Module:Rates

Documentation for this module may be created at Module:Rates/doc

-- <nowiki>
--
-- Formats drop rates and calculates two rates multiplied together (usually DAR and RDR)
--

local p = {}

-- Every DAR/RDR fraction between 1/2 and 1/1
local wholeFractions =
{
  [0.9] = "9/10",
  [0.88] = "22/25",
  [0.875] = "7/8",
  [0.85] = "17/20",
  [0.8] = "4/5",
  [0.6] = "3/5",
  [0.5625] = "9/16",
  [0.55] = "9/20",
  [0.5] = "1/2"
}

--
-- Rate calculation accessed through #invoke
--
-- @param frame {table}
-- @return {number}
--
function p.calcRate(frame)
  -- Separate the two numbers passed in as strings
  local mult = {}
  mult[1] = frame.args[1]
  mult[2] = frame.args[2]
  -- Initialize numbers for string conversion
  local frac = {}
  frac[1] = {}
  frac[2] = {}
  -- If either number is a fraction, split it up into numerator and denominator
  -- Thanks, Ender!
  for i=1,2,1 do
    for number in string.gmatch(mult[i], '([^/]+)') do
      table.insert(frac[i], number)
    end
    -- If either number wasn't a fraction, fill 1 in for its denominator
    if frac[i][2] == nil then
      frac[i][2] = 1
    end
  end
  -- These probably don't need to be redefined, but I'm still super new to Lua so I'll come back to it later xd
  local num1 = frac[1][1]
  local den1 = frac[1][2]
  local num2 = frac[2][1]
  local den2 = frac[2][2]
  return (num1/den1)*(num2/den2)
end

--
-- Number formatting. Pass in a number in either fraction, decimal, or whole format and convert it.
--
-- @param rate {string}
-- @param fmt {string} -- "f" for fraction, "p" for percent, "n" for both fraction and percent used in the Note template
-- @param digits {number} -- optional
-- @return {string}
--
local function fmtRate(rate, fmt, digits)
  local out = ""
  -- Don't want nil comparisons or whatever
  if digits == nil then
    digits = 0
  end
  local frac = {}
  -- If either number is a fraction, split it up into numerator and denominator
  -- Thanks, Ender!
  for number in string.gmatch(rate, '([^/]+)') do
    table.insert(frac, number)
  end
  -- If either number wasn't a fraction, fill 1 in for its denominator
  if frac[2] == nil then
    frac[2] = 1
  end
  local num = frac[1]
  local den = frac[2]
  -- Turn rate into a number!
  rate = num / den
  if fmt == "f" then
    if wholeFractions[rate] == nil then
      -- Set maximum number of decimal places
      if rate < 10 then
        -- Displays with two places between 1.01 ~ 9.99
        digits = math.max(digits, 2)
      elseif rate < 100 then
        -- Displays with one place between 10.1 ~ 99.9
        digits = math.max(digits, 1)
      else
        -- Otherwise just displays the whole number at 100+
        digits = math.max(digits, 0)
      end
      -- Even if we're displaying one or more decimal places, cut zeroes off
      out = out .. string.format("%s", string.format("1/%." .. digits .. "f", 1/rate)):gsub("%.?0+$", "")
    else
      out = out .. wholeFractions[rate]
    end
    return out
  elseif fmt == "p" then
    -- Display up to five decimal places. Cut zeroes off
    rate = string.format("%s%%", string.format("%f", string.format("%.5f", rate*100)):gsub("%.?0+$", ""))
    out = out .. rate
    return out
  end
end

--
-- Rate display accessed through #invoke
--
-- @param frame {table}
-- @return {string}
--
function p.displayRate(frame)
  -- Separate the rate (number passed in as string) from the format (string) and digits (string). digits parameter is optional
  local rate = frame.args[1]
  local fmt = frame.args[2]
  local digits = frame.args[3]
  local out = ""
  if fmt == "f" then
    -- Fraction
  	out = out .. fmtRate(rate, "f", digits)
  elseif fmt == "p" then
    -- Percentage
    out = out .. fmtRate(rate, "p")
  elseif fmt == "n" then
    -- Fraction (Percentage)
    out = out .. fmtRate(rate, "f", 2) .. " (" .. fmtRate(rate, "p") .. ")"
  end
  return out
end

return p