module String_map = Map.Make (String)
type t = {
		id: Id.t;
		title: string;
		authors: Person.Set.t;
		date: Date.t;
		string_map: string String_map.t;
		stringset_map: String_set.t String_map.t;
		body: string;
	}

let blank ?(id=(Id.generate ())) () = {
		id;
		title = "";
		authors = Person.Set.empty;
		date = Date.({ created = now (); edited = ""});
		string_map = String_map.empty;
		stringset_map = String_map.empty;
		body = "";
	}

let compare = Stdlib.compare
let newest a b = Date.(compare a.date b.date)
let oldest a b = Date.(compare b.date a.date)
let str key m = try String_map.find (String.lowercase_ascii key) m.string_map with Not_found -> ""
let set key m = try String_map.find (String.lowercase_ascii key) m.stringset_map with Not_found -> String_set.empty
let str_set key m = String_set.to_string @@ set key m
let with_str_set m key str = { m with stringset_map = String_map.add (String.lowercase_ascii key) (String_set.of_string str) m.stringset_map }

let with_kv x (k,v) =
	let trim = String.trim in
	match String.lowercase_ascii k with
	| "body" -> { x with body = String.trim v }
	| "title"-> { x with title = trim v }
	| "id"	 -> (match v with "" -> x | s -> { x with id = s })
	| "author"
	| "authors" -> { x with authors = Person.Set.of_string (trim v)}
	| "date"			 -> { x with date = Date.{ x.date with created	 = Date.of_string v }}
	| "date-edited"-> { x with date = Date.{ x.date with edited		= Date.of_string v }}
	| "licences" | "topics" | "keywords" | "series" as k -> with_str_set x k v
	| k -> { x with string_map = String_map.add k (trim v) x.string_map }

let kv_of_string line = match Str.(bounded_split (regexp ": *")) line 2 with
	| [ key; value ] -> Str.(replace_first (regexp "^#\\+") "" key), value
	| [ key ] -> Str.(replace_first (regexp "^#\\+") "" key), ""
	| _ -> "",""

let of_header front_matter =
	let fields = List.map kv_of_string (Str.(split (regexp "\n")) front_matter) in
	List.fold_left with_kv (blank ~id:Id.nil ()) fields

let front_matter_body_split s =
	if Str.(string_match (regexp ".*:.*")) s 0
	then match Str.(bounded_split (regexp "^$")) s 2 with
			 | front::body::[] -> (front, body)
			 | _ -> ("", s)
	else ("", s)

let of_string s =
	let front_matter, body = front_matter_body_split s in
	try
		let note = { (of_header front_matter) with body } in
		if note.id <> Id.nil then Ok note else Error "Missing ID header"
	with _ -> Error ("Failed parsing" ^ s)

let to_string x = 
	let has_len v = String.length v > 0 in
	let s field value = if has_len value then field ^ ": " ^ value ^ "\n" else "" in
	let a value = if Person.Set.is_empty value then "" else "Authors: " ^ Person.Set.to_string value ^ "\n" in
	let d field value = match value with "" -> "" | s -> field ^ ": " ^ Date.rfc_string s ^ "\n" in
	let rows = [
		s "ID" x.id;
		d "Date"     x.date.Date.created;
		d "Edited"   x.date.Date.edited;
		s "Title" x.title;
		a x.authors;
		s "Licences" (str_set "licences" x);
		s "Topics"   (str_set "topics" x);
		s "Keywords" (str_set "keywords" x);
		s "Series"   (str_set "series" x);
		s "Abstract" (str "abstract" x);
		s "Alias"    (str "Alias" x)
	] in
	String.concat "" rows ^ "\n" ^ x.body

let string_alias t =
	let is_reserved = function
		| '!' | '*' | '\'' | '(' | ')' | ';' | ':' | '@' | '&' | '=' | '+' | '$'
			| ',' | '/' | '?' | '#' | '[' | ']' | ' ' | '\t' | '\x00' -> true
		| _ -> false
	in
	let b = Buffer.create (String.length t) in
	let filter char =
		let open Buffer in
		if is_reserved char then (try (if nth b (pred (length b)) <> '-' then add_char b '-') with Invalid_argument _ -> prerr_endline "reserved")
		else add_char b char
	in
	String.(iter filter (lowercase_ascii t));
	Buffer.contents b

let alias t = match str "alias" t with "" -> string_alias t.title | x -> x
let short_id t = Id.short t.id