fs = require 'fs'
http = require 'http'
crypto = require 'crypto'
xml = require 'node-xml'

# return the current time in miliseconds (since the epoch)
now_ms = ->
	return new Date().getTime()

# soooo annoying that setTimeout takes the ms arg last
timeout = (ms, func) -> setTimeout func, ms

auth = {}

md5 = (str) ->
	sum = crypto.createHash 'md5'
	sum.update str
	return sum.digest 'hex'

new_auth_token = (user, pass) ->
	token = md5(user + md5(pass))
	auth.user = user
	auth.token = token
	return token

auth_file = "#{process.env.HOME}/.libre.fm-cmus.auth"
save_auth = (user, pass, callback) ->
	token = new_auth_token(user, pass)
	text = JSON.stringify user: user, token: new_auth_token(user, pass)
	fs.writeFile auth_file, text, 'utf8', callback
	return token

# load login credentials from settings file
load_auth = (callback) ->
	if auth.user and auth.token
		callback auth
		return

	fs.readFile auth_file, 'utf8', (err, data) ->
		if err
			callback err
		else
			auth = JSON.parse data
			callback null, auth

# elements look like: ['name', {attr: value, attr2: value2,...}, [contents]]
# text nodes look like elements with blank names: ['', {}, 'foo']
# so <foo bar="baz">qux<quux></quux>corge</foo> -> ['foo', {bar:'baz'}, [['',{},'qux'], ['cuux', {}, []], ['',{},'corge']]]
# callback(err, array)
parse_xml = (str, callback) ->
	done = false
	nests = [[]]
	huh = ->
		# FIXME switch to an xml parser that will tell me when it's done
		unless done
			done = true
			callback "xml parser failed to do anything with login server response"
			console.log "xml parser didn't exit: #{str}"
	parser = new xml.SaxParser (cb) ->
		cb.onStartElementNS (name, attr_tuples, prefix, uri, namespaces) ->
			attrs = {}
			for tuple in attr_tuples
				attrs[tuple[0]] = tuple[1]
			element = [name, attrs, []]
			nests[0].push element
			nests.unshift element[2]
		cb.onCharacters (str) ->
			if nests[0][nests[0].length - 1]?[0] is ''
				nests[0][nests[0].length - 1][2] += str
			else
				nests[0].push ['', {}, str]
		cb.onEndElementNS (name, attrs, prefix, uri, namespaces) ->
			nests.shift()
			if nests.length is 1
				done = true
				callback null, nests[0]
		cb.onEndDocument huh
	parser.parseString str
	timeout 1, huh

exports.parse_xml = parse_xml

# pass the js representation (nested arrays, etc)
# returns the lfm object or null
find_lfm_element = (parsed, callback) ->
	for element in parsed
		if element[0] is 'lfm'
			return element
	return null

# returns just the "lfm" element of xml (as described in parse_xml) or fires an error
# callback(err, array)
parse_lfm_xml = (text, callback) ->
	parse_xml text, (err, parsed) ->
		if err?
			# report this parse error
			callback err
			return
		lfm = find_lfm_element parsed
		if lfm?
			callback null, lfm
		else
			callback "Couldn't find lfm element in server response"
	return

# login and get a session key
# callback(err, sk)
login = (callback) ->
	load_auth (err, auth) ->
		return callback(err) if err?

		http.get { host: 'alpha.libre.fm', port: 80, path: "/2.0/?method=auth.getmobilesession&username=#{auth.user}&authToken=#{auth.token}"}, (res) ->
			if res.statusCode != 200
				console.log "login response code: #{res.statusCode}"
				callback "login response code: #{res.statusCode}"
				return

			res.setEncoding 'utf8'
			body = ''
			res.on 'data', (chunk) ->
				body += chunk
			res.on 'end', ->
				element = ''
				content = ''
				done = false
				huh = ->
					# FIXME switch to an xml parser that will tell me when it's done
					unless done
						done = true
						callback "xml parser failed to do anything with login server response"
						console.log "xml parser didn't exit: #{body}"
				parser = new xml.SaxParser (cb) ->
					cb.onStartElementNS (name, attrs, prefix, uri, namespaces) ->
						element = name
						content = ''
					cb.onCharacters (str) ->
						content += str
					cb.onEndElementNS (name, attrs, prefix, uri, namespaces) ->
						if element is 'key'
							done = true
							auth.sk = content
							auth.sk_date = now_ms
							console.log("got key \"#{content}\"")
							callback null, content
						else if element is 'error'
							done = true
							callback "login failed: \"#{content}\""
						# ignore other tags stuff in there
					cb.onEndDocument huh
				parser.parseString body
				timeout 1, huh

# callback(err, sk)
login_cached = (callback) ->
	if auth.sk
		callback null, auth.sk
	login callback


# callback(err)
tune = (tag, callback) ->
	login_cached (err, sk) ->
		return callback(err) if err?

		args = "method=radio.tune&station=librefm://#{tag}&sk=#{sk}"
		headers = { 'Content-Type': 'application/x-www-form-urlencoded', 'Content-Length': args.length }
		req = http.request { host: 'alpha.libre.fm', port: 80, method: 'POST', path: "/2.0/", headers: headers }, (res) ->
			if res.statusCode != 200
				# libre.fm always returns 200, even for authentication failures
				console.log "radio.tune response code: #{res.statusCode}"
				callback "radio.tune response code: #{res.statusCode}"
				return
			else
				res.setEncoding 'utf8'
				response_text = ''
				res.on 'data', (chunk) ->
					response_text += chunk
				res.on 'end', ->
					parse_lfm_xml response_text, (err, lfm) ->
						if err
							# parse error
							callback "Error while parsing server reply while tuning into \"#{tag}\" station: #{err}"
							return
						if lfm[1].status is 'ok'
							console.log "Tuned to #{tag}"
							callback()
							return
						for element in lfm[2]
							if element[0] is 'error'
								code = element[1].code
								if code is 4 # invalid authentication token
									delay = 0
									sk_age = now_ms() - auth.sk_date
									if sk_age < 30000
										console.log "Server said our auth token was invalid only #{sk_age}ms after we got it."
										delay = 30000 - sk_age
										console.log "Waiting another #{delay}ms before requesting another one."
									# get new auth token
									timeout delay, ->
										login (err, sk) ->
											if err
												callback err
												return
											tune tag, callback
											return
								else
									if typeof element[2][0]?[2] is 'string'
										message = JSON.stringify element[2][0][2]
									console.log "server response from tune: code #{code} message: #{message}"
									callback "Error during tune: code #{code} message: #{message}"
								return
						# looked through all elements, and didn't find one with name "error"
						callback "Error during tune: server responded without success or error message"

		req.on 'error', (err) ->
			console.log "tune post http error: #{err}"
			callback "tune post http error: #{err}"

		req.write args
		req.end()

# FIXME call tune automatically or remove "tag" argument
get_playlist = (tag, callback) ->
	login_cached (err, sk) ->
		return callback(err) if err?

		tune tag, (err)->
			return callback(err) if err?

			console.log "getting playlist with sk=#{sk}"
			http.get { host: 'alpha.libre.fm', port: 80, path: "/2.0/?method=radio.getPlaylist&sk=#{sk}"}, (res) ->
				if res.statusCode != 200
					callback "getPlaylist http response code: #{res.statusCode}"
					return

				res.setEncoding 'utf8'
				response_text = ''
				res.on 'data', (chunk) ->
					response_text += chunk
				res.on 'end', ->
					# while testing, got response_text === "BADSESSION"
					console.log "server responded"
					# console.log "server said: #{response_text}"
					parse_xml response_text, (err, response) ->
						if err?
							return callback "Error while parsing server reply while requesting playlist: #{err}"
						for element in response
							if element[0] is 'playlist'
								# FIXME write this bit
								console.log 'Yay we got a playlist!'
								console.log JSON.stringify element[0]
							else if element[0] is 'lfm'
								if element[1].status isnt 'failed'
									callback "Server responded to our playlist request with #{JSON.stringify response}"
									return

								# FIXME search for "error" element instead of assuming it's first
								code = element[2][0]?.code
								if code is 4 # invalid authentication token
									delay = 0
									sk_age = now_ms() - auth.sk_date
									if sk_age < 30000
										console.log "Server said our auth token was invalid only #{sk_age}ms after we got it."
										delay = 30000 - sk_age
										console.log "Waiting another #{delay}ms before requesting another one."
									# get new auth token
									timeout delay, ->
										login (err, sk) ->
											if err
												callback err
												return
											get_playlist tag, callback
											return
								else
									if typeof element[2][0]?[2] is 'string'
										message = JSON.stringify element[2][0][2]
									console.log "server response from tune: code #{code} message: #{message}"
									callback "Error during tune: code #{code} message: #{message}"
								return
						# looked through all elements, and didn't find one with name "error"
						callback "Error during tune: server responded without success or error message"

test = (tag, callback) ->
	get_playlist tag, ->
		if err?
			console.log err
			callback err
			return
		console.log 'yay'
		callback()

exports.test = test
exports.get_playlist = get_playlist
exports.tune = tune
exports.login = login # fixme remove this from the API and call it automatically
exports.new_auth_token = new_auth_token
exports.save_auth = save_auth