let esc = Converter.Html.esc

let element tag content = "<" ^ tag ^ ">" ^ content ^ "</" ^ tag ^ ">"

let opt_element tag_name content =
  if content <> ""
  then element tag_name content
  else ""

module P = Parsers.Plain_text.Make (Converter.Html)

let id txt = "<id>urn:uuid:" ^ Logarion.(Id.to_string txt.Text.uuid) ^ "</id>"
let title text = "<title>" ^ esc text.Logarion.Text.title ^ "</title>"

let authors text =
	let u acc addr = acc ^ element "uri" (Uri.to_string addr) in
  let open Logarion in
  let fn txt a =
  	a ^ "<author>" ^ (opt_element "name" @@ esc txt.Person.name)
  	^ (List.fold_left u "" txt.Person.addresses)
  	^ "</author>" in
  Person.Set.fold fn text.Text.authors ""

let updated txt = let open Logarion in
	"<updated>"^ Date.(txt.Text.date |> listing |> rfc_string) ^"</updated>"
	
let htm_entry base_url text =
  let open Logarion in
  let u = Text.short_id text in
  "<entry><link rel=\"alternate\" href=\"" ^ base_url ^ "/" ^ u ^ ".htm\" />"
  ^ title text ^ id text ^ updated text ^ authors text
  ^ (opt_element "summary" @@ esc @@ Text.str "abstract" text)
  ^ String_set.fold (fun elt a -> a ^ "<category term=\"" ^ esc elt ^ "\"/>") (Text.set "topics" text) ""
  ^ "<content type=\"xhtml\"><div xmlns=\"http://www.w3.org/1999/xhtml\">"
  ^ P.of_string text.body ""
  ^ "</div></content></entry>\n"

let gmi_entry base_url text =
  let open Logarion in
  let u = Text.short_id text in
  "<entry><link rel=\"alternate\" href=\"" ^ base_url ^ "/" ^ u ^ ".gmi\" />"
  ^ title text ^ id text ^ updated text ^ authors text
  ^ (opt_element "summary" @@ esc @@ Text.str "abstract" text)
  ^ String_set.fold (fun elt a -> a ^ "<category term=\"" ^ elt ^ "\"/>") (Text.set "topics" text) ""
  ^ "</entry>\n"

let feed title archive_id base_url alternate_type texts =
	let entry, self = match alternate_type with
		| "text/gemini" -> gmi_entry, base_url^"/gmi.atom"
		| "text/html" | _ -> htm_entry, base_url^"/feed.atom" in
  {|<?xml version="1.0" encoding="utf-8"?><feed xmlns="http://www.w3.org/2005/Atom" xml:base="|} ^ base_url ^ {|"><title>|}
  ^ title ^ {|</title><link rel="alternate" type="|} ^ alternate_type ^ {|" href="|}
  ^ base_url ^ {|/" /><link rel="self" type="application/atom+xml" href="|}
  ^ self ^ {|" /><id>urn:uuid:|} ^ Logarion.Id.to_string archive_id ^ "</id><updated>"
  ^ Ptime.to_rfc3339 (Ptime_clock.now ()) ^ "</updated>\n"
  ^ List.fold_left (fun acc t -> acc ^ entry base_url t) "" texts
  ^ "</feed>"