// Copyright 2024 PingCAP, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.

package ddl

import (
	"testing"

	"github.com/stretchr/testify/assert"
)

// TestSplitQueries tests the SplitQueries function
func TestSplitQueries(t *testing.T) {
	tests := []struct {
		name          string
		input         string
		expected      []string
		expectedError bool
	}{
		{
			name:          "Empty input",
			input:         "",
			expected:      []string(nil),
			expectedError: false,
		},
		{
			name:          "Single query without trailing semicolon",
			input:         "CREATE TABLE test (id INT)",
			expected:      []string{"CREATE TABLE `test` (`id` INT);"},
			expectedError: false,
		},
		{
			name:          "Single query with trailing semicolon",
			input:         "CREATE TABLE test (id INT);",
			expected:      []string{"CREATE TABLE `test` (`id` INT);"},
			expectedError: false,
		},
		{
			name: "Multiple queries with trailing semicolons",
			input: `
CREATE TABLE test1 (id INT);
CREATE TABLE test2 (name VARCHAR(20));
INSERT INTO test1 VALUES (1);
`,
			expected: []string{
				"CREATE TABLE `test1` (`id` INT);",
				"CREATE TABLE `test2` (`name` VARCHAR(20));",
				"INSERT INTO `test1` VALUES (1);",
			},
			expectedError: false,
		},
		{
			name: "Query with semicolons inside column values",
			input: `
CREATE TABLE test (name VARCHAR(50));
INSERT INTO test VALUES ('This; is; a test');
`,
			expected: []string{
				"CREATE TABLE `test` (`name` VARCHAR(50));",
				"INSERT INTO `test` VALUES (_UTF8MB4'This; is; a test');",
			},
			expectedError: false,
		},
		{
			name: "Query with escaped quotes inside strings",
			input: `
CREATE TABLE test (name VARCHAR(50));
INSERT INTO test VALUES ('This ''is'' a test');
`,
			expected: []string{
				"CREATE TABLE `test` (`name` VARCHAR(50));",
				"INSERT INTO `test` VALUES (_UTF8MB4'This ''is'' a test');",
			},
			expectedError: false,
		},
		{
			name: "Nested queries or functions with semicolons",
			input: `
CREATE TABLE test (id INT, name VARCHAR(50));
INSERT INTO test VALUES (1, CONCAT('Name;', 'Test'));
`,
			expected: []string{
				"CREATE TABLE `test` (`id` INT,`name` VARCHAR(50));",
				"INSERT INTO `test` VALUES (1,CONCAT(_UTF8MB4'Name;', _UTF8MB4'Test'));",
			},
			expectedError: false,
		},
		{
			name:          "Malformed SQL query",
			input:         "CREATE TABLE test (id INT;",
			expected:      nil,
			expectedError: true,
		},
		{
			name: "SQL injection edge case",
			input: `
CREATE TABLE users (id INT, name VARCHAR(50));
INSERT INTO users VALUES (1, 'test; DROP TABLE users; --');
`,
			expected: []string{
				"CREATE TABLE `users` (`id` INT,`name` VARCHAR(50));",
				"INSERT INTO `users` VALUES (1,_UTF8MB4'test; DROP TABLE users; --');",
			},
			expectedError: false,
		},
		{
			name: "Complex queries with comments",
			input: `
-- This is a comment
CREATE TABLE test (id INT); -- Inline comment
/* Multi-line
comment */
INSERT INTO test VALUES (1);
`,
			expected: []string{
				"CREATE TABLE `test` (`id` INT);",
				"INSERT INTO `test` VALUES (1);",
			},
			expectedError: false,
		},
		{
			name: "Queries with whitespace and newlines",
			input: `
    
    CREATE TABLE test (id INT);
    
    INSERT INTO test VALUES (1);
    
`,
			expected: []string{
				"CREATE TABLE `test` (`id` INT);",
				"INSERT INTO `test` VALUES (1);",
			},
			expectedError: false,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			result, err := SplitQueries(tt.input)
			if tt.expectedError {
				assert.Error(t, err)
			} else {
				assert.NoError(t, err)
				assert.Equal(t, tt.expected, result)
			}
		})
	}
}