class Gem::Resolver::Conflict

def ==(other) # :nodoc:
  self.class === other and
    @dependency == other.dependency and
    @activated  == other.activated  and
    @failed_dep == other.failed_dep
end

def conflicting_dependencies
  [@failed_dep.dependency, @activated.request.dependency]
end

def explain
  "<Conflict wanted: #{@failed_dep}, had: #{activated.spec.full_name}>"
end

def explanation
  activated   = @activated.spec.full_name
  dependency  = @failed_dep.dependency
  requirement = dependency.requirement
  alternates  = dependency.matching_specs.map {|spec| spec.full_name }
  unless alternates.empty?
    matching = <<-MATCHING.chomp
Gems matching %s:
  %s
    MATCHING
    matching = matching % [
      dependency,
      alternates.join(', '),
    ]
  end
  explanation = <<-EXPLANATION
Activated %s
which does not match conflicting dependency (%s)
Conflicting dependency chains:
  %s
versus:
  %s

  EXPLANATION
  explanation % [
    activated, requirement,
    request_path(@activated).reverse.join(", depends on\n    "),
    request_path(@failed_dep).reverse.join(", depends on\n    "),
    matching
  ]
end

def for_spec?(spec)
  @dependency.name == spec.name
end

def initialize(dependency, activated, failed_dep=dependency)
  @dependency = dependency
  @activated = activated
  @failed_dep = failed_dep
end

def pretty_print(q) # :nodoc:
  q.group 2, '[Dependency conflict: ', ']' do
    q.breakable
    q.text 'activated '
    q.pp @activated
    q.breakable
    q.text ' dependency '
    q.pp @dependency
    q.breakable
    if @dependency == @failed_dep
      q.text ' failed'
    else
      q.text ' failed dependency '
      q.pp @failed_dep
    end
  end
end

def request_path(current)
  path = []
  while current do
    case current
    when Gem::Resolver::ActivationRequest then
      path <<
        "#{current.request.dependency}, #{current.spec.version} activated"
      current = current.parent
    when Gem::Resolver::DependencyRequest then
      path << "#{current.dependency}"
      current = current.requester
    else
      raise Gem::Exception, "[BUG] unknown request class #{current.class}"
    end
  end
  path = ['user request (gem command or Gemfile)'] if path.empty?
  path
end

def requester
  @failed_dep.requester
end