require 'rexml/document'
require 'rexml/streamlistener'

module OhlohScm::Parsers
	class BazaarListener
		include REXML::StreamListener
		attr_accessor :callback

		def initialize(callback)
			@callback = callback
      @merge_commit = []
      @state = :none
      @authors = []
		end

		attr_accessor :text, :commit, :diff

		def tag_start(name, attrs)
      case name
      when 'log'
				@commit = Scm::Commit.new
				@commit.diffs = []
      when 'affected-files'
        @diffs = []
      when 'added', 'modified', 'removed', 'renamed'
        @action = name
        @state = :collect_files
      when 'file'
        @before_path = attrs['oldpath']
      when 'merge'
        # This is a merge commit, save it and pop it after all branch commits
        @merge_commit.push(@commit)
      when 'authors'
        @state = :collect_authors
        @authors = []
			end
		end

		def tag_end(name)
			case name
			when 'log'
				@callback.call(@commit)
      when 'revisionid'
        @commit.token = @text
      when 'message'
        @commit.message = @cdata
			when 'committer'
        committer = BzrXmlParser.capture_name(@text)
				@commit.committer_name = committer[0]
				@commit.committer_email = committer[1]
			when 'author'
        author = BzrXmlParser.capture_name(@text)
				@authors << {:author_name => author[0], :author_email => author[1]}
			when 'timestamp'
				@commit.committer_date = Time.parse(@text)
      when 'file'
        if @state == :collect_files
          @diffs.concat(parse_diff(@action, @text, @before_path))
        end
        @before_path = nil
        @text = nil
      when 'added', 'modified', 'removed', 'renamed'
        @state = :none
      when 'affected-files'
			  @commit.diffs = remove_dupes(@diffs)
      when 'merge'
        @commit = @merge_commit.pop
      when 'authors'
        @commit.author_name = @authors[0][:author_name]
        @commit.author_email = @authors[0][:author_email]
        @authors.clear
			end
		end

    def cdata(data)
      @cdata = data
    end

		def text(text)
			@text = text
		end

    private
    # Parse one single diff
    def parse_diff(action, path, before_path)
      diffs = []
      case action
        # A rename action requires two diffs: one to remove the old filename,
        # another to add the new filename.
        #   
        # Note that is possible to be renamed to the empty string!
        # This happens when a subdirectory is moved to become the root.
      when 'renamed'
        diffs = [ Scm::Diff.new(:action => 'D', :path => before_path),
                  Scm::Diff.new(:action => 'A', :path => path || '')]
      when 'added'
        diffs = [Scm::Diff.new(:action => 'A', :path => path)]
      when 'modified'
        diffs = [Scm::Diff.new(:action => 'M', :path => path)]
      when 'removed'
        diffs = [Scm::Diff.new(:action => 'D', :path => path)]
      end
      diffs.each do |d|
        d.path = strip_trailing_asterisk(d.path)
      end
      diffs
    end

    def strip_trailing_asterisk(path)
      path[-1..-1] == '*' ? path[0..-2] : path
    end 

    def remove_dupes(diffs)
      BzrXmlParser.remove_dupes(diffs)
    end 

	end

	class BzrXmlParser < Parser
    NAME_REGEX = /^(.+?)(\s+<(.+)>\s*)?$/
		def self.internal_parse(buffer, opts)
			buffer = '<?xml?>' if buffer.is_a?(StringIO) and buffer.length < 2
			begin
				REXML::Document.parse_stream(buffer, BazaarListener.new(Proc.new { |c| yield c if block_given? }))
			rescue EOFError
			end
		end

		def self.scm
			'bzr'
		end

    def self.remove_dupes(diffs)
      # Bazaar may report that a file was added and modified in a single commit.
      # Reduce these cases to a single 'A' action.
      diffs.delete_if do |d| 
        d.action == 'M' && diffs.select { |x| x.path == d.path && x.action == 'A' }.any?
      end 

      # Bazaar may report that a file was both deleted and added in a single commit.
      # Reduce these cases to a single 'M' action.
      diffs.each do |d| 
        d.action = 'M' if diffs.select { |x| x.path == d.path }.size > 1 
      end.uniq
    end

    # Bazaar expects committer/author to be specified in this format
    # Name <email>, or John Doe <jdoe@example.com>
    # However, we find many variations in the real world including
    # ones where only email is specified as name.
    def self.capture_name(text)
      parts = text.match(NAME_REGEX).to_a
      name = parts[1] || parts[0]
      email = parts[3]
      [name, email]
    end
	end
end