--[[
Copyright (c) 2014, Robert 'Bobby' Zenz
All rights reserved.

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modification, are permitted provided that the following conditions are met:

* Redistributions of source code must retain the above copyright notice, this
  list of conditions and the following disclaimer.

* Redistributions in binary form must reproduce the above copyright notice,
  this list of conditions and the following disclaimer in the documentation
  and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
--]]


--- Various mathematical functions.
mathutil = {}


--- Clamps one value to the given minimum/maximum values. Defaults to
-- 0 to 1 if min/max are omitted.
--
-- @param value The value to clamp.
-- @param min Optional. The minimum value, defaults to 0.
-- @param max Optional. The masximum value, defaults to 1.
-- @return The value clamped to the given range.
function mathutil.clamp(value, min, max)
	if min == nil or max == nil then
		return math.min(math.max(value, -1), 1)
	else
		return math.min(math.max(value, min), max)
	end
end

--- Gets the distance between the two given points or objects.
--
-- @param a The first object. Either a position or an ObjectRef.
-- @param b The second object. Either a position or an ObjectRef.
-- @return The distance between the two given points or objects.
function mathutil.distance(a, b)
	if type(a.getpos) == "function" then
		a = a:getpos()
	end
	
	if type(b.getpos) == "function" then
		b = b:getpos()
	end
	
	local distance_point = {
		x = math.abs(a.x - b.x),
		y = math.abs(a.y - b.y),
		z = math.abs(a.z - b.z)
	}
	
	local distance2d = math.sqrt(math.pow(distance_point.x, 2) + math.pow(distance_point.z, 2))
	local distance3d = math.sqrt(math.pow(distance2d, 2) + math.pow(distance_point.y, 2))
	
	return distance3d
end

--- Tests if the given value is within the given range.
--
-- @param value The value to test.
-- @param min The minimum value. It can also be a table with either two values,
--            the first being the minimum and the second being the maximum, or
--            with two named values, min and max.
-- @param max The maximum value. Not used if min is a table.
function mathutil.in_range(value, min, max)
	if type(min) == "table" then
		if min.min == nil then
			max = min[2]
			min = min[1]
		else
			max = min.max
			min = min.min
		end
	end
	
	if min > max then
		local temp = min
		min = max
		max = temp
	end
	
	return value >= min and value <= max
end

--- Gets the next lower prime from the given number.
--
-- @param number The number.
-- @return The next lower prime.
function mathutil.next_lower_prime(number)
	for lower = number, 0, -1 do
		if (lower <= 2 or math.fmod(lower, 2) ~= 0)
			and (lower <= 3 or math.fmod(lower, 3) ~= 0)
			and (lower <= 5 or math.fmod(lower, 5) ~= 0)
			and (lower <= 7 or math.fmod(lower, 7) ~= 0) then
			
			return lower
		end	
	end
	
	return 0
end

--- Rounds to the nearest number with the given decimal places.
--
-- @param value The value to round.
-- @param decimal_places Optional. The number of decimal places to round to,
--                       defaults to 0.
-- @return The rounded value.
function mathutil.round(value, decimal_places)
	decimal_places = decimal_places or 0
	
	local multiplicator = 10 ^ decimal_places
	return math.floor(value * multiplicator + 0.5) / multiplicator
end