-- https://github.com/mah0x211/lua-isa

-- constants
local INF_POS = math.huge;
local INF_NEG = -INF_POS;
local type = type;
local floor = math.floor;

-- type
local function isNil(arg)
    return type(arg) == 'nil';
end

local function isBoolean(arg)
    return type(arg) == 'boolean';
end

local function isString(arg)
    return type(arg) == 'string';
end

local function isNumber(arg)
    return type(arg) == 'number';
end

local function isFunction(arg)
    return type(arg) == 'function';
end

local function isTable(arg)
    return type(arg) == 'table';
end

local function isThread(arg)
    return type(arg) == 'thread';
end

local function isUserdata(arg)
    return type(arg) == 'userdata';
end

-- boolean
local function isTrue(arg)
    return arg == true;
end

local function isFalse(arg)
    return arg == false;
end

-- None
local function isNone(arg)
    return arg == nil or arg == false or arg == 0 or arg == '' or arg ~= arg;
end

-- arithmetic
local function isNaN(arg)
    return arg ~= arg;
end

-- integer
local function isFinite(arg)
    return type(arg) == 'number' and (arg < INF_POS and arg > INF_NEG);
end

local function isInt(arg)
    return isFinite(arg) and rawequal(floor(arg), arg);
end

local function isInt8(arg)
    return isInt(arg) and arg >= -128 and arg <= 127;
end

local function isInt16(arg)
    return isInt(arg) and arg >= -32768 and arg <= 32767;
end

local function isInt32(arg)
    return isInt(arg) and arg >= -2147483648 and arg <= 2147483647;
end

-- unsigned integer
local function isUnsigned(arg)
    return type(arg) == 'number' and (arg < INF_POS and arg >= 0);
end

local function isUInt(arg)
    return isUnsigned(arg) and rawequal(floor(arg), arg);
end

local function isUInt8(arg)
    return isUInt(arg) and arg <= 255;
end

local function isUInt16(arg)
    return isUInt(arg) and arg <= 65535;
end

local function isUInt32(arg)
    return isUInt(arg) and arg <= 4294967295;
end

local EXPORTS = {};

for k, v in pairs({
    -- type
    ['Nil'] = isNil,
    ['Boolean'] = isBoolean,
    ['String'] = isString,
    ['Number'] = isNumber,
    ['Function'] = isFunction,
    ['Table'] = isTable,
    ['Thread'] = isThread,
    ['Userdata'] = isUserdata,

    -- boolean
    ['True'] = isTrue,
    ['False'] = isFalse,

    -- None: nil | false | 0 | '' | nan
    ['None'] = isNone,

    -- arithmetic
    -- NaN
    ['NaN'] = isNaN,
    ['Finite'] = isFinite,

    -- integer
    ['Int'] = isInt,
    ['Int8'] = isInt8,
    ['Int16'] = isInt16,
    ['Int32'] = isInt32,

    -- unsigned integer
    ['Unsigned'] = isUnsigned,
    ['UInt'] = isUInt,
    ['UInt8'] = isUInt8,
    ['UInt16'] = isUInt16,
    ['UInt32'] = isUInt32,
}) do
    EXPORTS[k], EXPORTS[k:lower()] = v, v;
end

return EXPORTS;