require File.expand_path(File.dirname(__FILE__) + '/spec_helper')

describe LittleMathPet do
  context "when a single number is given" do
    equations = {
      "8"     => 8.0,
      "78.65" => 78.65,
      "-3.5"  => -3.5
    }
    
    equations.each do |equation, result|
      it "returns that number in float (#{equation} = #{result})" do
        LittleMathPet.new(equation).calc.should == result
      end
    end
  end

  context "when a simple equation is given" do
    equations = {
      "5+3"   => 8.0,
      "7-5"   => 2.0,
      "5-7"   => -2.0,
      "5*3"   => 15.0,
      "15/5"  => 3.0,
      "-15/5" => -3.0,
      "2^3"   => 8.0
    }
    
    equations.each do |equation, result|
      it "solves the equation (#{equation} = #{result})" do
        LittleMathPet.new(equation).calc.should == result
      end
    end
  end
  
  context "when a more complex equation is given" do
    equations = {
      "5+3+10" => 18.0,
      "7-5-2" => 0.0,
      "5-7+6" => 4.0,
      "5*3/10" => 1.5,
      "15/5*2" => 6.0,
      "-15/5*7" => -21.0
    }
    
    equations.each do |equation, result|
      it "solves the equation (#{equation} = #{result})" do
        LittleMathPet.new(equation).calc.should == result
      end
    end

    equations = {
      "5*3+10" => 25.0,
      "10+3*5" => 25.0,
      "5-7/2" => 1.5,
      "-8/2^2" => -2.0,
      "(5+2)*2" => 14.0
    }

    equations.each do |equation, result|
      it "respects the proper math order (#{equation} = #{result})" do
        LittleMathPet.new(equation).calc.should == equations[equation]
      end
    end
  end
  
  context "when a different grammar is used for the equation" do
    equations = {
      "5*3:10" => 1.5,
      "-8/2**2" => -2.0,
      "5 + 7" => 12.0,
      "[5+2] : 2" => 3.5
    }

    equations.each do |equation, result|
      it "solves the equation (#{equation} = #{result})" do
        LittleMathPet.new(equation).calc.should == result
      end
    end
  end
  
  context "when something unkown is given as math" do
    equations = [
      "five * 5",
      "something else",
      "+*+"
    ]
    
    equations.each do |equation|
      it "raises an exception (#{equation.inspect})" do
        begin
          LittleMathPet.new(equation).calc
          true.should == false
        rescue => e
          e.message.should == 'Invalid math expression'
        end
      end
    end
  end

  context "when a variable is given (x => 3)" do
    value = '3'
    equations = {
      "5+x+10" => 18.0,
      "7-5-x" => -1.0,
      "5*x/10" => 1.5,
      "15/5*x" => 9.0,
      "10+x*5" => 25.0,
      "x-7/2" => -0.5,
      "-9/x^2" => -1.0,
      "x*(2+3)/2" => 7.5
    }
    
    equations.each do |equation, result|
      it "uses it in place of x (#{equation} = #{result})" do
        LittleMathPet.new(equation).calc(:x => value).should == result
      end
    end
  end

  context "when multiple variables are given (a => 2, b => 5)" do
    values = {:a => 2, :b => 5}
    equations = {
      "5+a+10/b" => 9.0,
      "7-5-a*b" => -8.0,
      "5^a/10/b" => 0.5,
      "b*(a+3)/2" => 12.5
    }
    
    equations.each do |equation, result|
      it "uses them in place of the variables (#{equation} = #{result})" do
        LittleMathPet.new(equation).calc(values).should == result
      end
    end
  end
  
  context "when some variables are missing" do
    values = {:a => 2, :b => 5}
    equations = [
      "5+a+10/x",
      "7-5-a*y",
      "c^a/10/b",
      "v*(e+3)/2"
    ]
    
    equations.each do |equation, result|
      it "raises an exception (#{equation.inspect})" do
        begin
          LittleMathPet.new(equation).calc.should == result
          true.should == false
        rescue => e
          e.message.should == 'Invalid math expression'
        end
      end
    end
  end
end