local vec2        = require "modules.vec2"
local DBL_EPSILON = require("modules.constants").DBL_EPSILON
local abs, sqrt   = math.abs, math.sqrt

describe("vec2:", function()
	it("tests creating vectors", function()
		-- new empty vector
		local a = vec2()
		assert.is.equal(a.x, 0)
		assert.is.equal(a.y, 0)
		assert.is_true(a:is_vec2())
		assert.is_true(a:is_zero())

		-- new vector from table
		local b = vec2 { 0, 0 }
		assert.is.equal(b.x, 0)
		assert.is.equal(b.y, 0)

		local c = vec2 { x=0, y=0 }
		assert.is.equal(c.x, 0)
		assert.is.equal(c.y, 0)

		-- new vector from numbers
		local d = vec2(3.14159, -2.808)
		assert.is.equal(d.x,  3.14159)
		assert.is.equal(d.y, -2.808)

		-- new vector from other vector
		local e = d:clone()
		assert.is.equal(d, e)
	end)

	it("tests basic operators", function()
		local a = vec2(3, 5)
		local b = vec2(7, 4)
		local s = 2

		-- Add
		do
			local c = vec2():add(a, b)
			local d = a + b

			assert.is.equal(c.x, 10)
			assert.is.equal(c.y, 9)
			assert.is.equal(c, d)
		end

		-- Subtract
		do
			local c = vec2():sub(a, b)
			local d = a - b

			assert.is.equal(c.x, -4)
			assert.is.equal(c.y,  1)
			assert.is.equal(c, d)
		end

		-- Multiply
		do
			local c = vec2():mul(a, s)
			local d = a * s

			assert.is.equal(c.x, 6)
			assert.is.equal(c.y, 10)
			assert.is.equal(c, d)
		end

		-- Divide
		do
			local c = vec2():div(a, s)
			local d = a / s

			assert.is.equal(c.x, 1.5)
			assert.is.equal(c.y, 2.5)
			assert.is.equal(c, d)
		end

		-- Sign flip
		do
			local c = -a
			assert.is.equal(c.x, -3)
			assert.is.equal(c.y, -5)
		end
	end)

	it("tests normal, trim, length", function()
		local a = vec2(3, 5)
		local b = vec2():normalize(a)
		local c = vec2():trim(a, 0.5)

		assert.is_true(abs(b:len()  - 1)   < DBL_EPSILON)
		assert.is_true(abs(b:len()  - 1)   < DBL_EPSILON)
		assert.is_true(abs(b:len2() - 1)   < DBL_EPSILON * 2)
		assert.is_true(abs(c:len()  - 0.5) < DBL_EPSILON)
	end)

	it("tests distance", function()
		local a = vec2(3, 5)
		local b = vec2(7, 4)

		-- Distance
		do
			local c = a:dist(b)
			assert.is.equal(c, sqrt(17))
		end

		-- Distance Squared
		do
			local c = a:dist2(b)
			assert.is.equal(c, 17)
		end
	end)

	it("tests cross product", function()
		local a = vec2(3, 5)
		local b = vec2(7, 4)
		local c = a:cross(b)

		assert.is.equal(c, -23)
	end)

	it("tests dot product", function()
		local a = vec2(3, 5)
		local b = vec2(7, 4)
		local c = a:dot(b)

		assert.is.equal(c, 41)
	end)

	it("tests lerp", function()
		local a = vec2(3, 5)
		local b = vec2(7, 4)
		local s = 0.1
		local c = vec2():lerp(a, b, s)

		assert.is.equal(c.x, 3.4)
		assert.is.equal(c.y, 4.9)
	end)

	it("tests unpack", function()
		local a    = vec2(3, 5)
		local x, y = a:unpack()

		assert.is.equal(x, 3)
		assert.is.equal(y, 5)
	end)

	it("tests rotate", function()
		local a = vec2(3, 5)
		local b = vec2():rotate(a,  math.pi)
		local c = vec2():rotate(b, -math.pi)

		assert.is.equal(c.x, 3)
		assert.is.equal(c.y, 5)
	end)

	it("tests converting coordinates", function()
		local a    = vec2(3, 5)
		local r, t = a:to_polar()
		local b    = vec2.from_cartesian(r, t)

		assert.is.equal(b.x, a.x)
		assert.is.equal(b.y, a.y)
	end)

	it("tests perpendicular", function()
		local a = vec2(3, 5)
		local b = vec2():perpendicular(a)

		assert.is.equal(b.x, -5)
		assert.is.equal(b.y,  3)
	end)
end)