STREQ("b", get_order_by_column_name(fake, 0));
  EXPECT_EQ(8, fake->select_limit->val_int());
}

TEST_F(UnionSyntaxTest, IgnoredTrailingLimitOnQueryTerm) {
  Query_block *block1 = parse("(SELECT 1) UNION SELECT 2 LIMIT 123");
  Query_block *block2 = block1->next_query_block();
  EXPECT_EQ(2, block2->get_fields_list()->front()->val_int());

  // Neither query block should have a limit clause.
  EXPECT_EQ(nullptr, block1->select_limit);
  EXPECT_EQ(nullptr, block2->select_limit);

  Query_expression *query_expression = block1->master_query_expression();

  // The limit clause should belong to the whole query expression, i.e. the
  // "fake select lex".
  EXPECT_EQ(
      123,
      query_expression->query_term()->query_block()->select_limit->val_int());

  return;
  test_ignored_trailing_limit_on_query_term(
      "(SELECT 1) UNION (SELECT 2 LIMIT 3) LIMIT 4", 3);

  test_ignored_trailing_limit_on_query_term(
      "(SELECT 1) UNION ((SELECT 2 LIMIT 3)) LIMIT 4", 3);

  test_ignored_trailing_limit_on_query_term(
      "(SELECT 1) UNION (SELECT 2) LIMIT 4");

  test_ignored_trailing_limit_on_query_term(
      "(SELECT 1) UNION ((SELECT 2)) LIMIT 4");
}

TEST_F(UnionSyntaxTest, InnerVsOuterOrder) {
  Query_block *query_block =
      parse("(SELECT b, a FROM t1 ORDER by b, a LIMIT 3) ORDER by a, b");

  EXPECT_STREQ("b", get_order_by_column_name(query_block, 0));
  EXPECT_STREQ("a", get_order_by_column_name(query_block, 1));
  EXPECT_EQ(3, get_limit(query_block));

  Query_expression *query_expression = query_block->master_query_expression();
  EXPECT_STREQ("a", get_order_by_column_name(query_expression, 0));
  EXPECT_STREQ("b", get_order_by_column_name(query_expression, 1));
  //    EXPECT_EQ(2, get_limit(query_expression->fake_query_block));
}

TEST_F(UnionSyntaxTest, QueryTermIteratorReentrancy) {
  Query_block *query_block = parse(
      "(SELECT * FROM r UNION ALL SELECT * FROM s ORDER BY a LIMIT 10)"
      " UNION ALL "
      " (SELECT * FROM r UNION DISTINCT SELECT * FROM s) LIMIT 7");

  Query_expression *qe = query_block->master_query_expression();
  Query_terms<QTC_POST_ORDER, VL_VISIT_LEAVES> terms(qe->query_term());
  // set of nodes collected without any "interference"
  std::vector<Query_term *> nodes_a_priori;
  std::vector<Query_term *> nodes_outer;
  std::vector<Query_term *> nodes_inner;

  for (Query_term *term1 : terms) {
    nodes_a_priori.push_back(term1);
  }

  EXPECT_EQ(7, nodes_a_priori.size());

  for (Query_term *term1 : terms) {
    // run a second iterator over the same query terms and verify that it
    // doesn't interfere with the outer iterator's job
    for (Query_term *term2 : terms) {
      nodes_inner.push_back(term2);
    }
    EXPECT_EQ(nodes_a_priori, nodes_inner);
    nodes_inner.clear();
    nodes_outer.push_back(term1);
  }
  EXPECT_EQ(nodes_a_priori, nodes_outer);
}

}  // namespace union_syntax_unittest