<?php
    
    use yii\db\Migration;
    
    class m161101_143541_blog_article_to_category extends Migration
    {
        public function up()
        {
            /**
             * Create junction table to connect articles with categories
             */
            $this->createTable(
                'blog_article_to_category',
                [
                    'blog_article_id'  => $this->integer()
                                               ->notNull(),
                    'blog_category_id' => $this->integer()
                                               ->notNull(),
                ]
            );
            
            /**
             * Add foreign keys and indexes for junction table
             */
            $this->createIndex(
                'blog_article_to_category_uk',
                'blog_article_to_category',
                [
                    'blog_article_id',
                    'blog_category_id',
                ],
                true
            );
            
            $this->addForeignKey(
                'blog_article_to_category_art_fk',
                'blog_article_to_category',
                'blog_article_id',
                'blog_article',
                'id',
                'CASCADE',
                'CASCADE'
            );
            
            $this->addForeignKey(
                'blog_article_to_category_cat_fk',
                'blog_article_to_category',
                'blog_category_id',
                'blog_category',
                'id',
                'CASCADE',
                'CASCADE'
            );
        }
        
        public function down()
        {
            $this->dropForeignKey('blog_article_to_category_cat_fk', 'blog_article_to_category');
            $this->dropForeignKey('blog_article_to_category_art_fk', 'blog_article_to_category');
            $this->dropIndex('blog_article_to_category_uk', 'blog_article_to_category');
            $this->dropTable('blog_article_to_category');
        }
    }