# Puppet package provider for Python's `pip` package management frontend.
# <http://pip.pypa.io/>

require 'puppet/provider/package'
require 'puppet/util/http_proxy'

Puppet::Type.type(:package).provide :pip,
  :parent => ::Puppet::Provider::Package do

  desc "Python packages via `pip`.

  This provider supports the `install_options` attribute, which allows command-line flags to be passed to pip.
  These options should be specified as a string (e.g. '--flag'), a hash (e.g. {'--flag' => 'value'}),
  or an array where each element is either a string or a hash."

  has_feature :installable, :uninstallable, :upgradeable, :versionable, :install_options

  # Parse lines of output from `pip freeze`, which are structured as
  # _package_==_version_.
  def self.parse(line)
    if line.chomp =~ /^([^=]+)==([^=]+)$/
      {:ensure => $2, :name => $1, :provider => name}
    else
      nil
    end
  end

  # Return an array of structured information about every installed package
  # that's managed by `pip` or an empty array if `pip` is not available.
  def self.instances
    packages = []
    pip_cmd = self.pip_cmd
    return [] unless pip_cmd
    execpipe "#{pip_cmd} freeze" do |process|
      process.collect do |line|
        next unless options = parse(line)
        packages << new(options)
      end
    end

    # Pip can also upgrade pip, but it's not listed in freeze so need to special case it
    # Pip list would also show pip installed version, but "pip list" doesn't exist for older versions of pip (E.G v1.0)
    if version = self.pip_version
      packages << new({:ensure => version, :name => File.basename(pip_cmd), :provider => name})
    end

    packages
  end

  def self.cmd
    ["pip", "pip-python"]
  end

  def self.pip_cmd
    self.cmd.map { |c| which(c) }.find { |c| c != nil }
  end

  def self.pip_version
    pip_cmd = self.pip_cmd
    return nil unless pip_cmd

    execpipe [pip_cmd, '--version'] do |process|
      process.collect do |line|
        return line.strip.match(/^pip (\d+\.\d+\.?\d*).*$/)[1]
      end
    end
  end

  # Return structured information about a particular package or `nil` if
  # it is not installed or `pip` itself is not available.
  def query
    self.class.instances.each do |provider_pip|
      return provider_pip.properties if @resource[:name].downcase == provider_pip.name.downcase
    end
    return nil
  end

  # Use pip CLI to look up versions from PyPI repositories, honoring local pip config such as custom repositories
  def latest
    return nil unless self.class.pip_cmd
    if Puppet::Util::Package.versioncmp(self.class.pip_version, '1.5.4') == -1 # a < b
      return latest_with_old_pip
    end
    latest_with_new_pip
  end

  # Install a package.  The ensure parameter may specify installed,
  # latest, a version number, or, in conjunction with the source
  # parameter, an SCM revision.  In that case, the source parameter
  # gives the fully-qualified URL to the repository.
  def install
    args = %w{install -q}
    args +=  install_options if @resource[:install_options]
    if @resource[:source]
      if String === @resource[:ensure]
        args << "#{@resource[:source]}@#{@resource[:ensure]}#egg=#{
          @resource[:name]}"
      else
        args << "#{@resource[:source]}#egg=#{@resource[:name]}"
      end
    else
      case @resource[:ensure]
      when String
        args << "#{@resource[:name]}==#{@resource[:ensure]}"
      when :latest
        args << "--upgrade" << @resource[:name]
      else
        args << @resource[:name]
      end
    end
    lazy_pip *args
  end

  # Uninstall a package.  Uninstall won't work reliably on Debian/Ubuntu
  # unless this issue gets fixed.
  # <http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=562544>
  def uninstall
    lazy_pip "uninstall", "-y", "-q", @resource[:name]
  end

  def update
    install
  end

  # Execute a `pip` command.  If Puppet doesn't yet know how to do so,
  # try to teach it and if even that fails, raise the error.
  private
  def lazy_pip(*args)
    pip *args
  rescue NoMethodError => e
    # Ensure pip can upgrade pip, which usually puts pip into a new path /usr/local/bin/pip (compared to /usr/bin/pip)
    # The path to pip needs to be looked up again in the subsequent request. Using the preferred approach as noted
    # in provider.rb ensures this (copied below for reference)
    #
    # @note From provider.rb; It is preferred if the commands are not entered with absolute paths as this allows puppet
    # to search for them using the PATH variable.
    if pathname = self.class.cmd.map { |c| which(c) }.find { |c| c != nil }
      self.class.commands :pip => File.basename(pathname)
      pip *args
    else
      raise e, "Could not locate command #{self.class.cmd.join(' and ')}.", e.backtrace
    end
  end

  def install_options
    join_options(@resource[:install_options])
  end

  def latest_with_new_pip
    # Less resource intensive approach for pip version 1.5.4 and above
    execpipe ["#{self.class.pip_cmd}", "install", "#{@resource[:name]}==versionplease"] do |process|
      process.collect do |line|
        # PIP OUTPUT: Could not find a version that satisfies the requirement Django==versionplease (from versions: 1.1.3, 1.8rc1)
        if line =~ /from versions: /
          textAfterLastMatch = $'.chomp(")\n")
          versionList = textAfterLastMatch.split(', ').sort do |x,y|
            Puppet::Util::Package.versioncmp(x, y)
          end
          return versionList.last
        end
      end
      return nil
    end
  end

  def latest_with_old_pip
    Dir.mktmpdir("puppet_pip") do |dir|
      execpipe ["#{self.class.pip_cmd}", "install", "#{@resource[:name]}", "-d", "#{dir}", "-v"] do |process|
        process.collect do |line|
          # PIP OUTPUT: Using version 0.10.1 (newest of versions: 0.10.1, 0.10, 0.9, 0.8.1, 0.8, 0.7.2, 0.7.1, 0.7, 0.6.1, 0.6, 0.5.2, 0.5.1, 0.5, 0.4, 0.3.1, 0.3, 0.2, 0.1)
          if line =~ /Using version (.+?) \(newest of versions/
            return $1
          end
        end
        return nil
      end
    end
  end
end
