type info_t = { version: int; name: string; archivists: string list }
type text_t = { id: Msgpck.t; time: Msgpck.t; title: Msgpck.t; authors: Msgpck.t }
type t = { info: info_t; fields: string list; texts: Msgpck.t; peers: Msgpck.t }

let of_id id = Msgpck.Bytes (Id.to_bytes id)
let to_id pck_id = Id.of_bytes Msgpck.(to_bytes pck_id)

let person p = Msgpck.String (Person.to_string p)
let persons ps = List.rev @@ Person.Set.fold (fun p a -> person p :: a) ps []

let of_set field t =
	List.rev @@ String_set.fold (fun s a -> Msgpck.String s :: a) (Text.set field t) []

let date = function
	| None -> Int32.zero
	| Some date ->
		let days, ps = Ptime.Span.to_d_ps (Ptime.to_span date) in
		Int32.add Int32.(mul (of_int days) 86400l) Int64.(to_int32 (div ps 1000000000000L))

let to_sec = function
	Msgpck.Int i -> Int32.of_int i | Msgpck.Uint32 i -> i | x -> Msgpck.to_uint32 x

let public_peers () =
	Peers.fold_file (fun x a -> Msgpck.String x :: a) [] Peers.public_fname

let fields = Msgpck.(List [String "id"; String "time";  String "title"; String "authors"; String "topics"])
let to_fields fieldpack = List.map Msgpck.to_string (Msgpck.to_list fieldpack)

let to_pack a t =
	let open Text in
	Msgpck.(List [
		Bytes (Id.to_bytes t.uuid); of_uint32 (date (Date.listing t.date));
		String t.title; List (persons t.authors); List (of_set "topics" t)
	]) :: a

let pack_filename ?(filename="index.pck") archive =
	let dir = Store.KV.find "Export-Dir" archive.File_store.kv in (*raises Not_found*)
	dir ^ "/" ^ filename

let to_info = function
	| Msgpck.List (v::n::a::[]) ->
		let archivists = List.map Msgpck.to_string (Msgpck.to_list a) in
		Msgpck.({version = to_int v; name = to_string n; archivists})
	| _ -> invalid_arg "Pack header"

let unpack = function
	| Msgpck.List (i::f::texts::[]) ->
		Some { info = to_info i; fields = to_fields f; texts; peers = Msgpck.List [] }
	| Msgpck.List (i::f::texts::peers::[]) ->
		Some { info = to_info i; fields = to_fields f; texts; peers }
	| _ -> None

let list filename = try
	let texts_list = function
	| Msgpck.List (_info :: _fields :: [texts]) -> Msgpck.to_list texts
	| _ -> prerr_endline "malformed feed"; [] in
	let _pos, data = Msgpck.StringBuf.read @@ File_store.to_string filename in
	Ok (texts_list data)
	with Not_found -> Error "unspecified export dir"

let contains text = function
	| Msgpck.List (id::_time::title::_authors::_topics::[]) ->
		(match Id.of_bytes (Msgpck.to_bytes id) with
		 | None -> prerr_endline ("Invalid id for " ^ Msgpck.to_string title); false
		 | Some id -> text.Text.uuid = id)
	| _ -> prerr_endline ("Invalid record pattern"); false

let pack archive records =
	let header_pack = List.fold_left to_pack [] records in
	let info = Msgpck.(List [Int 0; String archive.File_store.name; List (persons archive.archivists)]) in
	Bytes.to_string @@ Msgpck.Bytes.to_string
		(List [info; fields; Msgpck.List header_pack; Msgpck.List (public_peers ())])

let add archive records =
	let fname = pack_filename archive in
	let append published (t, _f) = if List.exists (contains t) published then published else to_pack published t in
	match list fname with Error e -> prerr_endline e | Ok published_list ->
		let header_pack = List.fold_left append published_list records in
		let archive = Msgpck.(List [Int 0; String archive.File_store.name;
			List (persons archive.archivists)]) in
		File_store.file fname @@ Bytes.to_string
			@@ Msgpck.Bytes.to_string (List [archive; fields; Msgpck.List header_pack])

let unpublish _archive _records = ()