local ws = assert(http.websocket("wss://bitmap-ws.alula.me/"))

function parse_u16(data)
    local v = table.remove(data, 1)
    v = bit.bor(v, bit.blshift(table.remove(data, 1), 8))
    return v, data
end

function parse_u32(data)
    local v = table.remove(data, 1)
    v = bit.bor(v, bit.blshift(table.remove(data, 1), 8))
    v = bit.bor(v, bit.blshift(table.remove(data, 1), 16))
    v = bit.bor(v, bit.blshift(table.remove(data, 1), 24))
    return v, data
end

local chunk_id = 421
local chunk_state = { 0x48, 0x65, 0x6c, 0x6c, 0x6f }

local function send_chunk_request(chunk)
    ws.send(string.char(0x10, bit.band(chunk, 0xFF), bit.band(bit.brshift(chunk, 8), 0xFF)), true)
end

local function send_chunk_subscribe_request(chunk)
    ws.send(string.char(0x14, bit.band(chunk, 0xFF), bit.band(bit.brshift(chunk, 8), 0xFF)), true)
end

parallel.waitForAll(function()
    while true do
        local data, is_binary = ws.receive()
        data = { string.byte(data, 1, #data) }
        local opcode = table.remove(data, 1)
        if opcode == 0x00 then -- hello
            ver_major, data = parse_u16(data)
            ver_minor, data = parse_u16(data)
            os.queueEvent("obcb:hello", ver_major, ver_minor)
        elseif opcode == 0x01 then
            local clients = parse_u32(data)
            -- TODO: show them somewhere
            os.queueEvent("obcb:clients", clients)
        elseif opcode == 0x11 then
            chunk_index, data = parse_u16(data)
            if chunk_index == chunk_id then
                chunk_state = data
            end
            os.queueEvent("obcb:update")
        elseif opcode == 0x12 then
            offset, chunk = parse_u32(data)
            local c_id = math.floor(offset / 32768)
            local b_off = offset % 32768
            for i = 1, 32 do
                chunk_state[i + b_off] = chunk[i]
            end
            os.queueEvent("obcb:update")
        else
            print(table.unpack(data))
        end
    end
end,
function()
    local mon = peripheral.wrap("monitor_0")
    mon.setTextScale(0.5)
    mon.clear()
    local tw, th = term.getSize()
    send_chunk_request(chunk_id)
    send_chunk_subscribe_request(chunk_id)
    term.setCursorPos(1, 3)
    print("Showing chunk " .. chunk_id)
    print(string.format("Screen: %dx%d", mon.getSize()))
    while true do
        local ev = { os.pullEvent() }
        if ev[1] == "char" and ev[2] == "q" then
            break
        elseif ev[1] == "obcb:hello" then
            term.setCursorPos(1, 1)
            print(string.format("Hello: obcb v%d.%d", ev[2], ev[3]))
        elseif ev[1] == "obcb:clients" then
            term.setCursorPos(1, 2)
            print("Clients: " .. ev[2])
        elseif ev[1] == "obcb:update" then
            for y = 1, 81 do
                mon.setCursorPos(1, y)
                local tx = {}
                local bg = {}
                local fg = {}
                for x = 1, 164 do
                    local i = (y - 1) * 164 + (x - 1)
                    tx[x] = chunk_state[i * 2 + 1]
                    fg[x] = string.format("%x", bit.band(chunk_state[i * 2 + 2], 0xF))
                    bg[x] = string.format("%x", bit.band(bit.brshift(chunk_state[i * 2 + 2], 4), 0xF))
                end
                mon.blit(string.char(table.unpack(tx)), table.concat(bg), table.concat(fg))
            end
        end
    end
end)

ws.close()