From ce4aac238338dab4f774dea2815e28eb50a8e56e Mon Sep 17 00:00:00 2001
From: Jason Woofenden <jason@jasonwoof.com>
Date: Sun, 16 Oct 2011 00:21:27 -0400
Subject: [PATCH] tuned station

---
 api.coffee |  128 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 128 insertions(+)

diff --git a/api.coffee b/api.coffee
index 2ac50c5..52e6933 100644
--- a/api.coffee
+++ b/api.coffee
@@ -3,6 +3,10 @@ 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
 
@@ -38,7 +42,61 @@ load_auth = (callback) ->
 		else
 			callback null, JSON.parse data
 
+# 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
+
+# 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
+			# parse error
+			callback err
+			return
+		for element in parsed
+			if element[0] is 'lfm'
+				callback null, element
+				return
+		callback "Couldn't find lfm element in server response"
+		return
+	return
+
 # login and get a session key
+# callback(err, sk)
 login = (callback) ->
 	load_auth (err, auth) ->
 		return callback(err) if err?
@@ -73,6 +131,7 @@ login = (callback) ->
 						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'
@@ -83,7 +142,76 @@ login = (callback) ->
 				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()
 
+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
-- 
1.7.10.4