<?php

namespace CleantalkSP\SpbctWP\DB;

use CleantalkSP\SpbctWP\DB;

class ColumnsAnalyzer
{
    /**
     * @var array Table structure in fact
     */
    private $actual_schema;

    /**
     * @var array Table structure that should be
     */
    private $relevant_schema;

    /**
     * @var string[]
     */
    private $field_standard;

    /**
     * @var array
     */
    public $columns_to_create;
    /**
     * @var array
     */
    public $columns_to_delete;
    /**
     * @var array
     */
    public $columns_to_change;

    /**
     * @var bool
     */
    public $changes_required;

    public function __construct($table_name)
    {
        $this->field_standard = SQLSchema::getFieldStandard();

        $this->relevant_schema = SQLSchema::getByName($table_name);
        $this->relevant_schema = $this->convertSchemaToStandard($this->relevant_schema['columns']);

        $this->actual_schema = DB::getInstance()->fetchAll('SHOW COLUMNS FROM ' . $table_name, ARRAY_A);
        $this->actual_schema = $this->convertSchemaToStandard($this->actual_schema);

        $this->execute();

        $this->changes_required = $this->columns_to_change || $this->columns_to_create || $this->columns_to_delete;
    }

    /**
     * Create columns and drop excess columns
     */
    public function execute()
    {
        $this->columns_to_create = array_diff(
            array_column($this->relevant_schema, 'field'),
            array_column($this->actual_schema, 'field')
        );

        $this->columns_to_delete = array_diff(
            array_column($this->actual_schema, 'field'),
            array_column($this->relevant_schema, 'field')
        );

        $this->columns_to_change = array();
        foreach ( $this->relevant_schema as $relevant_column ) {
            foreach ( $this->actual_schema as $actual_column ) {
                if ( $relevant_column['field'] === $actual_column['field'] ) {
                    foreach ( array_keys($this->field_standard) as $field_param_name ) {
                        if ( $relevant_column[$field_param_name] !== $actual_column[$field_param_name] ) {
                            $this->columns_to_change[] = $relevant_column['field'];
                        }
                    }
                }
            }
        }
        $this->columns_to_change = array_unique($this->columns_to_change);
    }

    private function convertSchemaToStandard($schema)
    {
        $tmp_schema = array();
        foreach ( $schema as $fields_num => $fields ) {
            foreach ( $fields as $field_name => $field_value ) {
                $tmp_field_name  = strtolower($field_name);
                $tmp_field_value = '';
                if ( is_string($field_value) && $field_value !== 'null' ) {
                    $tmp_field_value = strtolower($field_value);
                    $tmp_field_value = preg_replace('@[\'"]@', '"', $tmp_field_value);
                    $tmp_field_value = preg_replace('@[\s]@', '', $tmp_field_value);
                    $tmp_field_value = preg_replace('@^[\'"](.*?)[\'"]$@', '$1', $tmp_field_value);
                }

                if ( ! array_key_exists($tmp_field_name, $this->field_standard) ) {
                    continue;
                }

                $tmp_schema[$fields_num][$tmp_field_name] = $tmp_field_value;
            }

            $tmp_schema[$fields_num] = array_merge($this->field_standard, $tmp_schema[$fields_num]);
        }

        return $tmp_schema;
    }
}