#!/usr/bin/env ruby
#
#	Rpdf2txt -- PDF to Text Parser
#	Copyright (C) 2003 Andreas Schrafl, Hannes Wyss
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
#
#	ywesee - intellectual capital connected, Winterthurerstrasse 52, CH-8006 Zürich, Switzerland
#	hwyss@ywesee.com,	aschrafl@ywesee.com
#
# TextState -- Rpdf2txt -- 29.11.2002 -- asschrafl@ywesee.com

module Rpdf2txt
  class PositionedElement
		USER_SPACE = 1000.0
    attr_accessor :media_box, :tmalpha, :tmbeta
    def fire_callbacks(previous_positioned_element, callback_handler)
    end
    def set_x(x)
      @tmx = @dtmx = 0
      @tmxoffset = x.to_f
    end
    def set_xscale(xscale)
      @tmxscale = (xscale.to_f * USER_SPACE).round.to_f / USER_SPACE
    end
    def set_y(y)
      @tmy = 0
      @tmyoffset = y.to_f
    end
    def set_yscale(yscale)
      @tmyscale = (yscale.to_f * USER_SPACE).round.to_f / USER_SPACE
    end
    def transformation_matrix=(tm)
      ### This shouldn't happen, but we do have an example of
      ### it happening in 
      ### /Producer (Hyf PDF Output Library 2.2.3 \(Windows\))
      ### /Producer (Mac OS X 10.4.6 Quartz PDFContext)
      @cmxscale = (tm[0,0] * USER_SPACE).round.to_f / USER_SPACE
      @cmalpha = tm[0,1]
      @cmbeta = tm[1,0]
      @cmyscale = (tm[1,1] * USER_SPACE).round.to_f / USER_SPACE
      @cmxoffset = tm[2,0]
      @cmyoffset = tm[2,1]
    end
    def whitespace_overlap?(previous)
      false
    end
    def update!(rotation=0)
      orientation = (rotation.to_f.round / 90) % 2
      x, y, x2, y2, bx, by = nil
      if orientation == 1
        x = @tmxoffset + @tmy * @tmalpha
        y = @tmyoffset + (@tmx + @dtmx) * @tmbeta
        x2 = bx = x + @font_size * @tmalpha
        y2 = y + @w * @tmbeta
        by = y + @boxwidth * @tmbeta
        @x = y + @cmxoffset
        @y = x + @cmyoffset
        @x2 = y2 + @cmxoffset
        @y2 = x2 + @cmyoffset
        @right_edge = by + @cmxoffset
      else
        x = @tmxoffset + (@tmx + @dtmx) * @tmxscale
        y = @tmyoffset - @tmy * @tmyscale
        x2 = x + @w * @tmxscale
        y2 = by = y - @font_size * @tmyscale
        bx = x + @boxwidth * @tmxscale
        @x = x + @cmxoffset
        @y = y + @cmyoffset
        @x2 = x2 + @cmxoffset
        @y2 = y2 + @cmyoffset
        @right_edge = bx + @cmxoffset
      end
    end
    def <=> (other)
      if(same_line(other))
        @x <=> other.x
      elsif(other.is_a?(self.class))
        # @cmyscale may be negative, reversing the sort-order
        (@y <=> other.y) \
          * (@cmyscale == 0 ? 1 : @cmyscale)
      else
        @y <=> other.y
      end
    end
  end
	class TextState < PositionedElement
    UTF = /utf/in
		attr_accessor :font, :txt
		include Comparable
		attr_reader :y, :x, :x2, :y2, :w, :boxwidth, :xscale, :font_size, :yscale,
                :right_edge
		def initialize(target_encoding='utf8')
      @boxwidth = 0
			@x = @tmx = @dtmx = @tmxoffset = @cmxoffset = 0.0
			@y = @tmy = @tmyoffset = @cmyoffset = 0.0
			@w = 0.0
      @tmalpha = @cmalpha = 0.0
      @tmbeta = @cmbeta = 0.0
			@tmxscale = @cmxscale = 1.0
			@tmyscale = @cmyscale = 1.0
			@lead = nil
			@font = nil
			@font_size = 1
			@char_spacing = 0
			@word_spacing = 0
			@target_encoding = target_encoding + '//TRANSLIT//IGNORE'
			self.transformation_matrix = Matrix[[1,0,0],[0,1,0],[0,0,1]]
		end
		def advance_x(kerning = 0)
			@dtmx += @w - kerning/USER_SPACE
		end
		def char_width(char)
			if(char.is_a? String)
				char = char[0]
			end
			w = 0.0
			if(@font && (width = @font.width(char)))
				w = width 
			elsif(@font && (avg = @font.attributes[:avgwidth]))
				w = avg
			end
      w = 300.0 if w == 0
			w += @char_spacing
			if(char==32)
				w += @word_spacing
			end
			w * @font_size / USER_SPACE
		end
    def whitespace_overlap?(previous)
      previous && empty? && same_line(previous) \
        && previous.x2 >= (@x + (@x2 - @x) / 2)
    end
    def send_content(previous, callback_handler)
			if(previous)
				if(previous.font != @font)
					callback_handler.new_font(@font)
				end
				if(previous.font_height != self.font_height)
					callback_handler.new_fontsize(self.font_height)
				end
			else
				callback_handler.new_font(@font)
      end
      callback_handler.send_flowing_data(@txt)
    end
		def space_width
			w = 300.0
			if(@font && (width = @font.width(32)))
				w = width
			elsif(@font && (avg = @font.attributes[:avgwidth]))
				w = avg
			end
			w += @char_spacing
			w * @font_size / USER_SPACE
		end
		def fire_early_callbacks(previous, callback_handler)
			if(previous)
				if(!same_line(previous))
          callback_handler.send_line_break
				elsif(!same_word(previous))
					if(spaces = previous.count_spaces(@x - previous.x2))
						callback_handler.send_flowing_data(' '*spaces.abs)
					end
				end
				if(new_paragraph(previous))
					callback_handler.send_paragraph
				end
			end
		end
    def count_lines(displacement)
      (displacement / lead).abs.ceil
    rescue
      1
    end
    def count_spaces(displacement)
      x = space_width * @tmxscale + @font_size * @tmalpha
      y = @font_size * @tmyscale + space_width * @tmbeta
      width = x * @cmxscale + y * @cmalpha
      if(width.nonzero? && displacement > width)
        (displacement / width).round
      end
    rescue ZeroDivisionError
      warn "Ignoring Division by Zero: #{displacement.inspect}/#{width.inspect}"
    end
    def empty?
      @txt.nil? || @txt.strip.empty?
    end
		def lead
			@lead || -font_height * 1.2
		end
		def font_height
			@font_size
		end
		def new_paragraph(last_text_state)
			return false if(last_text_state.font_size.nil?)
			#1.5 is an approximate value
			spacing = last_text_state.font_height * 1.5
			last_y = last_text_state.y
			((last_y - @y).abs > spacing.abs)
		end
		def recode_txt(txt)
      enc = @font.encoding
      if(enc.is_a?(Encoding))
        # it would certainly be nice to do without all this iconving,
        # but since CMaps always contain utf8, and using utf16 in 
        # Symbol.from_* is so much more practical than dealing with 
        # variable-length utf8 encoding for the characters in the
        # Symbol font, we'll leave it at dtsttcpw for the moment.
        if(@font.symbol?)
          txt = enc.convert_symbol(txt)
          if(UTF.match(@target_encoding))
            @utf16_iconv ||= Iconv.new(@target_encoding.to_s, 'utf16be')
            txt = @utf16_iconv.iconv(Symbol.to_utf16(txt))
          end
        elsif(tu = @font.to_unicode)
          txt = tu.to_utf8(txt)
          if(UTF.match(@target_encoding))
            @utf8_iconv ||= Iconv.new(@target_encoding.to_s, 'utf8')
            txt = @utf8_iconv.iconv(txt)
          else
            @symbol_iconv ||= Iconv.new('utf16be', 'utf8')
            txt = Symbol.from_utf16(@symbol_iconv.iconv(txt))
          end
        end
        txt
      # FIXME: fix how encodings and Symbol font are handled
      elsif(UTF.match(enc) && !UTF.match(@target_encoding) && @font.symbol?) 
        @symbol_iconv ||= Iconv.new('utf16be', 'utf8')
        txt = Symbol.from_utf16(@symbol_iconv.iconv(txt))
      else
        @iconv ||= Iconv.new(@target_encoding.to_s, enc.to_s)
        @iconv.iconv(txt)
      end
    rescue NoMethodError, Iconv::InvalidEncoding, Iconv::IllegalSequence => e
      txt
		end
		def same_column(other)
			return false unless same_line(other)
			if(other.is_a?(TextState))
				testwidth = other.space_width * 2.0
				width = @x - other.right_edge
				width < testwidth
			else
				false
			end
		end
		def same_line(other)
			if(other.is_a?(TextState))
				sy1, sy2 = [@y, self.y2].sort
				oy1, oy2 = [other.y, other.y2].sort

        pair = [[sy1, sy2], [oy1, oy2]].sort
        overlap = pair[0][1] - pair[1][0]

        [sy2 - sy1, oy2 - oy1].any? { |height|
          # negative overlap means the lines don't touch
          overlap / height > 0.4
        }
			else
				false
			end
		end
		def same_word(other)
			return false unless same_line(other)
			if(other.is_a?(TextState))
				testwidth = other.space_width / 2.0
				width = @x - other.x2
				width < testwidth
			else
				false
			end
		end
		def set_font(font)
      @iconv = nil
			@font = font
		end
		def set_font_size(size)
			@font_size = size.to_f
		end
		def set_lead(lead)
			@lead = lead.to_f
		end
		def set_char_spacing(line)
			@char_spacing = line.to_f * USER_SPACE 
		end
		def set_txt(txt)
			#call the unescape_txt method,
			#so that \334 is replaced by char Ü
			#otherwise the calculation of the string width is wrong!!!!
			unescape_txt!(txt)
			@boxwidth = 0
      txt.rstrip.each_byte do |char|
        @boxwidth += char_width(char)
      end
      @w = @boxwidth
      if white = txt[/\s+$/u]
        white.each_byte do |char|
          @w += char_width(char)
        end
      end
			@txt = recode_txt(txt)
		end
		def set_word_spacing(word_spacing)
			@word_spacing = word_spacing.to_f * USER_SPACE 
		end
		def step
      @dtmx = 0
			@tmy -= lead
		end
		def update_x(x_val)
      @dtmx = 0
			@tmx += x_val.to_f
		end
		def update_y(y_val)
      @dtmx = 0
			@tmy -= y_val.to_f
		end
		def unescape_txt!(txt)
			txt.gsub!(/\\([0-9]{3})/n) { |match| $1.oct.chr }
		end
		protected 
		attr_writer :x
	end
  class NontextElement < PositionedElement
    attr_accessor :current_page
    attr_reader :x, :y, :x2, :y2, :text_state
    def initialize
      @x = @matrix_x = 0.0
      @y = 0.0
      @w = 0.0
      @cmxscale = @tmxscale = 1.0
      @cmyscale = @tmyscale = 1.0
      @xscale = 1.0
      @yscale = 1.0
      @space_width = -1
      super
    end
    def empty?
      false
    end
    def fire_early_callbacks(previous, callback_handler)
      if(previous)
        unless(same_line(previous))
          callback_handler.send_line_break
        end
        if(@font && previous.font != @font)
          callback_handler.new_font(@font)
        end
      end
    end
    def same_column(other)
      false
    end
    def text_state=(ts)
      @media_box = ts.media_box
      @font = ts.font
      @text_state = ts.dup
    end
    def method_missing(name, *args, &block)
      @text_state.send(name, *args, &block)
    end
  end
  class HorizontalRule < NontextElement
    alias :x2 :x
    alias :y2 :y
    def initialize(x, y, dm)
      super()
      self.transformation_matrix = dm
      set_x(x)
      set_y(y)
    end
    def send_content(previous, callback_handler)
      if(previous && !same_line(previous))
        callback_handler.send_hr
      end
    end
    def same_line(other)
      if(other.is_a?(HorizontalRule))
        (other.y - @y).abs < 10
      else
        false
      end
    end
    def <=> other
      if other.is_a?(HorizontalRule) && same_line(other)
        0
      else
        super
      end
    end
  end
  class ImagePlacement < NontextElement
    attr_reader :resource
    def initialize(resource, x, y, dm)
      super()
      case resource
      when InlineImage
        @xobject = resource
      else
        @resource = resource.downcase[1..-1].to_sym
      end
      self.transformation_matrix = dm
      @x = x
      @y = y - @cmyscale / 2
    end
    def image
      xobject.image
    end
    def same_line(other)
      @y == other.y
    end
    def send_content(previous, callback_handler)
      if img = xobject
        callback_handler.send_image self
      end
    end
    def xobject
      @xobject ||= @current_page.resources.xobject(@resource)
    end
  end
end