#!/usr/bin/ruby 

=begin rdoc
This is a small helper script for keeping changelogs up to date.
It is copyright 2006 by Vincent Fourmond, and can be distributed under
the terms of the General Public License version 2.
=end


require 'tempfile'
# we need a decent parsing of command-line here...
# it is provided by optparse, which is quite cool...

require 'optparse'
require 'ostruct'
require 'etc'



# A class to describe and parse a changelog line
class CLLine
  # The text of the line:
  attr_accessor :line

  # The type of the line:
  # * :version (i.e. mkmf2 -- 0.1.2)
  # * :blank
  # * :name (describing the name [...])
  # * :entry ( starting with ' * ')
  # * :entry_cont (starting with enough blank space)
  # * :sig (signature)
  attr_accessor :kind

  # Hash that can be used to store interesting informations.
  attr_accessor :data

  def initialize(line = "")
    @line = line
    @data = {}
    
    # we parse the line here.
    case line
    when /^\s*(\w+)\s+\(\s*([\w.-]+)\s*\)\s*$/
      # this is a version line
      @kind = :version
      @data["package"] = $1
      @data["version"] = $2
    when /^\s+\*/
      @kind = :entry
    when /^\s*$/
      @kind = :blank
    when /^\s*\[\s*([^\]]+?)\s*\]/
      @kind = :name
      @data["name"] = $1
    when /\s*--\s*(.*?)\s*,\s*(.*?)\s*$/
      @kind = :sig
      @data["full name"] = $1
      @data["date"] = $2
      if @data["full name"] =~ /^(.*?)\s*<(.*)>/
        @data["name"] = $1
        @data["email"] = $2
      else
        # we take the email address for the name
        @data["name"] = @data["full name"]
      end
    when /^\s\s+\S+/
      @kind = :entry_cont
    end
  end

  # A small wrapper around the data structure...
  def [](str)
    return @data[str]
  end

  # Changes the current entry into a proper signature...
  def sign(email,date)
    @kind = :sig
    @line = " -- #{email}, #{date}"
    @data["full name"] = email
    @data["date"] = date.chomp
    if @data["full name"] =~ /^(.*?)\s*<(.*)>/
      @data["name"] = $1
      @data["email"] = $2
    else
      # we take the email address for the name
      @data["name"] = @data["full name"]
    end
  end

end

# An section consists of a version, entries and a signature
class CLSection
  # The CLLine object containing the version
  attr_accessor :version
  
  # The siganture
  attr_accessor :signature

  # The rest inbetween
  attr_accessor :entries

  # The names of the differents contributors. It is a hash where to a
  # name corresponds the CLLine object where it is found.
  attr_accessor :contributors
  
  # This function takes an array of CLLines, removes blank lines
  # then, takes everything between a version and a signature, removing them from
  # the array. You'd better make a copy of the array if you need it otherwise.
  def initialize(cllines)
    # Stripping trailing blank lines.
    while cllines[0] && cllines[0].kind == :blank
      cllines.shift
    end
    if cllines[0].kind != :version
      raise "Error parsing the changelog: version line expected"
    end
    @version = cllines.shift
    @entries = []
    @contributors = {}
    while cllines[0].kind != :sig
      @entries.push cllines.shift
      if @entries.last.kind == :name
        @contributors[@entries.last["name"]] = @entries.last
      end
    end
    @signature = cllines.shift
    # and removing all the blank lines after, to make sure nothing is left
    # in the array if it is the end of the changelog.

    while cllines[0] && cllines[0].kind == :blank
      cllines.shift
    end
  end
  
  # returns an array with the text lines of the section
  def lines
    lines = []
    lines << @version.line
    lines += @entries.collect { |e| 
      e.line
    }
    lines << @signature.line
  end

  # Returns the text for the section.
  def to_s
    return lines.join('')
  end

  def email_to_name(email)
    email =~ /^\s*(.*?)\s*<(.*)>/
    return $1
  end

  # returns the CLLine object corresponding to the last :entry of
  # a contributor. You need to provide it's short name
  def last_contributor_entry(name)
    if ! @contributors.key?(name)
      if name == sig_name
        return last_entry
      else
        return nil
      end
    end
    index = @entries.index(@contributors[name]) + 1
    last = nil
    while @entries[index] and @entries[index].kind == :blank
      last = @entries[index]
      index += 1
    end
    while @entries[index] and 
        (@entries[index].kind == :entry or 
        @entries[index].kind == :entry_cont)
      last = @entries[index]
      index += 1
    end
    
    # it can be the blank just after the name.
    return last
  end

  def last_entry
    entries = @entries.dup
    while a = entries.pop
      return a unless a.kind == :blank
    end
    return nil
  end

  def sig_name
    return @signature["name"]
  end

  # adds a contributor to the list, and make the corresponding entries
  def add_contributor(name)
    return if @contributors.key?(name)

    @contributors[name] = CLLine.new("  [#{name}]\n")
    
    # we add the contributor at the end:
    @entries.push @contributors[name]
    @entries.push CLLine.new("\n")
  end
    

  # This functions adds a new entry to the section, with the given
  # contributor name and returns an array containing:
  # * the line number where the entry was added
  # * an array containing the text lines
  #
  # The contributor name should include full email
  def add_entry(contributor, entry = "")
    # nil = ""
    if entry.nil?
      entry = ""
    end
    # we check if we need to add contributors name or not:
    name = email_to_name(contributor)
    new_entry = CLLine.new("  * #{entry}\n")
    if name != sig_name
      add_sig_name
      add_contributor(name)
    end
    last_entry_index = @entries.index(last_contributor_entry(name))
    # raise "Problem parsing the changelog ??" if last_entry_index.nil?
    # no, this is not right: we want to be able to deal with almost empty
    # Changelogs -- namely, the ones created by this very program ;-) !
    if last_entry_index.nil?
      last_entry_index = -1
      # we add an initial \n:
      new_entry.line = "\n#{new_entry.line}"
    end
    @entries[last_entry_index + 1, 0] = new_entry
    
    # last thing: we need to update the signature:
    @signature.sign(contributor, CLFile.date)
    return [@entries.index(new_entry) + 2, lines]
  end
  
  # Adds a name entry in the beginning with the name of the signature
  def add_sig_name
    return if @contributors.key?(sig_name)
    @contributors[sig_name] = 
      CLLine.new("  [#{sig_name}]\n")
    @entries.unshift @contributors[sig_name]
    @entries.unshift CLLine.new("\n")
  end

  # normalize makes sure that the entries start and end with a blank line, and
  # that there are never more than one blank line in a row
  def normalize
    # to be written...
  end
end

# The class describing the Changelog file.
class CLFile
  # The lines of the file
  attr_accessor :lines

  # The sections of the file
  attr_accessor :sections

  # returns the date in the wanted format...
  def CLFile.date
    return `date`
  end
  
  # file can be either an IO object or a file name.
  def initialize(file)
    if file.is_a? String
      file = File.open(file)
    end

    @lines = []
    for line in file
      @lines << CLLine.new(line)
    end
    @sections = []

    # we make a copy to feed it to CLSection
    lines = @lines.dup
    while lines.length > 0
      @sections.push CLSection.new(lines)
    end
  end
  
  def latest_version
    return @sections[0].version["version"]
  end

  # Creates a release of the given directory by parsing the changelog and
  # creating an appropriately named archive. The directory name will be
  # changed to match the _package_-_version_ convention.
  #
  # As is, it probably shouldn't be used directly, but rather through
  # a slightly more advanced interface.
  def CLFile.make_release(dir, changelog = "Changelog")
    base_dir = File.dirname(dir)
    
    ch = CLFile.new(File.join(dir, changelog))
    target_name = "#{ch.package_name}-#{ch.latest_version}"
    # First, we rename the directory to the correct name
    File.rename(dir, File.join(base_dir, target_name))
    # Then, we make an archive out of it:
    cmd = "cd #{base_dir}; tar cvzf #{target_name}.tar.gz #{target_name}"
    system cmd
    # and that's done !!!
    target_name
  end

  # This convenience function does the following:
  # * exports the given module from the given repository with the given tag
  # * looks for a Changelog file in it
  # * calls make_release
  # * and erases the exported directory

  def CLFile.cvs_release(mod, tag, rep = nil, changelog = "Changelog")
    # we first make up a temporary directory name...
    export_dir = "biniou-temp"
    cmd = "cvs " + if rep
                     " -d #{rep} "
                   else
                     ""
                   end +
      "export -d #{export_dir} -r #{tag} #{mod}"
    puts cmd
    system cmd
    tg = make_release(File.join(Dir::pwd, export_dir), 
                      changelog)
  end


  # Increases a version number and returns it
  def CLFile.increase_version(version)
    return version.sub(/(\w+)\W*$/) do |str|
      str.succ
    end
  end

  def increase_version
    return CLFile.increase_version(latest_version)
  end
  
  def package_name
    return @sections[0].version["package"]
  end
  
  # This is the most interesting function: it adds a new entry, or prompts
  # the user for it (via an external text editor). If version is :increase
  # then the latest version is taken and increased automatically. The output
  # is written to the file specified by target_file (which has to be an IO
  # object -- and a real file in case of user interaction).
  # This function returns true if the provided file has been modified in a
  # reasonable way (that is: either we provided text, or the user did actually
  # modify the file)
  def add_new_entry(target_file,email, 
                    version = nil, entry = nil,
                    editor = "nano",
                    verbose = false,
                    editor_line_syntax = "+%d") 
    if version.nil? or version == latest_version
      line_number, lines = @sections[0].add_entry(email, entry)
      text = lines.join('') + "\n" +  
        @sections[1..@sections.size - 1].collect do |v|
        v.to_s
      end.join("\n")
    else
      if version == :increase
        version = increase_version
      end
      text = CLFile.create_new(email, version,
                               package_name,if entry
                                              entry
                                            else
                                              ""
                                            end
                               ) + 
        @sections.collect do |v|
        v.to_s
      end.join("\n")
      line_number = 3
    end
    # now, text is the text of the changelog, and line_number
    # the number of the line which the user should edit

    target_file.print text
    target_file.close
    # closing the file so that its contents appear on
    # the hard drive...
    if(entry.nil?) 
      # interactive edition
      time_before = File::mtime(target_file.path)
      line_number_spec = sprintf(editor_line_syntax, line_number)
      cmd = "#{editor} #{line_number_spec} #{target_file.path}"
      puts cmd if verbose
      system cmd
      time_after = File::mtime(target_file.path)
      return time_before < time_after
    end
    return true
  end
  
  # Creates a new changelog from scratch and writes it to filename,
  # or returns the corresponding string. 
  def CLFile.create_new(email, version, package, 
                        entry = nil,
                        filename = nil)
    contents = "#{package} (#{version})\n\n" + if entry
                                                 "  * #{entry}\n\n"
                                               else
                                                 ""
                                               end +
      " -- #{email}, #{CLFile.date}\n" 
    if filename
      File.open(filename, "w") do |f|
        f.print contents
      end
    end
    return contents
  end

end


# new generic structure:
options = OpenStruct.new
options.version = nil

if ENV.has_key? "RCH_EMAIL"
  options.email = ENV["RCH_EMAIL"]
else
  # Try to make up something from the etc gecos field
  # and the environment variable EMAIL (or username@hostname if not defined)
  email = ""
  if ENV.has_key? "EMAIL"
    email = ENV["EMAIL"]
  else 
    # Make up one email, not nice-looking, but not too bad.
    email = "#{Etc.getpwuid.name}@localhost"
  end
  options.email = "#{Etc.getpwuid.gecos.split(',')[0]} <#{email}>"
end
options.package = nil

# The editor
if ENV.has_key? "EDITOR"
  options.editor = ENV["EDITOR"]
else
  options.editor = "nano"       # nano by default
end


# The editor's specification for a command-line 
if ENV.has_key? "EDITOR_LINE_SPEC"
  options.editor_line_spec = ENV["EDITOR_LINE_SPEC"]
else
  options.editor_line_spec = "+%d" # works for nano, and for others as well
end


options.verbose = false

opts = OptionParser.new do |opts|
  opts.banner = "$0 [options]"
  
  opts.on("-v","--version VERSION", 
          "Create a new entry for the version VERSION") do |version|
    options.version = version
  end

  opts.on("-e","--entry ENTRY", 
          "Adds the entry ENTRY without prompting the user") do |entry|
    options.entry = entry
  end

  opts.on("-i","--increase", 
          "Increase automatically the version number") do 
    options.version = :increase
  end

  opts.on("","--email EMAIL", 
          "Sets the full email address to EMAIL") do |email|
    options.email = email
  end

  opts.on("-p","--package PACKAGE", 
          "Sets the package name to PACKAGE") do |package|
    options.package = package
  end

  opts.on("-c","--create", 
          "Creates a brand new changelog. Version and package " +
          "have to be specified") do 
    options.create = true
  end

  opts.on("","--editor EDITOR", 
          "Specifies your default editor for editing the changelog") do |e| 
    options.editor = e
  end

  opts.on("","--line_spec SPEC", 
          "How rch should tell the editor which line to edit" +
          " (like for sprintf)") do |l| 
    options.editor_line_spec = l 
  end

  opts.on("","--release", 
          "Make an archive of the current directory, and name it " +
          " according to the changelog.") do 
    options.release = true
  end

  opts.on("","--cvs MODULE", 
          "Does a cvs release -- you need to specify a " +
          "tag and maybe a repository") do |mod|
    options.cvs_release = true 
    options.module = mod
  end

  opts.on("","--cvs-tag TAG", 
          "Does a cvs release") do |tag|
    options.tag = tag
  end

  opts.on("-v","--verbose", 
          "Prints out a command before executing it") do 
    options.verbose = true
  end


  opts.on("","--repository REP", 
          "Chooses the repository REP for --cvs") do |rep|
    options.repository = rep
  end


end

opts.parse!

file = "Changelog" 
if $*[0]
  file = $*[0]
end

if options.create
  if options.version && options.package
    CLFile.create_new(options.email, options.version, 
                      options.package,nil,file)
  else
    puts "You should specify a package name and a version"
  end
elsif options.cvs_release
  CLFile.cvs_release(options.module, options.tag,
                     options.repository,
                     file)
elsif options.release
  CLFile.make_release(Dir.pwd, file)
else
  cl = CLFile.new(file)

  # basic changelog addition:
  temp_file = Tempfile.new('changelog')
  if cl.add_new_entry(temp_file, options.email,
                      options.version, options.entry,
                      options.editor, options.verbose,
                      options.editor_line_spec)
    cmd = "cp '#{temp_file.path}' '#{file}'"
    puts cmd if options.verbose
    system cmd
  end
end