# Redmine - project management software
# Copyright (C) 2006-2011  Jean-Philippe Lang
# Copyright (C) 2007  Patrick Aljord patcito@ŋmail.com
#
# 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.

require 'redmine/scm/adapters/git_adapter'

class Repository::Git < Repository
  attr_protected :root_url
  validates_presence_of :url

  def self.human_attribute_name(attribute_key_name, *args)
    attr_name = attribute_key_name.to_s
    if attr_name == "url"
      attr_name = "path_to_repository"
    end
    super(attr_name, *args)
  end

  def self.scm_adapter_class
    Redmine::Scm::Adapters::GitAdapter
  end

  def self.scm_name
    'Git'
  end

  def report_last_commit
    extra_report_last_commit
  end

  def extra_report_last_commit
    return false if extra_info.nil?
    v = extra_info["extra_report_last_commit"]
    return false if v.nil?
    v.to_s != '0'
  end

  def supports_directory_revisions?
    true
  end

  def supports_revision_graph?
    true
  end

  def repo_log_encoding
    'UTF-8'
  end

  # Returns the identifier for the given git changeset
  def self.changeset_identifier(changeset)
    changeset.scmid
  end

  # Returns the readable identifier for the given git changeset
  def self.format_changeset_identifier(changeset)
    changeset.revision[0, 8]
  end

  def branches
    scm.branches
  end

  def tags
    scm.tags
  end

  def default_branch
    scm.default_branch
  rescue Exception => e
    logger.error "git: error during get default branch: #{e.message}"
    nil
  end

  def find_changeset_by_name(name)
    return nil if name.nil? || name.empty?
    e = changesets.find(:first, :conditions => ['revision = ?', name.to_s])
    return e if e
    changesets.find(:first, :conditions => ['scmid LIKE ?', "#{name}%"])
  end

  def entries(path=nil, identifier=nil)
    scm.entries(path,
                identifier,
                options = {:report_last_commit => extra_report_last_commit})
  end

  # With SCMs that have a sequential commit numbering,
  # such as Subversion and Mercurial,
  # Redmine is able to be clever and only fetch changesets
  # going forward from the most recent one it knows about.
  # 
  # However, Git does not have a sequential commit numbering.
  #
  # In order to fetch only new adding revisions,
  # Redmine needs to parse revisions per branch.
  # Branch "last_scmid" is for this requirement.
  #
  # In Git and Mercurial, revisions are not in date order.
  # Redmine Mercurial fixed issues.
  #    * Redmine Takes Too Long On Large Mercurial Repository
  #      http://www.redmine.org/issues/3449
  #    * Sorting for changesets might go wrong on Mercurial repos
  #      http://www.redmine.org/issues/3567
  #
  # Database revision column is text, so Redmine can not sort by revision.
  # Mercurial has revision number, and revision number guarantees revision order.
  # Redmine Mercurial model stored revisions ordered by database id to database.
  # So, Redmine Mercurial model can use correct ordering revisions.
  #
  # Redmine Mercurial adapter uses "hg log -r 0:tip --limit 10"
  # to get limited revisions from old to new.
  # But, Git 1.7.3.4 does not support --reverse with -n or --skip.
  #
  # The repository can still be fully reloaded by calling #clear_changesets
  # before fetching changesets (eg. for offline resync)
  def fetch_changesets
    scm_brs = branches
    return if scm_brs.nil? || scm_brs.empty?
    h1 = extra_info || {}
    h  = h1.dup
    h["branches"]       ||= {}
    h["db_consistent"]  ||= {}
    if changesets.count == 0
      h["db_consistent"]["ordering"] = 1
      merge_extra_info(h)
      self.save
    elsif ! h["db_consistent"].has_key?("ordering")
      h["db_consistent"]["ordering"] = 0
      merge_extra_info(h)
      self.save
    end
    save_revisions(h, scm_brs)
  end

  def save_revisions(h, scm_brs)
    # Remember what revisions we already processed (in any branches)
    all_revisions = []
    scm_brs.each do |br1|
      br = br1.to_s
      last_revision = nil
      from_scmid = nil
      from_scmid = h["branches"][br]["last_scmid"] if h["branches"][br]
      h["branches"][br] ||= {}

      revisions = scm.revisions('', from_scmid, br, {:reverse => true})
      next if revisions.blank?

      # Remember the last commit id here, before we start removing revisions from the array.
      # We'll do that for optimization, but it also means, that we may lose even all revisions.
      last_revision  = revisions.last

      # remove revisions that we have already processed (possibly in other branches)
      revisions.reject!{|r| all_revisions.include?(r.scmid)}
      # add revisions that we are to parse now to 'all processed revisions'
      # (this equals to a union, because we executed diff above)
      all_revisions += revisions.map{|r| r.scmid}

      # Make the search for existing revisions in the database in a more sufficient manner
      # This is replacing the one-after-one queries.
      # Find all revisions, that are in the database, and then remove them from the revision array.
      # Then later we won't need any conditions for db existence.
      # Query for several revisions at once, and remove them from the revisions array, if they are there.
      # Do this in chunks, to avoid eventual memory problems (in case of tens of thousands of commits).
      # If there are no revisions (because the original code's algoritm filtered them),
      # then this part will be stepped over.
      # We make queries, just if there is any revision.
      limit = 100
      offset = 0
      revisions_copy = revisions.clone # revisions will change
      while offset < revisions_copy.size
        recent_changesets_slice = changesets.find(
                                     :all,
                                     :conditions => [
                                        'scmid IN (?)',
                                        revisions_copy.slice(offset, limit).map{|x| x.scmid}
                                      ]
                                    )
        # Subtract revisions that redmine already knows about
        recent_revisions = recent_changesets_slice.map{|c| c.scmid}
        revisions.reject!{|r| recent_revisions.include?(r.scmid)}
        offset += limit
      end

      revisions.each do |rev|
        transaction do
          # There is no search in the db for this revision, because above we ensured,
          # that it's not in the db.
          db_saved_rev = save_revision(rev)
          parents = {}
          parents[db_saved_rev] = rev.parents unless rev.parents.nil?
          parents.each do |ch, chparents|
            ch.parents = chparents.collect{|rp| find_changeset_by_name(rp)}.compact
          end
          # saving the last scmid was moved from here, because we won't come in here,
          # if the revision was already added for another branch
        end
      end

      # save the data about the last revision for this branch
      unless last_revision.nil?
        h["branches"][br]["last_scmid"] = last_revision.scmid
        merge_extra_info(h)
        self.save
      end
    end
  end
  private :save_revisions

  def save_revision(rev)
    changeset = Changeset.new(
              :repository   => self,
              :revision     => rev.identifier,
              :scmid        => rev.scmid,
              :committer    => rev.author,
              :committed_on => rev.time,
              :comments     => rev.message
              )
    if changeset.save
      rev.paths.each do |file|
        Change.create(
                  :changeset => changeset,
                  :action    => file[:action],
                  :path      => file[:path])
      end
    end
    changeset
  end
  private :save_revision

  def heads_from_branches_hash
    h1 = extra_info || {}
    h  = h1.dup
    h["branches"] ||= {}
    h['branches'].map{|br, hs| hs['last_scmid']}
  end

  def latest_changesets(path,rev,limit=10)
    revisions = scm.revisions(path, nil, rev, :limit => limit, :all => false)
    return [] if revisions.nil? || revisions.empty?

    changesets.find(
      :all,
      :conditions => [
        "scmid IN (?)",
        revisions.map!{|c| c.scmid}
      ],
      :order => 'committed_on DESC'
    )
  end
end