#!/usr/bin/env ruby
require 'mysql2'
require 'securerandom'
require 'date'

@mysql_username = 'root'
@mysql_password = 'root'
@mysql_port = 3306
@mysql_host = '1.1.1.1'
@database_name = 'foo_database'
@number_of_transactions = 1000
@number_of_transactions_for_extra = 5000000
@tables_for_extra_data=%w(foo_table1 foo_table2)
@exclude_tables=%w(foo_excluded_table1 foo_excluded_table2)
@batches = 500

def main
  con = Mysql2::Client.new(
    host: @mysql_host,
    username: @mysql_username,
    password: @mysql_password,
    port: @mysql_port
  )

  tables = con.query "SELECT table_name FROM information_schema.tables WHERE table_schema=\'#{@database_name}\'"

  tables.each do |r|
    table = r['table_name']
    p table
    next if @exclude_tables.include?(table)
    number_of_transactions = @number_of_transactions
    number_of_transactions = @number_of_transactions_for_extra if @tables_for_extra_data.include?(table)
    table_fields = con.query("DESCRIBE #{@database_name}.#{table}")
    table_sql = "INSERT INTO #{@database_name}.#{table} ("
    for i in 1..(number_of_transactions/@batches)
  sql = ''
  for j in 1..@batches
    field_list = value_list = ''
    table_fields.each do |field|
      next unless valid_field?(field)
      field_list += "`#{field['Field']}`,"
      value_list += "#{value_to_insert(field)},"
    end
    field_list.chop!
    value_list.chop!
    if j==1
      sql = table_sql + "#{field_list}) VALUES (#{value_list}) "
      break if number_of_transactions < @batches
    else
      sql += ", (#{value_list})"
    end
  end
  con.query(sql)
  p i*@batches
  cool_off(100000, 10) if (i*@batches)%100000 == 0
  cool_off(500000, 45) if (i*@batches)%500000 == 0
    end
  end
rescue StandardError => e
  puts e
ensure
  con.close if con
end

def cool_off(cycles, sleep_time = 30)
  p "Cool off for #{sleep_time} sec every #{cycles} cycles"
  sleep(sleep_time)
end

def valid_field?(field)
  field['Extra'] != 'auto_increment'
end

def value_to_insert(field)
  field_type = field['Type']
  if field_type.include?('tinyint')
    random_boolean
  elsif field_type.include?('decimal') || field_type.include?('int') || field_type.include?('float')
    precision = field_type.scan(/\(\d*/).join('')
    precision[0] = ''
    random_int(2**(precision.to_i - 1))
  elsif field_type.include?('date')
    random_date
  elsif field_type.include?('binary') || field_type.include?('char')
    random_string(field_type.scan(/\d/).join('').to_i)
  elsif field_type.include?('json')
    "'{\"foo\": \"bar\"}'"
  else
    random_string
  end
end

def random_int(max = 100_000_000)
  SecureRandom.random_number(max)
end

def random_boolean
  random_int(2)
end

def random_string(limit = 50)
  "'#{SecureRandom.hex.slice(0, limit)}'"
end

def random_date
  "'#{Time.at(Time.now.to_i - SecureRandom.random_number(1_000_000_000))
    .to_date}'"
end

main