ComputerCraft Get Binary Files From HTTP

-- Download, fix, and save binary files for ComputerCraft
-- You are free to copy, alter, and distribute this under the following conditions:
-- 1) You leave these comments and credits attached
-- 2) You do not make money off of this
-- Program by James0x57 - http://youtube.com/James0x57
-- ComputerCraft by Dan200 - http://www.computercraft.info/
-- You'll want to have the source file open in a hex editor on your desktop when you use this.
-- ComputerCraft command to add this program: pastebin get U0RSyAj0 bHTTP

local args = {...};
local rnTrap = false;

function originalByte(input, index, originalX)
    local byt = string.byte(input, index);
    local userIn = nil;

    -- \r\n is replaced with \n throughout, this tries to handle it
    if rnTrap then -- last character in source file was 0x0D, user said next byte should be 0x0A
        rnTrap = false;
        return 0x0A, index; -- the index did not advance to the next character to handle this
    end

    if byt <= 0x7F then
        while byt == 0x0A do
            print("Byte 0x0A encountered.");
            print(string.format("Please check offset 0x%X of source file.", originalX));
            print("Enter 1 if original byte = 0x0A");
            print("Enter 2 if original byte = 0x0D");
            userIn = string.find("12", read());
            if userIn ~= nil then
                byt = ({0x0A,0x0D})[userIn];
                if byt == 0x0D then
                    print(string.format("At offset 0x%X of the source file,", originalX+1));
                    print("is there a byte = 0x0A?");
                    print("(this is a special case we need to fix)");
                    print("Enter 1 for 'Yes', 2 for 'No'");
                    if read() == "1" then
                        rnTrap = true; -- enter a second byte ( 0x0A ) after this is done
                        index = index - 1;
                    end
                end
                break;
            end
        end
        return byt, index;
    end

    if byt == 0xC2 then
        index = index + 1;
        byt = string.byte(input, index);
    elseif byt == 0xC3 then
        index = index + 1;
        byt = string.byte(input, index)+0x40;
    elseif byt == 0xE2 then
        index = index + 1;
        byt = string.byte(input, index);
        index = index + 1;
        if byt == 0x82 then
            byt = 0x80;
        elseif byt == 0x84 then
            byt = 0x99;
        else
            byt = string.byte(input, index);
            if byt == 0x9A then
                byt = 0x82;
            elseif byt == 0x9E then
                byt = 0x84;
            elseif byt == 0xA6 then
                byt = 0x85;
            elseif byt == 0xA0 then
                byt = 0x86;
            elseif byt == 0xA1 then
                byt = 0x87;
            elseif byt == 0xB0 then
                byt = 0x89;
            elseif byt == 0xB9 then
                byt = 0x8b;
            elseif byt == 0x98 then
                byt = 0x91;
            elseif byt == 0x99 then
                byt = 0x92;
            elseif byt == 0x9C then
                byt = 0x93;
            elseif byt == 0x9D then
                byt = 0x94;
            elseif byt == 0xA2 then
                byt = 0x95;
            elseif byt == 0x93 then
                byt = 0x96;
            elseif byt == 0x94 then
                byt = 0x97;
            elseif byt == 0xBA then
                byt = 0x9b;
            end
        end
    elseif byt == 0xC5 then
        index = index + 1;
        byt = string.byte(input, index);
        if byt == 0xA0 then
            byt = 0x8a;
        elseif byt == 0x92 then
            byt = 0x8c;
        elseif byt == 0xBD then
            byt = 0x8e;
        elseif byt == 0xA1 then
            byt = 0x9a;
        elseif byt == 0x93 then
            byt = 0x9c;
        elseif byt == 0xBE then
            byt = 0x9e;
        elseif byt == 0xB8 then
            byt = 0x9f;
        end
    elseif byt == 0xEF then
        index = index + 2;
        while true do
            print("Indeterminate 0xEFBFBD encountered.");
            print(string.format("Please check offset 0x%X of source file.", originalX));
            print("Enter 1 if original byte = 0x81");
            print("Enter 2 if original byte = 0x8D");
            print("Enter 3 if original byte = 0x8F");
            print("Enter 4 if original byte = 0x90");
            print("Enter 5 if original byte = 0x9D");
            userIn = string.find("12345", read());
            if userIn ~= nil then
                byt = ({0x81,0x8D,0x8F,0x90,0x9D})[userIn];
                break;
            end
        end
    else
        index = index + 1;
        byt = string.byte(input, index);
        if byt == 0x9C then
            byt = 0x98;
        elseif byt == 0x92 then
            byt = 0x83;
        elseif byt == 0x86 then
            byt = 0x88;
        end
    end
    return byt, index;
end


if #args > 1 and #args[1] > 10 and #args[2] > 2 and string.find(args[1], "http://", 1, 1, true)
    -- and string.find(args[1], ".nbs", -4, true) ~= nil -- example force source file type
    -- and string.find(args[2], ".nbs", -4, true) ~= nil -- example force destination file type
then
    local url = args[1];
    local fn = args[2];
    local dt = http.get(url).readAll();
    local fh = fs.open(fn, 'wb');
    local ret = "";
    local userIn = "";
    local temp = nil;
    local byt = 0;
    local originalX = 0;
    if dt ~= nil and #dt > 0 then
        local x = 1;
        while x <= #dt do
            byt, x = originalByte(dt, x, originalX);
            originalX = originalX + 1;
            if args[4] == 1 then -- debug mode
                ret = ret .. string.format("0%X ", byt):sub(-3);
                if #ret == 48 then
                    print(ret);
                    ret = "";
                end
            end
            if originalX % 250 == 0 then
                os.sleep(0); --yeild or die
            end
            fh.write(byt);
            x = x+1;
        end
    end

    if args[4] == 1 then -- debug mode
        print(ret);
    end

    if args[3] ~= 0 then
        print("If the last byte of the source file is either");
        print("0x0D (\\r) or 0x0A (\\n), then it is missing.");
        print("The last byte in the new file is 0x" .. string.format("0%X ", byt):sub(-3));
        print(string.format("its offset is 0x%X", originalX-1));
        while true do
            print("Do you want to appened another byte?");
            print("Enter 1 for 'Yes', 2 for 'No'");
            if read() == "1" then
                print("Enter the byte prefixed with \"0x\" to use hex:");
                userIn = read();
                temp, userIn = pcall(tonumber, userIn);
                if temp == true and userIn < 0x100 then
                    fh.write(userIn);
                    print(string.format("Appeneded byte! 0x%X", userIn));
                else
                    print("ERROR - Bad input");
                end
            else
                break;
            end
        end
    end
    fh.close();
    print("Binary file saved!");
else
    print("Bad arguments.");
end