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# Redmine - project management software

# Copyright (C) 2006-2011  Jean-Philippe Lang

#

# This program is free software; you can redistribute it and/or

# modify it under the terms of the GNU General Public License

# as published by the Free Software Foundation; either version 2

# of the License, or (at your option) any later version.

#

# This program 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 General Public License for more details.

#

# You should have received a copy of the GNU General Public License

# along with this program; if not, write to the Free Software

# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

module Redmine

  # Class used to parse unified diffs

  class UnifiedDiff < Array

    attr_reader :diff_type

    def initialize(diff, options={})

      options.assert_valid_keys(:type, :max_lines)

      diff = diff.split("\n") if diff.is_a?(String)

      @diff_type = options[:type] || 'inline'

      lines = 0

      @truncated = false

      diff_table = DiffTable.new(@diff_type)

      diff.each do |line|

        line_encoding = nil

        if line.respond_to?(:force_encoding)

          line_encoding = line.encoding

          # TODO: UTF-16 and Japanese CP932 which is imcompatible with ASCII

          #       In Japan, diffrence between file path encoding

          #       and file contents encoding is popular.

          line.force_encoding('ASCII-8BIT')

        end

        unless diff_table.add_line line

          line.force_encoding(line_encoding) if line_encoding

          self << diff_table if diff_table.length > 0

          diff_table = DiffTable.new(diff_type)

        end

        lines += 1

        if options[:max_lines] && lines > options[:max_lines]

          @truncated = true

          break

        end

      end

      self << diff_table unless diff_table.empty?

      self

    end

    def truncated?; @truncated; end

  end

  # Class that represents a file diff

  class DiffTable < Array

    attr_reader :file_name

    # Initialize with a Diff file and the type of Diff View

    # The type view must be inline or sbs (side_by_side)

    def initialize(type="inline")

      @parsing = false

      @added = 0

      @removed = 0

      @type = type

    end

    # Function for add a line of this Diff

    # Returns false when the diff ends

    def add_line(line)

      unless @parsing

        if line =~ /^(---|\+\+\+) (.*)$/

          @file_name = $2

        elsif line =~ /^@@ (\+|\-)(\d+)(,\d+)? (\+|\-)(\d+)(,\d+)? @@/

          @line_num_l = $2.to_i

          @line_num_r = $5.to_i

          @parsing = true

        end

      else

        if line =~ /^[^\+\-\s@\\]/

          @parsing = false

          return false

        elsif line =~ /^@@ (\+|\-)(\d+)(,\d+)? (\+|\-)(\d+)(,\d+)? @@/

          @line_num_l = $2.to_i

          @line_num_r = $5.to_i

        else

          parse_line(line, @type)

        end

      end

      return true

    end

    def each_line

      prev_line_left, prev_line_right = nil, nil

      each do |line|

        spacing = prev_line_left && prev_line_right && (line.nb_line_left != prev_line_left+1) && (line.nb_line_right != prev_line_right+1)

        yield spacing, line

        prev_line_left = line.nb_line_left.to_i if line.nb_line_left.to_i > 0

        prev_line_right = line.nb_line_right.to_i if line.nb_line_right.to_i > 0

      end

    end

    def inspect

      puts '### DIFF TABLE ###'

      puts "file : #{file_name}"

      self.each do |d|

        d.inspect

      end

    end

    private

    # Escape the HTML for the diff

    def escapeHTML(line)

        CGI.escapeHTML(line)

    end

    def diff_for_added_line

      if @type == 'sbs' && @removed > 0 && @added < @removed

        self[-(@removed - @added)]

      else

        diff = Diff.new

        self << diff

        diff

      end

    end

    def parse_line(line, type="inline")

      if line[0, 1] == "+"

        diff = diff_for_added_line

        diff.line_right = escapeHTML line[1..-1]

        diff.nb_line_right = @line_num_r

        diff.type_diff_right = 'diff_in'

        @line_num_r += 1

        @added += 1

        true

      elsif line[0, 1] == "-"

        diff = Diff.new

        diff.line_left = escapeHTML line[1..-1]

        diff.nb_line_left = @line_num_l

        diff.type_diff_left = 'diff_out'

        self << diff

        @line_num_l += 1

        @removed += 1

        true

      else

        write_offsets

        if line[0, 1] =~ /\s/

          diff = Diff.new

          diff.line_right = escapeHTML line[1..-1]

          diff.nb_line_right = @line_num_r

          diff.line_left = escapeHTML line[1..-1]

          diff.nb_line_left = @line_num_l

          self << diff

          @line_num_l += 1

          @line_num_r += 1

          true

        elsif line[0, 1] = "\\"

          true

        else

          false

        end

      end

    end

    def write_offsets

      if @added > 0 && @added == @removed

        @added.times do |i|

          line = self[-(1 + i)]

          removed = (@type == 'sbs') ? line : self[-(1 + @added + i)]

          offsets = offsets(removed.line_left, line.line_right)

          removed.offsets = line.offsets = offsets

        end

      end

      @added = 0

      @removed = 0

    end

    def offsets(line_left, line_right)

      if line_left.present? && line_right.present? && line_left != line_right

        max = [line_left.size, line_right.size].min

        starting = 0

        while starting < max && line_left[starting] == line_right[starting]

          starting += 1

        end

        ending = -1

        while ending >= -(max - starting) && line_left[ending] == line_right[ending]

          ending -= 1

        end

        unless starting == 0 && ending == -1

          [starting, ending]

        end

      end

    end

  end

  # A line of diff

  class Diff

    attr_accessor :nb_line_left

    attr_accessor :line_left

    attr_accessor :nb_line_right

    attr_accessor :line_right

    attr_accessor :type_diff_right

    attr_accessor :type_diff_left

    attr_accessor :offsets

    def initialize()

      self.nb_line_left = ''

      self.nb_line_right = ''

      self.line_left = ''

      self.line_right = ''

      self.type_diff_right = ''

      self.type_diff_left = ''

    end

    def type_diff

      type_diff_right == 'diff_in' ? type_diff_right : type_diff_left

    end

    def line

      type_diff_right == 'diff_in' ? line_right : line_left

    end

    def html_line_left

      if offsets

        line_left.dup.insert(offsets.first, '<span>').insert(offsets.last, '</span>')

      else

        line_left

      end

    end

    def html_line_right

      if offsets

        line_right.dup.insert(offsets.first, '<span>').insert(offsets.last, '</span>')

      else

        line_right

      end

    end

    def html_line

      if offsets

        line.dup.insert(offsets.first, '<span>').insert(offsets.last, '</span>')

      else

        line

      end

    end

    def inspect

      puts '### Start Line Diff ###'

      puts self.nb_line_left

      puts self.line_left

      puts self.nb_line_right

      puts self.line_right

    end

  end

end