Blockblockchain

-- BlockBlockchain ver 0.4
local computer = require("computer")
local c = require("component")
local data = c.data
local internet = c.internet
local os = require("os")

Block = {}

--Binary to hexadecimal function
function tohex(str)
    return (str:gsub('.', function (c)
        return string.format('%02X', string.byte(c))
    end))
end

--Block class
function Block:new(index, timestamp, data, previous_hash)
    newObj = {index = index,
            timestamp = timestamp,
            data = data,
            previous_hash = previous_hash,
            hash = Block:hash_block(index, timestamp, data, previous_hash)}
    print("Hash "..hash) -- схуяли оно только один раз, только при генерации генезис-блока, выполняется
    self.__index = self
    return setmetatable(newObj, self)
end

--Generate hash for block
function Block:hash_block(index, timestamp, data, previous_hash)
    return tohex(data.sha256(tostring(index)..
                tostring(timestamp)..
                tostring(data)..
                tostring(previous_hash)))

end

--Creating genesis (first) block
function create_genesis_block()
    return Block:new(0, computer.uptime(), "start", 0)
end

--Generating next block for blockchain
function next_block(last_block)
    local new_index = last_block["index"] + 1
    local new_timestamp = last_block["timestamp"] + computer.uptime()
    local new_data = "Block #"..tostring(new_index)
    local new_hash = last_block["hash"]
    return Block:new(new_index, new_timestamp, new_data, new_hash)
end



--TEST BEGINS HERE
blockchain = {}
blockchain[1] = create_genesis_block()
previous_block = blockchain[#blockchain]
for i=1, 5 do
    block_to_add = next_block(previous_block)
    blockchain[#blockchain+1] = block_to_add
    previous_block = block_to_add
    print("Block #"..block_to_add["index"].." has been created. Hash:" ..tohex(block_to_add["hash"])..". Previous: "..tohex(block_to_add["previous_hash"]))
end