local p = Proto("nifi", "Ni-Fi header")
local dt = DissectorTable.new("nifi")

p.fields.frame_type = ProtoField.uint16("nifi.type", "Frame type", base.DEC, {
	[0] = "Normal", -- Used for actual messages, ack packets
	[1] = "Announcement", -- TODO: send broadcast???
})
p.fields.original = ProtoField.bool("nifi.original", "Original") -- only 0 or 2
p.fields.gameid = ProtoField.uint16("nifi.gid", "Game ID", base.HEX, {
	[0xfffd] = "PictoChat (CMD)",
	[0x7dcb] = "PictoChat (ACK)",
	[0x5a5a] = "Mario Kart DS (CMD)",
	[0x7c02] = "Mario Kart DS (ACK)",
})
p.fields.magic = ProtoField.bytes("nifi.magic", "Magic")
p.fields.length = ProtoField.uint16("nifi.len", "Remaining message length")

local melon_type_enum_field = Field.new("melon.type.enum")

function p.init()
	-- register nifi as a subdissector for melon
	DissectorTable.get("melon"):add(0, p)
end

function p.dissector(buffer, pinfo, tree)
	local header_size = 12

	local subtree = tree:add(p, buffer(0, header_size), string.format("%s: %d bytes", p.description, header_size))
	subtree:add_le(p.fields.frame_type, buffer(0x00, 2))
	subtree:add_le(p.fields.original, buffer(0x02, 2))
	local original = buffer(0x02, 2):le_uint() > 0

	local melon_type = melon_type_enum_field()()
	local gameid_buf = buffer(0x04, 4)
	local gameid = 0
	if melon_type == 1 then -- CMD
		gameid_buf = gameid_buf(2, 2)
	elseif melon_type == 3 then -- ACK
		gameid_buf = gameid_buf(0, 2)
	end
	gameid = gameid_buf():le_uint()
	subtree:add_le(p.fields.gameid, gameid_buf)

	subtree:add_le(p.fields.magic, buffer(0x08, 2)) -- const 0x1401
	subtree:add_le(p.fields.length, buffer(0x0a, 2))
	local length = buffer(0x0a, 2):le_uint()

	-- pretty wireshark shit
	pinfo.cols.protocol = p.name
	pinfo.cols.info = string.format("GID %04x %s, %s", gameid, pinfo.cols.info, (original and "Original" or "Resend"))

	-- try to call subdissector for gameid
	dt:try(gameid, buffer(header_size, length):tvb(), pinfo, tree)

	return header_size
end