Argser.lua

-- written by MKlegoman357

local function argser (...)
  local args = {...}

  if type(args[1]) == "table" then
    args = args[1]
  end

  local function tryConvert (val, typ)
    if type(val) == typ then
      return true, val
    end

    if typ == "boolean" then
      return true, val:lower():sub(1, 1) == "t"
    elseif typ == "number" then
      local n = tonumber(val)

      return not not n, n
    elseif typ == "table" and type(val) == "string" then
      local t = textutils.unserialize(val)

      if type(t) == "table" then
        return true, t
      end
    end

    return false
  end

  return {
    rawArgs = args;
    args = {};

    options = {};

    lastName = nil;

    num = function (self, i, name, valueType)
      self.options[i] = {
        type = "#";
        name = name;

        i = i;

        valueType = valueType;
      }

      if name then
        self.options[name] = self.options[i]
      end

      self.lastName = name or i;

      return self
    end;

    switch = function (self, name, values, valueType)
      self.options[name] = {
        type = "-";
        name = name;

        hasValue = not not values;
        count = type(values) == "number" and values or values and math.huge or 0;

        valueType = valueType;
      }

      self.lastName = name;

      return self
    end;

    named = function (self, name, hasValue, valueType)
      self.options[name] = {
        type = "--";
        name = name;

        hasValue = hasValue;

        valueType = valueType;
      }

      self.lastName = name;

      return self
    end;

    alias = function (self, name, alias)
      if not alias then
        name, alias = self.lastName, name
      end

      self.options[alias] = self.options[name]

      return self
    end;

    func = function (self, name, func)
      if not func then
        name, func = self.lastName, name
      end

      local opt = self.options[name]

      if not opt then
        error("Argument '" .. name .. "' does not exist.", 2)
      end

      opt.func = func

      return self
    end;

    default = function (self, name, default)
      if default == nil then
        name, default = self.lastName, name
      end

      local opt = self.options[name]

      if opt and opt.func then
        if opt.type == "-" then
          for i, value in ipairs(default) do
            default[i] = opt.func(value)
          end
        else
          default = opt.func(default)
        end
      end

      self.args[name] = default

      if opt and opt.type == "#" then
        self.args[type(name) == "number" and opt.name or opt.i] = default
      end

      return self
    end;

    parse = function (self)
      local args = self.args
      local options = self.options
      local argn = 1
      local switch = nil
      local switchCount = 0

      for i, arg in ipairs(self.rawArgs) do
        if arg:sub(1, 1) == "-" then
          switch = nil

          if arg:sub(2, 2) == "-" then --named argument
            local name, hasValue, value = arg:match("^%-%-([_a-zA-Z0-9]+)(=?)(.*)$")
            local opt = options[name] and options[name].type == "--" and options[name]

            if hasValue == "" or opt and not opt.hasValue then
              value = true
            elseif opt and opt.hasValue and opt.valueType then
              local success, val = tryConvert(value, opt.valueType)

              if not success then
                error("Argument '" .. opt.name .. "' must be a valid " .. opt.valueType .. ".", 0)
              end

              value = val
            end

            if opt and opt.func then
              value = opt.func(value)
            end

            args[opt and opt.name or name] = value
          else -- switch
            local name = arg:sub(2)
            local opt = options[name] and options[name].type == "-" and options[name]
            local value = opt and not opt.hasValue or not opt or {}

            if not args[opt and opt.name or name] then
              args[opt and opt.name or name] = value
            end

            if opt and opt.hasValue then
              switch = opt
              switchCount = opt.count
            end
          end
        elseif switch then -- switch's argument
          if switch.valueType then
            local success, value = tryConvert(arg, switch.valueType)

            if not success then
              error("Argument '" .. switch.name .. "' must be a valid " .. switch.valueType .. ".", 0)
            end

            arg = value
          end

          local params = args[switch.name]

          if switch.func then
            arg = switch.func(arg)
          end

          params[#params + 1] = arg

          switchCount = switchCount - 1

          if switchCount <= 0 then
            switch = nil
          end
        else -- numbered argument
          local opt = options[argn] and options[argn].type == "#" and options[argn]

          if opt and opt.valueType then
            local success, value = tryConvert(arg, opt.valueType)

            if not success then
              error("Argument #" .. argn .. (opt.name and " (" .. opt.name .. ")" or "") .. " must be a valid " .. opt.valueType .. ".", 0)
            end

            arg = value
          end

          if opt and opt.func then
            arg = opt.func(arg)
          end

          args[argn] = arg

          argn = argn + 1

          if opt and opt.name then
            args[opt.name] = arg
          end
        end
      end

      return self
    end;
  }
end

return argser