<?php
/**
 * Plugins may load this file to gain access to special helper functions
 * for plugin installation. This file is not included by WordPress and it is
 * recommended, to prevent fatal errors, that this file is included using
 * require_once.
 *
 * These functions are not optimized for speed, but they should only be used
 * once in a while, so speed shouldn't be a concern. If it is and you are
 * needing to use these functions a lot, you might experience timeouts.
 * If you do, then it is advised to just write the SQL code yourself.
 *
 *     check_column( 'wp_links', 'link_description', 'mediumtext' );
 *
 *     if ( check_column( $wpdb->comments, 'comment_author', 'tinytext' ) ) {
 *         echo "ok\n";
 *     }
 *
 *     // Check the column.
 *     if ( ! check_column( $wpdb->links, 'link_description', 'varchar( 255 )' ) ) {
 *         $ddl = "ALTER TABLE $wpdb->links MODIFY COLUMN link_description varchar(255) NOT NULL DEFAULT '' ";
 *         $q = $wpdb->query( $ddl );
 *     }
 *
 *     $error_count = 0;
 *     $tablename   = $wpdb->links;
 *
 *     if ( check_column( $wpdb->links, 'link_description', 'varchar( 255 )' ) ) {
 *         $res .= $tablename . ' - ok <br />';
 *     } else {
 *         $res .= 'There was a problem with ' . $tablename . '<br />';
 *         ++$error_count;
 *     }
 *
 * @package WordPress
 * @subpackage Plugin
 */

/** Load WordPress Bootstrap */
require_once dirname( __DIR__ ) . '/wp-load.php';

if ( ! function_exists( 'maybe_create_table' ) ) :
    /**
     * Creates a table in the database if it doesn't already exist.
     *
     * @since 1.0.0
     *
     * @global wpdb $wpdb WordPress database abstraction object.
     *
     * @param string $table_name Database table name.
     * @param string $create_ddl SQL statement to create table.
     * @return bool True on success or if the table already exists. False on failure.
     */
    function maybe_create_table( $table_name, $create_ddl ) {
        global $wpdb;

        foreach ( $wpdb->get_col( 'SHOW TABLES', 0 ) as $table ) {
            if ( $table === $table_name ) {
                return true;
            }
        }

        // Didn't find it, so try to create it.
        // phpcs:ignore WordPress.DB.PreparedSQL.NotPrepared -- No applicable variables for this query.
        $wpdb->query( $create_ddl );

        // We cannot directly tell whether this succeeded!
        foreach ( $wpdb->get_col( 'SHOW TABLES', 0 ) as $table ) {
            if ( $table === $table_name ) {
                return true;
            }
        }

        return false;
    }
endif;

if ( ! function_exists( 'maybe_add_column' ) ) :
    /**
     * Adds column to database table, if it doesn't already exist.
     *
     * @since 1.0.0
     *
     * @global wpdb $wpdb WordPress database abstraction object.
     *
     * @param string $table_name  Database table name.
     * @param string $column_name Table column name.
     * @param string $create_ddl  SQL statement to add column.
     * @return bool True on success or if the column already exists. False on failure.
     */
    function maybe_add_column( $table_name, $column_name, $create_ddl ) {
        global $wpdb;

        // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- Cannot be prepared. Fetches columns for table names.
        foreach ( $wpdb->get_col( "DESC $table_name", 0 ) as $column ) {
            if ( $column === $column_name ) {
                return true;
            }
        }

        // Didn't find it, so try to create it.
        // phpcs:ignore WordPress.DB.PreparedSQL.NotPrepared -- No applicable variables for this query.
        $wpdb->query( $create_ddl );

        // We cannot directly tell whether this succeeded!
        // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- Cannot be prepared. Fetches columns for table names.
        foreach ( $wpdb->get_col( "DESC $table_name", 0 ) as $column ) {
            if ( $column === $column_name ) {
                return true;
            }
        }

        return false;
    }
endif;

/**
 * Drops column from database table, if it exists.
 *
 * @since 1.0.0
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param string $table_name  Database table name.
 * @param string $column_name Table column name.
 * @param string $drop_ddl    SQL statement to drop column.
 * @return bool True on success or if the column doesn't exist. False on failure.
 */
function maybe_drop_column( $table_name, $column_name, $drop_ddl ) {
    global $wpdb;

    // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- Cannot be prepared. Fetches columns for table names.
    foreach ( $wpdb->get_col( "DESC $table_name", 0 ) as $column ) {
        if ( $column === $column_name ) {

            // Found it, so try to drop it.
            // phpcs:ignore WordPress.DB.PreparedSQL.NotPrepared -- No applicable variables for this query.
            $wpdb->query( $drop_ddl );

            // We cannot directly tell whether this succeeded!
            // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- Cannot be prepared. Fetches columns for table names.
            foreach ( $wpdb->get_col( "DESC $table_name", 0 ) as $column ) {
                if ( $column === $column_name ) {
                    return false;
                }
            }
        }
    }

    // Else didn't find it.
    return true;
}

/**
 * Checks that database table column matches the criteria.
 *
 * Uses the SQL DESC for retrieving the table info for the column. It will help
 * understand the parameters, if you do more research on what column information
 * is returned by the SQL statement. Pass in null to skip checking that criteria.
 *
 * Column names returned from DESC table are case sensitive and are as listed:
 *
 *  - Field
 *  - Type
 *  - Null
 *  - Key
 *  - Default
 *  - Extra
 *
 * @since 1.0.0
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param string $table_name    Database table name.
 * @param string $col_name      Table column name.
 * @param string $col_type      Table column type.
 * @param bool   $is_null       Optional. Check is null.
 * @param mixed  $key           Optional. Key info.
 * @param mixed  $default_value Optional. Default value.
 * @param mixed  $extra         Optional. Extra value.
 * @return bool True, if matches. False, if not matching.
 */
function check_column( $table_name, $col_name, $col_type, $is_null = null, $key = null, $default_value = null, $extra = null ) {
    global $wpdb;

    $diffs = 0;

    // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- Cannot be prepared. Fetches columns for table names.
    $results = $wpdb->get_results( "DESC $table_name" );

    foreach ( $results as $row ) {

        if ( $row->Field === $col_name ) {

            // Got our column, check the params.
            if ( ( null !== $col_type ) && ( $row->Type !== $col_type ) ) {
                ++$diffs;
            }
            if ( ( null !== $is_null ) && ( $row->Null !== $is_null ) ) {
                ++$diffs;
            }
            if ( ( null !== $key ) && ( $row->Key !== $key ) ) {
                ++$diffs;
            }
            if ( ( null !== $default_value ) && ( $row->Default !== $default_value ) ) {
                ++$diffs;
            }
            if ( ( null !== $extra ) && ( $row->Extra !== $extra ) ) {
                ++$diffs;
            }

            if ( $diffs > 0 ) {
                return false;
            }

            return true;
        } // End if found our column.
    }

    return false;
}