<?php

namespace Tenweb_Manager {

  class MigrationDB extends Migration
  {

    /**
     * @return bool
     * @throws \Exception
     */
    public function run()
    {
      // get tables
      $tables = $this->get_tables();

      $file_to_save_database_data = self::get_tmp_dir() . "/" . self::MIGRATION_DB_FILE_NAME;
      //open sql file
      if (($db_file = fopen($file_to_save_database_data, "w+")) !== false) {
        // add sql headers
        $sql_header_string = "SET SQL_MODE = \"NO_AUTO_VALUE_ON_ZERO\";" . PHP_EOL . "SET time_zone = \"+00:00\";" . PHP_EOL . "SET foreign_key_checks = 0;" . PHP_EOL;

        $this->add_to_file($db_file, $sql_header_string . PHP_EOL);
        foreach ($tables as $table) {
          // get create table syntax
          if (($create_table = $this->get_create_table_str($table)) !== false) {
            // run drop table if table exists
            $drop_string = "DROP TABLE IF EXISTS `{$table}`";
            $this->add_to_file($db_file, $drop_string . ';' . PHP_EOL);
            // run create table
            $this->add_to_file($db_file, $create_table . ';' . PHP_EOL . PHP_EOL);
            // if table has data, run insert data
            $insert_data = $this->insert_data($table);
            if ($insert_data) {
              $this->add_to_file($db_file, $insert_data . ';' . PHP_EOL . PHP_EOL);
            }
          }
        }
        // after all close file
        fclose($db_file);

        return $file_to_save_database_data;
      } else {
        throw new \Exception("Unable open database sql file");
      }

    }


    /**
     * @param $table_name
     *
     * @return bool|string
     */
    private function insert_data($table_name)
    {
      // get table rows
      $table_data = $this->wpdb->get_results("SELECT * FROM `{$table_name}`", ARRAY_A);
      $columns = $this->get_table_structure($table_name);
      if (!empty($table_data)) {
        // generate insertion string
        $insert_rows = array();
        foreach ($table_data as $table_row) {
          $insert_values = array();
          foreach ($table_row as $field_name => $field_value) {
            if (empty($field_value)) {
              if ($columns[$field_name]["Null"] != "NO") {
                $insert_values[$field_name] = 'NULL';
              } else {
                if (strpos(strtolower($columns[$field_name]["Type"]), "int") !== false || $field_value === '0' ) {
                  $insert_values[$field_name] = '0';
                } else {
                  $insert_values[$field_name] = "''";
                }
              }
            } else {
              $insert_values[$field_name] = "'" . addslashes($field_value) . "'";
            }
          }
          $insert_values = "(" . implode(",", array_values($insert_values)) . ")";
          array_push($insert_rows, $insert_values);
        }

        if (count($insert_rows) > 0) {

          $insert_data = "INSERT INTO `{$table_name}` (" . implode(",", $this->get_table_columns($columns)) . ") VALUES ";
          $insert_data .= implode(",", $insert_rows);

          return $insert_data;
        }

      }

      return false;
    }


    /**
     * @param $table_structure
     *
     * @return array
     */
    private function get_table_columns($table_structure)
    {
      $columns = array_keys($table_structure);
      $columns = array_map(function ($value) {
        return "`" . $value . "`";
      }, $columns);

      return $columns;
    }

    /**
     * @param $table_name
     *
     * @return array
     */
    private function get_table_structure($table_name)
    {
      $table_columns = array();
      $table_structure = $this->wpdb->get_results("DESCRIBE `{$table_name}`", ARRAY_A);

      foreach ($table_structure as $column) {
        $table_columns[$column["Field"]] = $column;
      }

      return $table_columns;
    }

    /**
     * @param $table_name
     *
     * @return mixed
     */
    private function get_create_table_str($table_name)
    {
      // get create table syntax
      $create_table = $this->wpdb->get_row("SHOW CREATE TABLE `{$table_name}`", ARRAY_N);

      return !empty($create_table[1]) ? $create_table[1] : false;
    }

    /**
     * @return array
     */
    private function get_tables()
    {
      $tables = array();
      $data = $this->wpdb->get_results("SHOW TABLES FROM `{$this->wpdb->dbname}`");
      if (!empty($data)) {
        $key = 'Tables_in_' . $this->wpdb->dbname;
        foreach ($data as $table) {
          if(strpos($table->$key, $this->wpdb->prefix) === 0){
            array_push($tables, $table->$key);
          }
        }
      }

      return $tables;
    }

    /**
     * @param $file
     * @param $data
     *
     * @throws \Exception
     */
    private function add_to_file($file, $data)
    {
      if (fwrite($file, $data . ';' . PHP_EOL) === false) {
        throw new \Exception("Unable write data to db file");
      }
    }
  }
}