require 'rubygems'
require 'treetop'
require 'date'

require "#{ File.dirname __FILE__ }/eventual/syntax_nodes"

autoload :EsDatesParser, 'eventual/es'

module Eventual
  # Parses dates specified in natural language and returns an Eventual::Node object
  #     Eventual.parse( 'del 5 al 7 de junio del 2009' ).map
  #     => [#<DateTime: 4909975/2,0,2299161>, #<DateTime: 4909977/2,0,2299161>, #<DateTime: 4909979/2,0,2299161
  #
  # Options:
  # +:lang+: 
  #   Defaults to 'Es', the language to be used for parsing, currently only spanish is supported, hang on.
  # +:default_year+: 
  #   The default year to be used in case year is not specified in the text, defaults to current year
  # +:default_event_span+: 
  #   The duration in minutes an event has, defaults to 60
  # 
  def self.parse text, opts = {}
    lang    = opts.delete(:lang) || 'Es'
    year    = opts.delete(:default_year)
    span    = opts.delete(:default_event_span)
    
    raise ArgumentError, "Expected option `:default_year` to be an integer"        if year && !(Integer === year)
    raise ArgumentError, "Expected option `:default_event_span` to be an integer"  if span && !(Integer === span)
    
    parser = const_get("#{ lang.to_s[0..1].capitalize }DatesParser") rescue raise( NotImplementedError.new("Parsing has not yet been implemented for the language '#{lang}'"))
    node   = parser.new.parse(text) 

    node.year      = year if year
    node.time_span = span if span
    node
  end
end