#!/usr/bin/env lua5.1

--[[
This is a Gemtext→HTML static site generator. This program:
* Searches src/ for directories, then mirrors the directory tree to html/
* Reads all files in src/, attempts to render them from Gemtext to html, then outputs to the appropriate .html file in html/
* Reads files in src/w/ for h2 elements with dates in YYYY-MM-DD format, using them to render an RSS feed to html/index.xml; entries in the feed are sorted in descending order by file name so be sure to name them by date
* Recursively copies files from static/ to html/
This site generator depends on LuaFileSystem and geez
https://lunarmodules.github.io/luafilesystem/
https://pixelo789.codeberg.page/geez
It is assumed that LuaFileSystem is installed using LuaRocks, and that geez's geez.lua is placed in the same directory as this file.
]]--

local lfs = require "lfs"

local function iteratefiles(path, mode)
	local dattr = lfs.attributes(path)
	assert(dattr.mode == "directory")
	for file in lfs.dir(path) do
		if file ~= "." and file ~= ".." then
			local filepath = ("%s/%s"):format(path, file)
			local attr = lfs.attributes(filepath)
			if attr.mode == mode then
				coroutine.yield(filepath)
			end
			if attr.mode == "directory" then
				iteratefiles(filepath, mode)
			end
		end
	end
end

local function eachfile(path, mode)
	return coroutine.wrap(function() iteratefiles(path, mode) end)
end

local dirs = {}
for dir in eachfile("src", "directory") do table.insert(dirs, dir) end

do -- Set up output directory
	local hattr = lfs.attributes "html"
	if hattr and hattr.mode ~= "directory" then
		os.execute "rm html"
		hattr = nil
	end
	if not hattr then lfs.mkdir("html") end
	os.execute "cp -r static/* html"
end

-- Recreate the src/ directory tree in html/
for _, dir in ipairs(dirs) do
	local path = dir:gsub("^src", "html")
	lfs.mkdir(path)
end

-- File Rendering

local files = {}
for file in eachfile("src", "file") do table.insert(files, file) end
table.sort(files, function(a, b) return a > b end)

local htmltemplate = ""
do
	local file = io.open("templates/index.html", "r") or error "failed to load templates/index.html"
	for line in file:lines() do
		htmltemplate = htmltemplate .. line .. "\n"
	end
end

local geez = require "geez"

local function rendergemtext(path)
	local source = io.open(path, "r")
	local ast = geez.GeminiAST()
	local gemtext = ""
	local isroot = path:match "^src/index.gmi"
	local ispost = path:match "^src/w/"
	-- Manually insert links at the top of pages
	if not isroot then gemtext = gemtext .. "=>	/index.gmi	vtrlx.ca (Victoria Lacroix)\n" end
	if ispost then gemtext = gemtext .. "=>	/posts.gmi	All posts\n" end
	for line in source:lines() do
		gemtext = gemtext .. line .. "\n"
	end
	ast:load_str(gemtext)
	local html = ast:get_html_doc {
		indent_level = 1,
	}
	local path = path:gsub("^src", "html"):gsub(".gmi$", ".html")
	local dest = io.open(path, "w")
	local title = html:match "<h1>([^\n]*)</h1>"
	local date = html:match "<h2>%d%d%d%d%-%d%d%-%d%d</h2>"
	if not title then
		error(("no title: %s"):format(path))
	elseif ispost and not date then
		error(("no date on post: %s"):format(path))
	end
	local page = htmltemplate:format(title, html)
	dest:write(page)
	dest:close()
	return html
end

local atomfeed = [[
<?xml version="1.0" encoding="UTF-8"?>
<feed xmlns="http://www.w3.org/2005/Atom" xml:lang="en">
	<title>Victoria Lacroix's Writings</title>
	<link rel="self" type="application/atom+xml" href="https://vtrlx.ca/index.xml"/>
	<link rel="alternate" type="text/html" href="https://vtrlx.ca/"/>
	<updated>%sT12:00:00-05:00</updated>
	<id>https://vtrlx.ca/index.xml</id>
]]
local entrytemplate = [[
	<entry xml:lang="en">
		<title>%s</title>
		<published>%sT12:00:00-05:00</published>
		<updated>%sT12:00:00-05:00</updated>
		<author><name>Victoria Lacroix</name></author>
		<link rel="alternate" type="text/html" href="%s"/>
		<id>%s</id>
		<content type="html" xml:base="%s">
%s
		</content>
	</entry>
]]

local latest = ""
local function addarticle(path, html)
	local title = html:match "<h1>([^\n]*)</h1>"
	local date = html:match "<h2>(%d%d%d%d%-%d%d%-%d%d)</h2>"
	-- The last header containing "Update (xxxx-xx-xx)" where xxxx-xx-xx is a date will be treated as the last update time.
	local updated = date
	assert(title, date, updated)
	for m in html:gmatch "<h2>Update%s+%((%d%d%d%d%-%d%d%-%d%d)%)</h2>" do
		updated = m
	end
	if updated > latest then latest = updated end
	local url = "https://vtrlx.ca/" .. path:gsub("^src/", ""):gsub(".gmi$", ".html")
	html = geez.escape_text(html)
	local entry = entrytemplate:format(title, date, updated, url, url, url, html)
	atomfeed = atomfeed .. entry
end

for _, path in ipairs(files) do
	if not path:match ".gmi$" then
		error(("unaccepted file type: %s"):format(path))
	end
	local html = rendergemtext(path)
	if path:match "^src/w/%d%d%d%d%-%d%d%-%d%d%-.*.gmi$" then
		addarticle(path, html)
	end
end

do	-- Save RSS/atom/whatever feed to /index.xml
	atomfeed = atomfeed:gsub("%%s", latest) .. "</feed>\n"
	local feed = io.open("html/index.xml", "w")
	feed:write(atomfeed)
	feed:close()
end

-- Copy this script to main.lua in the rendered site, so that the latest version is live
os.execute "cp main.lua html/main.lua"