local com
function prompt()
    local block
    local data_table

    io.write("\n")
    print_help()

    while true do
        io.write("> ")
        input = io.read("*l")

        if input == "help" then
            print_help()
        elseif input == "quit" or input == "q" or input == "exit" then
            break
        elseif input == "create" then
            com:advertise_blockchain("test")
        elseif input == "new" then
            block = Block()
            if not block then
                error("An error has occurred: the block has not been created\n")
                os.exit()
            else
                print("Your block has been succefuly created.")
                print("Add data on this block before commiting it and advertising it.\n")
            end
        elseif input == "data" then
            if not block then
                print("You don't have any new current block to add data.")
                print("Please, create a new block to add data.\n")
            else
                print_add_help()
                while true do
                    io.write("current_block> ")
                    data_block = io.read("*l")

                    if data_block == "show" then
                        -- print data of your current block
                        data_table = block:get_data()

                        if table_is_empty(data_table) then
                            print("There is no data on this block yet\n")
                        else
                            print("\nINDEX\tDATA")
                            for key,value in pairs(data_table) do
                                print(key, value)
                            end
                            io.write("\n")
                        end
                    elseif data_block == "add" then
                        -- write data and put them on your block
                        print("\nWrite your current Block new data:")

                        -- prompt
                        io.write("current_block:add> ")

                        -- write new data
                        data_add = io.read("*l")
                        print("New data: " .. data_add .. "\n")

                        -- checking if the data is satisfactory to the user
                        print("Put this data on my block ?")
                        print("\ty/yes -- put it")
                        print("\tn/no -- quit without put any new data\n")
                        data_add_check = io.read("*l")

                        if data_add_check == "y" or data_add_check == "yes" then
                            -- set data on this block
                            block:set_data(data_add)
                        elseif data_add_check == "n" or data_add_check == "no" then
                            break
                        else
                            print("Invalid command\n")
                        end
                    elseif data_block == "remove" then
                        -- remove a particular data you put on your block
                        if table_is_empty(data_table) then
                            print("You don't have any data on your block\n")
                        else
                            print("\nWrite the index of the data you want remove (0 to remove all data):")
                            -- prompt
                            io.write("current_block:remove> ")
                            local index_remove = io.read("*n")

                            local table_length = table_length(data_table)
                            if index_remove <= table_length then
                                if index_remove == 0 then
                                    print("Remove all the data of this block ?")
                                    print("\ty/yes -- remove all")
                                    print("\tn/no -- quit without remove")
                                    local remove_all_check = io.read("*l")
                                        if remove_all_check == "y" or remove_all_check == "yes" then
                                            -- remove all data on this block
                                            block:remove_all()
                                        elseif remove_all_check == "n" or remove_all_check == "no" then
                                            break
                                        else
                                            print("Invalid command\n")
                                        end
                                else
                                    -- remove the data at the specify index
                                    block:remove(index_remove)
                                    print("Data at index " .. index_remove .. " have been remove\n")
                                end
                            else
                                print("Invalid index.\n")
                                print("Do \"show\" to see your data with their index\n")
                            end
                        end
                    elseif data_block == "clear" then
                        -- remove all data of your block
                        print("clear")
                    elseif data_block == "help_add" then
                        -- display the add play
                        print_add_help()
                    elseif data_block == "help" then
                        -- display the general help
                        print_help()
                    elseif data_block == "quit" or data_block == "q" or data_block == "exit" then
                        -- quit the add command
                        break
                    else
                        print("Invalid command\n")
                end
            end
        end
        elseif input == "commit" then
            print("commit")
        elseif input == "advertise" then
            print("advertise")
        elseif input == "request" then
            print("request")
        elseif input == "share" then
            print("share")
        elseif input == "validate" then
            print("validate")
        elseif input == "deny" then
            print("deny")
        elseif input == "accept" then
            print("accept")
        else
            print("Invalid command\n")
        end
    end
end