--BPB (Blob Parameter Block) structure: for using blob filters when reading/writing blobs
--encode(bpb_options_t) -> BPB encoded string.
--pass it to isc_open_blob2() or isc_create_blob2() to open/create a filtered blob object.

local pb = require 'fbclient_pb'

local codes = {
	isc_bpb_source_type       = 1, --signed byte: subtype at application endpoint; default = ?
	isc_bpb_target_type       = 2, --signed byte: subtype at database endpoint; default = ?
	isc_bpb_type              = 3, --blob type: isc_bpb_type_segmented or _stream, default is _segmented
	isc_bpb_source_interp     = 4, --charset at application endpoint; default = ?
	isc_bpb_target_interp     = 5, --charset at database endpoint; default = ?
	isc_bpb_filter_parameter  = 6, --filters convert one blob type to another; doc on filters is sparse at best
	isc_bpb_storage           = 7, --blob storage: optional, isc_bpb_storage_main or _temp, default is _main
}

local isc_bpb_type_enum = {
	isc_bpb_type_segmented = 0,
	isc_bpb_type_stream = 1,
}

local isc_bpb_storage_enum = {
	isc_bpb_storage_main = 0,
	isc_bpb_storage_temp = 2,
}

local encoders = {
	isc_bpb_source_type      = pb.encode_schar,
	isc_bpb_target_type      = pb.encode_schar,
	isc_bpb_type             = pb.encode_enum(isc_bpb_type_enum),
	isc_bpb_source_interp	 = pb.encode_short,
	isc_bpb_target_interp	 = pb.encode_short,
	isc_bpb_filter_parameter = pb.encode_short,
	isc_bpb_storage          = pb.encode_enum(isc_bpb_storage_enum),
}

local function encode(opts)
	return pb.encode('BPB', '\1', opts, codes, encoders)
end

return encode