dailyprogrammer.lua

#!/usr/bin/env lua

local FILE_NAME = '.dailyprogrammer.txt'
local T_MODES = {'easy','intermediate','difficult','hard'}
local t_links = {}

local function download()
	io.write('download ... ')
	io.flush()
	local http  = require('socket.http')

	local pat_entry = '<a class="title " href="([^"]+)"'
	local pat_next = '<a href="([^"]+)"[^>]+>next'

	local next_link = 'http://www.reddit.com/r/dailyprogrammer'
	repeat
		local html, code, header, status = http.request(next_link)
		assert(code==200)

		for x in html:gmatch(pat_entry) do
			table.insert(t_links, x)
		end

		next_link = html:match(pat_next)
	until not next_link

	-- write to file
	local file = assert(io.open(FILE_NAME, 'w'))
	for _,x in pairs(t_links) do
		file:write(x..'\n')
	end
	file:close()
	print('done.')
end

-------
-- main
-------
local update = (arg[1] == 'update')

local file = io.open(FILE_NAME,'r')
if not file or update then download() 
else 
	for link in file:lines() do
		table.insert(t_links, link)
	end
	file:close()
end

local t_mode = {}
for _,x in pairs(t_links) do
	local mode = x:match('(difficult)') or x:match('(intermediate)') or x:match('(easy)') or x:match('(hard)')

	if mode then
		if not t_mode[mode] then t_mode[mode] = {} end
		table.insert(t_mode[mode], x)
	end
end

for _,mode in pairs(T_MODES) do
	for _,link in pairs(t_mode[mode]) do
		print(mode..string.rep(' ',12-#mode),'http://reddit.com'..link)
	end
end