require 'tempfile'
require 'time'

module Redwood

class MessageFormatError < StandardError; end

## a Message is what's threaded.
##
## it is also where the parsing for quotes and signatures is done, but
## that should be moved out to a separate class at some point (because
## i would like, for example, to be able to add in a ruby-talk
## specific module that would detect and link to /ruby-talk:\d+/
## sequences in the text of an email. (how sweet would that be?)
##
## TODO: integrate with user's addressbook to render names
## appropriately.
class Message
  SNIPPET_LEN = 80
  RE_PATTERN = /^((re|re[\[\(]\d[\]\)]):\s*)+/i
    
  ## some utility methods
  class << self
    def normalize_subj s; s.gsub(RE_PATTERN, ""); end
    def subj_is_reply? s; s =~ RE_PATTERN; end
    def reify_subj s; subj_is_reply?(s) ? s : "Re: " + s; end
  end

  class Attachment
    attr_reader :content_type, :desc
    def initialize content_type, desc, part
      @content_type = content_type
      @desc = desc
      @part = part
      @file = nil
    end

    def view!
      unless @file
        @file = Tempfile.new "redwood.attachment"
        @file.print @part.decode
        @file.close
      end

      ## TODO: handle unknown mime-types
      system "/usr/bin/run-mailcap --action=view #{@content_type}:#{@file.path}"
    end
  end

  class Text
    attr_reader :lines
    def initialize lines
      ## do some wrapping
      @lines = lines.map { |l| l.wrap 80 }.flatten
    end
  end

  class Quote
    attr_reader :lines
    def initialize lines
      @lines = lines
    end
  end

  class Signature
    attr_reader :lines
    def initialize lines
      @lines = lines
    end
  end

  QUOTE_PATTERN = /^\s{0,4}[>|\}]/
  BLOCK_QUOTE_PATTERN = /^-----\s*Original Message\s*----+$/
  QUOTE_START_PATTERN = /(^\s*Excerpts from)|(^\s*In message )|(^\s*In article )|(^\s*Quoting )|((wrote|writes|said|says)\s*:\s*$)/
  SIG_PATTERN = /(^-- ?$)|(^\s*----------+\s*$)|(^\s*_________+\s*$)/
  SIG_DISTANCE = 15 # lines from the end
  DEFAULT_SUBJECT = "(missing subject)"
  DEFAULT_SENDER = "(missing sender)"

  attr_reader :id, :date, :from, :subj, :refs, :replytos, :to, :source,
              :cc, :bcc, :labels, :list_address, :recipient_email, :replyto,
              :source_info, :mbox_status

  bool_reader :dirty

  def initialize source, source_info, labels, snippet=nil
    @source = source
    @source_info = source_info
    @dirty = false
    @snippet = snippet
    @labels = labels

    header = @source.load_header @source_info
    header.each { |k, v| header[k.downcase] = v }

    %w(message-id date).each do |f|
      raise MessageFormatError, "no #{f} field in header #{header.inspect} (source #@source offset #@source_info)" unless header.include? f
      raise MessageFormatError, "nil #{f} field in header #{header.inspect} (source #@source offset #@source_info)" unless header[f]
    end

    begin
      @date = Time.parse header["date"]
    rescue ArgumentError => e
      raise MessageFormatError, "unparsable date #{header['date']}: #{e.message}"
    end

    if(@subj = header["subject"])
      @subj = @subj.gsub(/\s+/, " ").gsub(/\s+$/, "")
    else
      @subj = DEFAULT_SUBJECT
    end
    @from = Person.for header["from"]
    @to = Person.for_several header["to"]
    @cc = Person.for_several header["cc"]
    @bcc = Person.for_several header["bcc"]
    @id = header["message-id"]
    @refs = (header["references"] || "").scan(/<(.*?)>/).flatten
    @replytos = (header["in-reply-to"] || "").scan(/<(.*?)>/).flatten
    @replyto = Person.for header["reply-to"]
    @list_address =
      if header["list-post"]
        @list_address = Person.for header["list-post"].gsub(/^<mailto:|>$/, "")
      else
        nil
      end

    @recipient_email = header["delivered-to"]
    @mbox_status = header["status"]
  end

  def snippet
    to_chunks unless @snippet
    @snippet
  end

  def is_list_message?; !@list_address.nil?; end
  def is_draft?; DraftLoader === @source; end
  def draft_filename
    raise "not a draft" unless is_draft?
    @source.fn_for_offset @source_info
  end

  def save index
    index.update_message self if @dirty
    @dirty = false
  end

  def has_label? t; @labels.member? t; end
  def add_label t
    return if @labels.member? t
    @labels.push t
    @dirty = true
  end
  def remove_label t
    return unless @labels.member? t
    @labels.delete t
    @dirty = true
  end

  def recipients
    @to + @cc + @bcc
  end

  def labels= l
    @labels = l
    @dirty = true
  end

  def to_chunks
    m = @source.load_message @source_info
    message_to_chunks m
  end

  def header_text
    @source.load_header_text @source_info
  end

  def content
    [
      from && from.longname,
      to.map { |p| p.longname },
      cc.map { |p| p.longname },
      bcc.map { |p| p.longname },
      to_chunks.select { |c| c.is_a? Text }.map { |c| c.lines },
      subj,
    ].flatten.compact.join " "
  end

  def basic_body_lines
    to_chunks.find_all { |c| c.is_a?(Text) || c.is_a?(Quote) }.map { |c| c.lines }.flatten
  end

  def basic_header_lines
    ["From: #{@from.full_address}"] +
      (@to.empty? ? [] : ["To: " + @to.map { |p| p.full_address }.join(", ")]) +
      (@cc.empty? ? [] : ["Cc: " + @cc.map { |p| p.full_address }.join(", ")]) +
      (@bcc.empty? ? [] : ["Bcc: " + @bcc.map { |p| p.full_address }.join(", ")]) +
      ["Date: #{@date.rfc822}",
       "Subject: #{@subj}"]
  end

private

  ## everything RubyMail-specific goes here.
  def message_to_chunks m
    ret = [] <<
      case m.header.content_type
      when "text/plain", nil
        raise MessageFormatError, "no message body before decode" unless
          m.body
        body = m.decode or raise MessageFormatError, "no message body"
        text_to_chunks body.gsub(/\t/, "    ").gsub(/\r/, "").split("\n")
      when "multipart/alternative", "multipart/mixed"
        nil
      else
        disp = m.header["Content-Disposition"] || ""
        Attachment.new m.header.content_type, disp.gsub(/[\s\n]+/, " "), m
      end
    
    m.each_part { |p| ret << message_to_chunks(p) } if m.multipart?
    ret.compact.flatten
  end

  ## parse the lines of text into chunk objects.  the heuristics here
  ## need tweaking in some nice manner. TODO: move these heuristics
  ## into the classes themselves.

  def text_to_chunks lines
    state = :text # one of :text, :quote, or :sig
    chunks = []
    chunk_lines = []

    lines.each_with_index do |line, i|
      nextline = lines[(i + 1) ... lines.length].find { |l| l !~ /^\s*$/ } # skip blank lines
      case state
      when :text
        newstate = nil
        if line =~ QUOTE_PATTERN || (line =~ QUOTE_START_PATTERN && (nextline =~ QUOTE_PATTERN || nextline =~ QUOTE_START_PATTERN))
          newstate = :quote
        elsif line =~ SIG_PATTERN && (lines.length - i) < SIG_DISTANCE
          newstate = :sig
        elsif line =~ BLOCK_QUOTE_PATTERN
          newstate = :block_quote
        end
        if newstate
          chunks << Text.new(chunk_lines) unless chunk_lines.empty?
          chunk_lines = [line]
          state = newstate
        else
          chunk_lines << line
        end
      when :quote
        newstate = nil
        if line =~ QUOTE_PATTERN || line =~ QUOTE_START_PATTERN || line =~ /^\s*$/
          chunk_lines << line
        elsif line =~ SIG_PATTERN && (lines.length - i) < SIG_DISTANCE
          newstate = :sig
        else
          newstate = :text
        end
        if newstate
          if chunk_lines.empty?
            # nothing
          elsif chunk_lines.size == 1
            chunks << Text.new(chunk_lines) # forget about one-line quotes
          else
            chunks << Quote.new(chunk_lines)
          end
          chunk_lines = [line]
          state = newstate
        end
      when :block_quote
        chunk_lines << line
      when :sig
        chunk_lines << line
      end
 
      if state == :text && (@snippet.nil? || @snippet.length < SNIPPET_LEN) &&
          line !~ /[=\*#_-]{3,}/ && line !~ /^\s*$/
        @snippet = (@snippet ? @snippet + " " : "") + line.gsub(/^\s+/, "").gsub(/[\r\n]/, "").gsub(/\s+/, " ")
        @snippet = @snippet[0 ... SNIPPET_LEN]
      end
#      if @snippet.nil? && state == :text && (line.length > 40 ||
#                                             line =~ /\S+.*[^,!:]\s*$/)
#        @snippet = line.gsub(/^\s+/, "").gsub(/[\r\n]/, "")[0 .. 80]
#      end
    end

    ## final object
    case state
    when :quote, :block_quote
      chunks << Quote.new(chunk_lines) unless chunk_lines.empty?
    when :text
      chunks << Text.new(chunk_lines) unless chunk_lines.empty?
    when :sig
      chunks << Signature.new(chunk_lines) unless chunk_lines.empty?
    end
    chunks
  end
end

end