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#!/usr/bin/env lua5.3
-- this software is licensed under the terms of the GNU affero public license
-- v3 or later. view LICENSE.txt for more information.

-- if you host your own instance, please change the email address in the about
-- page and clearly distinguish your instance from https://zzcxz.citrons.xyz.

local env = os.getenv

local f = io.open("/dev/urandom", 'r')
local e = f and f:read(1)
if f then f:close() end
math.randomseed(os.time() + string.byte(e))

local function url_encode(str)
	return (str:gsub("([^A-Za-z0-9%_%.%-%~])", function(v)
		return string.upper(string.format("%%%02x", string.byte(v)))
	end))
end

local esc_sequences = {
	["<"] = "&lt;",
	[">"] = "&gt;",
	['"'] = "&quot;"
}
local function html_encode(x)
	local escaped = tostring(x)
	escaped = escaped:gsub("&", "&amp;")

	for char,esc in pairs(esc_sequences) do
		escaped = string.gsub(escaped, char, esc)
	end
	return escaped
end

local function parse_qs(str,sep)
	sep = sep or "&"
	local function decode(str, path)
		local str = str
		if not path then
			str = str:gsub('+', ' ')
		end
		return (str:gsub("%%(%x%x)", function(c)
				return string.char(tonumber(c, 16))
		end))
	end

	local values = {}
	for key,val in str:gmatch(string.format('([^%q=]+)(=*[^%q=]*)', sep, sep)) do
		local key = decode(key)
		local keys = {}
		key = key:gsub('%[([^%]]*)%]', function(v)
				-- extract keys between balanced brackets
				if string.find(v, "^-?%d+$") then
					v = tonumber(v)
				else
					v = decode(v)
				end
				table.insert(keys, v)
				return "="
		end)
		key = key:gsub('=+.*$', "")
		key = key:gsub('%s', "_") -- remove spaces in parameter name
		val = val:gsub('^=+', "")

		if not values[key] then
			values[key] = {}
		end
		if #keys > 0 and type(values[key]) ~= 'table' then
			values[key] = {}
		elseif #keys == 0 and type(values[key]) == 'table' then
			values[key] = decode(val)
		end

		local t = values[key]
		for i,k in ipairs(keys) do
			if type(t) ~= 'table' then
				t = {}
			end
			if k == "" then
				k = #t+1
			end
			if not t[k] then
				t[k] = {}
			end
			if i == #keys then
				t[k] = decode(val)
			end
			t = t[k]
		end
	end
	return values
end

<<<<<<< HEAD
local cookies = env "HTTP_COOKIE" and parse_qs(env "HTTP_COOKIE","; ") or {}
local flags = {}
for k,v in pairs(cookies) do
	local flag = k:match "flag_(.+)"
	if flag then
		flags[flag] = v
=======
local cookies = parse_qs(env "HTTP_COOKIE", "; ")
local flags = {}
for k, v in pairs(cookies) do
	if k:sub(1,5) == "flag_" then
		flags[k:sub(6)] = v
>>>>>>> master
	end
end

local function redirect(to)
	return "", {
		status = '303 see other',
		headers = { location = to },
	}
end

local function template(str)
	return function (t)
		return (str:gsub("$([A-Za-z][A-Za-z0-9]*)", function(v)
			return t[v] or ""
		end))
	end
end

local base = template [[
<!doctype html>
<html>
	<head>
		<link rel="stylesheet" href="/static/amethyst.css" />
		<meta charset="utf-8"/>
		<title>zzcxz: $title</title>
		<meta name="viewport" content="width=device-width, initial-scale=1">
	</head>
	<body>
		<h1>zzcxz</h1>
		<main>$content</main>
		<footer>
			<div id="about-links">
				<p><a href="/">back to start</a></p>
				<p><a href="/about">help</a></p>
				<p><a href="https://citrons.xyz/git/zzcxz.git/about">
					source code
				</a></p>
				<p><a href="https://citrons.xyz">citrons.xyz</a></p>
			</div>
		</footer>
	</body>
</html>
]]

local not_found = function() 
	return
		base {
			title = "not found",
			content = "the content requested was not found.",
		}, { status = '404 not found' }
end

local function parse_directive(line, directives)
	flags = flags or {}
	local directive, args = line:match "^#([A-Za-z]+)%s*(.-)\n?$"
	directive = directive and directive:lower()
	if not directive then
		return
	elseif directive == "pagetitle" then
		if args:match "^%s*$" then return end
		if utf8.len(args) > 150 then return end
		directives.title = args
	elseif directive == "redirect" then
		local redirect = args:match "^%s*(%w%w%w%w%w)%s*$"
		if not redirect then return end
		directives.redirect = redirect
	elseif directive == "set" then
		if args:match "^%s*$" then return end
		local flagname, text = args:match "^%s*(%w+)%s*(.-)%s*$"
		if not flagname then return end
		text = text or ""
		if utf8.len(flagname) > 150 or utf8.len(text) > 1000 then
			return
		end
		directives.flags_updated[flagname] = text
		flags[flagname] = text
	elseif directive == "unset" then
		local flagname = args:match "^%s*(%w+)%s*$"
		if not flagname then return end
		directives.flags_updated[flagname] = false
		flags[flagname] = nil
	else
		return
	end
	return true
end

local load_page
local function convert_markup(m)
	local result = {}
	local directives = {flags_updated = {}}
	local code_block = false
	for line in (m..'\n'):gmatch "(.-)\n" do
		if not code_block then
			if line:match "^%s*$" then
				goto continue
			end
			if line:sub(1,1) == '#' and
					parse_directive(line, directives, flags) then
				goto continue
			end

			line = html_encode(line)
			if line:sub(1,1) == ' ' then
				table.insert(result, '<pre><code>')
				code_block = true
			else
				line = line:gsub("%[(.-)%]",
					function(s)
						return ('<span class="important">%s</span>'):format(s)
					end
				)
				table.insert(result, ('<p>%s</p>'):format(line))
			end
		end
		if code_block then
			if line:sub(1,1) == ' ' then
				table.insert(result, line .. '\n') 
			else
				table.insert(result, '</code></pre>')
				code_block = false
			end
		end
		::continue::
	end
	if code_block then
		table.insert(result, '</code></pre>')
		code_block = false
	end

	if directives.redirect then
		local r = directives.redirect
		return (
			'<p class="note">this action will link to ' ..
			'<a href="/g/%s" target="_blank">%s</a>.</p>'
		):format(r, r), directives
	end

	return table.concat(result), directives
end

local function parse_page(s)
	local page = {}
	page.title = s:match "^(.-)\n"
	page.actions = {}
	local content = {}
	for line in (s..'\n'):gmatch "(.-\n)" do
		if line:sub(1,1) == '\t' then
			table.insert(content, line:sub(2))
		else
			local target, action = line:match "^(%w%w%w%w%w):(.-)\n$"
			if action then
				table.insert(page.actions, {action = action, target = target})
			end
		end
	end
	page.content = table.concat(content)

	return page
end

function load_page(p, raw)
	if not p:match("^%w%w%w%w%w$") then return nil end
	local f, bee = io.open('content/'..p)
	if not f then return nil end
	local s = f:read "a"
	f:close()
	if not s then return nil end
	if raw then return s end
	return parse_page(s)
end

local function new_action(page, action, result)
	local _, directives = convert_markup(result)
	local old = assert(io.open('content/'..page, 'a'))

	if directives.redirect then
		assert(old:write(('%s:%s\n'):format(directives.redirect, action)))
		old:close()
		return directives.redirect
	end

::generate_name::
	local new_name = {}
	for i=1,5 do
		table.insert(new_name, string.char(
			string.byte 'a' + math.random(0,25)))
	end
	new_name = table.concat(new_name)

	local exists = io.open('content/'..new_name, 'r')
	if exists then
		exists:close()
		goto generate_name
	end

	local new = assert(io.open('content/'..new_name, 'w'))

	action = action:gsub('\n', ' ')
	assert(new:write((directives.title or action)..'\n'))
	for line in (result..'\n'):gmatch "(.-\n)" do
		assert(new:write('\t' .. line))
	end
	assert(old:write(('%s:%s\n'):format(new_name, action)))

	if directives.backlinks then
		for _,d in ipairs(directives.backlinks) do
			assert(new:write(('%s:%s\n'):format(d.page, d.action)))
		end
	end

	new:close()
	old:close()

	return new_name
end

local map = {}

local page_template = template [[
	<h2>$title</h2>
	$content
	<ul class="actions">
	$actions
	</ul>
]]
map["^/g/(%w%w%w%w%w)$"] = function(p)
	local page = load_page(p)
	if not page then return not_found() end
	local _, directives = convert_markup(page.content)
	local cookies = {}
	for k,v in pairs(directives.flags) do
		table.insert(cookies,"flag_"..k.."="..url_encode(v).."; Secure")
	end
	if env "REQUEST_METHOD" ~= "POST" then
		local actions = {}
		for _,a in ipairs(page.actions) do
			table.insert(actions,
				('<li><a href="%s">%s</a></li>'):format(
					html_encode(a.target), html_encode(a.action)))
		end
		if not directives.deadend then
			table.insert(actions,
				([[
					<li><a class="important" href="%s/act#what">%s</a></li>
				]]):format(p, #page.actions == 0 and
					"do something..." or "do something else...")
			)
		end

		local cookies = {}
		for flagname, text in pairs(directives.flags_updated) do
			if text then
				table.insert(cookies,
					('flag_%s=%s; secure; max-age=999999999999')
						:format(flagname, url_encode(text)))
			else
				-- clear the cookie by expiring it in the past
				table.insert(cookies,
					('flag_%s=; expires=Thu, 01 Jan 1970 00:00:00 GMT;')
						:format(flagname))
			end
		end

		return base {
			title = html_encode(page.title),
			content = page_template {
				title = html_encode(page.title),
				content = convert_markup(page.content),
				actions = table.concat(actions),
			},
		}, {headers = {["set-cookie"] = cookies, bees = "3.14"}}
	else
		if directives.deadend then
			return base {
				title = "error",
				content = "forbidden",
			}, { status = '403 forbidden' }
		end

		local form = parse_qs(io.read "a")

		form.wyd = form.wyd or "something"
		form.happens = form.happens or "something"
		if utf8.len(form.wyd) > 150 then form.wyd = "something" end
		if utf8.len(form.happens) > 10000 then form.wyd = "something" end

		local new = new_action(p, form.wyd, form.happens)
		return redirect("/g/"..new)
	end
end

map["^/g/(%w%w%w%w%w)/$"] = function(p)
	return redirect('/g/'..p)
end

local edit_template = template [[
	$content
	<hr id="what"/>
	$preview
	<form method="POST">
		<p>
			<a href="/about#rules">READ THIS</a> before touching anything.
		</p>
		<h2>what do you do?</h2>
		<input
			type="text"
			id="wyd" name="wyd"
			value="$title"
			maxlength="150" required
		/>
		<h2>what happens next?</h2>
		<textarea
			id="happens" name="happens"
			maxlength="10000" required
		>$editing</textarea>
		<div class="buttons">
			<a href="../$page">cancel</a>
			<input type="submit" formaction="act#what" value="preview" />
			$submit
		</div>
	</form>
]]
local preview_template = template [[
	<h2>$title</h2>
	$content
	<hr />
]]
local submit_template = template [[
	<input type="submit" formaction="/g/$page" value="submit" />
]]
map["^/g/(%w%w%w%w%w)/act$"] = function(p)
	local page = load_page(p)
	if not page then return not_found() end

	local _, directives = convert_markup(page.content)
	if directives.deadend then return not_found() end

	if env "REQUEST_METHOD" ~= "POST" then
		return base {
			title = "do something new",
			content = edit_template {
				page = p,
				content = convert_markup(page.content),
			},
		}
	else
		local form = parse_qs(io.read "a")
		form.wyd = form.wyd or "something"
		form.happens = form.happens or "something"

		local prev, prev_direct = convert_markup(form.happens)
		
		return base {
			title = "do something new",
			content = edit_template {
				page = p,
				content = convert_markup(page.content),
				preview = preview_template {
					title =
						prev_direct.title and html_encode(prev_direct.title)
						or html_encode(form.wyd),
					content = prev,
				},
				title = html_encode(form.wyd),
				editing = html_encode(form.happens),
				submit = submit_template { page = p },
			},
		}
	end
end

map["^/g/(%w%w%w%w%w)/raw$"] = function(p)
	local page = load_page(p, true)
	if not page then return not_found() end

	return page, { content_type = 'text/plain' }
end

map["^/about/?$"] = function()
	local f = assert(io.open("about.html", 'r'))
	local h = assert(f:read 'a')
	f:close()

	return h
end

local function main()
	if env "PATH_INFO" == "/" then
		return redirect "/g/zzcxz"
	end

	for k,v in pairs(map) do
		local m = {(env "PATH_INFO"):match(k)}
		if m[1] then
			return v(table.unpack(m))
		end
	end
	return not_found()
end

local ok, content, resp = pcall(main)
if not ok or type(content) ~= 'string' then
	io.stderr:write(content..'\n')

	content = base {
		title = "internal error",
		content = "an internal error occurred."
	}
	resp = { status = '500 internal server error' }
end

resp = resp or {}
resp.content_type = resp.content_type or 'text/html'
resp.status = resp.status or '200 OK'
resp.headers = resp.headers or {}
resp.headers['content-type'] = resp.content_type
resp.headers['apioforms'] = math.random(0,104942)/2

print("status: "..resp.status)
for k,v in pairs(resp.headers) do
	if type(v) == "table" then
		for _, v2 in ipairs(v) do
			print(("%s: %s"):format(k, v2))
		end
	else
		print(("%s: %s"):format(k, v))
	end
end

print ""
io.write(content)