require 'trollop'
require 'mysql_backup/version'
require 'mysql_backup/backup_config'

module MysqlBackup
  class App
    def main

      opts = Trollop::options do
        version "mysql-backup #{MysqlBackup::VERSION} (c) 2015 @reednj"
        opt :config, "YAML config file", :type => :string
        opt :filename, "Name of backup output file", :type => :string
      end

      Dir.mkdir tmp_dir if !File.exist? tmp_dir
      @seed = (rand() * 10000).round.to_s

      begin
        config_path = opts[:config] || 'mysql-backup.conf'
        @config = BackupConfig.load_from config_path
      rescue => e
        puts "Error: Could not load config file at '#{config_path}' - #{e.message}"
        return
      end
      
      @output_file = opts[:filename] || "#{@config.database}.#{Date.today}.#{@seed}.sql.gz"
      self.create_backup

      @config.save_to.each do |path|
        begin
          self.save path
          puts File.join(path, filename)
        rescue => e
          puts "Could not save backup to #{path} - #{e.message}"
        end
      end

      self.clean
    end

    def create_backup
      password = ''
      password = "-p#{@config.password}" if @config.password?
      options = '--skip-comments'
      tables = @config.tables.join ' '
      run! "mysqldump -u #{@config.username} #{password} --host=#{@config.server} #{options} #{@config.database} #{tables} | gzip > #{tmp_path}"
    end

    def save(to_dir)
      if _remote_path? to_dir
        dest = File.join(to_dir, filename)
        run! "scp #{tmp_path} #{dest}"
      else
        p = File.expand_path to_dir
        dest = File.join(p, filename)
        FileUtils.copy tmp_path, dest
      end
    end

    def clean
      File.delete tmp_path
    end

    def filename
      @output_file
    end

    def tmp_dir
      File.expand_path "~/.tmp/"
    end

    def tmp_path
      File.join tmp_dir, "mysql.#{@seed}.bak"
    end

    # runs a shell command in such a way that if it fails (according to the exit status)
    # and exception will be raised with the stderr output
    def run!(cmd)
      output = `(#{cmd}) 2>&1`
      raise "#{output}" if $?.exitstatus != 0
    end

    # is this path on a remote server? do we need to use scp to copy the backup there?
    def _remote_path?(path)
      # not exactly foolproof, but it will do for now
      path.include? ':'
    end
  end
end