#!/usr/bin/env ruby -w
# encoding: UTF-8
#
# = ChargeSet.rb -- The TaskJuggler III Project Management Software
#
# Copyright (c) 2006, 2007, 2008, 2009, 2010, 2011
#               by Chris Schlaeger <chris@linux.com>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of version 2 of the GNU General Public License as
# published by the Free Software Foundation.
#

require 'TjException'

class TaskJuggler

  # A charge set describes how a given amount is distributed over a set of
  # accounts. It stores the percentage share for each account. The accumulated
  # percentages must always be 100% for a valid charge set. For consistency
  # reasons, accounts must always be leaf accounts of the same top-level
  # account. Percentage values must range from 0.0 to 1.0.
  class ChargeSet

    attr_reader :master

    # Create a new ChargeSet object.
    def initialize
      @set = {}
      @master = nil
    end

    # Add a new account to the set. Accounts and share rates must meet a number
    # of requirements. This method does some error checking and raises a
    # TjException in case of problems. It cannot check everything. Accounts can
    # later be turned into group accounts or the total share sum may not be
    # 100%. This needs to be checked at a later stage. Accounts may have a share
    # of nil. This will be set in ChargeSet#complete later.
    def addAccount(account, share)
      unless account.leaf?
        raise TjException.new,
          "Account #{account.fullId} is a group account and cannot be used " +
          "in a chargeset."
      end
      if @set.include?(account)
        raise TjException.new,
          "Account #{account.fullId} is already a member of the charge set."
      end
      if @master.nil?
        @master = account.root
      elsif @master != account.root
        raise TjException.new,
          "All members of this charge set must belong to the " +
          "#{@master.fullId} account. #{account.fullId} belongs to " +
          "#{account.root.fullId}."
      end
      if account.container?
        raise TjException.new,
          "#{account.fullId} is a group account. Only leaf accounts are " +
          "allowed for a charge set."
      end
      if share && (share < 0.0 || share > 1.0)
        raise TjException.new, "Charge set shares must be between 0 and 100%"
      end
      @set[account] = share
    end

    def each
      @set.each do |account, share|
        yield account, share
      end
    end

    # Check for accounts that don't have a share yet and distribute the
    # remainder to 100% evenly accross them.
    def complete
      # Calculate the current total share.
      totalPercent = 0.0
      undefined = 0
      @set.each_value do |share|
        if share
          totalPercent += share
        else
          undefined += 1
        end
      end
      # Must be less than 100%.
      if totalPercent > 1.0
        raise TjException.new,
          "Total share of this set (#{totalPercent * 100}%) excedes 100%."
      end
      if undefined > 0
        commonShare = (1.0 - totalPercent) / undefined
        if commonShare <= 0
          raise TjException.new,
            "Total share is 100% but #{undefined} account(s) still exist."
        end
        @set.each do |account, share|
          if share.nil?
            @set[account] = commonShare
          end
        end
      elsif totalPercent != 1.0
        raise TjException.new,
          "Total share of this set is #{totalPercent * 100} instead of 100%."
      end
    end

    # Return the share percentage for a given Account _account_.
    def share(account)
      @set[account]
    end

    # Return the set as comma separated list of account ID + share pairs.
    def to_s
      str = '('
      @set.each do |account, share|
        str += ', ' unless str == '('
        str += "#{account.fullId} #{share * 100}%"
      end
      str += ')'
    end

  end

end