#!/usr/bin/env ruby

require_relative './grammar.rb'
STDOUT.sync = true


class Chart

  def initialize n
    @m = []
    (n+1).times {
      _ = []
      (n+1).times { _ << [] }
      @m << _
    }
  end

  def at i, j
    @m[i][j]
  end

  def add r, i, j, right, dot=0
    item = Item.new(r)
    item.span.left = i
    item.span.right = right
    item.dot = dot
    at(i, j) << item
  end
end

class Span
  attr_accessor :left, :right

  def initialize left=nil, right=nil
    @left = left
    @right = right
  end
end

class Item < Rule
  attr_accessor :lhs, :rhs, :span, :dot

  def initialize rule_or_item
    @lhs = rule_or_item.lhs.dup
    @rhs = rule_or_item.rhs.dup
    if rule_or_item.class == Item
      @span = Span.new rule_or_item.span.left, rule_or_item.span.right
      @dot = rule_or_item.dot
    else
      @span = Span.new
    end
  end

  def to_s
    "#{lhs} -> #{rhs.map{|i|i.to_s}.insert(@dot,'*').join ' '} [dot@#{@dot}] [arity=#{arity}] (#{@span.left}, #{@span.right})"
  end
end

def visit n, depth, skip=0
  (depth-skip).times { |i|
    i += skip
    0.upto(n-(i+1)) { |j|
      yield j, j+i+1 if block_given?
    }
  }
end

def init active_chart, passive_chart, grammar, input, n
  # pre-fill passive chart w/ 0-arity rules
  grammar.rules.select { |r| r.rhs.first.class==T }.each { |r|
    input.each_index.select { |i| input[i].word==r.rhs.first.word }.each { |j|
      k = 1
      if r.rhs.size > 1
        z = r.rhs.index { |i| i.class==NT }
        if z
          z -= 1
        else
          z = r.rhs.size-1
        end
        if input[j..j+z].map { |i| i.word } == r.rhs[0..z].map { |i| i.word }
          k = z+1
        else
          next
        end
      end
      if k == r.rhs.size
        passive_chart.add(r, j, j+k, j+k, k)
      else
        (j+k).upto(n) { |l|  active_chart.add(r, j, l, j+k, k) }
      end
    }
  }
  # seed active chart
  s = grammar.rules.reject { |r| r.rhs.first.class!=NT }
  visit(n, n, 1) { |i,j|
    s.each { |r| active_chart.add(r, i, j, i) }
  }
end

def scan item, passive_chart, input, i, j
  while item.rhs[item.dot].class == T 
    if item.rhs[item.dot].word == input[item.span.left+item.dot].word
      item.dot += 1
      item.span.right = item.span.left+item.dot
      if item.dot == item.rhs.size
        passive_chart.add(item, i, j, item.span.left+item.dot, item.dot)
        break
      end
    else
      break
    end
  end
end

def parse i, j, sz, active_chart, passive_chart, g, input
  active_chart.at(i,j).each_with_index { |active_item,q|
    1.upto(sz) { |span|
      break if span==(j-i)
      i.upto(j-span) { |k|
        passive_chart.at(k, k+span).each { |passive_item|
          if active_item.rhs[active_item.dot].class==NT && passive_item.lhs.symbol == active_item.rhs[active_item.dot].symbol
            next if not active_item.span.right==passive_item.span.left
            new_item = Item.new active_item
            new_item.span.right = passive_item.span.right
            new_item.dot += 1
            scan new_item, passive_chart, input, i, j
            if new_item.dot == new_item.rhs.size
              passive_chart.at(i,j) << new_item
            else
              active_chart.at(i,j) << new_item
            end
          end
        }
      }
    }
  }
  # self-filling
  to_add_active = []
  to_add_passive = []
  passive_chart.at(i,j).each { |passive_item|
    active_chart.at(i,j).each { |active_item|
      if passive_item.lhs.symbol == active_item.rhs[active_item.dot].symbol
        new_item = Item.new active_item
        new_item.span.right = passive_item.span.right
        new_item.dot += 1
        scan new_item, passive_chart, input, i, j
        if new_item.dot == new_item.rhs.size
          to_add_passive << new_item
        else
          to_add_active << new_item
        end
      end
    }
  }
  to_add_active.each { |item| active_chart.at(i,j) << item }
  to_add_passive.each { |item| passive_chart.at(i,j) << item }
end

def preprocess s
  s.split.map { |i| T.new i }
end

def main
  #input = "ich sah ein kleines haus".split.map { |i| T.new i }
  input = preprocess "lebensmittel schuld an europäischer inflation"
  n = input.size

  puts "reading grammar .."
  g = Grammar.new 'grammar.x'

  puts "adding glue rules .."
  g.add_glue_rules

  #puts "adding pass-through rules .."
  #g.add_pass_through_rules input

  puts "initializing charts .."
  passive_chart = Chart.new n
  active_chart = Chart.new n
  init active_chart, passive_chart, g, input, n

  puts "parsing .."
  visit(n, n, 1) { |i,j| 
    parse i, j, n, active_chart, passive_chart, g, input
  }
  
  puts "---\npassive chart"
  visit(n, n, 0) { |i,j| puts "#{i},#{j}"; passive_chart.at(i,j).each { |item| puts ' '+item.to_s if item.span.left==i&&item.span.right==j }; puts }
end


main