MAX_HASHES_AT_A_TIME = 100
MAX_TO_BATCH_AT_A_TIME = 10
SLEEP_PERIOD = 5 # seconds

DEBUG = false

# general class to handle comparing and pushing data to the remote end
class UpdateAgent
  def initialize(data=nil)
    @attributes = []
    @data = []
    @create = []
    @update = []
    if data
      if data.is_a?(Array)
        @data = data
        @attributes = data.first.keys.sort
      else
        read_from_file(data)
      end
    end
    check_for_invalid_columns
  end
  
  def check_for_invalid_columns
    if invalid = @data.detect { |row| row['id'] }
      puts "Error: one or more records contain an 'id' column."
      puts "You must utilize 'legacy_id' rather than 'id' so that"
      puts "identity and foreign keys are maintained from your"
      puts "existing membership management database."
      exit
    end
  end
  
  # load data from csv file and do some type conversion for bools and dates
  # first row must be attribute names
  def read_from_file(filename)
    csv = FasterCSV.open(filename, 'r')
    @attributes = csv.shift
    record_count = 0
    @data = csv.map do |row|
      hash = {}
      row.each_with_index do |value, index|
        key = @attributes[index]
        next if IGNORE_ATTRIBUTES.include?(key)
        if DATETIME_ATTRIBUTES.include?(key)
          if value.blank?
            value = nil
          else
            begin
              value = DateTime.parse(value)
            rescue ArgumentError
              puts "Invalid date in #{filename} record #{index} (#{key}) - #{value}"
              exit(1)
            end
          end
        elsif BOOLEAN_ATTRIBUTES.include?(key)
          if value == '' or value == nil
            value = nil
          elsif %w(no false 0).include?(value.downcase)
            value = false
          else
            value = true
          end
        elsif INTEGER_ATTRIBUTES.include?(key)
          value = value.to_s != '' ? value.scan(/\d/).join.to_i : nil
        end
        hash[key] = value
      end
      record_count += 1
      print "reading record #{record_count}\r"
      hash
    end
    puts
    @attributes.reject! { |a| IGNORE_ATTRIBUTES.include?(a) }
  end
  
  def ids
    @data.map { |r| r['id'] }.compact
  end
  
  def legacy_ids
    @data.map { |r| r['legacy_id'] }.compact
  end

  def compare(force=false)
    compare_hashes(legacy_ids, force)
  end
  
  def has_work?
    (@create + @update).any?
  end

  def present
    puts "The following #{resource.name.downcase} records will be pushed..."
    puts 'legacy id  name'
    puts '---------- -------------------------------------'
    @create.each { |r| present_record(r, true) }
    @update.each { |r| present_record(r) }
    puts
  end
  
  def present_record(row, new=false)
    puts "#{row['legacy_id'].to_s.ljust(10)} #{name_for(row).to_s.ljust(40)} #{new ? '(new)' : '     '}"
    if DEBUG
      puts row.values_hash(@attributes)
      puts row['remote_hash']
    end
  end
  
  def confirm
    agree('Do you want to continue, pushing these records to OneBody? ')
  end
  
  # use ActiveResource to create/update records on remote end
  def push
    puts 'Updating remote end...'
    index = 0
    print "#{resource.name} 0/0\r"; STDOUT.flush
    (@create + @update).each_slice(MAX_TO_BATCH_AT_A_TIME) do |records|
      response = resource.post(:batch, {}, records.to_xml)
      statuses = Hash.from_xml(response.body)['records']
      statuses.select { |s| s['status'] == 'error' }.each do |status|
        puts "#{status['legacy_id']}: #{status['error']}"
      end
      index += records.length
      print "#{resource.name} #{index}/#{@create.length + @update.length}\r"; STDOUT.flush
      sleep SLEEP_PERIOD
    end
    puts
  end
  
  def data_by_id
    @data_by_id ||= begin
      by_id = {}
      @data.each { |r| by_id[r['legacy_id'].to_i] = r }
      by_id
    end
  end

  attr_accessor :attributes, :data
  attr_reader :update, :create
  
  class << self; attr_accessor :resource; end
  def resource; self.class.resource; end
  
  protected
  
  # ask remote end for value hashe for each record (50 at a time) 
  # mark records to create or update based on response
  def compare_hashes(ids, force=false)
    ids.each_slice(MAX_HASHES_AT_A_TIME) do |some_ids|
      print '.'; STDOUT.flush
      options = {:attrs => @attributes.join(','), :legacy_id => some_ids.join(',')}
      options.merge!(:debug => true) if DEBUG
      response = resource.post(:hashify, {}, options.to_xml)
      hashes = Hash.from_xml(response.body)['records']
      hashes.each do |record|
        row = data_by_id[record['legacy_id'].to_i]
        row['remote_hash'] = record['hash'] if DEBUG
        @update << row if force or row.values_hash(@attributes) != record['hash']
      end
      @create += some_ids.reject { |id| hashes.map { |h| h['legacy_id'].to_i }.include?(id.to_i) }.map { |id| data_by_id[id.to_i] }
      sleep SLEEP_PERIOD
    end
    puts
  end
end