# Triangle Project Code.

# Triangle analyzes the lengths of the sides of a triangle
# (represented by a, b and c) and returns the type of triangle.
#
# It returns:
#   :equilateral  if all sides are equal
#   :isosceles    if exactly 2 sides are equal
#   :scalene      if no sides are equal
#
# The tests for this method can be found in
#   about_triangle_project.rb
# and
#   about_triangle_project_2.rb
#
def triangle(a, b, c)
  raise TriangleError if (a <= 0) or (b <= 0) or (c <= 0)
  raise TriangleError if (a + b <= c) or (a + c <= b) or (b + c <= a)
  if a == b and b == c
    :equilateral
  elsif (a == b and a != c) or (a == c and a != b) or (b == c and b != a)
    :isosceles
  else
    :scalene
  end
end

# Error class used in part 2.  No need to change this code.
class TriangleError < StandardError
end