require 'smarter_dates/version'
require 'chronic'

module SmarterDates
  def self.included(klass) # :nodoc:
    bootstrap_smarter_dates(klass)

    @dt_attributes.each do |meth|
      klass.send(:define_method, "#{meth}=".to_sym, convert_to_dt(meth))
    end
  end

  # :call-seq:
  # Module.convert_to_dt method
  #
  # attempts to convert using Chronic, DateTime and-or Date, whichever works first
  # else simply yield the value

  def self.convert_to_dt(convert_me)
    Proc.new do |val|
      dt = val.respond_to?(:to_chronic_datetime) ? val.to_chronic_datetime : val
      if defined?(Rails)
        set_rails_dt_attributes!(convert_me, dt)
      else
        instance_variable_set(:"@#{convert_me}", dt)
      end
    end
  end

  private

  # :call-seq:
  # Module.dt_attributes Klass
  #
  # Any attribute ending in _at, _on, _dt, or _d are parsed by Chronic.parse
  # (for flexibility).  Values are passed as is to Chronic.parse()
  #
  # == Arguments
  # <tt>string</tt>:: A string

  def self.dt_attributes(klass)
    klass.instance_methods.select { |meth| meth.match(/_(?:at|on|dt|d)$/) }
  end

  def self.connected? # :nodoc:
    ActiveRecord::Base.connected?
  end

  def self.migrated? # :nodoc:
    return unless connected?
    ActiveRecord::Base.connection.table_exists? 'schema'
  end

  # :call-seq:
  # Module.rails_dt_attributes Klass
  #
  # Any attribute ending in _at, _on, _dt, or _d are parsed by Chronic.parse
  # (for flexibility).  Values are passed as is to Chronic.parse()
  #
  # == Arguments
  # <tt>string</tt>:: A string

  def self.rails_dt_attributes(klass)
    dt_attrs = []
    logger = Rails.logger
    begin
      dt_attrs = klass.column_names.select { |meth| meth.match(/_(?:at|on|dt|d)$/) }
      logger.debug(RuntimeError, "unused include - #{self.class.to_s} does not have any attributes ending in _at, _on, _dt, or _d") if migrated? && dt_attrs.empty?
    rescue ActiveRecord::StatementInvalid => _
    end
    dt_attrs.uniq
  end

  # :call-seq:
  # Module.set_rails_dt_attributes! attribute, value
  #
  # set attribute ending in _at, _on, _dt, or _d to date datetime
  #
  # == Arguments
  # <tt>attribute</tt>:: attribute to set
  # <tt>value</tt>:: a value

  def set_rails_dt_attributes!(meth,dt)
    if dt && meth.match(/_(?:on|d)$/)
      write_attribute meth, dt.to_date
    elsif dt && meth.match(/_(?:at|dt)$/)
      write_attribute meth, dt.to_datetime
    else
      write_attribute meth, dt
    end
  end

  # :call-seq:
  # Module.bootstrap_smarter_dates class
  #
  # Any attribute ending in _at, _on, _dt, or _d are parsed by Chronic.parse
  # (for flexibility).  Values are passed as is to Chronic.parse()
  #
  # == Arguments
  # <tt>class</tt>:: A class to have chronically-parsed dates

  def self.bootstrap_smarter_dates(klass)
    @dt_attributes = []
    if defined?(Rails)
      @dt_attributes.concat(rails_dt_attributes(klass))
    else
      @dt_attributes.concat(dt_attributes(klass))
    end
  end

end