cambridge/tetris/randomizers/history_6rolls_35bag.lua

local Randomizer = require 'tetris.randomizers.randomizer'

local History6Rolls35PoolRandomizer = Randomizer:extend()

function History6Rolls35PoolRandomizer:initialize()
    self.first = true
	self.history = {"Z", "S", "Z", "S"}
	self.pool = {
		"I", "I", "I", "I", "I",
        "T", "T", "T", "T", "T",
        "L", "L", "L", "L", "L",
        "J", "J", "J", "J", "J",
        "S", "S", "S", "S", "S",
        "Z", "Z", "Z", "Z", "Z",
        "O", "O", "O", "O", "O",
	}
    self.droughts = {
        I = 0,
        T = 0,
        L = 0,
        J = 0,
        S = 0,
        Z = 0,
        O = 0,
    }
end

function History6Rolls35PoolRandomizer:generatePiece()
    local index, x
    if self.first then
        local prevent = {"S", "Z", "O"}
        repeat
            index = math.random(#self.pool)
            x = self.pool[index]
        until not inHistory(x, prevent)
        self.first = false
    else
        for i = 1, 6 do
            index = math.random(#self.pool)
            x = self.pool[index]
            if not inHistory(x, self.history) or i == 6 then
                break
            end
        end
    end
    self.pool[index] = self:updateHistory(x)
    return x
end

function History6Rolls35PoolRandomizer:updateHistory(shape)
	table.remove(self.history, 1)
	table.insert(self.history, shape)

    local highdrought
    local highdroughtcount = 0
    for k, v in pairs(self.droughts) do 
        if k == shape then
            self.droughts[k] = 0
        else
            self.droughts[k] = v + 1
            if v >= highdroughtcount then
                highdrought = k
                highdroughtcount = v
            end
        end
    end
	return highdrought
end

function inHistory(piece, history)
	for idx, entry in pairs(history) do
		if entry == piece then
			return true
		end
	end
	return false
end

return History6Rolls35PoolRandomizer