package Encoder
import BigString
import BigNum
import Execute
import SeqWorker
// Encodes numbers into ones with higher bases and represents them in the shortest possible way
// Credits: Pipedream
public constant maxInt = 2147483647
public constant maxHash = 1000

public class Encoder
	string charset
	int base
	real digits	= 0.
	BigNum bignum

	construct(string charset)
		this.charset = charset
		this.base = charset.length()
		this.bignum = new BigNum(base)

	ondestroy
		destroy bignum

	function encode(int val, int max)
		digits = digits + log(max+1.,base+0.)
		bignum.mulSmall(max+1)
		bignum.addSmall(val)
		Log.trace("encoded val: " + val.toString() + " max: " + max.toString())

	function decode(int max) returns int
		return bignum.divSmall(max+1)

	function isEmpty() returns boolean
		return bignum.isZero()

	function length() returns real
		return digits

	function clean()
		bignum.clean()

	function pad()
		BigNum_l cur = bignum.list
		BigNum_l prev = null
		int maxlen = R2I(1.0 + length())

		while cur != null
			prev = cur
			cur = cur.next
			maxlen--

		while maxlen > 0
			prev.next = new BigNum_l()
			prev = prev.next
			maxlen--


	function toString(BigString big, PayloadCallback onFinish)
		Log.debug("toString digits: " + digits.toString())
		BigNum_l _cur = bignum.list
		doSeq() cb ->
			var continue = true
			if _cur != null
				big.addString(itochar(_cur.leaf))
				_cur = _cur.next
			else
				continue = false
				onFinish.customData = big castTo int
				onFinish.doStep()
			return continue

	function fromString(BigString bs, PayloadCallback onFinishString)
		int _i = 0
		var _cur = new BigNum_l()
		bignum.list = _cur
		Log.debug("from String")
		doSeq() cb ->
			var continue = true
			_cur.leaf = chartoi(bs.getString(_i, 1))
			if _i < bs.getLength()-1
				_cur.next = new BigNum_l()
				_cur = _cur.next
				_i++
			else
				continue = false
				destroy bs
				onFinishString.doStep()
			return continue

	function hash() returns int
		Log.debug("hash")
		int hash = 0
		int x
		BigNum_l cur = bignum.list
		while cur != null
			x = cur.leaf
			hash = ModuloInteger(hash+79*hash div (x+1) + 293*x div (1+hash - (hash div base)*base) + 479,maxHash)
			cur = cur.next
		Log.debug("hashed")
		return hash

	int hash = -1
	function save(BigString bs, PayloadCallback onFinish)
		Log.debug("save1")
		execute(() -> clean())
		Log.debug("save2")
		hash = -1
		execute() ->
			hash = hash()

		nullTimer() ->
			Log.debug("hash: " + hash.toString())
			execute(() -> encode(hash,maxHash))
			Log.debug("encoded hash")
			execute(() -> clean())
			Log.debug("clean")
			execute(() -> pad())
			Log.debug("before toString bs: " + bs.getLength().toString())
			execute(() -> toString(bs, onFinish))

	var inputhash = -1
	var comparehash = -1
	function load(BigString bs, PayloadCallback onFinishLoad)
		inputhash = -1
		comparehash = -1
		fromString(bs) cb ->
			Log.debug("loaded..")
			execute() ->
				inputhash = decode(maxHash)

			Log.debug("decoded..")
			execute(() -> clean())
			Log.debug("claned..")
			execute() ->
				comparehash = hash()

			Log.debug("hashed..")
			onFinishLoad.customData = (inputhash == comparehash).toInt()
			onFinishLoad.doStep()



	function chartoi( string c ) returns int
		int i = 0
		let cs = charset
		let len = base
		while i < len and c != SubString(cs,i,i+1)
			i = i + 1
		return i

	function itochar( int i ) returns string
		return SubString(charset,i,i+1)