local p = Proto("pictochat", "PictoChat")

p.fields.unknown = ProtoField.uint16("pictochat.unknown", "Unknown")

p.fields.msg_type = ProtoField.uint8("pictochat.msg_type", "Message type", base.DEC, {
	[0] = "???",
	[1] = "???",
	[10] = "Message start", -- sent before a message packet
	[24] = "Message end", -- sent after multi-frame message body packets
	[48] = "User join", -- these packets contain a username
	[52] = "Keepalive", -- constantly spammed (keep alive?)
	[86] = "Message body", -- contains tile data for drawing
	[184] = "???", -- user leave??
})
p.fields.length = ProtoField.uint16("pictochat.length", "Length")
p.fields.host = ProtoField.ether("pictochat.host", "Room host")
p.fields.src = ProtoField.ether("pictochat.src", "Source")
p.fields.dst = ProtoField.ether("pictochat.dst", "Destination")
p.fields.payload_len = ProtoField.uint16("pictochat.payload_len", "Payload length")
p.fields.data_len = ProtoField.uint8("pictochat.data_len", "Data length")
p.fields.data_end = ProtoField.bool("pictochat.data_end", "Data end")
p.fields.data_offset = ProtoField.uint16("pictochat.data_offset", "Data offset")
p.fields.data_sequence = ProtoField.uint16("pictochat.data_sequence", "Data sequence")
p.fields.data = ProtoField.bytes("pictochat.data", "Data")
p.fields.sequence = ProtoField.uint16("pictochat.sequence", "Packet sequence")
p.fields.magic_trailer = ProtoField.bytes("pictochat.magic_trailer", "Magic (trailer)")
p.fields.user_mac = ProtoField.ether("pictochat.user.mac", "Address")
p.fields.user_name = ProtoField.string("pictochat.user.name", "Nickname")
p.fields.user_msg = ProtoField.string("pictochat.user.msg", "Message")
p.fields.user_color = ProtoField.uint16("pictochat.user.color", "Color", base.DEC, {
	[0] = "Greyish blue",
	[1] = "Brown",
	[2] = "Red",
	[3] = "Light pink",
	[4] = "Orange",
	[5] = "Yellow",
	[6] = "Lime",
	[7] = "Light green",
	[8] = "Dark green",
	[9] = "Turqoise",
	[10] = "Light blue",
	[11] = "Blue",
	[12] = "Dark blue",
	[13] = "Dark purple",
	[14] = "Light purple",
	[15] = "Dark pink",
})
p.fields.user_bday_month = ProtoField.uint8("pictochat.user.bday_month", "Month")
p.fields.user_bday_day = ProtoField.uint8("pictochat.user.bday_day", "Day")
p.fields.msg_start_len = ProtoField.uint8("pictochat.msg.start_len", "Total length")

local pc_src_field = Field.new("pictochat.src")
local pc_dst_field = Field.new("pictochat.dst")
local data_remaining = 0

local state = {}

function p.init()
	-- register pictochat as a subdissector for nifi
	local dt = DissectorTable.get("nifi")
	dt:add(0xfffd, p) -- CMD messages
	-- dt:add(0x7dcb, p) -- ACK messages
end

function p.dissector(buffer, pinfo, tree)
	local subtree = tree:add(p, buffer(), string.format("%s: %d bytes", p.description, buffer():len()))
	subtree:add_le(p.fields.unknown, buffer(0x00, 2))
	subtree:add_le(p.fields.unknown, buffer(0x02, 2))
	subtree:add_le(p.fields.dst, buffer(0x04, 6))
	subtree:add_le(p.fields.src, buffer(0x0a, 6))
	subtree:add_le(p.fields.host, buffer(0x10, 6))
  subtree:add_le(p.fields.sequence, buffer(0x16, 2))
  subtree:add_le(p.fields.unknown, buffer(0x18, 2))
  subtree:add_le(p.fields.unknown, buffer(0x1a, 2))
  subtree:add_le(p.fields.msg_type, buffer(0x1c, 1))
	local msg_type = buffer(0x1c, 1):le_uint()
  subtree:add_le(p.fields.unknown, buffer(0x1d, 1))
  subtree:add_le(p.fields.unknown, buffer(0x1e, 2))
	buffer = buffer(0x20)

	-- pretty wireshark shit
	pinfo.cols.protocol = p.name
	pinfo.cols.src = tostring(pc_src_field())
	pinfo.cols.dst = tostring(pc_dst_field())

	subtree:add_le(p.fields.payload_len, buffer(0x00, 2))
	local payload_length = buffer(0x00, 2):le_uint()
	buffer = buffer(0x02)
	local payload = subtree:add(buffer(0x00, payload_length), "Payload: " .. payload_length .. " bytes")
	local buffer_next = buffer(payload_length)

	if
		msg_type == 48 -- user join
	then
		payload:add_le(p.fields.user_mac, buffer(0x0a, 6)) -- endianness is fucked
		payload:add(p.fields.user_name, buffer(0x10, 20), buffer(0x10, 20):le_ustring())
		payload:add(p.fields.user_msg, buffer(0x24, 52), buffer(0x24, 52):le_ustring())
		payload:add_le(p.fields.user_color, buffer(0x58, 2))
		local bday = payload:add(buffer(0x5a, 2), string.format("Birthday: %02d/%02d", buffer(0x5a, 1):uint(), buffer(0x5b, 1):uint()))
		bday:add(p.fields.user_bday_month, buffer(0x5a, 1))
		bday:add(p.fields.user_bday_day, buffer(0x5b, 1))
	end

	if
		msg_type == 10 -- msg start
	then
		payload:add_le(p.fields.msg_start_len, buffer(0x04, 2))
		data_remaining = buffer(0x04, 2):le_uint()

		local segment = buffer(0):bytes()
		local buf = ByteArray.tvb(segment, "Complete message???")
	end

	if
		msg_type == 24 or -- msg end
		msg_type == 86 -- msg body
	then
		payload:add_le(p.fields.unknown, buffer(0x00, 2))
		payload:add_le(p.fields.data_len, buffer(0x02, 1))
		local data_length = buffer(0x02, 1):le_uint()

		if data_remaining > 0 then
			data_remaining = data_remaining - data_length
			pinfo.cols.info = string.format("Message body [remaining 0x%04x (%d) bytes]", data_remaining, data_remaining)
		end

		payload:add_le(p.fields.data_end, buffer(0x03, 1))
		-- This appears to be some kind of offset for indicating where to store the
		-- current frame's data in a larger buffer. Messages sent in multiple parts
		-- increment this value by 160 for each new original (p.fields.original ==
		-- True) message.
		payload:add_le(p.fields.data_offset, buffer(0x04, 2))
		payload:add_le(p.fields.unknown, buffer(0x06, 2)) -- usually 0

		buffer = buffer(0x08)
		-- This appears to be the actual message data (the drawing) sent as an
		-- array of 8x8 tiles.
		payload:add(p.fields.data, buffer(0, data_length))
		buffer = buffer(data_length)

		payload:add_le(p.fields.data_sequence, buffer(0x00, 2))
		payload:add_le(p.fields.unknown, buffer(0x02, 2)) -- copy
		subtree:add_le(p.fields.unknown, buffer(0x04, 2))
		buffer = buffer(0x06)
	end

	buffer = buffer_next -- after payload
	subtree:add_le(p.fields.magic_trailer, buffer(0x02, 2)) -- const 0xb8b6
end