local p = Proto("melon", "MelonDS Ni-Fi header")

p.fields.magic = ProtoField.uint32("melon.magic", "Magic", base.HEX)
p.fields.src = ProtoField.int32("melon.src", "Instance ID", base.DEC)
p.fields.type = ProtoField.new("Type", "melon.type", ftypes.UINT32)
p.fields.type_enum = ProtoField.uint16("melon.type.enum", "Numeric message type enum", base.DEC, {
	[0] = "Regular",
	[1] = "CMD",
	[2] = "Reply",
	[3] = "ACK",
})
p.fields.type_aid = ProtoField.uint16("melon.type.aid", "Message type \"aid\" value")
p.fields.length = ProtoField.uint32("melon.len", "Remaining message length", base.DEC)
p.fields.timestamp = ProtoField.uint64("melon.timestamp", "Timestamp", base.DEC)

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

local txhdr_dissector = Dissector.get("txhdr")
local rxhdr_dissector = Dissector.get("rxhdr")

function p.dissector(buffer, pinfo, tree)
	local header_size = 0x18
	-- check buffer size
	if buffer:len() < header_size then return 0 end
	-- check magic ("NIFI")
	if buffer(0x00, 4):uint() ~= 0x4e494649 then return 0 end

	local subtree = tree:add(p, buffer(0, header_size), string.format("%s: %d bytes", p.description, header_size))
	subtree:add(p.fields.magic, buffer(0x00, 4))

	local instance = buffer(0x04, 4):le_uint()
	subtree:add_le(p.fields.src, buffer(0x04, 4))

	local type_tree = subtree:add_le(p.fields.type, buffer(0x08, 4))
		type_tree:add_le(p.fields.type_enum, buffer(0x08, 2))
		type_tree:add_le(p.fields.type_aid, buffer(0x0a, 2))

	subtree:add_le(p.fields.length, buffer(0x0c, 4))
	subtree:add_le(p.fields.timestamp, buffer(0x10, 8))

	-- pretty wireshark shit
	pinfo.cols.protocol = p.name
	pinfo.cols.src = string.format("instance %d", instance)
	pinfo.cols.info = p_type_enum_field().display

	-- melonds packets always contain NIFI packets
	local next_dissector = txhdr_dissector
	-- if instance ~= 0 then
	-- 	next_dissector = rxhdr_dissector
	-- end
	next_dissector:call(buffer(header_size):tvb(), pinfo, tree)

	return header_size
end