Class: EmailReplyTrimmer

Inherits:
Object
  • Object
show all
Defined in:
lib/email_reply_trimmer.rb

Constant Summary collapse

VERSION = 
"0.3.0"
DELIMITER = 
"d"
EMBEDDED = 
"b"
EMPTY = 
"e"
EMAIL_HEADER = 
"h"
QUOTE = 
"q"
SIGNATURE = 
"s"
TEXT = 
"t"

Class Method Summary collapse

Class Method Details

.compute_elided(text, lines) ⇒ Object 



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# File 'lib/email_reply_trimmer.rb', line 223

def self.compute_elided(text, lines)
  elided = []

  t = 0
  l = 0

  while t < text.size
    while l < lines.size && text[t] == lines[l]
      t += 1
      l += 1
    end
    elided << text[t]
    t += 1
  end

  elided.join("\n").strip
end

.extract_embedded_email(text) ⇒ Object 



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# File 'lib/email_reply_trimmer.rb', line 146

def self.extract_embedded_email(text)
  return if text.nil? || text =~ /\A[[:space:]]*\z/m

  # do some cleanup
  preprocess!(text)

  # from now on, we'll work on a line-by-line basis
  lines = text.split("\n")

  # identify content of each lines
  pattern = lines.map { |l| identify_line_content(l) }.join

  if index = pattern =~ /(?:h[eqd]*?){3,}[tq]/
    embedded = lines[index..-1].join("\n").strip
  elsif index = pattern =~ /b(?:[eqd]*){3,}[tq]/
    # Exception for email clients (macOS / iOS) which embed fwd emails in quotes.
    embedded = lines[index + 1..-1].map { |l| l.gsub(/^>\s*/, '') }.join("\n").strip
  end

  if index
    before = lines[0...(pattern[0...index] =~ /e*(b[eqd]*|b*[ed]*)$/)].join("\n").strip
    [embedded, before]
  end
end

.hoist_code_blocks(text) ⇒ Object 



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# File 'lib/email_reply_trimmer.rb', line 173

def self.hoist_code_blocks(text)
  blocks = {}
  pattern = /^```\w*$\n.*?^```$/m

  text.gsub!(pattern) do |block|
    token = SecureRandom.hex
    blocks[token] = block
    token
  end

  [text, blocks]
end

.identify_line_content(line) ⇒ Object 



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# File 'lib/email_reply_trimmer.rb', line 21

def self.identify_line_content(line)
  return EMPTY        if EmptyLineMatcher.match? line
  return DELIMITER    if DelimiterMatcher.match? line
  return SIGNATURE    if SignatureMatcher.match? line
  return EMBEDDED     if EmbeddedEmailMatcher.match? line
  return EMAIL_HEADER if EmailHeaderMatcher.match? line
  return QUOTE        if QuoteMatcher.match? line
  TEXT
end

.is_reply_at_end?(pattern) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/email_reply_trimmer.rb', line 241

def self.is_reply_at_end?(pattern)
  pattern =~ /^b[^t]+t[et]*$/
end

.preprocess!(text) ⇒ Object 



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# File 'lib/email_reply_trimmer.rb', line 186

def self.preprocess!(text)
  # normalize line endings
  text.gsub!("\r\n", "\n")

  # remove PGP markers
  text.gsub!(/\A-----BEGIN PGP SIGNED MESSAGE-----\n(?:Hash: \w+)?\s+/i, "")
  text.gsub!(/^-----BEGIN PGP SIGNATURE-----$[\s\S]+^-----END PGP SIGNATURE-----/, "")

  # remove unsubscribe links
  text.gsub!(/^Unsubscribe: .+@.+(\n.+http:.+)?\s*\z/i, "")

  # remove alias-style quotes marker
  text.gsub!(/^.*>{5} "[^"\n]+" == .+ writes:/, "")

  # change enclosed-style quotes format
  text.gsub!(/^>>> ?(.+) ?>>>$\n([\s\S]+?)\n^<<< ?\1 ?<<<$/) { $2.gsub(/^/, "> ") }
  text.gsub!(/^>{4,}[[:blank:]]*$\n([\s\S]+?)\n^<{4,}[[:blank:]]*$/) { $1.gsub(/^/, "> ") }

  # fix all quotes formats
  text.gsub!(/^((?:[[:blank:]]*[[:alpha:]]*[>|])+)/) { $1.gsub(/([[:alpha:]]+>|\|)/, ">") }

  # fix embedded email markers that might span over multiple lines
  (
    EmbeddedEmailMatcher::ON_DATE_SOMEONE_WROTE_REGEXES +
    EmbeddedEmailMatcher::SOMEONE_WROTE_ON_DATE_REGEXES +
    EmbeddedEmailMatcher::DATE_SOMEONE_WROTE_REGEXES +
    [EmbeddedEmailMatcher::DATE_SOMEONE_EMAIL_REGEX]
  ).each do |r|
    text.gsub!(r) do |m|
      m.count("\n") > 4 ? m : m.gsub(/\n+[[:space:]]*/, " ")
    end
  end

  # remove leading/trailing whitespaces
  text.strip!
end

.trim(text, split = false) ⇒ Object 



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# File 'lib/email_reply_trimmer.rb', line 31

def self.trim(text, split = false)
  return if text.nil? || text =~ /\A[[:space:]]*\z/m

  # do some cleanup
  preprocess!(text)

  # stash the code blocks - replace them with hashes
  text, blocks = hoist_code_blocks(text)

  # from now on, we'll work on a line-by-line basis
  lines = text.split("\n")
  lines_dup = lines.dup

  # create a string of characters, one per line, according to the line content
  pattern = lines.map { |l| identify_line_content(l) }.join

  # remove everything after the first delimiter
  if pattern =~ /d/
    index = pattern =~ /d/
    underscore_separator_before_embedded_email =
      lines[index] =~ /\A_+\z/ && pattern[(index + 1)..-1] =~ /b/

    unless underscore_separator_before_embedded_email
      pattern = pattern[0...index]
      lines = lines[0...index]
    end
  end

  # remove all mobile signatures
  while pattern =~ /s/
    index = pattern =~ /s/
    pattern.slice!(index)
    lines.slice!(index)
  end

  # when the reply is at the end of the email
  if is_reply_at_end?(pattern)
    index = pattern =~ /t[et]*$/
    pattern = ""
    lines = lines[index..-1]
  end

  # if there is an embedded email marker, not followed by a quote
  # then take everything up to that marker
  if pattern =~ /te*b[^q]*$/
    index = pattern =~ /te*b[^q]*$/
    pattern = pattern[0..index]
    lines = lines[0..index]
  end

  # if there is an embedded email marker, followed by a huge quote
  # then take everything up to that marker
  if pattern =~ /te*b[eqbh]*([te]*)$/ && $1.count("t") < 7 && pattern !~ /bq[eqbh]*t/
    index = pattern =~ /te*b[eqbh]*[te]*$/
    pattern = pattern[0..index]
    lines = lines[0..index]
  end

  # if there is some text before a huge quote ending the email,
  # then remove the quote
  if pattern =~ /t?e*[qbe]+$/
    index = pattern =~ /t?e*[qbe]+$/
    pattern = pattern[0..index]
    lines = lines[0..index]
  end

  # if there still are some embedded email markers, just remove them
  while pattern =~ /b/
    index = pattern =~ /b/
    pattern.slice!(index)
    lines.slice!(index)
  end

  # fix email headers when they span over multiple lines
  if pattern =~ /h+[hte]+h+e/
    index = pattern =~ /h+[hte]+h+e/
    size = pattern[/h+[hte]+h+e/].size
    size.times.each { |s| pattern[index + s] = EMAIL_HEADER }
  end

  # if there are at least 3 consecutive email headers,
  # take everything up to these headers
  if pattern =~ /t[eq]*h{3,}/
    index = pattern =~ /t[eq]*h{3,}/
    pattern = pattern[0..index]
    lines = lines[0..index]
  end

  # if there still are some email headers, just remove them
  while pattern =~ /h/
    index = pattern =~ /h/
    pattern.slice!(index)
    lines.slice!(index)
  end

  # remove trailing quotes when there's at least one line of text
  if pattern =~ /t/ && pattern =~ /[eq]+$/
    index = pattern =~ /[eq]+$/
    pattern = pattern[0...index]
    lines = lines[0...index]
  end

  # results
  trimmed = lines.join("\n").strip

  # re-inject code blocks
  blocks.each { |token, block| trimmed.gsub!(token, block) }

  if split
    [trimmed, compute_elided(lines_dup, lines)]
  else
    trimmed
  end
end