local ds = require("DataStructures")
local Dictionary, Stack, WordInfo, Environment = ds.Dictionary, ds.Stack, ds.WordInfo, ds.Environment
local Pointer = ds.Pointer

local InputStream = require("InputStream")
local CoreHelpers = {}

function CoreHelpers.defineWord(dict: Dictionary, str: string, func: function(Environment, ...: any): any..., imm: boolean)
	local info = WordInfo:new(func, imm)
	dict:define(str, info)
end

function CoreHelpers.standardInputRefill(): string
	local input = io.read().."\n"
	return input
end

function CoreHelpers._oneReadRefill(str: string): function(): string 
	local alreadyRead: boolean = false
	return function(): string
		if not alreadyRead then
			alreadyRead = true
			return str
		else
			return ""
		end
	end
end

function CoreHelpers._fileRefill(fname: string): function(): string
	local f = assert(io.open(fname, "r"))
	return function(): string
		local chunk = f:read(2^13)
		if not chunk then chunk = "" end
		return chunk
	end
end

function CoreHelpers.fileStream(fname: string): InputStream
	local istream = InputStream:new(CoreHelpers._fileRefill(fname))
	return istream
end

function CoreHelpers.oneReadInputStream(str: string): InputStream
	local iStream = InputStream:new(CoreHelpers._oneReadRefill(str))
	return iStream
end

function CoreHelpers.areNumbers(a: any, b: any): boolean
	return a is number and b is number
end

function CoreHelpers.getActiveDataStack(state: Environment): Stack
	return state.activeDataStack
end

function CoreHelpers.isNumber(token: string): boolean
	if tonumber(token) ~= nil then
		return true
	else
		return false
	end
end

function CoreHelpers.isWhitespace(chr: string): boolean
	return (chr == " " or
					chr == "\t" or
					chr == "\r" or
					chr == "\n" or
					chr == "\v" or
					chr == "\f")
end
function CoreHelpers.skipWhitespace(state: Environment)
	local chr = state.activeInputStream:curr()
	while (CoreHelpers.isWhitespace(chr)) do
		chr = state.activeInputStream:next()
	end
end

function CoreHelpers.popTwoOperands(state: Environment): any, any
	local stack = CoreHelpers.getActiveDataStack(state)
	local b: any = stack:pop()
	local a: any = stack:pop()
	return a, b
end


function CoreHelpers.parseToken(state: Environment): string
	local chr = ""
	local token = ""
	while(not CoreHelpers.isWhitespace(chr)) do
		token = token..chr
		chr = state.activeInputStream:next()
	end
	return token
end

function CoreHelpers.reset(env: Environment)
	env.instructionPointer.index = 0 -- will get incremented after this instruction
end

function CoreHelpers.ret(env: Environment)
	local retAddr = env.returnStack:pop() as Pointer
	env.instructionPointer = retAddr
end

function CoreHelpers.makeCall(body: {function(Environment)}): function(Environment)
	return function(e: Environment)
		e.returnStack:push(e.instructionPointer)
		e.instructionPointer = Pointer:new(body, 0)
	end
end





return CoreHelpers